Motion controller for redundant or nonredundant linkages
AssigneeRobotics Research Corporation
InventorsHarvard I. Vold, James D. Farrell
Life of this patent
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Abstract
A linkage mechanism, such as an industrial robot, comprises an electronic motion controller and a set of self-driven joints. A controller receives a series of end effector positions from memory or from a host control system which define a routine for the mechanism to execute in relation to a predetermined reference frame such as cartesian coordinates. Angular values for the joints are computed in real time which follow the predetermined reference frame values in a manner which avoids the problems of singularities and which efficiently accommodates kinematic redundancy. A corresponding drive signal is generated for each joint.
Claims34
An apparatus for moving an end effector in response to input signals which define a series of discrete positions along a path of a point associated with said end effector, said apparatus comprising:
- a. a manipulator upon which the end effector is mounted, the manipulator having a plurality of joints, at least one of said joints including an actuator;
- and
- b. a manipulator controller, including a means for providing drive signals to said actuators, the controller comprising:
- (1) means for generating data sets which identify cartesian coordinate values of points along said end effector path;
- (2) means for computing a set of joint angles corresponding to said cartesian coordinate points based on the constrained minimization of a convex objective function referenced to a fixed origin;
- (3) means responsive to said joint angles for producing a drive signal for each of said joint actuators;
- and
- (4) means for iterating the functions provided by means 1 through 4 to cause said end effector point to move through a series of increments along a path.
An apparatus for moving an end effector in response to input signals which define a series of discrete positions along a path of a joint associated with said end effector, said apparatus comprising:
- a. a manipulator upon which the end effector is mounted, the manipulator having a plurality of self-contained, modular joints linked in a series, each non-static, joint including an actuator and a means responsive to the position of the joint for producing a signal;
- and
- b. a manipulator controller, including a means for providing appropriately compensated servo drive signals to said actuators, said controller comprising:
- (1) means for generating data sets which identify cartesian coordinate values of points along said end effector path;
- (2) means for computing a set of joint angles corresponding to said cartesian coordinate points based on the constrained minimization of a non-linearlized convex objective function referenced to a fixed origin;
- (3) means responsive to said position signals and to said joint angle values for producing a drive signal for each of said joint actuators;
- and
- (4) means for iterating the functions provided by means 1 through 4 to cause said end effector point to move through a series of increments along a path.
A method of controlling the motion of a manipulator end effector in response to input signals, which signals define a series of discrete positions along a path of a point associated with said end effector, comprising the steps of:
- a. generating data sets which identify cartesian coordinate values of points along said end effector path;
- b. computing a set of joint angle corresponding to each of said cartesian coordinate points based on the constrained minimization of a convex objective function referenced to a fixed origin;
- c. producing, in response to said joint angles, a drive signal for each joint actuator;
- and
- d. interating steps a. through d. to cause said end effector point to move through a series of increments along said path.
Dependencies are inferred from the claim text.