Practical Control of Non-Friction Mechanism for Precision Positioning.

This paper describes the practical control of non-friction mechanism for precision positioning. Non-friction mechanism is often used for precision positioning. Even though it has a simple structure, still, plant identification is compulsory needed during designing a conventional controller. This makes the controller non-user-friendly and non-practical-used in industry. For overcoming this problem, practical controller design procedure based on NCTF (nominal characteristic trajectory following) controller is proposed. NCTF controller consists of a nominal characteristic trajectory (NCT) and a PI compensator, which is free from exact modeling and parameter identification. The NCT is determined using an open-loop time responses of the mechanism. The PI compensator is used to make the mechanism motion to follow the NCT and it is tuned without given model parameters. Non-friction mechanism has non-damping a characteristic and often has a short-working range. A suitable current input to stop the non-damping mechanism within a short working range in open-loop condition and to be able to improve the damping characteristic of the mechanism is necessary. The positioning performances of two different current inputs are examined and discussed. The positioning performance of NCTF control system is evaluated based on simulation and experimental result

Motion control of a 1-DOF pneumatic muscle actuator positioning system

A positioning system driven by a pneumatic muscle actuator was built in order to study the applicability and adaptability of the system into real time applications such as exoskeleton robots and industrial machines. PMA system has many advantages including high power to weight and power to volume ratio, light weight, clean, autonomous and safe. However, the highly nonlinear characteristics of PMA system made it difficult to control. This has been the main challenge in proposing a robust controller for positioning and tracking performance. This study aims to clarify a practical and easy to design controller design procedure for positioning of a PMA system. In addition to positioning performance, the present study focuses on the realization of easy to design a controller without the need for exact model parameters and knowledge in control theory for systems with high nonlinearities. A PI and PID controller using Ziegler-Nicholas design law is proposed and its PTP performance is presented. Finally, the robustness of the proposed controller have been tested in a tracking environment by using triangular and sinusoidal waveform

Practical and robust control for precision motion: AR-CM NCTF control of a linear motion mechanism with friction characteristics

This study presents the framework of the acceleration reference continuous motion nominal characteristic trajectory following (AR-CM NCTF) control system, and its effectiveness in a linear motion mechanism with friction characteristics is experimentally demonstrated in comparison with the other control methods. The overall control system comprises the feedback-loops for velocity reference and acceleration reference following controls. The AR-CM NCTF control is an enhanced continuous motion NCTF (CM NCTF) control that has been proposed for high-precision motion. It has the same structure as the CM NCTF controller with additional elements for high-precision motion. The design procedure of the AR-CM NCTF controller remains easy and is independent of friction characteristics. The usefulness and advantages of the proposed controller are shown in the experimental studies. Besides, this study also highlights the robustness of the AR-CM NCTF controller by examining its performances in point-to-point and tracking motions in the presence of mass and disturbance force variations. In the robust performance, the AR-CM NCTF controller is compared with two types of proportional derivative control systems with disturbance observers (PDDOs). The comparative experimental results illustrate that the AR-CM NCTF controller shows the higher motion performances the higher robustness to plant parameter variations than the PDDO controllers

Annotated Bibliography on Knowledge Bases

Annotated Bibliography on Knowledge Base

Hopping peak height algorithm for a one legged robot hopping height control

This paper presents the hopping peak height algorithm in controlling the hopping height of a one legged hopping robot. The hopping mechanism produces continuous and rhythmic pattern. The continuous and rhythmic pattern behaviors produce oscillation feedback to the closed loop system and continuously produce oscillation error to the controller. Therefore, hopping peak height algorithm is designed and embedded into the closed loop control system feedback to determine the hopping peak of each produced hopping as a feedback. The existence of the hopping peak height algorithm assists the PI-CPG controller to converge the hopping height error approximately to zero

Comprehensive Development And Control Of A Path-Trackable Mecanum-Wheeled Robot

This paper presents an intuitively straightforward yet comprehensive approach in developing and controlling a Mecanum-wheeled robot (MWR), with decent path tracking performance by using a simple controller as an end objective. The development starts by implementing two computer ball mice as sensors to realize a simple localization that is immune toward wheel slippage. Then, a linearization method by using open-loop step responses is carried out to linearize the actuations of the robot. Open-loop step response is handy, as it directly portrays the non-linearity of the system, thus achieving effective counteraction. Then, instead of creating a lookup table, polynomial regression is used to generate an equation in which the equation later represents an element of the linearizer. Next, a linear angle-to-gain (LA-G) method is introduced for path tracking control. The method is as easy as just linearly maps the summation of two angles-the angle between immediate and desired positions and the MWR's heading angle, into gains to control the wheels. Unlike the conventional control method which involves inverse kinematics, the LA-G method is directly a displacement-controlled approach and does not require the knowledge of parametric values, such as the robot's dimensions and wheel radius. Finally, all the methods are implemented, and the MWR experimentally demonstrates successfully tracking various paths, by merely using proportional controllers

