Evaluating curvature and making picture-overlaid trajectory of motion of largely bent carbon nanotube composite bucky gel actuator using camera measurement system

• We proposed a camera imaging measurement system for CNT actuators.
• Our proposed system implements the SNAKE method, which has higher noise tolerance.
• The proposed method can measure the curvature of a CNT actuator with high accuracy.
• Accuracy evaluation of our proposed system showed an average error of only 0.03 mm.

Carbon nanotube composite bucky gel actuators (CNT actuators) are ionic electromechanically active polymers that respond mechanically when low voltage (1–3 V) is applied to them. In general, the performance of CNT actuators is evaluated using curvature, which is calculated using single-laser displacement sensor data. However, recent studies have revealed that the actual curvature cannot be measured by a single laser. Several researchers suggest the use of high-speed laser profilometer measurements from which highly accurate data of the actuator behavior can be obtained. However, these data are very complicated and cannot be used to measure an actuator under very large deformations where the tip of the actuator cannot be observed by a laser sensor. Our aim is to develop a camera measurement system that implements the SNAKE method, which outputs the actuator behavior using a picture-overlaid trajectory of motion and is capable of measuring any actuator shape. In Experiment 1, we evaluated the accuracy of the camera measurement and obtained an accuracy of under 0.03 mm. In Experiment 2, we generated a picture-overlaid trajectory of motion of the actuator behavior and the curvature at each point along the bent actuator.