Development of Compact Linear Actuator Combining DC motor and Cylindrical Cam for Tactile Display

Abstract

This study aims to realize a tactile display which is constructed by arranging a lot of compact linear actuators on a plane and can represent 2D haptic information by controlling their position and force. In our previous works, a compact dual solenoid actuator (CDSA) was developed which can be controlled by sensorless position estimation technique. However, the frequency range of the accurate position control is narrow (less than 2.0 Hz). This paper proposes a compact linear actuator which is consists of a DC motor, planetary gear, and cylindrical cam. A rotary encoder which does not increase the horizontal cross section area is attached to obtain the position information. The lift angle of the cylindrical cam is designed as π/4 to achieve high backdrivability. Experiments of position control with a disturbance observer were conducted to confirm the control performance. As a result, when the frequency of the position command was less than 20 Hz, the accurate position control was achieved, whose gain was within plus or minus 1 dB. Therefore, the frequency range could be enhanced compared with the CDSA. This actuator is very useful because the actuator can be applied not only in haptic applications but also other applications such as human support in narrow space.