Grasping Force Compensation Using a Fingertip Mechanism with Contact Point Estimation

Abstract

Research has been extensively conducted on achieving stable grasping with a robot hand. Scientists have analyzed the slip and contact conditions and the grasping force. However, fault tolerance is a significant concern because the robot hand is expected to come into frequent contact with objects when the tactile sensor is positioned at the fingertip. Sensors that combine a flexible surface, such as gel, with a camera are less durable. Therefore, this paper proposes a method for contact point estimation and slip detection that does not require a tactile sensor. This method involves the combination of a pneumatically driven parallel link finger module and a fingertip mechanism using a pneumatic cylinder. Pressure change of the pneumatic cylinder is used to estimate the position of the contact point of the objects, and slippage is detected from the change in contact position. There is no need to place the sensor on the fingertip in this method. Therefore, this method is expected to improve failure resistance and help realize a robot hand that can grip stably. The ability to estimate the contact point position and compensate the grasping force for the slip via the proposed finger mechanism is confirmed via experiments.