2004 Vol.17(2)
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2004, 18(2).
Abstract:
The dynamic response involved in car-roadside barrier impacts is studied. The risk of occupant injures in such accidents is investigated. An approach based on accident analysis and mathematical modeling is developed and described in three steps. Firstly a study of car-roadside barrier impact accidents is carried out with available data to define a system including car, road, roadside barrier, and occupant. Secondly a mathematical model to simulate car-to-barrier impact is developed by using multi-body program MADYMO. Finally, dynamic responses of the occupant during impact are simulated using a car compartment model with a HYBRID III occupant model and an input load pulse calculated in the second step. The dynamic responses of the car are analyzed by changing impact conditions such as impact angle and impact velocity. The injury risks of the occupants are discussed in terms of the occupant kinematics and calculated parameters: accelerations of the head, chest, and pelvis, as well as HIC value. Verification of model with experimental data is performed. Possible countermeasures for highway vehicle traffic safety and improvement of roadside barrier design are presented. Research prospects in this field are also proposed.
The dynamic response involved in car-roadside barrier impacts is studied. The risk of occupant injures in such accidents is investigated. An approach based on accident analysis and mathematical modeling is developed and described in three steps. Firstly a study of car-roadside barrier impact accidents is carried out with available data to define a system including car, road, roadside barrier, and occupant. Secondly a mathematical model to simulate car-to-barrier impact is developed by using multi-body program MADYMO. Finally, dynamic responses of the occupant during impact are simulated using a car compartment model with a HYBRID III occupant model and an input load pulse calculated in the second step. The dynamic responses of the car are analyzed by changing impact conditions such as impact angle and impact velocity. The injury risks of the occupants are discussed in terms of the occupant kinematics and calculated parameters: accelerations of the head, chest, and pelvis, as well as HIC value. Verification of model with experimental data is performed. Possible countermeasures for highway vehicle traffic safety and improvement of roadside barrier design are presented. Research prospects in this field are also proposed.
2004, 18(2).
Abstract:
Start-up working condition is the key to the research of optimal engagement of automatic clutch for AMT. In order to guarantee an ideal dynamic performance of the clutch engagement, an optimal controller is designed by considering throttle angle, engine speed, gear ratio, vehicle acceleration and road condition. The minimum value principle is also introduced to achieve an optimal dynamic performance of the nonlinear system compromised in friction plate wear and vehicle drive quality. The optimal trajectory of the clutch engagement can be described in the form of explicit and analytical expressions and characterized by the deterministic and accurate control strategy in stead of indeterministic and soft control techniques which need thousands of experiments. For validation of the controller, test work is carried out for the automated clutch engagements in a commercial car with an traditional mechanical transmission, a hydraulic actuator, a group of sensors and a portable computer system. It is shown through experiments that dynamic behaviors of the clutch engagement operated by the optimal control are more effective and efficient than those by fuzzy control.
Start-up working condition is the key to the research of optimal engagement of automatic clutch for AMT. In order to guarantee an ideal dynamic performance of the clutch engagement, an optimal controller is designed by considering throttle angle, engine speed, gear ratio, vehicle acceleration and road condition. The minimum value principle is also introduced to achieve an optimal dynamic performance of the nonlinear system compromised in friction plate wear and vehicle drive quality. The optimal trajectory of the clutch engagement can be described in the form of explicit and analytical expressions and characterized by the deterministic and accurate control strategy in stead of indeterministic and soft control techniques which need thousands of experiments. For validation of the controller, test work is carried out for the automated clutch engagements in a commercial car with an traditional mechanical transmission, a hydraulic actuator, a group of sensors and a portable computer system. It is shown through experiments that dynamic behaviors of the clutch engagement operated by the optimal control are more effective and efficient than those by fuzzy control.
2004, 18(2).
Abstract:
In shipping and aircraft engineering, the vibrating motor or instrumentation is usually mounted on a non-rigid base. To apply isolation design effectively, it is necessary to investigate the nature vibration characteristics of the rigid motor, flexible base coupled system. A universal dynamic express for the coupled system is derived. A PC-based measurement solution is presented. And the system's dynamic behavior is then investigated numerically and experimentally. The results show that a strong interaction will exist between the motor's rigid mode and the flexible base's mode when the motor's mounting frequency is close to the flexible base's first natural frequency. The first natural frequency of the coupled system is generally lower than the motor's rigid mode frequency. At high frequency, the flexible base's modes are the dominant modes of the coupled system.
In shipping and aircraft engineering, the vibrating motor or instrumentation is usually mounted on a non-rigid base. To apply isolation design effectively, it is necessary to investigate the nature vibration characteristics of the rigid motor, flexible base coupled system. A universal dynamic express for the coupled system is derived. A PC-based measurement solution is presented. And the system's dynamic behavior is then investigated numerically and experimentally. The results show that a strong interaction will exist between the motor's rigid mode and the flexible base's mode when the motor's mounting frequency is close to the flexible base's first natural frequency. The first natural frequency of the coupled system is generally lower than the motor's rigid mode frequency. At high frequency, the flexible base's modes are the dominant modes of the coupled system.
2004, 18(2).
Abstract:
A generalized model is synthesized to characterize the asymmetric hysteresis force-velocity (F-v) properties of the magneto-rheological (MR) fluids damper. The model is represented as a function of the command current, excitation frequency, and displacement amplitude, based on the symmetric and asymmetric sigmoid functions. The symmetric hysteresis damping properties of the controllable MR-damper and properties of the conventional passive hydraulic damper can also be described by the proposed model. The validity of the model is verified by experiments, which show that the results calculated from the model are consistent with the measured data. In addition, it is shown that the model applies to a wide vibration frequency range. The proposed model has potential application in vehicle suspension design employing the symmetry MR-damper, and also in developing the asymmetry MR-damper especially for the vehicle suspension attenuation.
