Optimal Preview Control Research Articles

A METHOD FOR PREVIEW VIBRATION CONTROL OF SYSTEMS HAVING FORCING INPUTS AND RAPIDLY-SWITCHED DAMPERS

In a variety of applications, especially in large scale dynamic systems, the mechanization of different vibration control elements in different locations would be decided by limitations placed on the modal vibration of the system and the inherent dynamic coupling between its modes. Also, the quality of vibration control to the economy of producing the whole system would be another trade-off leading to a mix of passive, active and semi-active vibration control elements in one system. This termactiveis limited to externally powered vibration control inputs and the termsemi-activeis limited to rapidly switched dampers. In this article, an optimal preview control method is developed for application to dynamic systems having active and semi-active vibration control elements mechanized at different locations in one system. The system is then a piecewise (bilinear) controller in which two independent sets of control inputs appear additively and multiplicatively. Calculus of variations along with the Hamiltonian approach are employed for the derivation of this method. In essence, it requires the active elements to be ideal force generators and the switched dampers to have the property of on-line variation of the damping characteristics to pre-determined limits. As the dampers switch during operation the whole system's structure differs, and then values of the active forcing inputs are adapted to match these rapid changes. Strictly speaking, each rapidly switched damper has pre-known upper and lower damping levels and it can take on any in-between value. This in-between value is to be determined by the method as long as the damper tracks a pre-known fully active control demand. In every damping state of each semi-active damper the method provides the optimal matching values of the active forcing inputs. The method is shown to have the feature of solving simple standard matrix equations to obtain closed form solutions. A comprehensive 9-DOF tractor semi-trailer model is used to demonstrate the effectiveness of the method. Time domain predictions are made to compare performance of ride and tyre-to-road contact in the model for the presented method with those of some other active and semi-active suspension designs.

Model-based control of strip temperature for the heating furnace in continuous annealing

Presents the model of the heating furnace in continuous annealing processes for use in design of self-tuning control systems. A simplified mathematical model is derived from first principles. The model parameters are recursively estimated with an algorithm called recursive parameter estimation with a vector-type variable forgetting factor (REVVF). The REVVF algorithm was developed for such cases where some knowledge on parameter variability can be obtained beforehand. The control system of strip temperature presented here is hierarchical. The upper level is called "optimal preview control", which performs preset control. It previews the approaching setup change, which is the change of strip size or reference temperature, and optimizes the line speed and the strip temperature trajectory. Next, the lower level is called "temperature tracking control", which performs closed-loop control using the above trajectory as the control target. At this level, the generalized pole-placement self-tuning control was first employed; and later, the generalized predictive self-tuning control was introduced. These control methods were applied with some practical modifications and with the above mentioned REVVF. The control has been working successfully in several real plants.

A Superconducting Maglev Vehicle/Guideway System With Preview Control: Part II—Controller Design and System Behavior

Part II of this paper proposes the use of optimal preview control with integral action for a maglev vehicle with a superconducting electromagnetic suspension system operating on an elevated, flexible guide-way. The control system is designed based on a linearized model and then applied to a full-scale nonlinear simulation model of the maglev vehicle, magnet modules, and guideway (derived in Part I—Vehicle, Guideway, and Magnet Modeling). Simulation studies demonstrate the effectiveness of the controller and evaluate the vehicle performance under the influences of guideway flexibility, guideway irregularities, and aerodynamic disturbances.

Linear Quadratic Optimal Feedforward/Feedback Control

A generalized type of LQ-control problem, which treats a mixed attenuation of stored disturbance and initial state uncertainty, is discussed in the infinite-horizon time setting. For the generalized LQ-problem, an optimal preview control and worst-case initial uncertainties, i.e. those of initial state and the shape of stored disturbance, which maximize the cost functional of resulting closed loop system are clarified. The posed problem covers a part of predictive control problems and enables to attack LQ optimal preview servo-controller design.

Optimal Preview Control of a Two-dof Vehicle Model Using Stochastic Optimal Control Theory

SUMMARY An optimal preview control algorithm is applied to a two degree of freedom(dof) vehicle model travelling with constant velocity on a randomly profiled road. The road roughness is modelled as a homogeneous random process being the output of a linear first order filter to white noise. The input from the road irregularity is assumed to be measured at some distance in front of the vehicle and this measured infonnation is utilized by the active controller to prepare the system for the ensuing input. The preview control algorithm is obtained by minimizing a quadratic performance index and by describing the average behaviour of the system by the covariance matrix of the vehicle response state vector. Results are presented for full state feedback and significant improvements in sprung mass acceleration, suspension working space and road holding are observed.

