Fast Tracking Performance Research Articles

An Entire Strategy for Control of a Calender Roller System: Part II Settling Time-optimal Feedback Control

Fast tracking performance and settling times, and low energy consumption while minimizing vibrations must be provided by a high performance calender roller system. This paper is a continuation of a companion paper [ Textile Res. J. XX, 00—00 (2007)], a regulating reference input technology combined with the aforementioned PID type control scheme is proposed for robustness and dominant mode vibration suppression. This combination scheme possesses the advantages of simplicity and effectiveness, and because no additional sensors and actuators are required the resulting controllers lead to optimal settling time performance without unwanted residual vibrations. This control scheme has stability and robustness to parameter variations of the calender roller system since the controller guarantees the absolute stability of the system. The usefulness of this approach is demonstrated through computer simulations. This feedback control design is particularly well suited to perform calculations by computer, and eventually we hope to design a calender roller system that can actually be controlled directly by an on-line computer.

H∞ model matching two-degree-of-freedom control with adaptive torque ripple cancellation for high performance direct drive systems

This study presents a novel adaptive robust control scheme to achieve a fast and accurate tracking performance in direct-drive (DD) systems under parameter and load uncertainties. The control combines an outer loop based on H∞ model matching (MM) in a two-degree-of-freedom (2-DOF) control structure, with an adaptive cancellation loop to increase torque ripple suppression further for improved tracking performance. A modified H∞ MM 2-DOF approach is taken by designing both the feedback loop and reference controller to achieve an improved tracking performance in the sense of H∞ MM criterion with integral action, while the robustness of the system is naturally satisfied by the 2-DOF control structure. Experimental results taken on a permanent magnet synchronous motor (PMSM) driven direct-drive system demonstrate a good tracking performance under a variety of reference trajectories. The results also demonstrate the robustness of the method against payload uncertainties and torque pulsations, except for the cogging torque components around the corner frequency. To improve attenuation of cogging torque terms further, the H∞ based outer loop is combined with an adaptive cancellation scheme derived based on the Lyapunov criteria. The developed adaptive robust control scheme demonstrates an improved robustness and tracking performance over a large frequency range.

IMPROVING CONTOUR MACHINING PRECISION BY THE LINEAR SERVO ROBUST TRACKING CONTROL

To reduce the contour error of the part machine, for the linear servo drive system, a robust tracking control strategy based on combining zero phase error tracking control (ZPETC) with the disturbance observer (DOB) is proposed. The zero phase error tracking controller is designed to ensure that the system has fast tracking performance and implements exactly tracking; while the DOB can overcome the influences of the uncertainties of the parameters perturbation, the external load disturbances, unmodelled dynamic and mechanical nonlinearity etc. DOB can compensate for each axis according to predicted disturbance information to eliminate the influences of the disturbance to the system, thus the stability and robustness of the system are obtained. The simulation results show that the control scheme not only can enhance the fast tracking performance in the linear servo system, but also has a strong robustness to parametric variations and resistance disturbances. Therefore the contour error is reduced effectively, and the precision of the contour machining is improved greatly.

Envelope Tracking Techniques for Flicker Mitigation and Voltage Regulation

Envelope tracking has many important applications in electrical distribution systems for either flicker meters or flicker compensators. This paper presents a novel control technique for flicker mitigation. This technique is based on the instantaneous tracking of the measured voltage envelope. The ADAptive LINEar neuron (ADALINE) algorithm, and the Recursive Least Square (RLS) algorithm are introduced for the flicker envelope tracking. The ADALINE algorithm is characterized by a light computational demand, unlike that of existing techniques; the RLS algorithm outperforms the ADALINE algorithm by its fast convergence and robust tracking performance. Both the ADALINE and the RLS algorithms give accurate results even under rapid dynamic changes. The paper investigates the effects of different parameters on the performance of the ADALINE algorithm and that of the RLS algorithm. Extensive simulations of the proposed flicker tracking algorithms are conducted to evaluate their performance for the tracking and mitigation of voltage flicker. The ADALINE and the RLS algorithms are examined by tracking and mitigating the flicker produced by a resistance welder and an arc furnace in a simple distribution system simulated in the PSCAD/EMTDC package.

Rapid Tracking With Automatic Trajectory Optimization for Speed

An automatic trajectory optimization scheme, which takes the system dynamics into account, is presented in this paper. It is developed for use in conjunction with the rapid-tracking learning control. It optimizes the reference trajectory such that tracking will be speeded up whenever the actuator capability is not fully utilized, and slowed down whenever the actuator would otherwise saturate. This yields not only excellent fast tracking performance but also a new reference trajectory which accommodates the saturation constraint of the control actuator. Application of the proposed strategy in control practice will ease the burden of having to precisely design the timing of a reference trajectory in a tracking control problem. The resulting controlled system is able to precisely track short but highly complex trajectories at the highest speed physically possible. Simulation and experimental results of simultaneously controlling two motors to emulate servoing an x-y table are given to demonstrate the effectiveness of the proposed methodology.

Unbiased Separation and Enhancement of Sources by Using a Zero Tracking Algorithm with Post Processing Adaptive Noise Reduction

This paper proposes and investigates a new structure for the unbiased separation, tracking, and enhancement of uncorrelated sources by a linear array. The structure consists of a matrix preprocessing beamformer followed by an adaptive linear combiner and a postprocessing beamformer. The weights of the adaptive linear combiner are updated by using the LMS algorithm and, together with the preprocessor, implement an adaptive array whose response zeros are adjusted to minimize the output power with unity element weight vector norm constraint. By properly designing the preprocessor, first-order movements in the response zeros can be individually and proportionally controlled by first order changes in the weights in the linear combiner, and the preprocessor outputs will be due to individual sources and receiver noise in the steady state. By measuring the powers of the preprocessor outputs, it will be possible to determine if a particular preprocessor output is due to an actual source (if the associated zero is tracking a source) or merely receiver noise (if the associated zero is not tracking any source). Further SNR enhancement is then carried out by making use of those preprocessor outputs due to receiver noise to remove the correlated receiver noise components in the other preprocessor outputs tracking actual sources through the use of a matrix postprocessor. Apart from the implementation of the preprocessor and postprocessor which will be inevitable in any source separation system and which have to be designed only occasionally and whenever the response zeros have been found to have changed significantly, the algorithm has an implementation complexity which is proportional to the array size. However, as the preprocessor outputs are due primarily to individual sources in the steady state, the algorithm has only one single asymptotic time constant controlled by the designed misadjustment level and has fast tracking performance.

Missile autopilot design via functional inversion and time-scaled transformation

This paper presents a new approach to acceleration control of STT (Skid-To-Turn) missiles. In the design and stability analysis of our autopilot, we assume perfect roll-stabilization but consider fully all other nonlinearities of the missile dynamics including the coupling effect due to bank angle. Our autopilot controller consists of a partial-linearizing controller and a dynamic compensator. The partial-linearizing controller along with a time scaled transformation can convert the nonlinear missile dynamics to the so-called normalized system which is completely independent of Mach number and almost independent of air density. The dynamic compensator is designed based on this normalized system. This normalized system greatly simplifies the design process of an autopilot controller regardless of flight conditions. Our autopilot controller can provide fast and exact set-point tracking performance but without the slow-varying conditions on angle of attack and side-slip angle required often in the prior works.