Method and apparatus for controlling a work implement

A method for controlling a work implement, the method comprising:

• a) providing a control member accessible to an operator of the work implement, the control member controllably displaceable by an operator from a neutral position to produce control signals indicating a first direction and a first magnitude;
• b) displacing the control member from the neutral position;
• c) providing the control signals to an input of a controller,
• d) providing to the controller one or more transducer signals identifying a current configuration of the work implement;
• e) in the controller:
• i) computing a desired path for the work implement, the desired path comprising a sequence of desired positions by:
• A) periodically sampling the control signal and the transducer signal;
• B) for each sample computing a desired direction and a desired velocity of the work implement from the control signal;
• and,
• C) for each sample extending the desired path by computing a new desired position, the new desired position obtained by determining on the desired path a path point which is closest to an actual position of the work implement and adding a vector to the path point, the vector having the desired direction and a length proportional to the desired velocity;
• and,
• ii) generating controller output signals at a processor output to operate actuators so as to move the work implement in a direction from the actual position to the new desired position with a velocity proportional to the distance between the actual position and the new desired position;
• and,
• f) applying the controller output signals to actuators on the work implement to actuate the actuators to move the work implement.

A method for controlling a work implement, the method comprising:

• a) providing a control member (71) accessible to an operator of the work implement (41), the control member controllably displaceable by an operator from a neutral position (73);
• b) displacing the control member (71) from the neutral position (73) in a first direction relative to a reference axis (75) through a distance equal to a first fraction of a distance between the neutral position and a maximum displacement of the control member (71) in the first direction;
• c) providing an output signal (j) representing the displacement of the control member (71) at an input of a controller (80), the output signal identifying at least the first direction and the first fraction;
• d) providing to the controller (80) one or more transducer output signals (.theta..sub.act) identifying a current configuration of the work implement;
• e) in the controller,
• i) computing a maximum velocity (.nu..sub.max) of the work implement (41) in a desired direction of motion corresponding to the first direction;
• ii) computing a desired velocity of the work implement, the desired velocity proportional to the first fraction multiplied by the maximum velocity;
• and,
• iii) generating controller output signals at a processor output corresponding to the desired direction and the desired velocity, and,
• f) applying the controller output signals to actuators on the work implement (41) to cause the actuators to move the work implement in the desired direction at the desired velocity.

A control system for a work implement comprising an articulated arm (41) the system comprising:

• a) a control member accessible to an operator of the work implement (41), the control member controllably displaceable by an operator from a neutral position (73) in a desired direction through a desired fraction of a maximum displacement distance to produce a control signal (j);
• b) two or more angular position transducers, one of the transducers coupled to each of two or more pivoting joints on the articulated arm, the transducers producing transducer signals representing a current configuration of the articulated arm;
• c) a controller connected to receive the control signals and the transducer signals, the controller comprising:
• i) means (1310) for computing a desired velocity from the control signal;
• ii) vector computation means (1314) for computing from the desired velocity a vector (.delta.p) to be added to a previously computed trajectory;
• iii) path point computation means (1316, 1318) for computing from the transducer signal a path point (p.sub.path) on the previously computed trajectory closest to an actual position of the arm (41);
• iv) vector addition means for extending the previously computed trajectory by adding the vector (.delta.p) to the path point (p.sub.path);
• and,
• v) control means for operating actuators (44,50,60) associated with the joints (42,52,58) to move an endpoint (65) of the arm along the extended trajectory.

A control system for a work implement comprising two or more movable coupled members (40,48,56) and a number of actuators (44,50,60) for moving the coupled members relative to one another, the control system comprising:

• a) one or more operator controls collectively having at least two degrees of freedom, the controls manipulable by an operator of a work implement to produce first and second output signals indicating a degree of displacement of the controls from a neutral position toward a maximum displacement;
• b) one or more transducers coupled to the work implement, the transducers producing transducer output signals representing relative positions of the coupled members;
• c) a processor connected to receive the first and second output signals and the transducer output signal, the processor having an output and adapted to:
• i) compute a desired direction of motion from the first and second output signals;
• ii) compute a maximum velocity of the work implement in the desired direction of motion from the transducer output signals;
• and,
• iii) generate controller output signals at the processor output to actuate the actuators to move the work implement in the desired direction at a calculated velocity wherein the ratio of the calculated velocity to the maximum velocity is generally proportional to a ratio between the displacement of the controls to the maximum displacement;
• wherein the processor output is coupled to apply the controller output signals to the actuators (44,50,60).

A controller for a work implement, the controller comprising:

• a) a set of one or more control inputs for receiving a control signal from one or more operator controls, the control signal representing;
• b) a set of one or more transducer inputs for receiving transducer signals representing a current configuration of a work implement;
• c) a processor connected to the control inputs and the transducer inputs, the processor having one or more controller outputs, the processor adapted to
• i) compute a desired direction of motion from the control signal;
• ii) compute a maximum speed of the work implement in the desired direction of motion from the transducer output signals;
• and,
• iii) generate controller output signals at the processor output to actuate the actuators to move the work implement in the desired direction at a calculated speed wherein the ratio of the calculated speed to the maximum speed is proportional to the ratio between the displacement of the controls to the maximum displacement.