Type synthesis of 2R1T remote center of motion parallel mechanisms with a passive limb for minimally invasive surgical robot.

• Propose a type synthesis method to design 2R1T RCM PMs with a passive limb. • Propose several novel 2R RCM composite joints and 2R1T RCM passive limbs. • Obtain numerous 2R1T RCM PMs with a passive limb. • Propose evaluation criteria that enable the selection of the optimal designs. In view of the demands for medical imaging compatibility and efficient space occupation around the surgical site, this paper proposes remote center of motion (RCM) parallel mechanisms (PMs) with a passive limb to enable more flexible arrangement of the limbs and actuators in a RCM surgical manipulator. A type synthesis method is proposed to design the 2R1T RCM PMs with a passive limb based on the Lie group. The motion requirements for the RCM mechanism are first expressed in the form of Lie group. The motion arrangement and kinematic structure development are then implemented to obtain the active and passive limbs. By means of this approach, numerous 2R1T RCM PMs with a passive limb are synthesized. The actuated joints are then selected, and a few qualitative evaluation indices are proposed. Finally, the motion configurations of two generated mechanisms are validated through simulation. The proposed method is universally effective for the type synthesis of multi-degree of freedom RCM PMs with a passive limb. [ABSTRACT FROM AUTHOR]