Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Reexamination Certificate
1999-12-10
2001-03-20
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
C318S568210, C318S646000, C254S001000
Reexamination Certificate
active
06204620
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention relates to the method of controlling a powered manipulator within a workspace by operator inputs.
2. Description of the Prior Art
The moving of heavy objects from one location to another traditionally is accomplished by the use of a powered manipulator or more typically, an unpowered manipulator that utilizes overhead rails or a bridge gantry with a carriage movably supported thereon. An arm is pivotally attached to the carriage to lift the objects from overhead. When moving a heavy object, it is desirable to have the operator as close to the object as possible to make movement of the object more intuitive as if the operator was actually lifting and moving the object. To this end, it is desirable to utilize power assisted manual manipulators.
Methods to control a power assisted manual manipulator must provide adequate operator safety and still provide an intuitive human interface. One method of controlling an assist device is comprises the steps of utilizing an actuator to sense the required force for lifting a load, providing an end-effector to interface between a human operator and the load, engaging the load with the end effector, detecting a magnitude of human force imparted by the operator on the end-effector as the operator lifts the load and using the magnitude of the human force to regulate the actuator and cause the actuator to lift the load. This method utilizes the imparted force by the operator to govern the force provided to assist in lifting the load. In this way an operator maintains the feel of lifting the load and moving it but exerts only enough force to control the moving of the load.
Another method of moving a load is exemplified by a power assist device used by an operator to pick up an instrument panel off a rack and guide the instrument panel into a vehicle cabin for attachment therein. The operator does not support the weight of the instrument panel and is free to move the instrument panel around the workspace without constraint. The deficiency in this method is that there is no restraint on powered manipulator motion. As a result, the power assist device can be freely wielded by the operator, and the operator may inadvertently move the instrument panel into anything, damaging both the instrument panel and whatever the panel hits.
SUMMARY OF THE INVENTION AND ADVANTAGES
A method of controlling a powered manipulator having at least one motor is disclosed. The powered manipulator utilized in the method includes a plurality of force sensors on a manual control handle combined with a microprocessor for controlling the powered manipulator within mechanical limits of the powered manipulator is disclosed. The method includes the steps of imparting a force on the control handle, sensing the direction and magnitude of the force with the plurality of force sensors and sending the force data to the microprocessor, processing the force data from the plurality of force sensors with the microprocessor to create movement commands for the powered manipulator, and moving the powered manipulator in response to the movement commands from the microprocessor. The method is characterized by programming the microprocessor for establishing virtual constraints to limit the movement of the powered manipulator within a virtual workspace.
Accordingly, the established virtual constraints allow freedom of movement of the powered manipulator without the risk of the powered manipulator bumping into objects within the work area when moving a workpiece. Additionally, the virtual constraints assist the operator in guiding the powered manipulator to a specific position by gradually diminishing the area in which the powered manipulator can be moved. As appreciated, this method accomplishes controlled movement of a load without sacrificing operator safety. Further, the evident advantages associated with an intuitive human interface are maintained.
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McGee Dean
Swanson Peter
Fanuc Robotics North America
Howard & Howard
Leykin Rita
Nappi Robert E.
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