In this brief, pneumatic actuators with inexpensive solenoid valves were chosen for development of a masterslave tele operation system. To efficiently control the switching ON/OFF valves in terms of the force output by the piston, a new hybrid algorithm was successfully developed and implemented in experiments. This technique not only took into account the nonlinear behavior of the mass flow rate, but also the switching control of the solenoid valves. The results showed that it was possible to achieve transparent teleoperation without using more costly proportional servovalves. In experiments, it was observed that with the 4CH bilateral teleoperation control architecture employing this hybrid control algorithms, satis- factory force and position tracking between the master and the slave was obtained under both free-motion and contact- motion conditions.
While the proposed hybrid control in this brief is based on a one-step-ahead prediction of pressures in the pneumatic chambers, an aspect of future work is to extend the control law to involve a multi-step prediction in order to improve the tracking performance. Finally, nonlinear control strategies for pneumatic actuators with solenoid valves such as those in [7] and [27] have not been implemented in teleoperation systems yet. This represents an alternative research path to be investigated.