Presents the design and implementation of a new robotic system for assisting surgeons in performing minimally invasive surgical procedures. This system is designed for collaborative operation between the surgeon and the robot. In addition, it has the following attributes: quick interchangeable end tools, programmable collaboration with the surgeon, and coordinated motion of multiple robotic devices for performing complex procedures. Two such devices have been built, with a variety of end-tools. The system has demonstrated direct manual operation and surgeon-supervised autonomous stitching and knot tying. In addition to the mechanical design and kinematic analysis, several autonomous knot-tying algorithms and the associated kinematic requirements are discussed. Note that, as the focus here is on the robot design and control, other important aspects on the clinical deployment of surgical robots such as safety, fault detection and amelioration, man-machine interface design, etc., are not addressed here.