scholarly journals Design of an Observer-Based Architecture and Non-Linear Control Algorithm for Cogging Torque Reduction in Synchronous Motors

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2077 ◽  
Author(s):  
Pierpaolo Dini ◽  
Sergio Saponara
Keyword(s):  
Control Algorithm ◽  
Permanent Magnets ◽  
Position Control ◽  
Deterministic Model ◽  
Initial Conditions ◽  
Angular Position ◽  
Observer Design ◽  
Control Technique ◽  
Servo Drive ◽  
Cogging Torque

The problem of cogging torque is due to a magnetic behavior, intrinsic to synchronous machines and due to the presence of permanent magnets themselves. Cogging torque is a significant problem when the servo drive is used for applications where high precision in terms of position control is required. In this paper we present a method of cogging torque reduction by means of a control technique based on mathematical modeling of the cogging phenomenon itself in order to exploit this knowledge directly in the controller design. The mathematical model is inserted in the dynamic model of the synchronous machine in order to exploit the feedback linearization, providing an expression of the control law in which the contribution of the deterministic knowledge of the phenomenon is directly present. The cogging phenomenon physically depends on the angular position of the rotor, as well as the deterministic model we use to define the control vector. This makes it interesting and innovative to determine whether the control algorithm can be inserted within a sensor-less architecture, where rotor position and angular velocity measurements are not available. For this purpose, we present the use of an extended Kalman filter (EKF) in the continuous-time domain, discussing the advantages of an observer design based on a dynamic motor model in three-phase and direct-square axes. Results are presented through very accurate simulation for a trajectory-tracking problem, completing with variational analysis in terms of variation of initial conditions between EKF and motor dynamics, and in terms of parametric variation to verify the robustness of the proposed algorithm. Moreover, a computational analysis based on Simulink Profiler is proposed, which provides some indication for possible implementation on an embedded platform.

scholarly journals Cogging Torque Reduction in Brushless Motors by a Nonlinear Control Technique

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2224 ◽  
Author(s):  
Pierpaolo Dini ◽  
Sergio Saponara
Keyword(s):  
Permanent Magnet ◽  
Electric Drive ◽  
Feedback Linearization ◽  
Permanent Magnets ◽  
Position Control ◽  
Angular Position ◽  
Control Technique ◽  
Electrical Machine ◽  
Brushless Motors ◽  
Cogging Torque

This work addresses the problem of mitigating the effects of the cogging torque in permanent magnet synchronous motors, particularly brushless motors, which is a main issue in precision electric drive applications. In this work, a method for mitigating the effects of the cogging torque is proposed, based on the use of a nonlinear automatic control technique known as feedback linearization that is ideal for underactuated dynamic systems. The aim of this work is to present an alternative to classic solutions based on the physical modification of the electrical machine to try to suppress the natural interaction between the permanent magnets and the teeth of the stator slots. Such modifications of electric machines are often expensive because they require customized procedures, while the proposed method does not require any modification of the electric drive. With respect to other algorithmic-based solutions for cogging torque reduction, the proposed control technique is scalable to different motor parameters, deterministic, and robust, and hence easy to use and verify for safety-critical applications. As an application case example, the work reports the reduction of the oscillations for the angular position control of a permanent magnet synchronous motor vs. classic PI (proportional-integrative) cascaded control. Moreover, the proposed algorithm is suitable to be implemented in low-cost embedded control units.

scholarly journals Design of a magnetic encoder using Hall effect

2019 ◽  
Vol 13 (2) ◽  
pp. 254-261
Author(s):  
William Alejandro López-Contreras ◽  
José Danilo Rairán-Antolines
Keyword(s):  
Hall Effect ◽  
Relative Motion ◽  
Direct Current ◽  
Permanent Magnets ◽  
Position Control ◽  
Angular Position ◽  
Linearization Method ◽  
Acquisition Process ◽  
Voltage Variation ◽  
Hall Sensors

We present the design of a magnetic encoder to measure angular position. The proposed encoder includes two Hall sensors in quadrature in a fixed platform. In addition, and over the sensors, there are two permanent magnets in a shaft. The relative motion between the fixed and the movable components generate a voltage variation in the sensors, which serve to generate the approximation of the angular position. We detail the acquisition process and the linearization method, because we consider that these are the most important contributions of this work. Lastly, we show the application of the encoder in the position control of a direct current motor to show the performance of the encoder estimating fast and slow angular position changes.

scholarly journals A Control Strategy of Actively Actuated Eccentric Mass System for Imbalance Rotor Vibration

