PID Regulator Research Articles

PID regulation of robot manipulators: stability and performance

Position control of robot manipulators using a novel PID control configuration derived from modeling error compensation ideas is introduced. The PID control law stability depends only on the inertial parameters of the robot. A simple proof of semiglobal PID stabilization of robot manipulators is provided. It is shown that the performance of the inverse dynamics control can be recovered by the PID control in the high-gain limit. Simple tuning guidelines derived from the proposed PID control configuration and closed-loop stability analysis are presented.

Modeling and PID Control of Constrained Robot with Kinematic Uncertainty

This paper investigates a model-based method for robot manipulator control by describing the kinematics and dynamics of constrained robot when contacting a dynamic environment. This modeling method is suitable for hybrid control laws. The simulation results obtained from the PID regulators are presented. Those results suggest that, in practice, fixed PID parameters may not perform well because of the strong nonlinearity of the system and the uncertainty from outside. This will lead to further modified PID methods such as a fuzzy logic self-turning PID controller.

Digital Servo IC for Optical Disc Drives

This paper addresses the use of PID regulators to achieve some of the main control goals in an optical disc drive: (i) focusing of the laser spot on the disc surface, (ii) tracking the continuous data spiral during playback, and (iii) radially searching the target location on disc during an access procedure. The servo loops employed to perform the control tasks mentioned above will be described and a dedicated PID-based digital servo integrated circuit (DSIC) will also be introduced.

Robust pole placement design via the LTR approach

This paper deals with a new method for tuning the RST regulators. Robustness appears as the result of a polynomial reinterpretation of the Loop Transfer Recovery techniques. It requires neither the state space context nor the Kalman formalism, but only some direct manipulation of the assigned poles. The corresponding pole placement strategy leads to a very simple and efficient design, which makes the LTR/RPP regulators as easy to tune as the classical PID regulators.

A Simple Adaptive PID Tuner

This paper introduces a new approach, which is based on a stochastic-deterministic recursive adaptive scheme, estimating the process parameters and the time delay at the same time and using design formulas for automatic tuning of the PID regulator parameters.

舶用制御システムのゲイン自動調整について

舶用制御システムのゲイン自動調整について

Automatic tuning of nonlinear PID controllers for unsymmetrical processes

Relay auto-tuning of linear PID regulators is now a proven technology in the process control industry. In this paper it is extended to auto-tune nonlinear PID controllers for unsymmetrical processes. Two sets of PID parameters, each for one operating mode, are obtained with a single relay experiment. Excellent performance of the auto-tuned nonlinear control system is substantiated by simulations.

Tuning PID Controllers for Disturbance Rejection Based on Linear Quadratic Optimal Methods

Structural stability and sensitivity properties of a PID regulator tuned as a linear quadratic optimal controller (LQOC) are presented. The solution of the LQOC control problem gives as a result a PID structure, but only when a resticted class of models for the disturbance and the plant is considered. The concept of robustness is introduced for those models which can not be included in the class of models leading to PID structures. This method gives as a result, a set of simple tuning rules for PID regulators, which can be applied to a wide range of processes and disturbances.

Robust Tuning of PID Regulators Based on Step-Response Identification

Robust control design requires an accurate knowledge of the uncertainty bound around the nominal model. While classical identification theory qualifies the uncertainty in identified models through confidence regions of the estimated parameters, recent works have studied frequency-domain error bounds for models identified via least-squares like techniques. In this paper a quantification of errors in models identified through stepresponse methods is proposed. A model error bound is derived based upon an elaboration of the step response of the process. This bound is then used to formulate simple rules for a robust tuning of PID controllers. A simulation example is also presented, where a comparison of the closed-loop performance obtained with the proposed tuning rules and with other common tuning rules is shown.

Automatic Tuning of PID Regulators in Presence of Model Perturbations near the Desired Closed-Loop Cutoff

A methodfor the automatic tuning of PID regulators is presented. The proposed technique relies on the closedloop identification of two points of the plant Nyquist diagram, and is specifically aimed at improving robustness against model perturbations with significant effects near the desired cutoff frequency. This is achieved by means of convenient tuning formulae, which allow one to impose some control on the direction along which the open-loop Nyquist diagram will cross the unit circle. Also, attention is paid so as to achieve low computational effort and moderate tuning time.

Digital temperature regulator

This article examines a digital temperature regulator for the 0–1250°C range. The regulator has an error amounting to ±0.3% of this range. It has a four-sided double circuit board construction with a common bus. The static characteristic of the thermcouple of the unit is linearized. Control points are stored in nonvolatile memory. The unit provides for positional and PID regulation, generates a signal if the thermocouple fails, and performs other functions.

A Study on Automatic Tuning of Ship's PID Regulators

The classical PID control law is still used for many marine control systems. Gain tuning in the controller is, however, a formidable task for mariners. This paper provides a simple and a safe automatic P, I, D gains tuning method using relay control, for typical marine controllers with PID control law.In this method, a limit cycle with small amplitude is occurred, at the beginning, through a proper actuator such as a rudder, a thruster and so on, and then the amplitude and the period of the limit cycle are observed. Since the two quantities obtained under such limit cycle equivalently correspond to those by the ultimate method (Ziegler Nichols scheme), these are utilizable as the parameters for obtaining the optimal gains recommended by Ziegler Nichols.The on-board computer control system using the above method is applied to typical three types of ship's controller ; (1) autopilot system, (2) yaw control system through bow thruster and (3) diesel engine governor system, and the results of the full scale experiments using a small training ship are discussed.

