Victor Manuel Hernández-Guzmán

DC/DC Buck Power Converter as a Smooth Starter for a DC Motor Based on a Hierarchical Control

In this paper a smooth starter, based on a dc/dc Buck power converter, for the angular velocity trajectory tracking task of a dc permanent magnet motor is presented. To this end, a hierarchical controller is designed, which is integrated by a control associated with the dc motor based on differential flatness at the high level, and a control related with the dc/dc Buck converter based on a cascade control scheme at the low level. The control at the high level allows the dc motor angular velocity to track a desired trajectory and also provides the desired voltage profile that must be tracked by the output voltage of the dc/dc Buck power converter. In order to assure the latter, a cascade control at the low level is designed, considering a sliding mode control for the inner current loop and a proportional-integral control for the outer voltage loop. The hierarchical controller is tested through experiments using MATLAB-Simulink and the DS1104 board from dSPACE. The obtained results show that the desired angular velocity trajectory is well tracked under abrupt variations in the system parameters and that the controller is robust in such operation conditions, confirming the validity of the proposed controller.

Two-Stage Control Design of a Buck Converter/DC Motor System without Velocity Measurements via a-Modulator

This paper presents a two-stage control design for the “Buck power converter/DC motor” system, which allows to perform the sensorless angular velocity trajectory tracking task. The differential flatness property of the DC-motor model is exploited in order to propose a first-stage controller, which is designed to achieve the desired angular velocity trajectory. This controller provides the voltage profiles that must be tracked by the Buck converter. Then, a second-stage controller is meant to assure the aforementioned. This controller is based on flatness property of the Buck power converter model, which provides the input voltage to the DC motor. Due to the fact that the two-stage controller proposed uses the average model of the system, as a practical and effective implementation of this controller, a -modulator is employed. Finally, in order to verify the control performance of this approach, numerical simulations are included.

Trajectory Tracking in a Mobile Robot without Using Velocity Measurements for Control of Wheels

In this paper we present a solution for the trajectory tracking problem in a newt mobile robot. We exploit the differential flatness property of the robot kinematic model to propose an input-output linearization controller which allows both the position and the orientation to track a desired trajectory. An important assumption is that robot has to be initially placed at a point on such a desired trajectory. This controller provides the velocity profiles that the robot wheels have to track and a second controller has to be designed in order to ensure the latter. This is accomplished by means of another differential flatness based control scheme which does not require measurements of any mechanical variables, i.e. velocities, to control the DC motors used as actuators at the wheels. We verify our findings through numerical simulations.

A New Tuning Procedure for PID Control of Rigid Robots

This paper is concerned with classical PID control of rigid robots. We introduce a tuning procedure for selection of the PID gains ensuring asymptotic stability in a domain which can be enlarged arbitrarily. The novelty of our approach relies on the fact that conditions for stability are formulated as expressions that have to be satisfied at each joint instead of conditions on norms of gain and parameter matrices as reported previously. This allows better performances than those obtained using tuning procedures previously reported in the literature.

PI Control Plus Electric Current Loops for PM Synchronous Motors

We present a solution for velocity control in permanent magnet synchronous motors. We formally prove that velocity converges to the constant desired value from any initial condition. Our controller is so simple that it only differs from the linear control strategy commonly implemented in commercial drives by two simple adaptive terms. Moreover, identical velocity responses are obtained with both controllers. Hence, our results explain how the linear control strategy implemented in most commercial drives works and also provide tuning guidelines for that control strategy. We remark that this has been a long standing unsolved problem.

Pid control of robot manipulators equipped with brushless dc motors

This paper is concerned with PID control of rigid robots equipped with brushless DC (BLDC) motors when the electric dynamics of these actuators is taken into account. We show that an adaptive PID controller yields global stability and global convergence to the desired link positions. Moreover, we also show that virtually the PID part of the controller suffices to achieve the reported global results. We present a theoretical justification for the torque control strategy, commonly used in practice to control BLDC motors. Our controller does not require the exact knowledge of neither robot nor actuator parameters.

A New Adaptive Self-Tuning Fourier Coefficients Algorithm for Periodic Torque Ripple Minimization in Permanent Magnet Synchronous Motors (PMSM)

Torque ripple occurs in Permanent Magnet Synchronous Motors (PMSMs) due to the non-sinusoidal flux density distribution around the air-gap and variable magnetic reluctance of the air-gap due to the stator slots distribution. These torque ripples change periodically with rotor position and are apparent as speed variations, which degrade the PMSM drive performance, particularly at low speeds, because of low inertial filtering. In this paper, a new self-tuning algorithm is developed for determining the Fourier Series Controller coefficients with the aim of reducing the torque ripple in a PMSM, thus allowing for a smoother operation. This algorithm adjusts the controller parameters based on the components harmonic distortion in time domain of the compensation signal. Experimental evaluation is performed on a DSP-controlled PMSM evaluation platform. Test results obtained validate the effectiveness of the proposed self-tuning algorithm, with the Fourier series expansion scheme, in reducing the torque ripple.

PD control for robot manipulators actuated by switched reluctance motors

This article is concerned with position regulation in direct-drive n degrees of freedom rigid robots equipped only with revolute joints when actuated by switched reluctance motors. Our controller represents an extension to this case of a previous work in the literature which was proposed for a single-switched reluctance motor when moving a simple linear mechanical load. We show how to avoid a singularity present in such a previous controller. We also introduce some simplifications since the number of terms to be fedback is smaller. Further, a linear proportional inner electric current loop is included instead of a velocity dependent one.

A saturated pd controller for robots equipped with brushless dc-motors

In this paper we are concerned with control of rigid robots equipped with brushless DC-motors (BLDC) when the electric dynamics of these actuators is taken into account. We show for the first time that a saturated PD controller suffices to achieve global asymptotic stability. Our controller is the simplest controller proposed until now to solve this problem: it only requires position measurements and linear feedback of electric current.

Velocity and Current Inner Loops in a Wheeled Mobile Robot

In this note we are concerned with the control of a non-holonomic mobile robot, including the kinematic and the mechanical models of the robot as well as the electrical dynamics of the brushed DC motors used as actuators. We present, for the first time, a formal justification for a control strategy based on velocity and current inner loops driven by proportional controllers. Although this strategy is well known and very common in practice, a formal stability analysis supporting these ideas had not been presented until now.