Behaviour of NiTi Based Smart Actuator for the Development of Planar Parallel Micro-Motion Stage

Recently, the application of smart materials such as shape memory alloys (SMAs) as actuators is gaining huge importance. SMA-based actuators are light in weight and provide higher work/mass. SMA undergoes simple actuation process such as Joule heating. Nitinol (NiTi) SMA can restore larger strains as compared to others. It can serve as active prismatic joint to provide linear motion in various robotic manipulators. The study correlates the deflection of (a) single NiTi spring and (b) series-connected NiTi springs with input parameters (time and current) to understand its behavioural complexity. The study revealed that the rate of NiTi spring contraction is dependent on time and current. To predict the actuation motion, several regression models were developed. This study defined the feasible current range for the actuation of NiTi spring based on contraction rate and precision. The contraction rate for single NiTi spring differs from the series connection of two NiTi springs which results a new set of polynomial regression model. The developed mathematical models can help control the smart actuation-based planar parallel robotic manipulators.