Toward switching motor control

Traditionally focused on applications where humans are safely out of reach, the field of robotics was developed to perform repetitive tasks with high precision and accuracy. In contrast, recent developments have opened up a new subfield of robotics in which users are in direct contact with robotic devices. This physical interaction requires the device to be sensitive to human contact while maintaining performance. While hardware designs have progressed to fill this new area, the underlying controller remains nearly the same as that developed for industrial robots decades ago, imposing limits on the performance of the overall system. To address the unique requirements of these human-interactive robotic devices, we are working to replace the traditional amplifier with a high-speed switching controller. Combining the simplicity and efficiency of pulsewidth modulation with the high bandwidth of linear amplifiers, this approach demonstrates performance gains when implemented as a closed-loop current controller. We also extend this design to the proposal of a third-order architecture to combine an amplifier and servo controller into an integrated system with the potential to overcome the fundamental limits of today's systems and enable the future of human-interactive robotics.