Dextrous motion control of a redundant SCARA robot

A kinematically redundant SCARA type robot with increased manoeuvrability provided by an additional axis is presented. By means of a dextrous motion control approach the extra degree of freedom is used to perform several secondary goals in order to maintain the system availability even in restricted configurations. For this purpose the primary end-effector task is enhanced by an appropriate homogeneous motion from a gradient projection onto the Jacobian null space. Different performance criteria are used to avoid joint limits, singularities or nonconservative joint motions. In order to enable safe manipulation in restricted environments the robot arm is prevented from colliding with work space obstacles represented by artificial potential fields.