A generalized model is synthesized to characterize the asymmetric hysteresis force-velocity (F-v) properties of the magneto-rheological (MR) fluids damper. The model is represented as a function of the command current, excitation frequency, and displacement amplitude, based on the symmetric and asymmetric sigmoid functions. The symmetric hysteresis damping properties of the controllable MR-damper and properties of the conventional passive hydraulic damper can also be described by the proposed model. The validity of the model is verified by experiments, which show that the results calculated from the model are consistent with the measured data. In addition, it is shown that the model applies to a wide vibration frequency range. The proposed model has potential application in vehicle suspension design employing the symmetry MR-damper, and also in developing the asymmetry MR-damper especially for the vehicle suspension attenuation.
2004, 18(2).
Abstract:
It is shown that the basis of the ellipsoidal acoustic infinite element Burnett method, the multipole expansion, cannot represent real ellipsoidal acoustic field exactly. To solve the problem, a weight of angular direction is added to the multipole expansion. The comparison of the modified method and the prime method shows that the modified method can describe and solve the ellipsoidal acoustic field more accurately than ever. A dilating sphere is used to test the new method further. Unlike other infinite element methods, varied ratio of the ellipsoidal artificial boundary instead of sphere is used. The pressure value of the artificial boundary is utilized as the initial value of the new method. Then the radiating phenomena of the ellipsoidal acoustic field can be researched using the new method. These examples show the feasibility of the adaptive method.
It is shown that the basis of the ellipsoidal acoustic infinite element Burnett method, the multipole expansion, cannot represent real ellipsoidal acoustic field exactly. To solve the problem, a weight of angular direction is added to the multipole expansion. The comparison of the modified method and the prime method shows that the modified method can describe and solve the ellipsoidal acoustic field more accurately than ever. A dilating sphere is used to test the new method further. Unlike other infinite element methods, varied ratio of the ellipsoidal artificial boundary instead of sphere is used. The pressure value of the artificial boundary is utilized as the initial value of the new method. Then the radiating phenomena of the ellipsoidal acoustic field can be researched using the new method. These examples show the feasibility of the adaptive method.
2004, 18(2).
Abstract:
Sheet metal dieless forming is a new metal forming technology. This technol-ogy adopts the principle of rapid prototyping technology, so it can form sheet metal parts without traditional die and moulds. According to the characteristic of sheet metal dieless forming technology a new way of tool path generation based on the STL file for sheet metal dieless forming is proposed.
Sheet metal dieless forming is a new metal forming technology. This technol-ogy adopts the principle of rapid prototyping technology, so it can form sheet metal parts without traditional die and moulds. According to the characteristic of sheet metal dieless forming technology a new way of tool path generation based on the STL file for sheet metal dieless forming is proposed.
2004, 18(2).
Abstract:
Lead zirconate titanium solid-solution (PZT) thin films with various thickness are synthesized on titanium substrates by repeated hydrothermal treatments. Young modulus, electric-field- induced displacement and the density of the PZT film are measured respectively. Bimorph- type bending actuators are fabricated using these films. The model, which is used to analyze the driving ability of bimorph-type bending actuators by hydrothermal method, is set up. It can be seen that the driving ability of bimorph-type bending actuators can be greatly improved by optimizing the thickness of PZT thin film and substrate from the theoretical analysis results. The measured values are expected to agree with the theoretical values calculated by the above model.
Lead zirconate titanium solid-solution (PZT) thin films with various thickness are synthesized on titanium substrates by repeated hydrothermal treatments. Young modulus, electric-field- induced displacement and the density of the PZT film are measured respectively. Bimorph- type bending actuators are fabricated using these films. The model, which is used to analyze the driving ability of bimorph-type bending actuators by hydrothermal method, is set up. It can be seen that the driving ability of bimorph-type bending actuators can be greatly improved by optimizing the thickness of PZT thin film and substrate from the theoretical analysis results. The measured values are expected to agree with the theoretical values calculated by the above model.
2004, 18(2).
Abstract:
Based on the motion equations of an unbalanced spherical rotor with contactless suspension, three methods of MUM (mass unbalance measurement) are put forward to measure the total mass unbalance, radical mass unbalance and radical mass unbalance of the rotor. Total mass unbalance is obtained when the unbalanced rotor plays as a simple pendulum in static situation. The pendulant period and pendulant midpoint indicate magnitude and direction of total mass unbalance of the rotor respectively. Analysis of the motion equations by using the averaging method yields that the rotor will do a special side oscillation when an auxiliary system makes the rotor spin about its pole axis which is orientating toward the local vertical. The radical mass unbalance can be obtained by building a proper displacement sensor to sense the amplitude of the side oscillation. Necessary analysis of the motion equations also shows that when the rotor spins at a small angular velocity and the rotary axis is perpendicular to the vertical, the pole axis of the rotor will process slowly about the vertical by virtue of the axial mass unbalance. The axial mass unbalance can be estimated from the time history of the spin vector of the rotor. Finally, measurement precision of the three methods is compared and how the external torque affects the measurement precision for the three methods are examined.
Based on the motion equations of an unbalanced spherical rotor with contactless suspension, three methods of MUM (mass unbalance measurement) are put forward to measure the total mass unbalance, radical mass unbalance and radical mass unbalance of the rotor. Total mass unbalance is obtained when the unbalanced rotor plays as a simple pendulum in static situation. The pendulant period and pendulant midpoint indicate magnitude and direction of total mass unbalance of the rotor respectively. Analysis of the motion equations by using the averaging method yields that the rotor will do a special side oscillation when an auxiliary system makes the rotor spin about its pole axis which is orientating toward the local vertical. The radical mass unbalance can be obtained by building a proper displacement sensor to sense the amplitude of the side oscillation. Necessary analysis of the motion equations also shows that when the rotor spins at a small angular velocity and the rotary axis is perpendicular to the vertical, the pole axis of the rotor will process slowly about the vertical by virtue of the axial mass unbalance. The axial mass unbalance can be estimated from the time history of the spin vector of the rotor. Finally, measurement precision of the three methods is compared and how the external torque affects the measurement precision for the three methods are examined.
