Force-Controlled Movement on Irregular Curved Surfaces for Constant-Pressure Contour-Following in Rubber Tapping Applications

—Tapping of rubber trees is a manual task whereby liquid latex is acquired from rubber tree by means of precise cuts made by a skilled worker. This paper outlines a method of using a 6 degree-of-freedom robot arm for automated rubber tapping which attempts to create a constant force of 25N towards the centre of the tree as the end effector is moved around it in a cutting motion (semicircular helix). Internal torque sensors at the joints are used to sense the contact force. An ABB GoFa robot is used for this purpose and the force is sensed via their Force Control Standard library. The force estimated by the robot is validated with an external force sensor and results show that reduced manipulability has a negative impact on controller stability. Furthermore, the accuracy of the force estimation functionality is degraded when the trajectory of the robot causes the angular velocity of one or more of the joints to slow.     «

—Tapping of rubber trees is a manual task whereby liquid latex is acquired from rubber tree by means of precise cuts made by a skilled worker. This paper outlines a method of using a 6 degree-of-freedom robot arm for automated rubber tapping which attempts to create a constant force of 25N towards the centre of the tree as the end effector is moved around it in a cutting motion (semicircular helix). Internal torque sensors at the joints are used to sense the contact force. An ABB GoFa robot is u...     »