Medical robotic system with sliding mode control
First Claim
1. A method for controlling a joint in a medical robotic system in response to user manipulation of a master input device, comprising:
- computing a distance from a sliding surface using at least a position error associated with commanded movement of the joint;
computing a reaching law gain as a function of the absolute value of the distance;
computing a current state for an integrator using a prior state of the integrator and the distance;
computing a product of the reaching law gain and the distance;
limiting the product to be less than a maximum control action;
modifying the current state of the integrator using the limited product so as to limit a sum of the product and the current state of the integrator to be less than the maximum control action;
computing a sliding mode control action by summing the product and the modified current state of the integrator, andprocessing the sliding mode control action to generate one or more command signals to drive the joint according to the user manipulation of the master input device.
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Accused Products
Abstract
A medical robotic system has a joint coupled to medical device or a slave manipulator or robotic arm adapted to hold and/or move the medical device for performing a medical procedure, and a control system for controlling movement of the joint according to user manipulation of a master manipulator. The control system includes at least one joint controller having a sliding mode control for reducing stick-slip behavior on its controlled joint during fine motions of the joint. The sliding mode control computes a distance to a sliding surface, computes a reaching law gain, and processes the distance and reaching law gain to generate a sliding mode control action that is in absolute value less that a maximum desired feedback control action. The sliding mode control action is then further processed to generate a feedback torque command for the joint motor.
137 Citations
42 Claims
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1. A method for controlling a joint in a medical robotic system in response to user manipulation of a master input device, comprising:
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computing a distance from a sliding surface using at least a position error associated with commanded movement of the joint; computing a reaching law gain as a function of the absolute value of the distance; computing a current state for an integrator using a prior state of the integrator and the distance; computing a product of the reaching law gain and the distance; limiting the product to be less than a maximum control action; modifying the current state of the integrator using the limited product so as to limit a sum of the product and the current state of the integrator to be less than the maximum control action; computing a sliding mode control action by summing the product and the modified current state of the integrator, and processing the sliding mode control action to generate one or more command signals to drive the joint according to the user manipulation of the master input device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A medical robotic system having a master input device, a plurality of joints coupled to corresponding of a medical device or a robotic arm for moving the medical device, and a processor responsive to user manipulation of the master input device to control movement of one of the plurality of joints, wherein the improvement comprises configuration of the processor to control such movement by:
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computing a distance from a sliding surface using at least a position error associated with commanded movement of the joint; computing a reaching law gain as a function of the absolute value of the distance; computing a current state for an integrator using a prior state of the integrator and the distance; computing a product of the reaching law gain and the distance; limiting the product to be less than a maximum control action; modifying the current state of the integrator using the limited product value so as to limit a sum of the product and the current state of the integrator to be less than the maximum control action; computing a sliding mode control action by summing the product and the modified current state of the integrator; and processing the sliding mode control action to generate one or more command signals to drive the joint according to the user manipulation of the master input device. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for controlling a joint coupled to a medical device or a robotic arm adapted to move the medical device, in response to user manipulation of a master input device, comprising;
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computing a distance from a sliding surface using at least a position error associated with commanded movement of the joint; computing a reaching law gain as a function of the absolute value of the distance; computing a sliding mode control action by multiplying the reaching law gain and the distance; limiting the sliding mode control action to be less than a maximum control action; and processing the limited sliding mode control action to generate one or more command signals to drive the joint according to the user manipulation of the master input device. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A medical robotic system having a master input device, a joint coupled to a medical device or a robotic arm adapted to move the medical device, and a processor responsive to user manipulation of the master input device to control movement of the joint, wherein the improvement comprises the processor being configured to control such movement by:
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computing a distance from a sliding surface using at least a position error associated with commanded movement of the joint; computing a reaching law gain using the distance; computing a sliding mode control action by multiplying the reaching law gain and the distance; limiting the sliding mode control action to be less than a maximum control action, processing the limited sliding mode control action to generate one or more command signals to drive the joint according to the user manipulation of the master input device. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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41. A medical robotic system comprising:
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a joint coupled to a medical device or a robotic arm adapted to move the medical device; and a controller configured to control movement of the joint by;
computing a distance from a sliding surface using the following equation;
σ
=λ
·
(QC−
QL)+(VC−
VL)2,wherein σ
represents the distance, λ
is a parameter value, (QC−
QL) is a position error and (VC−
VL) is a velocity error associated with commanded movement of the joint;
computing a sliding mode control action based at least in part on the distance to the sliding surface; and
causing the joint to be moved at least partially in response to the sliding mode control action.
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42. A medical robotic system comprising:
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a joint coupled to a medical device or a robotic arm adapted to move the medical device; and a controller configured to control movement of the joint by;
computing a distance from a sliding surface;
computing a reaching law gain using the following equation;
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Specification