In this section, experiments with a 1-DOF teleoperation system are reported. As illustrated in Fig. 5, the setup consists of two master and slave identical manipulators. The low- friction cylinders (Airpel model) have a 16-mm diameter and a 100-mm stroke. In terms of actuators, the pneumatic cylinder uses four solenoid valves for each manipulator. The pneumatic solenoid valves (Matrix model) used to control the air flow have switching times of approximately 1.3 ms (opening time) and 0.2 ms (closing time). In terms of sensors, a low-friction linear variable differential transformer sensor is connected to each cylinder in order to measure the positions of the master and the slave. Also, the end effector of each manipulator is equipped with a force sensor in order to measure the operator and environment forces. In addition, each cylinder chamber is equipped with a pressure sensor. The system was supplied with air at an absolute pressure of 300 kPa.
The controller is implemented using a dSPACE board
(DS1104), running at a sampling rate of 500 Hz. This value has been chosen according to the open/close bandwidth of the valves and to guarantee acceptable tracking response. This sampling rate is also higher than the bandwidth, above which the human finger cannot distinguish two consecutive force stimuli, which is 320 Hz [26].