2004, 18(2).
Abstract:
Most used products must be maintained before they are reused. The modeling method for maintenance design of product level reuse based on quality function deployment is presented. A fuzzy linear optimization model is developed under financial uncertainty. Objective of the model is to maximize improvement rate of customer satisfaction level. Maintenance cost constrain is fuzzy. The algorithm for solution to the model is given. Its optimized results not only give attention to satisfaction degree of cost constraint, but also maximize objective value. An illustrative example involved water bump reuse is studied and the results show that the proposed model can effectively help maintenance planner determine the better design scheme.
Most used products must be maintained before they are reused. The modeling method for maintenance design of product level reuse based on quality function deployment is presented. A fuzzy linear optimization model is developed under financial uncertainty. Objective of the model is to maximize improvement rate of customer satisfaction level. Maintenance cost constrain is fuzzy. The algorithm for solution to the model is given. Its optimized results not only give attention to satisfaction degree of cost constraint, but also maximize objective value. An illustrative example involved water bump reuse is studied and the results show that the proposed model can effectively help maintenance planner determine the better design scheme.
2004, 18(2).
Abstract:
In electronics packaging the time-pressure dispensing system is widely used to squeeze the adhesive fluid in a syringe onto boards or substrates with the pressurized air. However, complexity of the process, which includes the air-fluid coupling and the nonlinear uncertainties, makes it difficult to have a consistent process performance. An integrated dispensing process model is first introduced and then its input-output regression relationship is used to design a run to run control methodology for this process. The controller takes EWMA scheme and its stability region is given. Experimental results verify the effectiveness of the proposed run to run control method for dispensing process.
In electronics packaging the time-pressure dispensing system is widely used to squeeze the adhesive fluid in a syringe onto boards or substrates with the pressurized air. However, complexity of the process, which includes the air-fluid coupling and the nonlinear uncertainties, makes it difficult to have a consistent process performance. An integrated dispensing process model is first introduced and then its input-output regression relationship is used to design a run to run control methodology for this process. The controller takes EWMA scheme and its stability region is given. Experimental results verify the effectiveness of the proposed run to run control method for dispensing process.
2004, 18(2).
Abstract:
A novel methodology for a walk-assisting balance system of the exoskeleton robot for disabled people is presented. The experiment on the walk-assisting balance system is implemented using a mini-type ropewalker robot. The mechanism of the ropewalker robot is designed, its dynamic model is built, and its control system based on PWM is developed. The emulations in Matlab and the results of experiments prove that this methodology is effective.
A novel methodology for a walk-assisting balance system of the exoskeleton robot for disabled people is presented. The experiment on the walk-assisting balance system is implemented using a mini-type ropewalker robot. The mechanism of the ropewalker robot is designed, its dynamic model is built, and its control system based on PWM is developed. The emulations in Matlab and the results of experiments prove that this methodology is effective.
2004, 18(2).
Abstract:
A new nonholonomic transmission mechanism is proposed based on the nonholonomic theory and nonlinear control principle, and combined with conditions of the nonholonomic motion planning and control, that is researched to compose method of the motion transfer chain from this transmission mechanism, on which a new nonholonomic manipulator is designed. This nonholonomic manipulator is a controllable multi-joint manipulator that actuated only by two-servo electromotor. Its motion expresses the characteristic of nonholonomy constraint and nonlin-ear, and that also satisfies the chained form convertibility. And then, using the nonlinear control principle of chained system, motion characteristic of the nonholonomic manipulator is applied. From simulation verification and analysis, the usefulness of the theoretical design and control strategies is shown, and that is important in design and research of handiness robot and multi-finger robot hand.
A new nonholonomic transmission mechanism is proposed based on the nonholonomic theory and nonlinear control principle, and combined with conditions of the nonholonomic motion planning and control, that is researched to compose method of the motion transfer chain from this transmission mechanism, on which a new nonholonomic manipulator is designed. This nonholonomic manipulator is a controllable multi-joint manipulator that actuated only by two-servo electromotor. Its motion expresses the characteristic of nonholonomy constraint and nonlin-ear, and that also satisfies the chained form convertibility. And then, using the nonlinear control principle of chained system, motion characteristic of the nonholonomic manipulator is applied. From simulation verification and analysis, the usefulness of the theoretical design and control strategies is shown, and that is important in design and research of handiness robot and multi-finger robot hand.
2004, 18(2).
Abstract:
Assembly sequence planning will be more difficult due to the increasing complexity of products. An integrated approach to assembly sequence planning of complex products applying decomposition-planning-combination strategy is presented. First, an assembly is decomposed into a hierarchical structure using an assembly structure representation based on connectors. Then, an assembly planning system is used to generate the sequences that are locally optimal for each leaf partition in the structure hierarchy. By combining the local sequences systematically in a bottom-up manner and choosing suitable ones from the merged sequences, the assembly sequence of each parent structure including the whole assembly is generated. An integrated system has been completed. A complex product is given to illustrate the feasibility and the practicality of the approach.
Assembly sequence planning will be more difficult due to the increasing complexity of products. An integrated approach to assembly sequence planning of complex products applying decomposition-planning-combination strategy is presented. First, an assembly is decomposed into a hierarchical structure using an assembly structure representation based on connectors. Then, an assembly planning system is used to generate the sequences that are locally optimal for each leaf partition in the structure hierarchy. By combining the local sequences systematically in a bottom-up manner and choosing suitable ones from the merged sequences, the assembly sequence of each parent structure including the whole assembly is generated. An integrated system has been completed. A complex product is given to illustrate the feasibility and the practicality of the approach.
2004, 18(2).
