Pneumatic system and low-level control of a soft machine table inspired by caterpillar locomotion

Abstract

This paper presents the design of the pneumatic system and the low-level control strategy of a soft machine table inspired by caterpillar locomotion. The soft table surface is embedded with inflatable chambers and the surface deformation is controlled by a pneumatic system to provide actuation. The pneumatic system is modularized so that each pneumatic module controls one soft actuator in the actuation system. Each pneumatic module includes five solenoid valves and a small rotary pump. A support structure is designed to hold one set of pneumatic components in position. Multiple support structures can be connected together to form the pneumatic system of the soft table. The overall control architecture for the soft table is discussed. A master-slave communication architecture is established to control each soft actuator via a pneumatic module independently. The user can input commands through an user interface on a computer, smart phone or tablet. Low-level actuation is controlled by the embedded program coded into the module microcontrollers. The valves operates in a series of ON/OFF switching corresponding to the movement phases. The air outflow of the rotary pump is controlled to work with the valve operations to provide actuation on the table surface. A software calibration strategy used to adjust the performance of different size soft actuators is presented.