Position/Force Sensorless Force Control Using Reaction Force Observer for Compact Dual Solenoid Actuator

Abstract

This study aims to develop a tactile display which can represent 2D haptic information. In our previous works, sensorless position control for a compact dual solenoid actuator (CDSA) has been proposed to realize a compact actuation system for the tactile display. To represent the haptic information, contact force control is also required. This paper proposes position/force sensorless force control using the position estimation and a reaction force observer (RFOB). The RFOB is constructed based on the motion equation of the CDSA. Experiments were conducted to validate the performance of the force control. The results show that the contact force is accurately controlled with about 5 mN error which is 6 % of the force command offset. The gain of the proposed force control becomes more than -2.6 dB when the command frequency was less than 20 Hz. The control phase delay was 14.0 ms which came from the cut-off frequency of the low pass filter in the RFOB. The experimental results with change of the mover position showed that the contact force was accurately controlled when the position was at 0.0 ~ 0.2 [mm]. This proposal is useful because a compact actuation system whose position and force are controllable without position and force sensors is realized.