This thesis details the design and implementation of a distributed digital control system for use in a common type of industrial robot arm, the PUMA 560. Previous and existing industrial robotic control systems suffer from the use of outdated technology, with the complex control electronics occupying a large space, and control signals to and from the robot being transferred using a bulky, unreliable cable.
The design presented in this thesis uses a recently released Digital Signal Processor (DSP) that is optimised for digital motion control on each joint of the robot arm, with the individual controllers communicating with each other and the host PC via a Controller Area Network (CAN). Each joint controller is located physically close to the motor it is operating, resulting in a major reduction in the wiring harness complexity and cost. The design rationale and decisions for this controller are given, along with an description of the hardware resulting from this process.
The DSP software written for the controller is overviewed, along with the control techniques to run the robot. Currently, a proportional only controller has been implemented, but the DSP has ample computing power to experiment with more advanced control techniques and such features as real time vibration analysis and damping. The responses of the controllers on each joint are discussed, as are possible future enhancements to the system. A fully functional robot control system is operational, although with a inaccurate control loop, but it is expected that by the end of the semester each joint should be running a full PID controller at an update rate of 20kHz.