Importance

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Abstract

A robot is disclosed having a plurality of movable links or members interconnected end-to-end in series. Associated with each is an actuator and position transducer. Some of the links are relatively massive and cannot be readily moved without power assistance when the robot is manually programmed, while other links or members, namely those constituting the wrist, are relatively lightweight which permits movement thereof without power assistance during manual programming. A force transducer is connected in series with the output element of the robot in association with one of the massive links located between the wrist and the stationary base on which the robot is mounted. The transducer senses forces during programming applied to the massive links via the wrist when manual programming forces are applied to the robot output. The force transducer provides an output signal for each of the massive links correlated to the component of the manual programming force transmitted thereto via the wrist. These force transducer output signals are all compensated for inertial forces applied to the massive links due to acceleration of the wrist mass, while only those force transducer output signals associated with massive links moving in a vertical plane are compensated for gravitational forces applied thereto resulting from the effects of wrist mass. During programming, the inertial and/or gravitational force compensated force transducer output signals are applied to the actuators of their respectively associated massive links to move the massive links in power-assisted fashion, while the lightweight links of the wrist move in unpowered fashion in response to the manual force applied thereto during programming. The power-assisted motion provided to the massive links by their respectively associated actuators, coupled with the unpowered motion of the lightweight links constituting the wrist, collectively produce motion of the robot output element in the direction to which the manual force is applied thereto during manual programming. The transducer outputs can also be compensated for nonuniform acceleration of the wrist by modifying the force transducer output in accordance with the third derivative with respect to time of the displacement of the wrist. This enhances the 'feel' of the robot during manual programming.

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First Claim