Electromyography operated soft finger-like actuator for prosthesis

Soft robotics has a variety of applications in a broad spectrum of industries as it is an intersection of material technology, engineering and biology which offers innovative solutions. The primary aim of the proposed research article is to develop and actuate a finger-like soft actuator utilising an EMG (electromyography) sensor, a micro-controller, and an air pump. The EMG sensors detect muscle movement and transmit the signal to the microcontroller. The microcontroller transmits the pulse to the air pump through the DC pump controller (MOSFET). The bending angle of the soft actuator is determined by the utilisation of a digital gyroscope (MPU 6060), while the force created by the soft actuator is measured using analogue force sensors. The EMG sensor is calibrated using the MyoWare, which is a more precise version of an EMG sensor. The force sensor is calibrated using a load cell (1 kg capacity), while the gyro sensor is calibrated using a servo motor and 32-bit servo controller. The current work utilises a CPID controller to regulate the DC air pump, through feedback obtained from the MPU6050 sensor. The system’s response using a PID controller is also compared to the response of a basic close-loop system and an ON/OFF controller. In the present work, a methodology to fabricate a fibre-reinforced soft finger-like actuator using an FDM 3D printer and a silicon moulding technique and control it using sensors is expounded. Reinforcement is carried out for unidirectional bending. The experimental results demonstrate that the CPID controller effectively positioned the soft actuator close to the desired bending angle of + 32.6 degrees, with a pressure of + 14.4 kPa. This level of accuracy was adequate for an amputee to successfully grip an object, as indicated by the force sensor mounted at the tip of the soft actuator. The experimental setup was successfully tested on four individuals for 10 cycles.