Design and implementation of a laboratory scale single axis solar tracking system

The renewable solar energy can be produced by using the Photovoltaic (PV) panel which converts the solar energy to the electrical energy. Global warming can be reduced by using the solar energy to generate electricity. Therefore in this project, an active type single axis solar tracking system is designed and constructed. The solar tracking system can enhance the amount of solar energy harvest throughout the day as compared to the fixed solar panel. A laboratory-scale single axis solar tracking system is developed to have a better understanding on the working mechanism of the solar tracking system. By using the laboratory-scale system, the system becomes portable and convenient to be allocated at the suitable workplace for solar tracking process. Moreover, the laboratory scale solar tracking system can be easily controlled and programmed by the users such as angle of rotation of the solar panel and the direction of rotation. In this project, microcontroller is used as an integrated control unit and the plant is actuated by the DC geared motor. The validity of the laboratory-scale single axis solar tracking system was examined experimentally. The solar tracking system operates by rotating to the desired angle in every hour. The workspace of the solar tracking system is determined and identified. The solar tracking system workspace must be identified and examined carefully before the installation to prevent any accidents occurred during operation. This research is important for Faculty of Electrical Engineering of Universiti Teknikal Malaysia Melaka (UTeM) to identify the safety workspace for the solar tracking system due to the actual solar tracking system plant is still cannot be operated because of the limited workspace

Positioning control of XY table using 2-DOF PID controller

A two-degree-of-freedom (2-DOF) PID controller is designed for an AC servo ball screw driven XY table. XY table is widely used in manufacturing industry especially in CNC machineries. The most commonly used controller in industries is conventional PID controller. This controller has satisfactory performance, simple structure, and is one-degree-of-freedom (1DOF). Nonetheless, PID controller can only achieve either good set-point response or good disturbance response. This leads to introduction of 2-DOF PID controller which can achieve both good set-point response and disturbance response. In this project, 2-DOF PID is used for accurate tracking purpose. 2-DOF PID controller is designed using two-steps-tuning-method. Disturbance response is optimized by tuning parameters of 〖 K〗_P,T_i,〖and T〗_D using Ziegler-Nichols 2nd method, followed by optimization of set-point response by tuning of 2-DOF parameters, α and β. Tracking performance of 2-DOF PID controller is compared with conventional PI and 1-DOF PID. Maximum absolute error, sum of absolute error, and mean square error are analyzed for all tracking performance of compensated system. Result shows that tracking error compensation (set-point response) of 1-DOF PID controller is better than 2-DOF PID controller. However, this is due to tuning of α and β parameters in simulation in this project. α and β values should be tuned experimentally. Disturbance response of 1-DOF PID and 2-DOF PID are almost similar due to same 〖 K〗_P,T_i,〖and T〗_D values are used in both controllers

Optimization Techniques In PID Controller On A Nonlinear Electro-Hydraulic Actuator System

The controller is an important component in the nonlinear control system, especially for the system that needs accuracy in position tracking. Electro-Hydraulic Actuator (EHA) system i s a popular nonlinear system that is used by researchers. Proportional- Integral-Derivative (PID) controller is the most popular controller that is normally used in the industry. This i s mainly because of i ts simplicity in the design process. However, there are three constants that need to be assigned in the PID controller, often we called thi s as the parameters s election process or the PID tuning process. In this paper, a comparison s tudy for the selection process of the PID parameters process will be conducted among Ziegler-Nichols tuning method, conventional Particle Swarm Optimization (PSO) technique and Priority-based Fitness Particle Swarm Optimization (PFPSO) technique. PFPSO is one of the improved versions of the conventional PSO technique. The s imulation study wi ll be conducted on a nonlinear Electro-Hydraulic Actuator (EHA) system. A simple robustness test on the PID controller will be evaluated in terms of actuator internal leakage. Results showed that the PID performed better whe n its controller's parameters are selected using PFPSO technique rather than the Ziegler-Nichols method and conventional PSO technique