Configuration Control of Planar Underactuated Robotic Manipulator using Terminal Sliding Mode

Robotic manipulators find their applications in various fields. Some applications need cheap and light weight robotic manipulators. This need is fulfilled by using underactuated robotic manipulators, where few joints are unactuated, either by design or actuator failure. Further, it may be desired for the end effector of the robotic manipulator to reach a particular position in Cartesian space so that all its joints whether active or passive achieve their desired angular positions from any arbitrary initial positions. It is a challenging task to control such an underactuated robotic manipulator. In the present work, a finite time convergent and robust controller is presented for joint configuration control of three link planar articulated underactuated robotic manipulator using a combination of terminal sliding mode control and higher order sliding mode. Dynamic coupling between the joints has been put to use for controlling movement of passive joint. Simulation results show that all the joints obtain their desired angular positions. The control design is aimed at getting a chatter free and robust control.