Encoder-based Control Research Articles

Super-Resolution Velocity Reconstruction and Control of Ultrasonic Motors.

Accurate and fast velocity feedback signal is essential for the velocity control of ultrasonic motors (USMs). However, the low operating velocity of USMs results in a long velocity detection dead time (VDDT) of incremental encoders, which seriously restricts the dynamic control performance of USMs. Therefore, this article presents a super-resolution velocity control (SRVC) scheme based on the velocity reconstruction for the USM. First, the mathematical model of the USM is derived from the mechanical characteristics and the electromechanical coupling characteristics. Then, the velocity reconstruction method is proposed by combining the model estimated velocity and the encoder measured velocity. The closed-loop control scheme using the reconstructed velocity is implemented by a self-designed driving circuit. Experimental results show the velocity reconstruction method not only can break through the limitation of the encoder resolution to reduce the VDDT but also has a high-velocity accuracy. Furthermore, compared with the existing encoder-based control scheme, the proposed SRVC scheme has a faster velocity response under different loads.

A Family of Adaptive Position Estimators for PMSM Using the Gradient Descent Method

This article presents an evaluation of a family of adaptive position estimators (APEs) for anisotropy-based self-sensing control (SSC) of permanent magnet synchronous machine (PMSM). The APEs use the gradient descent method (GDM) to minimize a cost function and thus estimate the rotor position. Three different APEs have been developed in previous work and are revised in this article. Their dynamic performance is experimentally evaluated and compared with each other and with an encoder-based control using the same test bench. Simplified models are derived, which allow an analytic calculation of the individual speed control loop dynamics. The speed control bandwidth using the latest APE reaches almost 50% of when using a 2000 slot incremental encoder. In addition, this version of APE with GDM features parameter tuning based on analytic equations.

Fuzzy Logic Based-Active Fault Tolerant Control of Speed Sensor Failure for Five-Phase PMSM

The present study seeks to investigate the problem of fault tolerant speed control of the five-phase Permanent Magnet Synchronous Motor (PMSM) in the presence of speed sensor fault. Indeed, the sensors which are the most sensitive elements play a significant role in the closed loop control. In this context, an active Fault Tolerant Control (FTC) is developed based on fuzzy controller. Using the Sliding Mode Observer (SMO), the reconfiguration scheme which alternates between the measured speed value and the estimated one is proposed during failure occurrences so as to preserve the best control performance. The five-phase PMSM is monitored by a fuzzy logic controller to reduce disturbances that can occur under fault conditions. The two techniques which are used to illustrate consistency in the proposed approach are the following: the sliding mode with encoder or without encoder-based control and the fuzzy logic control for efficient decision sent to the field-oriented control. Simulation tests, in terms of the measured and the estimated speed responses, have been carried out on the five phase PMSM drive. The results demonstrate that the proposed FTC scheme can validate the proposed FTC strategy and guarantee service continuity.

Moving Track Control System of Based on Gyroscope and Photoelectric Coder

Aiming at moving track control of mobile robot, this paper studied the practical implementation of linear control algorithm in moving track control of robot, expounded and proved its feasibility and analyzed stability constraint condition of the algorithm, and then analyzed effects of control parameters on moving track through simulation. Finally, the paper applies the algorithm on actual control of robot, and designed gyroscope and photo-electricity encoder-based control system of mobile robot for green house application.

Sensorless control of inverter-fed induction motor drives

Sensorless control is considered to be a lower cost alternative than the position or speed encoder-based control of induction motors. Two popular sensorless control methods, namely, the model reference adaptive system (MRAS) and the Luenberger observer (LO) methods are compared for speed and torque control characteristics. They are also compared against the well-known vector control principle. For the drive system simulated, the torque and speed obtained from sensorless control are almost identical to those obtained from the vector control method. However, the torque ripple for the sensorless methods is observed to be higher than vector control-based method. The MRAS method introduces higher torque ripple when compared to the Luenberger observer. In addition, speed estimation methods employed in sensorless control are more sensitive to motor parameter variations.

Adapting a teleoperated device for autonomous control using three-dimensional positioning sensors: experiences with the NIST RoboCrane

The National Institute of Standards and Technology (NIST) Construction Metrology and Automation Group, in cooperation with the NIST Intelligent Systems Division, is researching robotic structural steel placement through an ongoing program entitled “Performance of Innovative Technologies for Automated Steel Construction.” This program, initiated in response to an American Institute of Steel Construction request for a 25% reduction in time to erect steel structures, focuses on the development of an Automated Steel Construction Testbed to research advanced concepts in crane automation, laser-based site metrology, laser radar (LADAR) imaging, construction component tracking, sensor-based data exchange and web-enabled 3D-visualization. The steel manipulator used in this test facility is the NIST RoboCrane, a 6 df parallel kinematic machine capable of both teleoperative and programmed control. A laser-based 3D site measurement system (SMS) retrofitted on RoboCrane provides position and orientation (pose) information to reduce errors in the encoder-based control system and map the crane's location relative to other components in the work environment, which enables autonomous path planning and navigation.