Abstract:
The mechanical characteristics of the electro-hydraulic servo system in the centrifuge field are analyzed. The hydraulic pressure law in the centrifuge field indicates the existence of the centrifuge hydraulic pressure. The me-chanical characteristics of the slide-valve and the dual nozzle flapper valve are studied, and it is found that the centrifuge field can not only increase the driving force or moment of the function units, but also decrease the stability of the components. Finally by applying Gauss minimum constraint principle, the dynamic model of the electro-hydraulic vibrator in the centrifuge field is established, and the mechanical restriction of the system is also presented. The study will be helpful for the realization of the combined vibration and centrifuge test system.
The mechanical characteristics of the electro-hydraulic servo system in the centrifuge field are analyzed. The hydraulic pressure law in the centrifuge field indicates the existence of the centrifuge hydraulic pressure. The me-chanical characteristics of the slide-valve and the dual nozzle flapper valve are studied, and it is found that the centrifuge field can not only increase the driving force or moment of the function units, but also decrease the stability of the components. Finally by applying Gauss minimum constraint principle, the dynamic model of the electro-hydraulic vibrator in the centrifuge field is established, and the mechanical restriction of the system is also presented. The study will be helpful for the realization of the combined vibration and centrifuge test system.
2004, 18(2).
Abstract:
The 2D digital simplified flow valve is composed of a pilot-operated valve designed with both rotary and linear motions of a single spool, and a stepper motor under continual control. How the structural parameters affect the static and dynamic characteristics of the valve is first clarified and a criterion for stability is presented. Experiments are designed to test the performance of the valve. It is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters. Nevertheless, it is possible to maintain the dynamic response at a fairly high level, while keeping the leakage of the pilot stage at an acceptable level. One of the features of the digital valve is stage control. In stage control the nonlinearities, such as electromagnetic saturation and hysteresis, are greatly reduced. To a large extent the dynamic response of the valve is decided by the executing cycle of the control algorithm.
The 2D digital simplified flow valve is composed of a pilot-operated valve designed with both rotary and linear motions of a single spool, and a stepper motor under continual control. How the structural parameters affect the static and dynamic characteristics of the valve is first clarified and a criterion for stability is presented. Experiments are designed to test the performance of the valve. It is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters. Nevertheless, it is possible to maintain the dynamic response at a fairly high level, while keeping the leakage of the pilot stage at an acceptable level. One of the features of the digital valve is stage control. In stage control the nonlinearities, such as electromagnetic saturation and hysteresis, are greatly reduced. To a large extent the dynamic response of the valve is decided by the executing cycle of the control algorithm.
2004, 18(2).
Abstract:
The D'Alembert-Lagrange equation is introduced and used to derive the formulas of momentary efficiency for external gearing of standard involutes spur gears. The gearings with correct and increased center distance are discussed. The momentary efficiency formula is calculated and analyzed using software Matlab. The derived formula of momentary efficiency is also compared with the traditional formula.
The D'Alembert-Lagrange equation is introduced and used to derive the formulas of momentary efficiency for external gearing of standard involutes spur gears. The gearings with correct and increased center distance are discussed. The momentary efficiency formula is calculated and analyzed using software Matlab. The derived formula of momentary efficiency is also compared with the traditional formula.
2004, 18(2).
Abstract:
Arc spectral information is a rising information source which can solve many problems that can not be done with arc electric information and other arc information. It is of important significance to develop automatic control technique of welding process. The basic theory and methods on it play an important role in expounding and applying arc spectral information. Using concerned equation in plasma physics and spectrum theory, a system of equations including 12 equations which serve as basic theory of arc spectral information is set up. Through analyzing of the 12 equations, a basic view that arc spectral information is the reflection of arc state and state variation, and is the most abundant information resource reflecting welding arc process is drawn. Furthermore, based on the basic theory, the basic methods of test and control of arc spectral information and points out some applications of it are discussed.
Arc spectral information is a rising information source which can solve many problems that can not be done with arc electric information and other arc information. It is of important significance to develop automatic control technique of welding process. The basic theory and methods on it play an important role in expounding and applying arc spectral information. Using concerned equation in plasma physics and spectrum theory, a system of equations including 12 equations which serve as basic theory of arc spectral information is set up. Through analyzing of the 12 equations, a basic view that arc spectral information is the reflection of arc state and state variation, and is the most abundant information resource reflecting welding arc process is drawn. Furthermore, based on the basic theory, the basic methods of test and control of arc spectral information and points out some applications of it are discussed.
2004, 18(2).
Abstract:
Based on the analysis of heat radiation intensity from flame, a new mathematical model of the tube-wall temperature of heated tubes is developed by taking down-fired, upright-tube cylindrical furnace for example. The proposed mathematical model can be employed to indicate both the position and size of the hot spot at fire-facing wall of heated tube of combustion chamber, and is characteristic of simplicity and efficiency. If coupled with thermoelectric couple or infrared viewer, the presented location method of combustion hot spot can offer engineers very valuable proposal to keep furnace running more safely. The same is true for any other type of tubular furnaces.
Based on the analysis of heat radiation intensity from flame, a new mathematical model of the tube-wall temperature of heated tubes is developed by taking down-fired, upright-tube cylindrical furnace for example. The proposed mathematical model can be employed to indicate both the position and size of the hot spot at fire-facing wall of heated tube of combustion chamber, and is characteristic of simplicity and efficiency. If coupled with thermoelectric couple or infrared viewer, the presented location method of combustion hot spot can offer engineers very valuable proposal to keep furnace running more safely. The same is true for any other type of tubular furnaces.
2004, 18(2).
