RTOS based embedded controller implementation of a bilateral control system

Abstract

Bilateral tele-operation involves realization of the
law of action and reaction between the human and the remote
environment. In this research, an embedded system based
bilateral control was developed on a microcontroller based
motor driver platform. Bilateral tele-operation needs real-time
representation of the forces and positions. This challenge was
accomplished by incorporating a real-time operating system
(RTOS) with a resource limited microcontroller. Sensorless
torque detection technique was used to find the external torque
while disturbance observer was used as a disturbance rejection
tool and also to improve the system’s robustness. When the
motion controller was implemented on a microcontroller,
0 - 30 Hz frequency of force bandwidth could be achieved. In
an ideal bilateral control, force/position errors should be zero.
The experimental results in contact motion showed a force error
less than 4 % and a position error less than 6 %, which validates
the proposal. This was a significant achievement as the bilateral
controllers have never been successfully implemented using a
microcontroller.