James J. Carroll

Tracking control of rigid-link electrically – driven robot manipulators

This paper illustrates a simple, hand-crafted approach which can be used to design tracking controllers for rigid-link electrically-driven (RLED) robot manipulators. The control methodology is intuitively simple since it is based on concepts readily identified by most control engineers. To illustrate the approach, we develop a corrective tracking controller for the RLED robot dynamics which yields global exponential stability for the link tracking error under the assumption of exact model knowledge. To compensate for the uncertainties in the rigid-link electrically-driven robot model, we then design a corrective robust tracking controller which yields global uniform ultimate bounded stability of the link tracking error. The proposed controller is robust with regard to parametric uncertainties and additive bounded disturbances while correcting for the typically ignored electrical actuator dynamics.

Adaptive Tracking Control of a Switched Reluctance Motor Turning an Inertial Load

Using nonlinear models of the motor and load, an adaptive tracking controller is developed for switched reluctance (SR) motors turning an inertial load. The proposed controller uses full state measurements (i.e., motor position, velocity, and the per phase winding currents) to yield a global uniform asymptotic stability (GUAS) [1] result for the motor position tracking error despite parametric uncertainty throughout the entire electro-mechanical system dynamics.

Robust tracking of rigid-link flexible-joint electrically-driven robots

The authors present a simple approach for designing tracking controllers for rigid-link flexible-joint robot manipulators. The control approach is intuitively simple since it is based on concepts which are familiar to most control engineers. To illustrate the approach, the authors develop a robust tracking controller that achieves global uniform ultimate boundedness, stability of the link tracking error in spite of bounded disturbances, and model uncertainty. They then discuss some extensions for rigid-link electrically driven and for rigid-link flexible-joint electrically driven robot manipulators.<<ETX>>

Integrator backstepping techniques for the tracking control of permanent magnet brush DC motors

A series of motor control experiments is described. The results are based on a nonlinear design technique called integrator backstepping. This model-based approach is applied to the design and implementation of high-performance trajectory tracking controllers for a BDC (brush DC) motor driving a single-link robot. Two controllers are proposed: an embedded computed torque controller which requires full-state feedback and an output feedback controller which only requires position measurement (i.e., observed backstepping). Both controllers require exact knowledge of the electromechanical dynamics in order to guarantee GES tracking performance. Extensions of the proposed backstepping techniques are discussed for more complex electromechanical systems, and for systems with uncertainty. The proposed controllers are simulated and implemented on a state-of-the-art DSP (digital signal processing) based workstation using a user-developed real-time DAC (data acquisition and control) system.<<ETX>>

Review and unification of reduced-order force control methods

In this paper, we compare some of the recent methods developed for simultaneous position and force control of a single a-link constrained robot manipulator. Mathematical models of the constrained manipulator are introduced and the advantages and disadvantages of the associated control formulations are discussed. The similarities between each of the proposed formulations are also highlighted. Finally, a transformation is presented which generalizes the methods of decompling force from the position dynamics.

Robust tracking control of a brushless DC motor with application to direct-drive robotics

A hand-crafted methodology is used to develop a robust tracking control for a brushless direct-current (BLDC) motor turning an inertial load. Using nonlinear models of the motor and load, a global uniform ultimate boundedness (GUUB) stability result for the motor position tracking error is obtained. The control is robust with respect to parametric uncertainty and additive bounded disturbances throughout the entire electromechanical system. The approach assumes full state measurement (i.e., motor position, velocity, and the per phase winding currents).<<ETX>>

Semiglobal position tracking control of brushless DC motors using output feedback

This paper uses an observed backstepping procedure to design a position tracking controller for a permanent magnet brushless direct-current (BLDC) motor driving an inertial load. The electromechanical system contains nonlinearities in both the output position and the intermediate states between the motor position output and the motor voltage input. A semiglobal exponential stability (SES) result is obtained for the motor position tracking error given an exact nonlinear model of the entire electromechanical system and measurement of the motor position only, i.e., output feedback.<<ETX>>

Tracking control of permanent magnet brushless DC motors using partial state feedback

This paper uses an observed backstepping procedure to design a position and velocity tracking controller for permanent magnet brushless DC motors. A semiglobal exponential stability result is obtained for the motor position and velocity tracking error given an exact nonlinear model of the electromechanical system and measurements of the motor position and velocity.<<ETX>>

Review and Unification of Reduced Order Force Control Methods

In this paper, we compare some of the recent methods developed for simultaneous position and force control of a single a-link constrained robot manipulator. Mathematical models of the constrained manipulator are introduced and the advantages and disadvantages of the associated control formulations are discussed. The similarities between each of the proposed formulations are also highlighted. Finally, a transformation is presented which generalizes the methods of decompling force from the position dynamics.

Robust control of robot manipulators during constrained and unconstrained motion

Two robust controllers are developed for the position and force control of a single n-joint nonredundant manipulator. The control strategies are shown to apply when the manipulator is unconstrained and when it is constrained by a rigid environment. Starting with the model of the robot dynamics and constraints in joint space, a dynamic equation is developed with respect to a set of task space coordinate variables. Using this task space model, the two control strategies are developed for the manipulator, and are shown to be robust with respect to uncertainty in the system. The robust control strategies have the following characteristics: (1) exponential convergence for motion tracking, (2) the controller is continuous for all times of interest, and (3) the controller is the same for constrained and unconstrained motion.<<ETX>>