Advanced Motor Control for Improving the Trajectory Tracking Accuracy of a Low-Cost Mobile Robot

This research was funded by the Grant PID2019-111278RB-C21 funded by MCIN/AEI/ 10.13039/501100011033 and “ERDF A way of making Europe”.Peer reviewedPublisher PD

Control of complex nonlinear dynamic rational systems

© 2018 Quanmin Zhu et al. Nonlinear rational systems/models, also known as total nonlinear dynamic systems/models, in an expression of a ratio of two polynomials, have roots in describing general engineering plants and chemical reaction processes. The major challenge issue in the control of such a system is the control input embedded in its denominator polynomials. With extensive searching, it could not find any systematic approach in designing this class of control systems directly from its model structure. This study expands the U-model-based approach to establish a platform for the first layer of feedback control and the second layer of adaptive control of the nonlinear rational systems, which, in principle, separates control system design (without involving a plant model) and controller output determination (with solving inversion of the plant U-model). This procedure makes it possible to achieve closed-loop control of nonlinear systems with linear performance (transient response and steady-state accuracy). For the conditions using the approach, this study presents the associated stability and convergence analyses. Simulation studies are performed to show off the characteristics of the developed procedure in numerical tests and to give the general guidelines for applications

Computer Control: An Overview

Computer control is entering all facets of life from home electronics to production of different products and material. Many of the computers are embedded and thus ``hidden'' for the user. In many situations it is not necessary to know anything about computer control or real-time systems to implement a simple controller. There are, however, many situations where the result will be much better when the sampled-data aspects of the system are taken into consideration when the controller is designed. Also, it is very important that the real-time aspects are regarded. The real-time system influences the timing in the computer and can thus minimize latency and delays in the feedback controller. The paper introduces different aspects of computer-controlled systems from simple approximation of continuous time controllers to design aspects of optimal sampled-data controllers. We also point out some of the pitfalls of computer control and discusses the practical aspects as well as the implementation issues of computer control. Published as a Professional Briefs by IFAC

Advanced Anti-Windup Techniques for the Limitation of the Effects of the Actuator Saturation

In this thesis an industrial issue is analysed. The issue consist on the undesirable effect of actuator sturation. Two approaches are given to solve the issue: an accurate inertia identification algorithm based on the DFT coefficient; and advanced anti-windup compensators. The principle of the modern anti-windup (DLAW and MRAW, LMI-based design approach), and a systematic design design procedure for the observer-based anti-windup are given. Simulation and test results are also given.ope

Diagonal Stability of Systems with Rank-1 Interconnections and Application to Automatic Generation Control in Power Systems

We study a class of matrices with a rank-1 interconnection structure, and derive a simple necessary and sufficient condition for diagonal stability. The underlying Lyapunov function is used to provide sufficient conditions for diagonal stability of approximately rank-1 interconnections. The main result is then leveraged as a key step in a larger stability analysis problem arising in power systems control. Specifically, we provide the first theoretical stability analysis of automatic generation control (AGC) in an interconnected nonlinear power system. Our analysis is based on singular perturbation theory, and provides theoretical justification for the conventional wisdom that AGC is stabilizing under the typical time-scales of operation. We illustrate how our main analysis results can be leveraged to provide further insight into the tuning and dynamic performance of AGC

The application of estimation and control techniques in 2 modes of exercise for the spinal cord injured

A spinal cord injury (SCI) can result in a loss of sensory and motor capacity, dysfunction of the autonomic nervous system and also in a number of secondary health conditions including muscular atrophy, cardiovascular disease and osteoporosis. The impact of these secondary health conditions may be reduced through exercise which loads the muscles, skeleton and central cardiovascular system. A number of new exercise methods are emerging in the field of rehabilitation. Functional electrical stimulation (FES) is a technique for inducing artificial muscular contractions that has been applied to facilitate cycling amongst adults with a spinal cord injury. Preliminary data has demonstrated the feasibility of FES cycling in the paediatric SCI population. The use of an electric motor to provide torque assistance where required allows the exercise to continue for longer periods and over a wider range of cadences. In this thesis, a feedback control system is devised whereby the cadence can be automatically controlled to reference levels using such a motor, and tested during FES cycling of children with an SCI. The use of robot-assisted body weight supported devices is gaining popularity in the rehabilitation world. Their application has thus far been focused on rehabilitation of gait via neural re-learning. However, robot-assisted gait can also elicit a significant cardiovascular response and thus has potential as a tool for exercise training and testing. In this thesis, a method for estimating the work rate contributed by an exercising subject is developed and then incorporated into a feedback control scheme where the objective is to regulate the work rate to reference values. This enables specific work rate profiles to be performed during robot-assisted gait as is often required for standard exercise tests and training. In addition to controlling the mechanical variables during exercise, it is also possible to control some of the physiological variables. A feedback system whose goal is to control the rate of oxygen uptake rate is developed which also incorporates the work rate control method. This allows a predetermined level of physiological response to be achieved so that the training is of sufficient intensity to promote improvements in physical capacity and fitness. This thesis examines the application of estimation and control techniques in two exercise modes for the spinal cord injured. The ultimate aim of the exercise is to reduce the severity of the secondary health conditions that spinal cord injured people face. The estimation and control algorithms allow the exercise to be regulated with respect to speed and intensity and therefore have utility in both training and testing applications

Nonlinear constrained and saturated control of power electronics and electromechanical systems

Power electronic converters are extensively adopted for the solution of timely issues, such as power quality improvement in industrial plants, energy management in hybrid electrical systems, and control of electrical generators for renewables. Beside nonlinearity, this systems are typically characterized by hard constraints on the control inputs, and sometimes the state variables. In this respect, control laws able to handle input saturation are crucial to formally characterize the systems stability and performance properties. From a practical viewpoint, a proper saturation management allows to extend the systems transient and steady-state operating ranges, improving their reliability and availability. The main topic of this thesis concern saturated control methodologies, based on modern approaches, applied to power electronics and electromechanical systems. The pursued objective is to provide formal results under any saturation scenario, overcoming the drawbacks of the classic solution commonly applied to cope with saturation of power converters, and enhancing performance. For this purpose two main approaches are exploited and extended to deal with power electronic applications: modern anti-windup strategies, providing formal results and systematic design rules for the anti-windup compensator, devoted to handle control saturation, and “one step” saturated feedback design techniques, relying on a suitable characterization of the saturation nonlinearity and less conservative extensions of standard absolute stability theory results. The first part of the thesis is devoted to present and develop a novel general anti-windup scheme, which is then specifically applied to a class of power converters adopted for power quality enhancement in industrial plants. In the second part a polytopic differential inclusion representation of saturation nonlinearity is presented and extended to deal with a class of multiple input power converters, used to manage hybrid electrical energy sources. The third part regards adaptive observers design for robust estimation of the parameters required for high performance control of power systems