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Digital control for multiaxis robots

  • US 4,786,847 A
  • Filed: 11/20/1986
  • Issued: 11/22/1988
  • Est. Priority Date: 11/20/1986
  • Status: Expired due to Term
First Claim
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1. A completely digital control for a robot operating at a predetermined sampling rate and having an arm with each of a plurality of joints driven by an electric DC motor, each of said DC motors in turn supplied with drive current by a power amplifier bridge circuit having power switches connected therein to supply motor winding current in the positive direction or the negative direction, said robot control comprising:

  • digital means for generating position commands at the sampling rate for each of the robot axes in accordance with a stored robot program;

    means for sensing the position of each of said motors;

    means for generating digital position feedback signals synchronously with the sampling rate in response to said position sensing means;

    means for generating digital velocity feedback signals synchronously with the sampling rate for each of said motors;

    means for sensing the polarity and magnitude of motor current for each of said joint motors;

    means for generating digital current feedback signals synchronously with the sampling rate in response to said current sensing means;

    digital means for generating torque commands for each of the robot axes at the sampling rate in response to said position commands and said position and velocity feedback signals;

    digital means for generating motor voltage commands for each of the robot axes at the sampling rate in response to said torque commands and said digital current feedback signals;

    pulse width modulation means for generating digital motor control signals for each of the robot axes at the sampling rate in response to said voltage commands; and

    means for coupling said digital control signals for each axis to control terminals of the corresponding power switches to control on/off switch time and satisfy said motor voltage commands and thereby satisfy said position commands.

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