Research On Embedded Shape Memory Alloy Actuator Drive

Miniaturization of the robot is a tendency, also it is a difficult problem. The research and development of new actuators are the key of the problem. As a sound member of the new function material family, shape memory alloy (SMA) has been widely used in engineering and robot. Especially, the simple, light and high power density flexible SMA actuator (SMAA) takes on the characters that can relax the break of the load and prevent the contacted objects from being collided, holding much promise for the future of assembled robotics, appliance robotics, space robotics and walking robotics. In almost all the design of existing robot hands using SMAAs, the actuating components are physically separated from the reversing components as well as the driving units are seperated from the executing units, in result of complicated frames and inflexible moves. Therefore, putting forward a new type of Embedded SMA actuator (ESMAA) and focusing on a compact, flexible system and precision position control. The thesis investigates the ESMAA prototype unit, assembled ESMAA-based flexible robot, curvature sensor, detection circuit, as well as the control strategy. The achievements obtained are summarized as follows: 1. The novel ESMAA and assembled three-fingered ESMAA-based flexible robot are designed and developed. Each ESMAA is consisted of two knuckles (Φ12mm×45mm) and a connecting part(Φ12mm×3mm). Three ESMAAs are distributed on the vertexes of an equilateral triangle. 2. A curvature sensor of ESMAA is designed, and the experimental results of different paste are compared. The relation between curvature and output voltage of bridge circuit is analyzed theoretically and experimentally. 3. A 80C196KC singlechip-based ESMAA-based robot servo system is completed. Multiplex strain sampling circuit and multiplex PWM control circuit are equipped. 4. With position detection and strain feedback, P+,PI+ control strategies are investigated theoretically and experimentally. The experimental grasping system with the three-fingered flexible robot hand mentioned above is developed. The hand is 60g weight, with ability to grasp a copper sphere with 240g in heavy and 20 mm in radius. During the grasping process, the hand is able to move flexibly and respond quickly.