Control system for reducing internally generated frictional and inertial resistance to manual positioning of a surgical manipulator

• US 7,819,859 B2
• Filed: 06/30/2006
• Issued: 10/26/2010
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Original Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Inventors: Larkin, David Q., Prisco, Giuseppe, Nowlin, William C
• Primary Examiner(s): Johnson, III; Henry M
• Assistant Examiner(s): LIPITZ, JEFFREY BRIAN
• Application Number:
  US11/479,144
• Publication Number:
  US 20070142823A1
• Time in Patent Office: 1,579 Days
• Field of Search: 606/1, 606/130, 345/156
• US Class Current: 606/1
• CPC Class Codes: A61B 34/30 Surgical robots
• CPC Class Codes: A61B 34/32 operating autonomously
• CPC Class Codes: A61B 34/35 for telesurgery
• CPC Class Codes: A61B 34/37 Master-slave robots A61B34/35 takes precedence
• CPC Class Codes: A61B 34/70 Manipulators specially adapted for use in surgery
• CPC Class Codes: A61B 34/75 Manipulators having means for prevention or compensation of hand tremors
• CPC Class Codes: A61B 90/361 Image-producing devices, e.g. surgical cameras
• CPC Class Codes: B25J 9/1638 compensation for arm bending/inertia, pay load weight/inertia
• CPC Class Codes: B25J 9/1641 compensation for backlash, friction, compliance, elasticity in the joints
• CPC Class Codes: B25J 9/1689 Teleoperation
• CPC Class Codes: G05B 2219/41213 Lookup table for load, motor torque as function of actual position
• CPC Class Codes: G05B 2219/41426 Feedforward of torque
• CPC Class Codes: Y10S 901/02 Arm motion controller
• CPC Class Codes: Y10S 901/15 Jointed arm
• CPC Class Codes: Y10S 901/28 Joint
• CPC Class Codes: Y10S 901/30 End effector

Abstract

A robotic control system is placed in clutch mode so that a slave manipulator holding a surgical instrument is temporarily disengaged from control by a master manipulator in order to allow manual positioning of the surgical instrument at a surgical site within a patient. Control systems implemented in a processor compensate for internally generated frictional and inertial resistance experienced during the positioning, thereby making movement more comfortable to the mover, and stabler from a control standpoint. Each control system drives a joint motor in the slave manipulator with a saturated torque command signal which has been generated to compensate for non-linear viscous forces, coulomb friction, cogging effects, and inertia forces subjected to the joint, using estimated joint angular velocities, accelerations and externally applied torques generated by an observer in the control system from sampled displacement measurements received from a sensor associated with the joint.

Claims

1. A robotic surgical system comprising:

a master manipulator;

a slave manipulator having a plurality of jointed structures for providing multiple degrees of freedom movement to a surgical instrument when coupled to the slave manipulator, a plurality of motors to drive movement of the plurality of jointed structures, and a plurality of sensors to measure movement of corresponding of a plurality of joints of the plurality of jointed structures;

a master/slave control system configured to control movement of the slave manipulator in response to manipulation of the master manipulator;

at least one control system configured to generate a signal by processing measurements received from a corresponding one of the plurality of sensors to drive a corresponding one of the plurality of motors so as to reduce effects of internally generated frictional and inertial resistance when at least a portion of the slave manipulator is manually moved in order to position or orientate the surgical instrument at a surgical site within a patient; and

a switch to engage the master/slave control system and disengage the at least one control system when the switch is in a first state and to disengage the master/slave control system and engage the at least one control system when the switch is in a second state.

2. The robotic surgical system according to claim 1, further comprising a switch activating mechanism disposed on the slave manipulator so as to allow a user proximate to the slave manipulator to interact with the switch activating mechanism to place the switch in the first and second states.

3. The robotic surgical system according to claim 2, wherein the switch activating mechanism is implemented by a button provided on the slave manipulator.

4. In a robotic surgical system including a master manipulator, a slave manipulator, a master/slave control system for controlling movement of the slave manipulator in response to movement of the master manipulator, the slave manipulator coupled to a surgical instrument and having a plurality of joints, a plurality of motors driving the joints, and a plurality of sensors for detecting motion of the joints;

the improvement comprising;

a slave manipulator control system including an observer coupled to one of the sensors and configured to estimate a velocity and acceleration of the joint corresponding to the sensor, and a signal generator configured to generate a signal to drive the motor corresponding to the joint using the estimate of the velocity and acceleration of the joint, so as to reduce internally generated frictional and inertial resistance when manually moving at least a portion of the slave manipulator in order to position or orientate the surgical instrument; and

a user operable switch to engage the master/slave control system and disengage the slave manipulator control system when the switch is in a first state, and to disengage the master/slave control system and engage the slave manipulator control system when the switch is in a second state.