Decentralized Control of Active Vehicle Suspensions With Preview

In this paper, decentralized control of active vehicle suspensions with preview of road irregularities is considered using a two-degree-of-freedom vehicle model. It is shown that by taking advantage of the separation between the eigenvalues of the slow subsystem representing the body mode, and the fast subsystem corresponding to the wheel mode, the design of the preview controller can be decoupled. Since decentralized preview controllers are synthesized independently for two single-degree-of-freedom systems, analytical solutions are obtained. The results of the analysis and simulations demonstrate that the performance of the system with the proposed controller is comparable to that of the optimal preview controller based on a fully interconnected system.

Performance enhancement of limited-bandwidth active automotive suspensions by road preview

A refined approach for the implementation of preview control in discrete time based on methods from earlier work is given. This allows the use of multiple preview inputs and reduces the system order of a discrete-time preview system significantly with respect to former methods, while describing the dynamic system in an exact form and yielding an equivalent control law. This method is applied to a limited-bandwidth quarter-car system, which incorporates an actuator in series with a passive spring, the combination being in parallel with a passive damper. Control design is carried out using discrete-time linear quadratic regulator (LQR) theory with tyre deflection, suspension working space, vertical body acceleration and control demand. How the optimal preview control law works in a physical sense is worked out regarding the feedforward gain matrix. It is shown that, as a part of the optimal control strategy, the preview controller "concentrates" in some sense on what it can do best for any amount of preview time. The conclusions from that are backed up considering performance indices and their components for variation of preview time, actuator bandwidth and the constraints in the cost function. Emphasis is put on the investigation of how the actuator bandwidth influences the performance capabilities of the system. General relationships between cast reduction, cost-component reduction, preview time and system bandwidth are exposed. By increasing preview time, the cost function can be reduced until it reaches a saturation value, which depends on the actuator bandwidth chosen. Increasing the actuator bandwidth beyond a certain value has only a small influence on the preview time needed for the diminishing returns to set in. Improving the road holding requires fast actuators, but comparatively short preview distances. Ride comfort can be influenced by a rather slow controller, but requires a long preview time.

Optimal Preview Control of an Active Suspension System for Railway Vehicles.

The preview control problem is one in which a controller can use future information as well as present and past information in deciding the control. In this paper the application of optimal preview control to an active suspension system for railway vehicles is discussed. Since many vehicles pass on the same railline repeatedly, preview control is an applicable for its active suspension. The results of simulations and experiments which are performed for optimal preview control system and for a conventional LQ control system show that optimal preview control improves ride quality drastically and reduces energy spent for control. Furthermore, identification of disturbance is also studied.

Decoupled preview control system and its application to induction motor drive

This paper shows that optimal preview control system approaches to a decoupled preview control system as the weighting factors for the control input variables in the quadratic performance index tend towards zero. Therefore, to examine the characteristics of the decoupled preview control system also means to examine the asymptotic characteristics of the optimal preview control system. By this property, relationships between the design parameters and the response of the optimal preview control system become clear and the design of the optimal preview control can be simplified by utilizing the properties that the decoupled preview control system features. Further, the decoupled preview control method is applied to the vector control system for an induction motor drive. By this application, a trade off between the conditions of the vector control and the magnitude of input variables becomes easy. To demonstrate the significance of this proposed method, simulation results of this application are carried out.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Disturbance suppression control with review action of linear DC brushless motor

This paper proposes a new preview and disturbance suppression control for a coreless type linear DC brushless motor (LDM). The brushless and coreless type linear DC motor is coggingless and has long life. It is suitable for high-speed operation and many precise positioning control purposes. However, it has disadvantages in that it is greatly affected by the parameter and load variation in the servo system with the LDM because it is not equipped with auxiliary mechanisms. The influence of the parameter variation and load change of the servo system are regarded as an equivalent disturbance signal and the compensation action is applied by utilizing the estimated value of the equivalent disturbance. The proposed control system is an optimal preview control system of type 1 comprising the estimation and compensating loop. In the proposed system, the disturbance suppression, improvement of phase delay of the whole control system, and lowering effect of the value of the input variables are attained in this control system for LDMs. Experimental studies for the LDM itself and a linear X-Y table made by the LDMs are shown and the above improvements are confirmed. >

Preview Control of Active Suspension Using Disturbance Information of Front Wheel.

This paper deals with the application of an optimal preview control to an active vehicle suspension system. The responses of the front wheel are useful to estimate the disturbance from the road surface to be applied to the rear wheel. It is the strategy of this preview control that all state variables are measured and fed to the front and rear controllers, and also fed-forward as preview information of road disturbance to the rear wheel. The design is based on a two-degree-of-freedom dynamic model with two wheels. The advantage of preview control is shown by computer simulations.

