Sensorless temperature estimation and control of shape memory alloy actuators using thermoelectric devices

A method for feedback control of the temperature of shape memory alloy (SMA) actuators without using dedicated temperature sensors is presented in this paper. Thermoelectric devices (TEDs) are used to simultaneously sense and control the SMA temperature by alternating between driving the TEDs via the Peltier effect and measuring the local temperature difference across the TEDs via the Seebeck effect. A low-order ARX model that estimates the SMA temperature is derived. This model is used for feedback control of the SMA temperature in lieu of an external temperature sensor. A controller is implemented, which demonstrates the performance of the estimation technique. This method will enable the production of large arrays of TED-driven SMA tendon actuators, particularly for large DOF robotic systems.