Research On Key Technologies Of Motor Driving System For Robot Joints

With the aging of the world and the rising labor costs,the use of industrial robots instead of human labor has become a global trend.At this stage,robots have been widely used in welding,handling,medical,and service fields.The robot joint is mainly composed of the main motion controller,the motor and the drive system,the sensor,the reducer,etc.,and a key component that affects the joint performance of the robot is the motor and the drive system.According to the research status at home and abroad,most of the motors used in robot joints are stepper motors and permanent magnet synchronous motors.At present,with the development of control theory and the continuous improvement of application requirements,the performance requirements of motor drive systems in various fields are getting higher and higher.In this paper,firstly,the existing stepping motor drive system has the disadvantages of buffeting,low speed,weak load capacity and easy out-of-step.It focuses on how to improve the high-speed load capacity and positioning accuracy of the closed-loop drive system of stepping motor.Secondly,aiming at the problem that the current permanent magnet AC servo system does not respond fast enough and the positioning accuracy is not high in the trajectory motion control,this paper focuses on how to further improve the dynamic response speed and positioning accuracy of the permanent magnet AC servo drive system.In this paper,the research background and significance of the subject and the existing closed-loop drive system of stepping motor and the control method of permanent magnet AC servo drive system are described.Secondly,in order to improve the high-speed capability and load capacity of the stepping motor drive system,the existing stepper motor drive system has the disadvantages of chattering,low speed,weak load capacity and easy out-of-synchronization.The hybrid controller's high-speed heavy-duty closed-loop drive method includes two core contents:position-speed hybrid controller design and lead angle feedforward control.In order to improve the dynamic response speed of the permanent magnet AC servo drive system,a current prediction control method is proposed for the permanent magnet AC servo system in the case of trajectory motion control where the response speed is not fast enough and the positioning accuracy is not high.The positioning accuracy of the servo drive system is introduced.A load torque identification algorithm is introduced.A load moment identification and feedforward compensation method for permanent magnet synchronous motor based on predictive control is proposed.Then,in order to verify the effectiveness of the proposed method,the Simulink simulation model was established,the software and hardware of the drive system were developed,and the test platform was built to test the performance of the drive system.Finally,based on the design simulation model and test platform,the algorithm is verified.The verification is mainly divided into two major contents:Firstly,for the stepping motor closed-loop drive system,the high-speed performance and load capacity of the drive system are tested.The experimental results show that compared with the traditional open-loop drive system,the proposed hybrid-based system The controller's high-speed heavy-duty closed-loop drive system can achieve a maximum speed of 2000r/min under no-load conditions and a high-speed running speed of about 50%at no-load.At the same operating speed,its load capacity is greater than that of conventional open-loop.In the drive system,the effective torque can be increased to more than 81.25%of the holding torque;the same load moment is applied under the same pulse position,and the hybrid closed-loop drive system has faster response speed and positioning accuracy.Secondly,for the permanent magnet AC servo drive system,through the speed control,load start and load disturbance suppression performance test,the results show that the drive system based on predictive control has faster speed than the drive system based on traditional PI control.The dynamic response speed and the recovery time when the load disturbance changes are shorter,which speeds up the identification speed of the estimated load torque.Finally,by using the estimated load torque as feedforward compensation,the speed response and positioning accuracy of the drive system are further improved.