Improvement of performance in bilateral teleoperation by using FPGA

Bilateral teleoperation has been needed in many scenes such as space activities or undersea, work on a atomic power plant and minimally invasive surgery, etc. In bilateral teleoperation, transfer of keen tactile sense as if the operator directly touch the environment without using the robot is required. Wide frequency bandwidth of force sensing is required to achieve transfer of a keen tactile sensation. Bilateral controller based on acceleration control with disturbance observer is available to achieve transfer of a keen tactile sensation. The frequency bandwidth of force sensing is determined by cut-off frequency of low-pass filter used in disturbance observer. The cut-off frequency is in inverse proportion to a sampling period. Therefore, shortening of the sampling period improves performance of bilateral teleoperation. In this paper, bilateral teleoperation system by using FPGA(Field Programmable Gate Array) is introduced. FPGA is a LSI that user can design its internal logic. When motion controller is implemented on FPGA, it operates faster than that implemented in a PC(Personal computer) with RTOS(Real Time Operating System). The sampling period is shortened from 100/its to 10μs by using FPGA.