On Numerical Simulation Approach for Multiple Resonance Modes in Servo Systems

For a load object, the air balance compensated servo electric cylinder is used as the actuator to drive the vertical part to aim target. The nonlinear links in the super load electric cylinder servo system include the trigonometric nonlinear relationship between the pitch angle and the motor angle, the time-varying relationship between the pitch angle and the supporting torque and gravity distance of the electric cylinder, the servo system and other nonlinear links. Simply using the position PID control algorithm can not meet the tracking accuracy requirements of the system. By using the fuzzy PID control algorithm with nonlinear compensation, the tracking accuracy problem in the servo system can be effectively solved. The fuzzy PID control algorithm with nonlinear feedforward compensation is designed. The simulation and test results show that the method effectively improves the servo control accuracy.

Dynamic modeling and control for dual-flexible servo system considering two-dimensional deformation based on neural network compensation

Servo system modeling and reduction of mechatronic system through finite element analysis for control design

Electro-hydraulic servo systems have been frequently used in the fin position servo system of a missile because of their high power and good positioning capability. The objective of this paper is to realize a self-tuning fuzzy controller for the position control of an electro-hydraulic fin servo system. In this paper, we propose a new self-tuning fuzzy controller, which can improve the overall performance of the electro-hydraulic fin position servo system. The uniqueness of this self-tuning fuzzy controller is that the performance evaluation of the fin position servo system is carried out in a phase plane mapped to a decision rule table. The effectiveness of this control scheme is verified by comparison with a fixed fuzzy control with initial rules through a series of simulation studies.

This paper presents the design and analysis of a dual-stage servo system with an instrumented suspension for use in hard disk drives. The dual-stage system is equipped with a microelectromechanical system microactuator (MA), either rotational or translational, as a secondary actuator. In both cases, the MA has a resonance mode at 2.2 kHz and has virtually no other modes up to 40 kHz. Two design approaches, the sensitivity decoupling design and the multiobjective optimization, are applied to the design of the servo system. With either approach, the translational dual-stage actuator achieves better tracking performance than the rotational one by about 13%, which is achieved mainly by attenuating airflow-excited suspension vibrations. This improvement is significant when the servo system's track misregistration (TMR) budget approaches the level of 5-10 nm. The airflow-excited suspension vibrations then become a significant contribution to the TMR

This paper extends the existing Proximate Time-optimal Servomechanism (PTOS) control methodology to the more typical second-order servo systems with a damping element. A parameterized design of expanded PTOS control law with a speed-dependent linear region is presented for rapid and smooth set-point tracking using a bounded input signal. The control scheme uses the time-optimal bang-bang control law to accomplish maximum acceleration or braking whenever appropriate and then smoothly switches into a linear control law to achieve a bumpless settling. The control scheme is then applied to the position-velocity control loop in a permanent magnet synchronous motor servo system for set-point position regulation. Numerical simulation has been conducted, followed by experimental verification based on a TMS320F2812 digital signal controller board. The results confirm that the servo system can track a wide range of target references with superior transient performance and steady-state accuracy.

Two major sources of load oscillations in servo systems are dealt with in this contribution, namely pulsating torque disturbances and torsional flexibility. After reviewing the state of the art in torque ripple compensation, a compact model of torque disturbances is presented and algorithms are given for the identification of model parameters. Thanks to its compactness, the model allows the implementation of a straightforward and effective disturbance compensation technique. Torsional flexibility is modelled by a classical two-mass model with spring and damper. A short review on the control of elastic joints is given. Then a careful analysis of the properties of the two-mass model is performed, leading to the design of a P/PI controller where suppression of load oscillations rather than fast setpoint tracking of the motor position is pursued. Further improvements of the load behaviour can be achieved by a notch filter placed outside the velocity loop. Finally, the most complete solution available with only motor position measurements, an LQG controller with feedforward actions for load setpoint tracking, is investigated. Experimental and simulation results are given to assess the effectiveness of the proposed approach.

This paper focuses on the development of a stable Mamdani type-2 fuzzy logic based controller for automatic control of servo systems. The stability analysis of the fuzzy controller has been done by employing the concept of Lyapunov. The Lyapunov approach results in the derivation of an original stability analysis that can be used for designing the rule base of our proposed online gain adaptive Interval Type-2 Fuzzy Proportional Derivative controller (IT2-GFPD) for servo systems with assured stability. In this approach a quadratic positive definite Lyapunov function is used and sufficient stability conditions are satisfied by the adaptive type-2 fuzzy logic control system. Illustrative simulation studies with linear and nonlinear models as well as experimental results on a real-time servo system validate the stability and robustness of the developed intelligent IT2-GFPD. A comparative performance study of IT2-GFPD with other controllers in presence of noise and disturbance also proves the superiority of the proposed controller.