Abstract:
The pneumatic artificial muscles are widely used in the fields of medical robots, etc. Neural networks are applied to modeling and controlling of artificial muscle system. A single-joint artificial muscle test system is designed. The recursive prediction error (RPE) algorithm which yields faster convergence than back propagation (BP) algorithm is applied to train the neural networks. The realization of RPE algorithm is given. The difference of modeling of artificial muscles using neural networks with different input nodes and different hidden layer nodes is discussed. On this basis the nonlinear control scheme using neural networks for artificial muscle system has been introduced. The experimental results show that the nonlinear control scheme yields faster response and higher control accuracy than the traditional linear control scheme.
The pneumatic artificial muscles are widely used in the fields of medical robots, etc. Neural networks are applied to modeling and controlling of artificial muscle system. A single-joint artificial muscle test system is designed. The recursive prediction error (RPE) algorithm which yields faster convergence than back propagation (BP) algorithm is applied to train the neural networks. The realization of RPE algorithm is given. The difference of modeling of artificial muscles using neural networks with different input nodes and different hidden layer nodes is discussed. On this basis the nonlinear control scheme using neural networks for artificial muscle system has been introduced. The experimental results show that the nonlinear control scheme yields faster response and higher control accuracy than the traditional linear control scheme.
2004, 18(2).
Abstract:
An extended crowding genetic algorithm (ECGA) is introduced for solving optimal pump configuration problem, which was presented by T. Westerlund in 1994. This problem has been found to be non-convex, and the objective function contained several local optima and global optimality could not be ensured by all the traditional MINLP optimization method. The concepts of species conserving and composite encoding are introduced to crowding genetic algorithm (CGA) for maintain the diversity of population more effectively and coping with the continuous and/or discrete variables in MINLP problem. The solution of three-levels pump configuration got from DICOPT++ software (OA algorithm) is also given. By comparing with the solutions obtained from DICOPT++, ECP method, and MIN-MIN method, the ECGA algorithm proved to be very effective in finding the global optimal solution of multi-levels pump configuration via using the problem-specific information.
An extended crowding genetic algorithm (ECGA) is introduced for solving optimal pump configuration problem, which was presented by T. Westerlund in 1994. This problem has been found to be non-convex, and the objective function contained several local optima and global optimality could not be ensured by all the traditional MINLP optimization method. The concepts of species conserving and composite encoding are introduced to crowding genetic algorithm (CGA) for maintain the diversity of population more effectively and coping with the continuous and/or discrete variables in MINLP problem. The solution of three-levels pump configuration got from DICOPT++ software (OA algorithm) is also given. By comparing with the solutions obtained from DICOPT++, ECP method, and MIN-MIN method, the ECGA algorithm proved to be very effective in finding the global optimal solution of multi-levels pump configuration via using the problem-specific information.
2004, 18(2).
Abstract:
First the kinematic principle of singularity is proved, that is the intersecting point of three normal planes of three velocities at three non-collinear points in a rigid body lying in the plane determined by the three corresponding points. It is a sufficient and necessary condition that the velocities of three non-collinear points in a rigid body can determine a screw motion of the body. Based on this principle, a simple and direct new method to distinguish the singularity of the parallel manipulator is derived. With this new kinematic method, the 3-RPS parallel manipulator is studied. Its singularity loci are obtained for some orientations for the first time and verified with Grassmann line geometry and screw theory and the force Jacobian matrix.
First the kinematic principle of singularity is proved, that is the intersecting point of three normal planes of three velocities at three non-collinear points in a rigid body lying in the plane determined by the three corresponding points. It is a sufficient and necessary condition that the velocities of three non-collinear points in a rigid body can determine a screw motion of the body. Based on this principle, a simple and direct new method to distinguish the singularity of the parallel manipulator is derived. With this new kinematic method, the 3-RPS parallel manipulator is studied. Its singularity loci are obtained for some orientations for the first time and verified with Grassmann line geometry and screw theory and the force Jacobian matrix.
2004, 18(2).
Abstract:
NC code or STL file can be generated directly from measuring data in a fast reverse-engineering mode. Compressing the massive data from laser scanner is the key of the new mode. An adaptive compression method based on triangulated-surfaces model is put forward. Normal-vector angles between triangles are computed to find prime vertices for removal. Ring data structure is adopted to save massive data effectively. It allows the efficient retrieval of all neighboring vertices and triangles of a given vertices. To avoid long and thin triangles, a new re-triangulation approach based on normalized minimum-vertex-distance is proposed, in which the vertex distance and interior angle of triangle are considered. Results indicate that the compression method has high efficiency and can get reliable precision. The method can be applied in fast reverse engineering to acquire an optimal subset of the original massive data.
NC code or STL file can be generated directly from measuring data in a fast reverse-engineering mode. Compressing the massive data from laser scanner is the key of the new mode. An adaptive compression method based on triangulated-surfaces model is put forward. Normal-vector angles between triangles are computed to find prime vertices for removal. Ring data structure is adopted to save massive data effectively. It allows the efficient retrieval of all neighboring vertices and triangles of a given vertices. To avoid long and thin triangles, a new re-triangulation approach based on normalized minimum-vertex-distance is proposed, in which the vertex distance and interior angle of triangle are considered. Results indicate that the compression method has high efficiency and can get reliable precision. The method can be applied in fast reverse engineering to acquire an optimal subset of the original massive data.
2004, 18(2).
Abstract:
Based on a level set model, a topology optimization method has been suggested recently. It uses a level set to express the moving structural boundary, which can flexibly handle complex topological changes. By combining vector level set models with gradient projection technology, the level set method for topological optimization is extended to a topological optimization problem with multi-constraints, multi-materials and multi-load cases. Meanwhile, an appropriate nonlinear speed mapping is established in the tangential space of the active constraints for a fast convergence. Then the method is applied to structure designs, mechanism and material de-signs by a number of benchmark examples. Finally, in order to further improve computational efficiency and overcome the difficulty that the level set method cannot generate new material interfaces during the optimization process, the topological derivative analysis is incorporated into the level set method for topological optimization, and a topological derivative and level set algorithm for topological optimization is proposed.
