A multi-posture 3D printed actuator composed of VT-type bidirectional deflection fishbone-like modules based on shape memory alloy wires

In this paper, a multi-posture actuator (MPA) composed of VT-type bidirectional deflection fishbone-like modules (VBFM) based on shape memory alloy (SMA) wires is proposed for realizing multi-posture deformation control. Through sizing of the VT-type structure and the arrangement of VBFM in series, it is possible to realize the actuator design meeting specific deformation requirements. The thermo-mechanical coupling analysis model based on kinematics, dynamics, thermodynamics and SMA models is established to study the VBFM deflection angle and multi-posture performance of the MPA. The experimental and numerical results show that the MPA can achieve the target postures and the maximum deflection angle of the single VBFM can reach about 1.8°, and the 5-VBFM MPA can deflect a maximum angle of approximately 9° in one direction. In addition, the load actuation performance of 1-VBFM and 5-VBFM MPA is investigated, and the results show that the actuated deflection angle increases with the input electrical power within its effective range and decreases with the external resistance load. When multiple modules are combined, the deflection angle can be accumulated, and they can be used in medical robotic arms, space cleaning grab mechanisms, etc.