A two-degree-of freedom (2DOF) control structure is proposed for read/write head servo systems of hard disk drives (HDD). This structure may be applied to both track seeking and track following, and it makes mode switches found in conventional HDD servo systems unnecessary. Two possible approaches are studied, emphasizing the rejection of disturbances and the effects of modeling uncertainties. One approach uses a disturbance observer (DOB), and the other uses adaptive robust control (ARC). Simulation results show that the 2DOF structure with ARC provides better performance than either the conventional servo system with mode switches or the 2DOF structure with DOB.

The increasing use of computer numerical control (CNC) machines requires better prediction of the reliability of their servo control systems. A novel reliability prediction model based on radial basis function (RBF) neural network optimized by improved particle swarm optimization (IPSO) was proposed. It can overcome the disadvantages of conventional methods, which are time consuming and resource intensive. The major influences on the reliability of servo system include torque, temperature, current, and complexity. An improved algorithm for predicting the mean time between failure (MTBF) of servo systems based on a particle swarm optimization (PSO) and an RBF neural network algorithm is proposed. Two common problem of the PSO: local minimization and slow convergence were solved by the IPSO. “Zero failure” data preprocessing, data normalization, and small-sample data enhancement were performed on the original data. A homogenized sampling method is proposed to extract training and testing samples. Experimental results show that the improved PSO-based RBF neural network is superior to back propagation (BP) and RBF networks in terms of accuracy in servo system reliability prediction.

The paper presents the design of linear-quadratic Gaussian (LQG) controller with Kalman filter for reference tracking of electrohydraulic servo system. The servo control system is intended for steering application of mobile machines. The controller design is developed on the base of identification procedure through experimentally measured data for single input, multiple output (SIMO) model of the steering servo system. Once the controller has been synthesized in simulation conditions, it is embedded into a specialized for mobile applications programmable logic controller (PLC) and experimentally tested with a laboratory model of a real servo system.

The chapter presents the mathematical models of free and forced oscillations of the comprehensive mechanical system “fixture–workpiece” describing the proposed adjustable locating-and-clamping module with a high level of flexibility for providing CNC multiaxis machining operation. With the aim to increase the fixture rigidity and detuning from a resonance mode, the eigenfrequencies and maximum displacements are determined using the numerical simulation model realized by the ANSYS software. The proposed mathematical model is proved by the results of numerical simulation on the example of fork-type parts considering contact stiffness of functional elements and values of clamping and cutting forces and moments. As a result, the advantage of the proposed manufacturing process in comparison on the typical one is justified. Particularly, the first eigenfrequency for the proposed manufacturing process is 1.64 times more than the same frequency for the typical manufacturing process. Additionally, the rigidity of a new fixture design is significantly increased, as well as detuning from a resonance mode is ensured. The proposed methodology allows estimating physical parameters of the proposed mathematical model by the results of numerical simulation and experimental research for ensuring dynamic stability of the highly complicated mechanical system “CNC machine tool–flexible fixture–spatial workpiece–precise cutting tool.”

The ever increasing demand for higher storage capacity and smaller magnetic hard disk drives have driven the need of developing a high performance head positioning servo control system. To meet the challenge, this paper presents the design and real-time implementation of a robust two-degree-of-freedom servo system for physical 3.5-in. hard disk drive with single voice-coil-motor actuator using a multi-objective evolutionary algorithm toolbox. Besides the simplicity in controller structure, such an evolutionary servo control system is capable of meeting various performance specifications of hard disk drives in both the time and frequency domains. It is shown that the servo system optimally moves the magnetic head onto the desired track with minimal control effort, and keeps it on the track robustly against plant uncertainties or runout disturbances. Validation results of the evolutionary servo control system are compared with classical PID and RPT controllers, which show excellent closed-loop response and robustness in the face of practical perturbations in HDD.

This paper proposes a novel approach for AC servo system control of electrical injection molding machine. Based on the Permanent-Magnet Synchronous Motor(PMSM) vector control, position servo system is achieved using repetitive control(RC), and then the controller is designed in order to tracking the periodic reference. Not only the principle and arithmetic of RC are detailed, but also the mathematic model of PMSM and the design process are included in this paper. At last, the simulation is presented for the given periodic reference of position. And the effectiveness, briefness, and feasibility of the proposed approach are demonstrated by the results of simulation.

The composition and working principle of electric hydraulic servo control system are briefly described. A program is designed about digital servo controller based on DSP structure, and the servo system is achieved to control position by using TMS320LF2407A’s powerful digital processing capabilities, rich peripheral interfaces and optimal control algorithm of deviation, meanwhile it also has complete self-testing, setting parameters online and other functions. It is shown that the digital servo controller runs reliably, achieves real-time and precise control effect, and can meet the TRT and other systems’ control requirements with the experimental results.