Based on a level set model, a topology optimization method has been suggested recently. It uses a level set to express the moving structural boundary, which can flexibly handle complex topological changes. By combining vector level set models with gradient projection technology, the level set method for topological optimization is extended to a topological optimization problem with multi-constraints, multi-materials and multi-load cases. Meanwhile, an appropriate nonlinear speed mapping is established in the tangential space of the active constraints for a fast convergence. Then the method is applied to structure designs, mechanism and material de-signs by a number of benchmark examples. Finally, in order to further improve computational efficiency and overcome the difficulty that the level set method cannot generate new material interfaces during the optimization process, the topological derivative analysis is incorporated into the level set method for topological optimization, and a topological derivative and level set algorithm for topological optimization is proposed.
2004, 18(2).
Abstract:
The transformation process of an m-DOF free-floating robot from one static state to a different static state has m degrees of freedom. The proposed approach of these transformations utilizes a series of single-DOF transformation processes as an alternative to the m-DOF transformation process. Two static state transformation processes are studied in detail. First, a single-DOF transformation process is established using a newly defined concept, referred to as transformation planning, and the definite integral of conservation of angular momentum. Second, the governing equation of the single-DOF transformation process is established using the dynamic equations of motion of the robot. This allows the joint torques to be computed to effect the state transformation. Finally, an extension of the single-DOF transformation process is proposed to extend the application of this proposed transformation methodology to create a transformation net which allows the reconfiguration of a robot from one state to many other possible states.
The transformation process of an m-DOF free-floating robot from one static state to a different static state has m degrees of freedom. The proposed approach of these transformations utilizes a series of single-DOF transformation processes as an alternative to the m-DOF transformation process. Two static state transformation processes are studied in detail. First, a single-DOF transformation process is established using a newly defined concept, referred to as transformation planning, and the definite integral of conservation of angular momentum. Second, the governing equation of the single-DOF transformation process is established using the dynamic equations of motion of the robot. This allows the joint torques to be computed to effect the state transformation. Finally, an extension of the single-DOF transformation process is proposed to extend the application of this proposed transformation methodology to create a transformation net which allows the reconfiguration of a robot from one state to many other possible states.
2004, 18(2).
Abstract:
When robot is at singular configuration, the limited hand velocity would require some joints with infeasible speeds so as to lead unsafety of the system. A method of solving the approximate velocity of joint near singular configuration point by adding damped vector is proposed and a modified algorithm is provided. With the analysis of J–1, the singular configurations of 6R robot are divided into structure boundary singularity , boundary singularity , inner singularity and wrist singularity. The conditions of singularities of the robot have been ascertained. The computer simulations of the singularities of the robot are developed, which have many advantages over previous description methods of the singular configurations of robot. With the help of boundary singularity analysis, a application in welding trajectory planning checking of the robot has been carried out and the simulation result proved visualized and useful.
When robot is at singular configuration, the limited hand velocity would require some joints with infeasible speeds so as to lead unsafety of the system. A method of solving the approximate velocity of joint near singular configuration point by adding damped vector is proposed and a modified algorithm is provided. With the analysis of J–1, the singular configurations of 6R robot are divided into structure boundary singularity , boundary singularity , inner singularity and wrist singularity. The conditions of singularities of the robot have been ascertained. The computer simulations of the singularities of the robot are developed, which have many advantages over previous description methods of the singular configurations of robot. With the help of boundary singularity analysis, a application in welding trajectory planning checking of the robot has been carried out and the simulation result proved visualized and useful.
2004, 18(2).
Abstract:
The increasing complexity and size of configuration knowledge bases requires the provision of advanced methods supporting the development of the actual configuration process and design reuse. A new framework to find a feasible and practical product configuration method is presented in mass customization. The basic idea of the approach is to integrate case-based reasoning (CBR) with a constraint satisfaction problem(CSP). The similarity measure between a crisp and range is also given, which is common in case retrieves. Based on the configuration model, a product platform and customer needs, case adaptation is carried out with the repair-based algorithm. Lastly, the methodology in the elevator configuration design domain is tested.
The increasing complexity and size of configuration knowledge bases requires the provision of advanced methods supporting the development of the actual configuration process and design reuse. A new framework to find a feasible and practical product configuration method is presented in mass customization. The basic idea of the approach is to integrate case-based reasoning (CBR) with a constraint satisfaction problem(CSP). The similarity measure between a crisp and range is also given, which is common in case retrieves. Based on the configuration model, a product platform and customer needs, case adaptation is carried out with the repair-based algorithm. Lastly, the methodology in the elevator configuration design domain is tested.
2004, 18(2).
Abstract:
Acoustic signals from diesel engines not only contain useful information but also include considerable noise components. To extract information for condition monitoring purposes the continuous wavelet transform (CWT) is used for the characterization of engine acoustics. The characteristics of the CWT in terms of the representation of short duration transient signals are reviewed firstly. Wavelet selection and CWT implementation are then detailed. With the wavelet transform, the major sources of the exterior radiation sound of the engine front are surveyed. The research provides a reliable basis for engineering practice to reduce vehicle sound level. Furthermore, the identification results of the measured acoustic signals are compared with the identification results of the measured surface vibration, and good agreement is observed.
Acoustic signals from diesel engines not only contain useful information but also include considerable noise components. To extract information for condition monitoring purposes the continuous wavelet transform (CWT) is used for the characterization of engine acoustics. The characteristics of the CWT in terms of the representation of short duration transient signals are reviewed firstly. Wavelet selection and CWT implementation are then detailed. With the wavelet transform, the major sources of the exterior radiation sound of the engine front are surveyed. The research provides a reliable basis for engineering practice to reduce vehicle sound level. Furthermore, the identification results of the measured acoustic signals are compared with the identification results of the measured surface vibration, and good agreement is observed.