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 69
Author(s):  
DaeYi Jung
Keyword(s):  
Power Consumption ◽  
Centrifugal Force ◽  
Control Strategy ◽  
Vibration Isolation ◽  
Position Control ◽  
Angular Position ◽  
Fine Tuning ◽  
Control Technique ◽  
Mass System ◽  
Rotor Imbalance

This paper explores the new control strategy of an actively actuated eccentric mass system (AAEMS) for cancelling the rotor imbalance vibration. The AAEMS consists of an eccentric mass with an actuator that actively moves around the circular guided track attached to the rotating rotor thus can generate an effective centrifugal force perpendicular to any tangential direction of the guided circular trajectory. Therefore, once the magnitude and angular position of the inherited static imbalance of the rotor are identified, this actively controlled system can be dispatched to the target angular position(s) where the effective centrifugal force due to rotor imbalance is completely or partially removed. This novel device is currently available and widely used in the vibration isolation problem. However, the study of its control strategy is quite limited, thus, herein, we proposed a new possible control technique, guaranteeing both the robust vibration isolation performance and less control power consumption. To meet such needs, three primary functions of AAEMS are addressed here. First, two (Extended) Kalman filters were employed to sequentially estimate the unknown imbalance of the rotor and the unknown coulomb friction induced between the contact surface of the circular track and the counter-contacted parts of AAEMS. Second, the position control of the AAEMS is achieved by a linear quadratic regulator (LQR)-based optimal control law, simultaneously minimizing the imbalance vibration of the rotor as well as the power consumption of its own actuator. Third, for the situation where the estimation and control errors are presented, thus causing the failure to an acceptable threshold for imbalance vibration, the trial-error-based fine-tuning angular position control was proposed. The effectiveness of the proposed control strategy was evaluated via the simulations and this study shows the practical potential for addressing the AAEMS-based imbalance vibration elimination.

Soft Robotic Rehabilitation Exoskeleton (REHAB Glove) for Hand Therapy

2017 ◽  
Author(s):  
Mahdi Haghshenas-Jaryani ◽  
Caleb Nothnagle ◽  
Rita M. Patterson ◽  
Nicoleta Bugnariu ◽  
Muthu B. J. Wijesundara
Keyword(s):  
Control Algorithm ◽  
Position Control ◽  
Angular Position ◽  
Healthy Individuals ◽  
Hand Rehabilitation ◽  
Robotic Rehabilitation ◽  
Angular Velocities ◽  
Controlled Motion ◽  
Actuator Design ◽  
Flexion And Extension

This paper presents the design, control, and validation of a soft robotic exoskeleton system, the REHAB Glove, for hand rehabilitation. The system is comprised of five hybrid soft-and-rigid robotic digits that apply controlled flexion and extension motion to fingers. The previous actuator design of the soft robotic digit was improved for kinematic compatibility with anatomical motions of the hand in relation to range of motion, center of rotation, and dorsal skin lengthening. The design was validated using motion capture and analysis. A position control algorithm, which controls finger angular trajectories (angular position and velocity), was developed based on motion sensor feedback. The operation of this algorithm was verified using a 90° digit tip trajectory with two angular velocities of 15°/sec and 30°/sec. A pilot study was carried out with five healthy individuals to evaluate the performance of the REHAB Glove in providing therapeutic schemes. The results show that the REHAB Glove is able to provide controlled motion compatible with the kinematics and dynamics of the human.

scholarly journals A Novel BLDC-Like DTC Control Technique for Induction Motors

2012 ◽  
Vol 2012 ◽  
pp. 1-8
Author(s):  
Andrea Rossi ◽  
Carlo Concari
Keyword(s):  
Induction Motor ◽  
Control Algorithm ◽  
Permanent Magnets ◽  
Induction Motors ◽  
Low Cost ◽  
Control Technique ◽  
Motor Speed ◽  
Speed Range ◽  
High Dynamic ◽  
Wide Speed Range

DC brushless motors are widely adopted for their simplicity of control, even in sensorless configuration, and their high torque density. On the other hand, induction motors are very economical due to the absence of permanent magnets; for the same reason they can easily be driven in the flux-weakening region to attain a wide speed range. Nevertheless, high dynamic induction motors drives, based on field-oriented (FOC) or predictive control, require large amounts of computing power and are rather sensitive to motor parameter variations. This paper presents a simple DTC induction motor control algorithm based on a well-known BLDC control technique, which allows to realize a high dynamic induction motor speed control with wide speed range. The firmware implementation is very compact and occupies a low amount of program memory, comparable to volt-per-Hertz- (V/f-) based control algorithms. The novel control algorithm presents also good performance and low current ripple and can be implemented on a low-cost motion control DSP without resorting to high-frequency PWM.

