Ena Ishii

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 mus by using an FPGA. The implemented controller is evaluated by experiments.

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 mus to 10 mus by using FPGA

Bilateral Teleoperation Based on Modal System Design

Technology for teleoperation has been needed in many scenes. Especially in robotic surgery, It is required that to transmit the tactile sensation to the operator. To attain that need, teleoperation method called bilateral has developed. Bilateral means transmit information each other. Environmental information is transmitted both from master to slave and from slave to master in bilateral teleopera- tion. In bilateral teleoperation, environmental information of master and slave should be exchanged in common coordinates. It is difficult to define a common coordinates in different structured bilateral teleoperation. Mode based control for bilateral teleoperation is proposed in this paper. Coordinates based on geometric mode is used to common coordinates to exchange the environmental information be- tween master robot and slave robot. Geometric environmen- tal mode is quarried by quarry matrix and hypothetical axes bilateral controller based on acceleration control is applied to hypothetical mode motors. Hypothetical mode master motor and mode slave motor are transformed to mode common motor and mode differential motor. Force servo controller is applied to mode common motor and position regulator is applied to mode differential motor. Viability of proposed method is shown in experimental result.