Surgical robots rotate through precision motors driving a multi-joint arm. High-precision servo systems and motion control algorithms work together.
Drive system
Three main parts support rotation:
Servo motors: brushless DC motors such as the Maxon EC-i series. Positioning accuracy can reach 0.001 degrees. Torque range is 0.01 to 2 N·m.
Reducers: harmonic drives such as the HD series or planetary gears. Reduction ratio is 50:1 to 160:1. Backlash is less than 1 arcmin.
Encoders: absolute optical encoders such as the Heidenhain EQN series. Resolution is 27 bit/rev.
Motion transfer
Wrist joints: cable drive as in the Da Vinci series or linkage mechanisms. They provide ±90° pitch and 360° rotation.
Instrument rotation: a worm gear mechanism provides continuous 360° rotation around the instrument axis.
Remote center of motion (RCM): a parallelogram structure keeps all motion around the incision point.
Control accuracy parameters
Repeat positioning accuracy: less than 0.1 mm (Da Vinci Si system)
Maximum motion speed: 10 cm/s
Force feedback resolution: 0.01 N (Verb Surgical system)
Motion scaling: 3:1 or 5:1
Safety braking
Electromagnetic brake: locks the joint immediately when power is lost.
Dual encoder verification: the main encoder and the motor-end encoder are compared in real time.
Torque monitoring: joint torque is monitored continuously and triggers a stop when abnormal.
The latest models such as the Da Vinci SP1098 system use improved direct drive motors to reduce transmission chain error. Joint degrees of freedom reach 7, one more redundant degree than traditional models. All motion data must meet IEC 80601-2-77 medical robot safety standard.
Hansheng Automation machines precision parts for surgical robot joints and drive systems from customer drawings, including single-piece and small-batch orders.
