2.1.1.2. Master Tele Manipulators
There are two MTMs per system, one for the left hand and one for the right hand. The left and right MTMs are identical except for the wrist gimbal assemblies which are mirrored.
The MTMs are used to track the position of the surgeon’s hand and provide some force feedback (i.e. they are haptic devices).
da Vinci Classic and S MTM
Basic information:
Each MTM is attached to the surgeon console using 4 bolts. The first axis (rotation) should be vertical.
7 motorized degrees of freedom, 7 actuators with optical encoders. MTMs are over-actuated
The first 4 motors are located on the shoulder and use cable transmission, the last 3 are on the wrist and use gears
Some joints (second to fourth) are controlled by multiple actuators (actuator to joint coupling matrix)
All joints have analog potentiometers, used for both homing and safety checks
The gripper has an analog position sensor (Hall effect) and is not motorized
The arm is designed with counter weights to stay as balanced as possible
Motors are used to:
Fine tune the gravity compensation
Enforce the wrist orientation to match the PSM’s orientation (teleoperation).
Provide some force feedback to reflect mechanical limits on the patient’s side
The 7th degree of freedom allows the wrist platform to move around and provides a large rotational space (SO3)
The gripper uses a combination of passive springs to emulate grasping forces