scholarly journals Force-Free Control for Direct Teaching of a Surgical Assistant Robot End Effector with Wire-Driven Bidirectional Telescopic Mechanism

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3498
Author(s):  
Youqiang Zhang ◽  
Cheol-Su Jeong ◽  
Minhyo Kim ◽  
Sangrok Jin
Keyword(s):  
Control Algorithm ◽  
Position Control ◽  
Friction Model ◽  
Surgical Instruments ◽  
Control Input ◽  
End Effector ◽  
Motor Current ◽  
Direct Teaching ◽  
End Effectors ◽  
Teaching Operation

This paper shows the design and modeling of an end effector with a bidirectional telescopic mechanism to allow a surgical assistant robot to hold and handle surgical instruments. It also presents a force-free control algorithm for the direct teaching of end effectors. The bidirectional telescopic mechanism can actively transmit force both upwards and downwards by staggering the wires on both sides. In order to estimate and control torque via motor current without a force/torque sensor, the gravity model and friction model of the device are derived through repeated experiments. The LuGre model is applied to the friction model, and the static and dynamic parameters are obtained using a curve fitting function and a genetic algorithm. Direct teaching control is designed using a force-free control algorithm that compensates for the estimated torque from the motor current for gravity and friction, and then converts it into a position control input. Direct teaching operation sensitivity is verified through hand-guiding experiments.

scholarly journals Neural Network Based Contact Force Control Algorithm for Walking Robots

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 287
Author(s):  
Byeongjin Kim ◽  
Soohyun Kim
Keyword(s):  
Neural Network ◽  
Contact Force ◽  
Force Control ◽  
Control Algorithm ◽  
Position Control ◽  
Linear Quadratic Regulator ◽  
Walking Robots ◽  
Test Model ◽  
Linear Quadratic ◽  
Contact Force Control

Walking algorithms using push-off improve moving efficiency and disturbance rejection performance. However, the algorithm based on classical contact force control requires an exact model or a Force/Torque sensor. This paper proposes a novel contact force control algorithm based on neural networks. The proposed model is adapted to a linear quadratic regulator for position control and balance. The results demonstrate that this neural network-based model can accurately generate force and effectively reduce errors without requiring a sensor. The effectiveness of the algorithm is assessed with the realistic test model. Compared to the Jacobian-based calculation, our algorithm significantly improves the accuracy of the force control. One step simulation was used to analyze the robustness of the algorithm. In summary, this walking control algorithm generates a push-off force with precision and enables it to reject disturbance rapidly.

scholarly journals Design of Satellite Attitude Control Algorithm Based on the SDRE Method Using Gas Jets and Reaction Wheels

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Luiz C. G. de Souza ◽  
Victor M. R. Arena
Keyword(s):  
Attitude Control ◽  
Control Algorithm ◽  
Controller Design ◽  
Algorithm Design ◽  
Large Angle ◽  
Space Mission ◽  
Control Technique ◽  
Gas Jets ◽  
State Dependent ◽  
Highly Nonlinear

An experimental attitude control algorithm design using prototypes can minimize space mission costs by reducing the number of errors transmitted to the next phase of the project. The Space Mechanics and Control Division (DMC) of INPE is constructing a 3D simulator to supply the conditions for implementing and testing satellite control hardware and software. Satellite large angle maneuver makes the plant highly nonlinear and if the parameters of the system are not well determined, the plant can also present some level of uncertainty. As a result, controller designed by a linear control technique can have its performance and robustness degraded. In this paper the standard LQR linear controller and the SDRE controller associated with an SDRE filter are applied to design a controller for a nonlinear plant. The plant is similar to the DMC 3D satellite simulator where the unstructured uncertainties of the system are represented by process and measurements noise. In the sequel the State-Dependent Riccati Equation (SDRE) method is used to design and test an attitude control algorithm based on gas jets and reaction wheel torques to perform large angle maneuver in three axes. The SDRE controller design takes into account the effects of the plant nonlinearities and system noise which represents uncertainty. The SDRE controller performance and robustness are tested during the transition phase from angular velocity reductions to normal mode of operation with stringent pointing accuracy using a switching control algorithm based on minimum system energy. This work serves to validate the numerical simulator model and to verify the functionality of the control algorithm designed by the SDRE method.

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