2004, 18(2).
Abstract:
With the rapid development of electronics and the growing demand for higher vehicle performance, intelligent shift technology is becoming increasingly important, and it promises to be a developing trend in vehicle automatic transmissions. A new simulation model is presented, which includes engine, powertrain, tire and vehicle dynamics models. Based on the model, simulation experiments are conducted to investigate the slope shift strategy. The data and conclusions obtained from the simulations are valuable contributions to the development of an intelligent slope shift strategy.
With the rapid development of electronics and the growing demand for higher vehicle performance, intelligent shift technology is becoming increasingly important, and it promises to be a developing trend in vehicle automatic transmissions. A new simulation model is presented, which includes engine, powertrain, tire and vehicle dynamics models. Based on the model, simulation experiments are conducted to investigate the slope shift strategy. The data and conclusions obtained from the simulations are valuable contributions to the development of an intelligent slope shift strategy.
2004, 18(2).
Abstract:
In order to make good use of the ability to approach any function of BP (back propagation) network and overcome its local astringency, and also make good use of the overall search ability of GA (genetic algorithms), a proposal to regulate the network's weights using both GA and BP algorithms is suggested. An integrated network system of MGA (mended genetic algorithms) and BP algorithms has been established. The MGA-BP network's functions consist of optimizing GA performance parameters, the network's structural parameters, performance parameters, and regulating the network's weights using both GA and BP algorithms. Rolling forces of 4-stand tandem cold strip mill are predicted by the MGA-BP network, and good results are obtained.
In order to make good use of the ability to approach any function of BP (back propagation) network and overcome its local astringency, and also make good use of the overall search ability of GA (genetic algorithms), a proposal to regulate the network's weights using both GA and BP algorithms is suggested. An integrated network system of MGA (mended genetic algorithms) and BP algorithms has been established. The MGA-BP network's functions consist of optimizing GA performance parameters, the network's structural parameters, performance parameters, and regulating the network's weights using both GA and BP algorithms. Rolling forces of 4-stand tandem cold strip mill are predicted by the MGA-BP network, and good results are obtained.
2004, 18(2).
Abstract:
A new method to drive and control micro in-pipe robot by means of magnetic field outside pipe is put forward, in which wireless micro robot can move forward driven by the vibration of its legs through converting magnetic energy into mechanical one under the action of piezomagnetism and magnetomechanical coupling of its micro GMA, when time varied oscillating magnetic field with different frequency applied outside pipe. Firstly its systematical structure and operation principle are introduced, and energy converting process from outside magnetic one into mechanical one is analyzed through setting up the magnetic and mechanical dynamic model of GMA and establishing dynamic model of two stage amplifier of mobile carrier. Robot systematical experiments show the correctness of the theoretical analysis and its feasibility. As a result, drive and control method without cable through outside magnetic field is realized.
A new method to drive and control micro in-pipe robot by means of magnetic field outside pipe is put forward, in which wireless micro robot can move forward driven by the vibration of its legs through converting magnetic energy into mechanical one under the action of piezomagnetism and magnetomechanical coupling of its micro GMA, when time varied oscillating magnetic field with different frequency applied outside pipe. Firstly its systematical structure and operation principle are introduced, and energy converting process from outside magnetic one into mechanical one is analyzed through setting up the magnetic and mechanical dynamic model of GMA and establishing dynamic model of two stage amplifier of mobile carrier. Robot systematical experiments show the correctness of the theoretical analysis and its feasibility. As a result, drive and control method without cable through outside magnetic field is realized.
2004, 18(2).
Abstract:
With the establishment of the nonlinear coupled lateral and torsion vibration equations of rub-impact Jeffcott rotor and through numerical simulations, the influences on lateral and torsion vibration behavior by rotor-to-stator clearance are analyzed, which prove that there is strong impact on coupled lateral and torsion vibration behavior. Smaller the clearance is, more complex the motion of rotor is. When the clearance is larger, the frequency spectrum of rub-impact rotor is mainly composed of 1/2X, 1/3X and 1/4X components. With the decrease of clearance, quasi-periodic and chaotic motions will be present. Under different clearances, the bifurcation diagrams of lateral and torsion vibrations can be divided into rub-free zone, rub-light zone and three complex motion zones in which the motion trend of lateral vibration is similar to that of the torsion vibration. Compared with the lateral vibration, the torsion vibration is of more motion forms and more abundant frequency components in amplitude spectrum.
With the establishment of the nonlinear coupled lateral and torsion vibration equations of rub-impact Jeffcott rotor and through numerical simulations, the influences on lateral and torsion vibration behavior by rotor-to-stator clearance are analyzed, which prove that there is strong impact on coupled lateral and torsion vibration behavior. Smaller the clearance is, more complex the motion of rotor is. When the clearance is larger, the frequency spectrum of rub-impact rotor is mainly composed of 1/2X, 1/3X and 1/4X components. With the decrease of clearance, quasi-periodic and chaotic motions will be present. Under different clearances, the bifurcation diagrams of lateral and torsion vibrations can be divided into rub-free zone, rub-light zone and three complex motion zones in which the motion trend of lateral vibration is similar to that of the torsion vibration. Compared with the lateral vibration, the torsion vibration is of more motion forms and more abundant frequency components in amplitude spectrum.
2004, 18(2).
Abstract:
Vibratory synchronization transmission (VST) is a kind of special physical phenomenon in inertia vibration mechanical systems. For an inertia vibration mechanical system driven by one pair of motors runs in step, even the power supply of one motor is cut off, the motor can continue to keep rotating state under the vibration exciting of the machine body driven by only one other motor. And its rotating frequency will be the same as that of the other one. The transient process of this wonderful physical phenomenon has not been described quantitatively according to current-existing mechanical models. On the basis of investigation of the engineering characteristics of VST, a mechanical and electrical coupling mathematical model of a two-shaft inertia vibration machine is established. With this model, the transient process of VST is recurred quantitatively and successfully, and a reasonable explanation is given.
