Reducing Intersample Ripple of Actuator in Multirate Environment by A Joint Space Interpolator

Zusammenfassung (Abstract) :

Chattering is a very undesired phenomenon in technical systems. There can be many causes for it. In this paper, at first simulation results are shown that insufficient setpoint updating can also lead to chattering in form of intersample ripple. The difference between setpoint updating rate and the control frequency can be traced back to the multi-layered software architecture of an overall system. As a solution, a joint space interpolator is suggested, which is a novel construction mainly combining a trajectory interpolator with a jitter buffer in joint space. On the one hand it provides supplementary setpoints to the controller and on the other hand it ensures very strict real-time performance of the closed-loop system. At last, experiment results are shown to support the proposed method. This scheme is implemented for, but not limited to, actuators utilizing geared brushless DC (BLDC) motors with FPGA-based controllers. The simulations and experiments have focus on robotic motion control in joint space.

Stichworte :

chattering, multirate, frequency lifting, interpolation, jitter buer, FPGA, BLDC Motor, joint space, motion control, robotics