Thermal management of silicon micro robot driven by neural networks IC control SMA actuator

Abstract

This paper discusses both thermal management of a microrobot and a control IC. The developed microrobot is fabricated by the MEMS (Micro Electro Mechanical Systems) technology. The miniature actuator is constructed by SMA (Shape Memory Alloy) wires and a rotor. It shows rotational motion by heating and cooling process of the SMA wire. Moreover, artificial neural networks are used for the miniature control system. The artificial neural networks mimic a brain system of living organisms. Therefore, it is expect to respond accidental events. To combine the control system and the robotic structure, the P-HNNs (Pulse-type Hardware Neural Networks) IC is designed. The microrobot that combined with the P-HNNs IC was achieved, and it showed the walking motion. However, the miniature SMA actuator shows a speed limit by the cooling time. Moreover, P-HNNs IC is influenced by a change in the temperature. Therefore, the thermal management of the SMA actuator and the neural networks IC are discussed in this paper. The SMA actuator is discussed in the rotor shape and material. The neural networks IC is focused on a heat generation source. By the results, the copper material and two-hole shape rotor that had small area and small conductor were suitable for the miniature SMA actuator. The heat generation was observed by the current mirror and P-HNNs circuit. The developed SMA actuator was combined to the microrobot, it showed the walking motion and the walking speed was 12 mm/min.