Vibratory synchronization transmission (VST) is a kind of special physical phenomenon in inertia vibration mechanical systems. For an inertia vibration mechanical system driven by one pair of motors runs in step, even the power supply of one motor is cut off, the motor can continue to keep rotating state under the vibration exciting of the machine body driven by only one other motor. And its rotating frequency will be the same as that of the other one. The transient process of this wonderful physical phenomenon has not been described quantitatively according to current-existing mechanical models. On the basis of investigation of the engineering characteristics of VST, a mechanical and electrical coupling mathematical model of a two-shaft inertia vibration machine is established. With this model, the transient process of VST is recurred quantitatively and successfully, and a reasonable explanation is given.
2004, 18(2).
Abstract:
As a result of the fierceness of business competition, companies, to remain competitive, have to charm their customers by anticipating their needs and being able to rapidly develop exciting new products for them. To overcome this challenge, technology forecasting is considered as a powerful tool in today's business environment, while there are as many success stories as there are failures, a good application of this method will give a good result. A methodology of integration of patterns or lines of technology evolution in TRIZ parlance is presented, which is also known as TRIZ technology forecasting, as input to the QFD process to design a new product. For this purpose, TRIZ technology forecasting, one of the TRIZ major tools, is discussed and some benefits compared to the traditional forecasting techniques are highlighted. Then a methodology to integrate TRIZ technology forecasting and QFD process is highlighted.
As a result of the fierceness of business competition, companies, to remain competitive, have to charm their customers by anticipating their needs and being able to rapidly develop exciting new products for them. To overcome this challenge, technology forecasting is considered as a powerful tool in today's business environment, while there are as many success stories as there are failures, a good application of this method will give a good result. A methodology of integration of patterns or lines of technology evolution in TRIZ parlance is presented, which is also known as TRIZ technology forecasting, as input to the QFD process to design a new product. For this purpose, TRIZ technology forecasting, one of the TRIZ major tools, is discussed and some benefits compared to the traditional forecasting techniques are highlighted. Then a methodology to integrate TRIZ technology forecasting and QFD process is highlighted.
2004, 18(2).
Abstract:
A new type of composite CVT(continuously variable transmission) systems featured by power flow divergence and dual-mode convergence, capable of improving CVT's efficiency and power capacity or making AMTs(automated manual transmissions) become continuously variable, is studied. With specific mechano-mechanical and electromechanical composite CVT systems as detailed examples, its basic working principles are expatiated. General methods and key points in designing and realizing such systems are also analyzed and discussed.
A new type of composite CVT(continuously variable transmission) systems featured by power flow divergence and dual-mode convergence, capable of improving CVT's efficiency and power capacity or making AMTs(automated manual transmissions) become continuously variable, is studied. With specific mechano-mechanical and electromechanical composite CVT systems as detailed examples, its basic working principles are expatiated. General methods and key points in designing and realizing such systems are also analyzed and discussed.
2004, 18(2).
Abstract:
The presentation method of the mechanical motion scheme must support the whole process of conceptual design. To meet the requirement，a semantic network method is selected to represent process level, action level, mechanism level and relationships among them. Computer aided motion cycle chart exploration can be realized by the representation and revision of time coordination of mechanism actions and their effect on the design scheme. The uncertain reasoning technology based on semantic network is applied in the mechanism types selection of the needle driving mechanism of industrial sewing mechanism, and the application indicated it is correct, useful and advance.
The presentation method of the mechanical motion scheme must support the whole process of conceptual design. To meet the requirement，a semantic network method is selected to represent process level, action level, mechanism level and relationships among them. Computer aided motion cycle chart exploration can be realized by the representation and revision of time coordination of mechanism actions and their effect on the design scheme. The uncertain reasoning technology based on semantic network is applied in the mechanism types selection of the needle driving mechanism of industrial sewing mechanism, and the application indicated it is correct, useful and advance.
2004, 18(2).
Abstract:
Bonding with adhesives is an important technique for building up hybrid microsystems. Some adhesives are tested with capillary dispensing system for microassembly, and volume of drop-lets less than 10 nl with good repeatability can be acquired. 1-part UV curing adhesive hardens rapidly and is suitable for bonding of transparent microparts. Light-activated adhesive starts the curing process in an adjustable short period of time after the radiation of visible light, and thus suits bonding of non-transparent microparts. A method is proposed for bonding the guides of a miniature linear motor being developed by collaborate research center 516 (SFB516) in Germany. With the method high assembly accuracy in the vertical direction can be guaranteed. By making small grooves on the stator for containing adhesive, the deterioration of the accuracy due to the thickness of adhesive layer can be avoided. The criteria on deciding the size of the groove are given and analyzed. Vision based inspection method is introduced for automatic assembly of the guides. The dispensing volume and position of dispensed adhesive droplets can be detected for ensuring the bonding quality.
Bonding with adhesives is an important technique for building up hybrid microsystems. Some adhesives are tested with capillary dispensing system for microassembly, and volume of drop-lets less than 10 nl with good repeatability can be acquired. 1-part UV curing adhesive hardens rapidly and is suitable for bonding of transparent microparts. Light-activated adhesive starts the curing process in an adjustable short period of time after the radiation of visible light, and thus suits bonding of non-transparent microparts. A method is proposed for bonding the guides of a miniature linear motor being developed by collaborate research center 516 (SFB516) in Germany. With the method high assembly accuracy in the vertical direction can be guaranteed. By making small grooves on the stator for containing adhesive, the deterioration of the accuracy due to the thickness of adhesive layer can be avoided. The criteria on deciding the size of the groove are given and analyzed. Vision based inspection method is introduced for automatic assembly of the guides. The dispensing volume and position of dispensed adhesive droplets can be detected for ensuring the bonding quality.
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