Staubli International Ag.

Westinghouse Electric Corporation

Unimation, Inc.

Eimei M Onaga

Richard J Casler, Jr

Kenneth E Daggett

Richard A Johnson

Barrett L Booth

Leonard C Vercellotti

Rajan C Penkar

Roy E Lancraft

Norman J Bergman

Vincent P Jalbert

Kim Ngoc Trinh

Lane L Woodland

Chi Sha

James A Hart

Booth Barrett L

Marcus D Nuncy

Workpoint torque control is employed in an electron multiaxis robot controller. Robot axis torque is determined from axis motor current feedback. Axis torque requests are based on torque command and torque feedback in an axis torque control mode or on the basis of position, velocity and torque commands and position, velocity and torque feedback in a combined position/torque control mode, or an indirect torque control mode.

Multiaxis robot controller having workpoint torque control

A pulse width modulation (PWM) control circuit provides for improved implementation of position, velocity and current feedback loops for digital servo control of a multi axis robot. The PWM circuit utilizes a single resistor for sensing joint motor drive current. Circuitry is also disclosed for reducing audible noise and motor heating in large servo motors used for joint arms operated at relatively low PWM frequencies by reducing the motor ripple current.

Digital robot control having pulse width modulator operable with reduced

The partitioning of circuitry and software on electronic boards in a robot control is arranged to enable respective controls for varied types of robots to be readily assembled and packaged with use of a few standard boards. The basic control system is formed from an arm interface (AIF) board and a torque processor (TP) board and a servo control (SCM) board. The AIF board has a VME bus terminated in multiple pin connectors for interconnection with the TP and SCM boards and any other boards or additional units to be included in a particular robot control. An AIF connector is also provided for TP board connection on a VMX bus. Robot controls with extended control performance are packaged by including additional boards. For example, the system control board includes a VME bus connector for connection to the AIF board to provide a robot control with higher control capacity. Input/output devices such as programmable controllers, peripherals such as CRTs, and supervisory computers can also be coupled to the control through AIF interconnectors. The AIF board contains robot dependent circuitry so that different AIF boards can be used to assemble different controls for different robots. For example, different board circuitry is used for absolute position feedback as opposed to incremental position feedback or for brush type DC motors are opposed to brushless DC motors.

Universal robot control board configuration

A digital control provides adaptive feedforward torque control for a robot having a plurality of arm joints. An electric motor drives each of the robot arm joints and a power amplifier supplies drive current to each motor under controlled operation. Each joint motor has feedback control loop means including position and velocity control loops driving a torque control loop in accordance with position commands to generate motor commands for controlling the associated power amplifier. The motion of said joint motor generates position and velocity feedback signals respectively for combination with the position and velocity commands to generate an error signal as a torque command for each of the torque control loops from the corresponding position and velocity control loops. Load force is sensed at the endmost robot joint. The actual load moment for each robot joint on the basis of the load force and the dynamic/kinematic data moment is computed for each robot joint on the basis of stored dynamic and kinematic data for the robot arm. The data and load moments are combined for each joint and applied as a feedforward torque for combination with the position and velocity errors in generating the torque command for each of the torque control loops. A feedback signal representative of the joint motor drive current is combined with the torque command to generate a torque error signal in each torque control loop.

Robot control system having adaptive feedforward torque control for

A modular digital robot control includes an electronic arm interface board provided with circuitry for performing robot arm dependent functions. Included are circuitry for generating power amplifier control signals in response to input voltage command signals and circuitry for processing and manipulating position, velocity and motor current feedback signals. An electronic torque processor board is provided with paired torque microprocessors for operating each of respective torque control loops for respective robot joint motors. The torque microprocessors generate the voltage commands in response to input torque commands and feedback motor current signals. An electronic servo control board is provided with paired position/velocity microprocessors for operating position and velocity control loops for the respective joint motors. The position/velocity microprocessors generate the torque commands in response to input position commands and feedback position and velocity signals. The servo control board further includes system resource facilities providing general support for the operation of the microprocessors and includes a DMC controller and two asynchronous controllers for communications interfacing with local input/output devices and other systems and devices. When executed in one of the position/velocity microprocessors, a stored motion program uses trajectory planning and interpolation to generate position commands in accordance with predefined moves set forth in a robot program. The servo control, torque processor and arm interface boards are interconnected to provide a complete basic control for the robot joint motors. An optional fourth electronic board can be connected to the basic control. It is called a system board and it includes paired system microprocessors that execute the motion program enabling the expanded control to provide extended robot control performance.

Modular robot control system

A digital control for a multiaxis robot includes position, velocity and torque controls that drive a motor voltage control loop. Pulse width modulated control signals operate power switches in a power bridge to control the current to each robot joint motor. A single resistor is connected in the bridge circuit to supply motor current feedback needed for control loop operation.

Digital robot control having an improved current sensing system for

A control system is provided for a workcell having a plurality of electric robots and a plurality of workcell equipment items in turn having a plurality of control and sensor devices associated therewith. Respective electronic robot controllers are disposed at respective workcell locations to operate robots as a part of the workcell process. Each robot controller has a floppy disk or other means for loading program data for one of the robot controllers. A first input/output control module is disposed at another workcell location and it has connected thereto as inputs a first group of the sensor devices and as outputs a first group of the control devices. Second and third input/output control modules are disposed at additional workcell locations and have connected thereto as inputs second and third groups of the sensor devices and as outputs second and third groups of the control devices. Additional input/output control modules are associated with the other robot controllers, and are similarly connected and placed in spaced workcell locations.

