Application And Software Development Of Process Control System For Assembly Robot

Assembly process is a subsequent handling of production. Compare with other industrial robot, such as welding, painting and handling, assembly tasks require dynamic interaction between robot manipulator with the environment, hence force controlling is necessary for ensuring the quality of robot assembly. With regard to the traditional position control mode for most industrial robots, it is necessary to introduce force feedback into the control loop of the assembly robots. To meet the requirements of the assembly robot project, in which compliant object placement, peg in hole and other typical tasks are important for robot assembly, the key techniques of active compliance control and the development of the process control system for assembly robot is presented in this dissertation.Firstly, the requirements of the assembly task are analyzed and the designed functions introduced. The assembly robot hardware system consists of industrial robot, six axis force/torque sensor, gripper and PC. The force sensor, the gripper and the camera is fixed at the end of the robot arm, connected by specific mechanical adapters. A three-layered software system is developed for the assembly robot using the client/server architecture.The design and development of the assembly robot control software system is described. The software system includes gripper control, Ethernet communication of the robot controller and the force sensor data acquisition and display. In the software system, the problem of communication and synchronization among different threads are solved. For typical assembly task such as compliant parts placement, the assembly process is analysis. The application layer communication protocol for force control task is designed and protocol analysis program is developed. A hybrid position/force control strategy based on admittance control is realized. For another typical assembly task, i.e, peg in hole task, gravity compensation algorithm is designed and implemented. Then the control strategy for different sub tasks of the peg in hole task is designed. Finally, with the assembly robot vision positioning module, the founction of process control system for assembly robot is tested, include active compliant moduel and visual positioning module. Typical assembly tasks such as compliant parts placement and peg in hole are completed as designed. The desired objectives is achieved.