Improvement of performances in bilateral teleoperation by using FPGA

Bilateral teleoperation has been needed in many areas, such as space activities, work on an atomic power plant, minimally invasive surgery, etc. In bilateral teleoperation, transfer of keen tactile sense, which is as if the operator directly touches the environment, is required. Sensing of wide-frequency-bandwidth force information is required in achieving the transferring of a keen tactile sensation. A bilateral controller based on acceleration control with disturbance observers is available to achieve transfer of a keen tactile sensation. In this bilateral controller, the frequency bandwidth of sensed force is determined by the cutoff frequency of a low-pass filter used in the disturbance observer. The cutoff frequency is in inverse proportion to a sampling period. Therefore, shortening of the sampling period improves performance of bilateral teleoperation. In this paper, a bilateral-teleoperation system using a field-programmable gate array (FPGA) is introduced. The FPGA is an large scale integration where a user can design its internal logic. When the motion controller is implemented on an FPGA, it operates faster than that implemented in a personal computer with a real-time operating system. The sampling period is shortened from 100 to 10 mu s by using an FPGA. The implemented controller is evaluated by experiments.