Robotic workcell control system having improved input/output interfacing

A digital position and velocity feedback system is provided for a multiaxis robot control and it employs an LSI chip to process incremental position signals for position change and velocity computations. At low speeds, velocity is computed from the reciprocal of elasped time. At higher speeds, velocity is computed from the rate at which incremental position signals are generated.

Position and velocity feedback system for a digital robot control

Circuitry is provided for applying a pulse width modulation (PWM) scheme to a brushless DC motor that operates as a robot axis drive. A pulse width modulation (PWM) scheme provides for digital implementation of robot control commands. For this purpose, it provides time stabilized current sampling synchronized to the sampling frequency of the position and velocity loops in the robot control. The brushless drive application circuitry provides for application of the PWM control outputs to commutate the motor energization from winding pair to winding pair.

Digital robot control providing pulse width modulation for a brushless

A digital robot control is provided with position/velocity and torque control loops with microprocessor servo controllers in each. The position/velocity servo controller includes two microprocessors that operate as a servo engine in providing position/velocity control for six robot axes. One microprocessor operates as a manager to perform data processing and coordination tasks supportive to position/velocity control. The other microprocessor performs position and velocity servo calculation tasks and operates as a slave processor to the position/velocity control manager. The programming for the position/velocity control sends manager position and other commands and position and velocity feedback from other control levels to the position/velocity calculator and sends torque commands received from the calculator to the next lower control level. The calculator employs position/velocity control algorithms in making torque command calculations.

Multiprocessor position/velocity servo control for multiaxis digital

A digital robot control includes a position/velocity microprocessor control and a torque microprocessor control for each of multiple robot axes. Digital position, velocity and motor current feedback signals are generated from motor sensor signals for use in making microprocessor control calculations. Another motor sensor generates an overlimit signal when motor temperature rises above a limit value to indicate excessive motor current. The torque microprocessor makes a backup motor energy calculation from the feedback motor current signal from each joint motor and compares the result to a stored motor energy limit. The robot is shut down if either limit is exceeded.

Multiaxis robot control having improved energy monitoring system for

A digital robot control is provided with cascaded position/velocity and torque control loops with microprocessor servo controllers in each. The servo controller includes two microprocessors that operate as a servo engine in providing motion control for six robot axes. One microprocessor is structured to perform data processing and coordination tasks. The other one performs calculation tasks and operates as a slave processor to the first.

Multiprocessor torque servo control for multiaxis digital robot control

A robot is provided with an arm having a plurality of motor driven joints. A power amplifier supplies drive current to each joint motor. Respective digital feedback control loop arrangements generate voltage commands from which signals are generated to operate the power amplifiers. Digital motor current, position and velocity feedback signals are generated for position, velocity and torque control loops in the digital feedback control loop arrangement. System resource facilities provide general support for the operation of the digital feedback control loops and include three separate communications controllers, a dual port microprocessor interfacing memory, a time stamp clock, a program memory and a nonvolatile data memory. A system level microprocessor based system or a microprocessor based position/velocity control system executes motion software from the program memory means according to whether the user desires an expanded performance robot control or a basic robot control. In the basic control, only the position/velocity microprocessor system is included and it is coupled to the system resource facilities. In the expanded control, both microprocessor systems are included and both are coupled to the system resource facilities.

Basic digital multi-axis robot control having modular performance

A digital robot control includes a position/velocity microprocessor control and a torque microprocessor control for each of multiple robot axes. Digital position, velocity and motor current feedback signals are generated from motor sensor signals for use in making microprocessor control calculations. A backup velocity determination is made for each joint motor by the torque microprocessor from the motor current feedback, the motor command terminal voltage and the motor resistance and inductance. The robot is shut down if the difference between the feedback and backup velocity values exceeds a predetermined limit.

Multiaxis digital robot control having a backup velocity monitor and

A completely digital robot control operates at a predetermined sampling rate. The robot arm has a plurality of joints with each driven by an electric brushless or brush-type DC motor which is in turn supplied with drive current by a power amplifier bridge circuit having power switches connected therein to supply motor winding current in the forward or reverse direction. Incremental or absolute encoders and tachometers provide for generating digital position and velocity feedback signals generated synchronously with the sampling rate. Digital motor current feedback signals are also generated synchronously with the sampling rate. Paired position/velocity microprocessors generate torque commands for each of the robot axes at the sampling rate in response to the position commands and the position and velocity feedback signals. Paired torque microprocessors generate motor voltage commands for each of the robot axes at the sampling rate in response to the torque commands and the current feedback signals. Pulse width modulators generate digital motor control signals for each of the robot axes at the sampling rate in response to the voltage commands. The digital control signals for each axis are coupled to control terminals of the corresponding power switches to control on/off switch time and satisfy the motor voltage commands and thereby satisfy the position commands.

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Brookfield Center, CT, United States of America

Eimei M Onaga