How to Increase Robustness of PID Regulators

A new approach is proposed to improve the robustness of simple PID controls. This scheme widens the critical medium frequency domain and increases the achievable bandwidth.

Stability of Turning Processes with Actively Controlled Linear Motor Feed Drives

Using linear motors as machine tool feed drives has the potential of enhancing machining performance by eliminating gear related mechanical problems and increasing speed and accuracy, but introduces a stability concern due to a strong dynamic feedback interaction between the machining process and the drives. This paper investigates the stability aspect of this dynamic interaction and the use of active damping to achieve machining stability in turning. Various necessary and sufficient conditions for stability at all cutting speeds are derived, and have been used to study the effect of damping and gear reduction in system stability. The interaction of the cutting process with the tool servo loop is seen to have significant instability consequences in systems with small drive gear reductions. Both theoretical stability and experimental cutting results are presented for PD and PID regulation. Results show that actively controlled linear motors can provide sufficient dynamic stiffness for stable turning operation.

Analysis of Achievable PID Performances Versus Optimal LQR Control

Supervision of process control techniques can be based either on the observation of the real behavior or on the theoretical achievable performances of the closed loop system.In this paper, the PID regulator is taken as an optimal LQR controller applied to an extended plant, in order to weight the integral of the output. By this statement of the problem, some properties of the closed loop system are studied as a function of the integral weight. As expected, the cost function of the PID increases with the weight, and we analyze its asymptotic behavior. The robustness loop margin decreases, and it is possible to determine which values of the parameters in the cost function define a PID with an acceptable margin. Moreover, the existence of an asymptotic PID is proved.

Multiobjective optimization of a plastic injection molding process

It is well known that the PID regulator has been very successful and widely accepted for controlling industrial systems where one objective function is the performance criterion. The question is whether the same success can be achieved for more than one objective function using the basic PID controller, while preserving its simplicity for use by an operator. Here the authors explore the use of multiobjective optimization for the purpose of extending PID controllers to applications that require the optimization of multiple objectives. An algorithm is implemented that runs in real-time and provides immediate feedback to a process operator about the current operating point. It was applied to the tuning of a PID controller to meet multiple objectives for the plastication phase of an injection molding process. The algorithm was implemented on an injection molding machine and allowed to tune the controller on-line. Simulation and experimental results are presented and compared. >

Knowledge-based simulation for process monitoring and regulatory control

A knowledge-based simulation is described for the monitoring and regulatory control of a juice purification process in cane sugar production. In the paper, the problem description is analysed and a set of requirements are identified. To meet these requirements, a scheme is presented that organises the domain knowledge into suitable structured modules, such as object classes, libraries, rule sets, rules, instance objects etc. A number of user interface facilities are developed to monitor and exercise the application, such as tuning the PID regulators, fault diagnosis, restoring the normal status, etc. Two scenarios are described to explain the remedial operations carried out when a regulator is out of tune or faulty, or when a valve is stuck. The system can be used with the actual process in a sugar factory or with other similar process control applications. >

Design of adaptive PID regulators based on recursive estimation of the process parameters

Abstract This paper introduces a new approach based on a stochastic-deterministic recursive adaptive scheme, estimating the process parameters and the time delay at the same time and using design formulae for automatic tuning of PID regulator parameters.

A High-Speed Auto-Tuning PID Regulator Based on Programmable Logic Devices

In this paper, the prototype of an auto-tuning PID regulator for fast processes is presented. The regulator is based on The Logic Cell Arrays technology, which allows the user to reach sampling frequencies higher thаn 20kHz. The auto-tuning procedure relies on preliminary closed-loop experiments with a relay. Experimental results obtained by the use of the prototype for speed control of a DC motor are also reported.

DAML - A Language for Modelling and Simulation of Digital Control Systems

The hybrid characteristics of digital control processes, which have to be analysed both in the discrete and the continuous time domains, makes the problem of optimal control design especially difficult. A prior theoretical design is usually carried out in one domain and does not include all the nonlinear constraints resulting from finite precision implementation. In the paper a computer-aided simulation system, suitable for solving these problems, is presented. A general concept of an associated programming language, the digital and analogue modelling language DAML, is given. The language supplies facilities for programming analog plants and digital controllers, various types of arithmetic, and different levels of precision. The blockdiagram representation of the plant structure, including non-linear and userdefined functions, and a number of discrete controller descriptions, including the z-transfer function, the state-space representation, extensions of the linear-flowgraph notation, as well as a high-level programming language, can be applied. In order to model typical restrictions of implementation, the fixed-, floating-and block-floating-point digital-controller mechanizations can be used. A discrete PID regulator for a stationary plant and an adaptive algorithm for a robotic manipulator illustrate applicability of DAML.