Preview Control for Vehicle Lateral Guidance in Highway Automation

The continuous time deterministic optimal preview control algorithm is applied to the lateral guidance of a vehicle for an automated highway. In the lateral guidance problem, the front wheel steering angle of the vehicle is controlled so that the vehicle follows the center for a lane with small tracking error and maintains good ride quality simultaneously. A preview control algorithm is obtained by minimizing a quadratic performance index which includes terms representing the passenger ride quality as well as the lateral tracking error, each of these terms is multiplied by a frequency dependent weight. This design method is known as a frequency shaped linear quadratic (FSLQ) optimal control approach. It permits incorporating frequency domain design specifications such as high frequency robustness and ride quality in the optimal controller design. It is shown that the optimal preview control law consists of a feedback control term and two feedforward control terms. The feedback term is exactly the same as that of traditional LQ control algorithm. The feedforward preview control action significantly improves the tracking performance and ride quality. Frequency-domain analyses, as well as numerical simulation results, show the improvements achieved by using the preview control algorithm in both the frequency and time domains.

Decoupled Preview Control System and its Application to Induction Motor Drive

This paper shows that optimal preview control system approaches to a decoupled preview control system as weighting (actors for control input variables in quadratic performance index tends to zero. By this property, relation between design parameters and response of optimal preview control system becomes clear. The decoupled preview control method is applied to vector control system for induction motor drive. By this application, trade off between conditions of vector control and the magnitude of input variables becomes easy.

Disturbance Suppression Control with Preview Action of Linear DC Brushless Motor

This paper proposes a disturbance suppression control with preview action for brushless & coreless type linear DC motor (LDM). Brushless & coreless type linear DC motor is coggingless and has long life. It is suitable for high speed and precise positioning control. Parameter variation and load change are regarded as equivalent disturbance signal and the compensation action is applied by utilizing the estimated value of the equivalent disturbance in the inner loop. Next, optimal preview control system is synthesized including the disturbance suppression control system mentioned above. Disturbance suppression, improving of phase delay and lowing of input peak value are attained in this control system for LDM. Experimental studies applied to LDM and linear X-Y table made by LDM are shown and these effects are also confirmed.

Disturbance suppression control with preview action for a linear dc brushless motor

AbstractThis paper proposes a disturbance suppression control with preview action for a brushless and coreless‐type linear dc motor. The brushless and coreless‐type linear dc motor is coggingless and has long life. It is suitable for high speed and precise positioning control. Parameter variation and load change are regarded as an equivalent disturbance signal and the compensation action is applied by utilizing the estimated value of the equivalent disturbance inside the inner loop. Next, an optimal preview control system is synthesized including the disturbance suppression control system mentioned in the foregoing. Disturbance suppression, improving phase delay and lowering the input peak value are attained in this control system. These effects are confirmed by applying the linear dc motor.

非干渉予見制御系の性質を用いた最適予見制御系の漸近性質

非干渉予見制御系の性質を用いた最適予見制御系の漸近性質

Optimal Preview Control of Rear Suspension Using Nonlinear Neural Networks

SUMMARY The performance of neural networks to be used for identification and optimal control of nonlinear vehicle suspensions is analyzed. It is shown that neuro-vehicle models can be efficiently trained to identify the dynamical characteristics of actual vehicle suspensions. After trained, this neuro-vehicle is used to train both front and rear suspension neuro-controllers under a nonlinear rear preview control scheme. To do that, a neuro-observer is trained to identify the inverse dynamics of the front suspension so that front road disturbances can be identified and used to improve the response of the rear suspension. The performance of the vehicle with neuro-control and with LQ control are compared.

Disturbance Suppression Control with Preview Action of Linear DC Brushless Motor.

This paper proposes a disturbance suppression control with preview action for brushless & coreless type linear DC motor. Brushless & coreless type linear DC motor is coggingless and has long life. It is suitable for high speed and precise positioning control. Parameter variation and load change are regarded as equivalent disturbance signal and the compensation action is applied by utilizing the estimated value of the equivalent disturbance inside the inner loop. Next, Optimal preview control system is synthesized including the disturbance suppression control system mentioned above. Disturbance suppression, improving of phase delay and lowering of input peak value are attained in this control system. These effects are confirmed by applying the linear DC motor.

Feedforward digital tracking controllers for motion control applications

This paper reviews digital tracking control algorithms for motion control applications. In tracking control, the control objective is to steer the control object along the time-varying desired output. Two design approaches are presented for the case where the desired signal is known in advance, i.e. previewable. One approach is based on the mathematical inverse of a closed-loop system consisting of a controlled plant and a feedback controller. If the mathematical inverse is asymptotically stable, i.e. the closed-loop system does not possess zeros outside the unit circle (unstable zeros), it is an ideal feedforward controller for achieving perfect tracking under the preview assumption. For closed-loop systems with unstable zeros, a cancellation technique for the phase shift induced by unstable zeros is introduced. Another approach is based on linear quadratic optimal control and is known as finite optimal preview control. In this approach, the feedback controller and feedforward controller are determined s...

最適予見サーボ系を用いたPWMインバータ制御の実験的検討

最適予見サーボ系を用いたPWMインバータ制御の実験的検討