1996 Vol.9(4)
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1996, 10(4).
Abstract:
This research characterizes grasping by multifingered robot hands through investigation of the space of contact forces into four subspaces, a method is developed to determine the dimensions of the subspaces with respect to the connectivity of the object. The relationship reveals the differences between three types of grasps classified and indicates how the contact force can be decomposed crresponding to each type of grasp. The subspaces and the determination of their dimensions are illustrated by examples.
This research characterizes grasping by multifingered robot hands through investigation of the space of contact forces into four subspaces, a method is developed to determine the dimensions of the subspaces with respect to the connectivity of the object. The relationship reveals the differences between three types of grasps classified and indicates how the contact force can be decomposed crresponding to each type of grasp. The subspaces and the determination of their dimensions are illustrated by examples.
1996, 10(4).
Abstract:
A prodouct modeling and a process planning that are two essential bases of realizing concurrent engineering are investigated, a logical modeling technique, grammar representation scheme of technology knowledge and architecture of expert system for process planning within concurrent engineering environment are proposed. They have been utilized in a real research project.
A prodouct modeling and a process planning that are two essential bases of realizing concurrent engineering are investigated, a logical modeling technique, grammar representation scheme of technology knowledge and architecture of expert system for process planning within concurrent engineering environment are proposed. They have been utilized in a real research project.
1996, 10(4).
Abstract:
Based on the kinematics of the multi-body system, a general model for the positioning errors of NC machine tools by means of the lower numbered body array and the geometric constraint is presented. The parameters indentification of geometric errors by an improved 22-line method is discussed. Moreover, an inteligent error compensation controller has been developed. All these are verified by a series of experiments on XH714 machining center. The results show that the prositioning errors with compensation have been reduced to ±7μm from 50 μm.
Based on the kinematics of the multi-body system, a general model for the positioning errors of NC machine tools by means of the lower numbered body array and the geometric constraint is presented. The parameters indentification of geometric errors by an improved 22-line method is discussed. Moreover, an inteligent error compensation controller has been developed. All these are verified by a series of experiments on XH714 machining center. The results show that the prositioning errors with compensation have been reduced to ±7μm from 50 μm.
1996, 10(4).
Abstract:
A new theory-the fuzzy probability logic theory is presented. This theory incorporates the genterally-used fuzzy logic and the traditionally-used probability logic theory in attempt to emulate the rational fault diagnosis under uncertainty. According to the theory, an inference model, named as FSL, is thus designed to be devoted to the building of a fault diagnosis expert system for rotating machinery (ROSLES). The system is put into operation on a vibration simulator stand for 300 MW turbine generator set (1：10) and satisfactory results are gained.
A new theory-the fuzzy probability logic theory is presented. This theory incorporates the genterally-used fuzzy logic and the traditionally-used probability logic theory in attempt to emulate the rational fault diagnosis under uncertainty. According to the theory, an inference model, named as FSL, is thus designed to be devoted to the building of a fault diagnosis expert system for rotating machinery (ROSLES). The system is put into operation on a vibration simulator stand for 300 MW turbine generator set (1：10) and satisfactory results are gained.
1996, 10(4).
Abstract:
The static and dynamic characteristics of underwater plasma arc, arc shape and heating features to the workpieces, are studied. It shows that underwater plasma arc has higher energy rate, higher rates of heating and cooling. Furthermore, it reduces the pollutions of noise, arc light, dust and ozone; strengthens the cooling of nozzle, thus it is advantageous to develop various new technologies of underwater material processing. The static characteristic is rising. The dynamic characteristic is of quasi-cyclic fluctuations whose mechanisms and solving methods are pointed out.
The static and dynamic characteristics of underwater plasma arc, arc shape and heating features to the workpieces, are studied. It shows that underwater plasma arc has higher energy rate, higher rates of heating and cooling. Furthermore, it reduces the pollutions of noise, arc light, dust and ozone; strengthens the cooling of nozzle, thus it is advantageous to develop various new technologies of underwater material processing. The static characteristic is rising. The dynamic characteristic is of quasi-cyclic fluctuations whose mechanisms and solving methods are pointed out.
1996, 10(4).
Abstract:
Combining the characteristics of servo systems, tracking variable structure control law is studied. Two kinds of new variable control law, the generalized exponential approaching varibale structure control law and the integral variable strucuture control law are put forward for discrete time domain. Taking pump-controlled-motor rotational speed servo system for example, the experiment investigation and digital simulation of integral variable structure control law for discrete time domain are performed, the fightness of conclusions are verified.
Combining the characteristics of servo systems, tracking variable structure control law is studied. Two kinds of new variable control law, the generalized exponential approaching varibale structure control law and the integral variable strucuture control law are put forward for discrete time domain. Taking pump-controlled-motor rotational speed servo system for example, the experiment investigation and digital simulation of integral variable structure control law for discrete time domain are performed, the fightness of conclusions are verified.
1996, 10(4).
Abstract:
The chassis frame of a heavy lectra haul is analysed by both modal experiment method and finite element method (FEM). The first ten order modal parameters of the chassis frame have been obtained satisfactorily. These parameters have important reference value in designing the chassis frame properly and provide a necessary basis for the fault diagnostics of the truck.
The chassis frame of a heavy lectra haul is analysed by both modal experiment method and finite element method (FEM). The first ten order modal parameters of the chassis frame have been obtained satisfactorily. These parameters have important reference value in designing the chassis frame properly and provide a necessary basis for the fault diagnostics of the truck.
