Design and Analysis of a Pneumatic-Electric End-Effector for Force Control Applications

To overcome the drawbacks of the existing pneumatic force-controlled end-effector, such as low dynamic response and low force control accuracy, a novel pneumatic-electric force-controlled end-effector is proposed in this paper. It consists of a base, a moving platform, a voice coil motor (VCM), a nitrogen spring, and six extension springs. By integrating the VCM with a nitrogen spring and six extension springs parallelly, the proposed force-controlled end-effector has the advantages of high output force, high dynamic response, and high force-control accuracy. The dynamic analysis of the VCM and the stiffness analysis of the nitrogen spring are conducted. Based on the dynamic model of the system, a PID based force controller is implemented. To validate the proposed design, modelling, and control approaches, a prototype of the pneumatic-electric end-effector is fabricated. Experimental results show that the pneumatic-electric end-effector achieves excellent force-control performance with ±0.1N force control accuracy and 70ms response time.