Enhancing Gripper Force Regulation For Fragile Object Handling: Current-Sensed Motor Controllers

A multitude of industries are on the verge of getting automated and the need for human like touch at low cost and simple implementation is increasing. Nevertheless, one of the main problems associated is controlling the gripping force on objects which often requires either electric grippers with expensive and complicated sensor systems or soft robotic grippers actuated by either air suction or deformation. However, both these grippers are expensive and not precise when controlling grasp force. This research focuses on the development of a low-cost gripper design consisting of three fingers actuated using a DC motor. The current through the actuator was measured to identify grasping point. The gripper was tested to grasp soft objects like tomatoes and fragile hard objects like eggs. The current was measured using the inbuilt analog to digital converter of the microcontroller using a shunt resistor. Results obtained was filtered for noise using an exponential filter in software. At threshold values ranging from 780 to 850 on the microcontroller serial output the objects were generally grasped. This mechanism proved to be effective at identifying the grasping point of objects however a more high-resolution data with further experimentation is required to accurately determined the exact point of grasping.