WAVELET TRANSFORM IN TANDEM WITH AUTOREGRESSIVE TECHINIQUE FOR MONITORING AND DIAGNOSIS OF MACHINERY
1996, 10(4).
Abstract:
A new approach is advanced based on wavelet transform in tandem with autoregressive technique. Wavelets and wavelet packets decompose dynamic signal into different bands and provide multiresolution or multiscale view of signal. Autoregressive technique possesses effective function for short data processing. The approach is abopted to analyse nonstationary vibration signals of mining excavator. The results indicate that nonstationary operating condition can be monitored and diagnosed. Transient toothmeshing frequency and rotating speed are measured. Weak vibration signal of defective ball bearing is extracted from strong vibration of gearbox and diagnosed successfully. This approach is effective for nonstationary condition monitoring and early diagnosis of latent fault.
A new approach is advanced based on wavelet transform in tandem with autoregressive technique. Wavelets and wavelet packets decompose dynamic signal into different bands and provide multiresolution or multiscale view of signal. Autoregressive technique possesses effective function for short data processing. The approach is abopted to analyse nonstationary vibration signals of mining excavator. The results indicate that nonstationary operating condition can be monitored and diagnosed. Transient toothmeshing frequency and rotating speed are measured. Weak vibration signal of defective ball bearing is extracted from strong vibration of gearbox and diagnosed successfully. This approach is effective for nonstationary condition monitoring and early diagnosis of latent fault.
1996, 10(4).
Abstract:
The data measured by using the two-disc tester show that the concentration of EP additives and the viscosity temperature characteristic of lubricant have a cooperation effect on the friction coefficient in boundary lubrication.
The data measured by using the two-disc tester show that the concentration of EP additives and the viscosity temperature characteristic of lubricant have a cooperation effect on the friction coefficient in boundary lubrication.
1996, 10(4).
Abstract:
On the basis of deep investigation of locomotive traction gears manufactured at bome and abroad, a variety of measures are putted forward to improve the driving load-bearing capacity and working life of our country's high-speed locomotive traction gears. The measures include the following five aspects: optimally selectin the material and heat treatment process, optimally designing the tooth profile, reasonably choosing the manufacture accuracy and technique, optimally choosing the lubricant and the way of lubrication and seal, improving the dynamic feature of the gearing. In the respect of the tooth profile, a hob with optimal cutter angles is designed to make root thickness on the dangerous section as large as possible and the stress concentration as small as possible. Addendum modification coeffient is optimized to minimize the maximum flash temperature in the course of meshing. Finally, finite element analysis method is used to calculate the deformation and the stress of teeth accurately. And on this basis, optimal profile correction and axial modification have been designed with regard to the start, continuious running and high speed travel of the locomotive.
On the basis of deep investigation of locomotive traction gears manufactured at bome and abroad, a variety of measures are putted forward to improve the driving load-bearing capacity and working life of our country's high-speed locomotive traction gears. The measures include the following five aspects: optimally selectin the material and heat treatment process, optimally designing the tooth profile, reasonably choosing the manufacture accuracy and technique, optimally choosing the lubricant and the way of lubrication and seal, improving the dynamic feature of the gearing. In the respect of the tooth profile, a hob with optimal cutter angles is designed to make root thickness on the dangerous section as large as possible and the stress concentration as small as possible. Addendum modification coeffient is optimized to minimize the maximum flash temperature in the course of meshing. Finally, finite element analysis method is used to calculate the deformation and the stress of teeth accurately. And on this basis, optimal profile correction and axial modification have been designed with regard to the start, continuious running and high speed travel of the locomotive.
1996, 10(4).
Abstract:
On-line measurement and control method of moving wire vibration are developed. The response measurement of the wire is indirectly accomplished by "vibration transfer method" and active control is carried out on the vibration receiving body by piezoelectric ceramics. The fundamental principles of measurement and control are stated and experimental results are presented.
On-line measurement and control method of moving wire vibration are developed. The response measurement of the wire is indirectly accomplished by "vibration transfer method" and active control is carried out on the vibration receiving body by piezoelectric ceramics. The fundamental principles of measurement and control are stated and experimental results are presented.
1996, 10(4).
Abstract:
The characteristics of novel cone-generated cylindrical worm and the machining principle of using a grinding wheel with two degree-of-freedom motions are described. A systematic study is made on the first enveloping process of the grinding wheel forming a worm and the second enveloping process of the worm forming a worm wheel with the meshing theory of kinematic method. Some numerical calculation formulas and important conclusions are obtained.
The characteristics of novel cone-generated cylindrical worm and the machining principle of using a grinding wheel with two degree-of-freedom motions are described. A systematic study is made on the first enveloping process of the grinding wheel forming a worm and the second enveloping process of the worm forming a worm wheel with the meshing theory of kinematic method. Some numerical calculation formulas and important conclusions are obtained.
1996, 10(4).
Abstract:
A feedforward compensation method of the motion errors of NC machine tools implemented with software is proposed, with which the motion effors can be compensated whithout changing the original computer control systems of the NC machine tools. The experimental results show that the circular interpolation profile machining errors decrease by a factor of 2/3 after compensated.
A feedforward compensation method of the motion errors of NC machine tools implemented with software is proposed, with which the motion effors can be compensated whithout changing the original computer control systems of the NC machine tools. The experimental results show that the circular interpolation profile machining errors decrease by a factor of 2/3 after compensated.
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