Ming-Chang Shih

Robust control of a novel active pneumatic vibration isolator through floor vibration observer

Active vibration control techniques have been widely applied to enhance passive vibration isolators. The active strategy can improve the common disadvantages of the passive pneumatic isolator, such as resonant character and poor isolation performance at low frequency. In the study, a novel active pneumatic vibration isolator is designed. The isolator uses a passive isolator to support the weight of the payload and a pneumatic actuator to suppress the vibration disturbance through active control strategy. This investigation proposes a robust H∞ controller in order to have good disturbance rejection ability and robustness. According to the linearized nominal plant and appropriate weighting functions, the robust controller can be obtained and implemented by measuring vibration of payload and disturbance. However, it costs higher in practical implementation because two precision accelerometers must be used to measure the vibration at the same time. Therefore, the proportional integral observer (PI observer) is designed to estimate the disturbance and achieve trade-off between cost and performance. Because the PI observer can also estimate the state variables of the active isolation system, the linear quadratic control is also adopted to compare the isolation results with robust control strategies. The simulations and the experimental results show that the proposed robust control scheme improves the disadvantages of the passive pneumatic isolator. Furthermore, the PI observer can estimate the disturbance precisely, and almost the same isolation performance is met comparing to direct disturbance measurement.

Visual Control of an Automatic Manipulation System by Microscope and Pneumatic Actuator

This paper presents an automatic manipulation system consisting of microscope and pneumatic actuator. Through image captured by microscope with a CCD camera, the position between the probe and the object can be calculated in the image plane. A visual fuzzy controller is designed to improve the precision of a nonlinear pneumatic manipulator. From the experimental results, the position error of the system is below 1 pixel. The system can be applied to puncture fish embryo.

Dynamic analysis and control of an anti-lock brake system for a motorcycle with a camber angle

This paper analyses the dynamic response of a motorcycle with an anti-lock brake system (ABS) and camber or steering angle. Most studies have assumed that motorcycles brake in a straight line – that is, without a steering or camber angle. In this work, the performance of an ABS modulator is designed and analysed at first. Then, a controller is designed for motorcycle turning. The controller uses angular acceleration and the pressure value in brake calipers on the front and rear wheels, camber angle and lateral acceleration as commands to control brake pressure on each wheel to prevent wheel locking. The equation of motion for a motorcycle is based on Weirs equations. This motorcycle model combines a mathematical equation of the ABS modulator, tyre model and controller in simulations.

An experimental study on the longitudinal and lateral adhesive coefficients between the tyre and the road for a light motorcycle

The paper presents an analytical approach for estimating the longitudinal and the lateral adhesive coefficients between the tyre and the road surface through the Pacejka ‘magic formula’ tyre model for both pure-slip and combined-slip conditions. The Pacejka ‘magic formula’ tyre model describes the relationship between the normal force and the adhesive force. The relationship between the vehicle velocity and the parameters of the Pacejka ‘magic formula’ tyre model is discussed in the study. One may analyse the adhesive coefficient through genetic algorithm identification to search for the parameters of the Pacejka ‘magic formula’ tyre model from experimental data. A test stand is set up for adhesive force experiments. Only brake slip is studied in the experiments.

A study on optimum design and dynamic behavior of a hydrostatic guideway on rotary machine tool

Because of the oil chamber of the traditional hydrostatic guideway only has one oil outlet, which is easy to concentrate the pressure of the oil chamber at the outlet, leading to non-uniform pressure distribution. Hence, the objective of this study is to design a uniform pressure distribution of hydrostatic guideway. In the design process, the configuration results of the guideway obtained by the analysis of pressure distribution for single chamber and chamber combination. The optimum parameters of each chamber have been determined by using HTGA/Gray approach. This approach will be more robust, stability, and quickly convergent than Taguchi and GA approaches. Furthermore, this study discusses dynamic behavior of the designed guideway and the referenced guideway under external load. Finally, the optimization results clearly indicate that the optimized guideway has better performance than the referenced guideway. And the experimental results are used to verify the feasibility and the practicality of this study.

Comparison Precision of Oil Film Thickness of a Hydrostatic Bearing by Using Different Controllers under External Load

This paper describes a hydrostatic bearing to maintain the oil film thickness, which integrates the hydraulic servo control technology. This study has designed the different intelligent nonlinear controllers by using a non-contact displacement sensor to feedback the oil film thickness of the bearing. This study proposes a fuzzy controller, a self-tuning fuzzy controller and a self-tuning fuzzy sliding mode mechanism to modify the output scaling factor and adds a dead zone compensator to achieve a constant oil film thickness. Finally, the experimental results are used to verify the feasibility and practical implementation success of this study.

Force and Position Control of the Pneumatic Cylinders through a Microscope with a CCD Camera

In this paper, the pneumatic driven manipulation system is driven by the pneumatic cylinders. The proposed system is built by the designed pneumatic force control system and the microscope, which is integrated with the control interface. Firstly, the characteristics of the pneumatic force control system are measured as the proportional pressure control valve. In accordance with these nonlinear characteristics, a self tuning fuzzy controller with a dead zone compensator is designed to improve precision of the pneumatic force control system. From experimental results, the force error can be controlled within ±1 mN. Next, the real-time image is captured by the microscope with a 1/2 type CCD camera. Through designed image processing, image tracking and image recognition, visual image is used to define the position a probe tip. The distance between the target position and a probe tip can be calculated. Finally, the force control of the pneumatic force control system, calculating the distance between the target position and a probe tip, the control processes are integrated with designed the control interface. Visual C++ code from MFC is used to finish the control interface. From experimental results, the position error can be controlled within ± 1 pixel.

A Study on Optimization Design and Performance Test of an Aerostatic Bearing

This paper discusses about how to optimize design of an aerostatic bearing. In order to achieve the objective, there are four necessary qualifications: high load capacity, high stiffness, low flow rate and uniformly pressure distribution, those make an aerostatic bearing optimized. The finite difference method is employed to obtain the numerical solution of the pressure distribution between the surface of aerostatic bearing and worktable. The performance is determined by the pressure distribution of aerostatic bearing. Furthermore, this study proposed an integrated optimal approach that is HTGA/Gray. Comparing with many kinds of optimal theories finds out the most suitable parameters of an aerostatic bearing. Finally, the experimental results for the load capacities and flow rates clearly indicate that the proposed aerostatic bearing can enhance ability effectively.

Hybrid vision control apply on automatic pneumatic micromanipulation system

This paper describes an automatic pneumatic micromanipulation system consisting of a servo pneumatic micromanipulator and microscope observation system. In order to acquire an accurate sample, the probe position with image processing methods is applied to discriminate the sample contour from background. The pneumatic micromanipulator system is a nonlinear system, a hybrid vision controller is designed to control the position of the pneumatic micr o-manipulator and the motion of the micromanipulation system by microscope with a 1/2 type CCD image device. Experimental results shows the steady state errors remain within ± 1 pixel, and the automatic sample puncturing is successful.

Design and Control of the 3 Axes Pneumatic Servo Micromanipulator for the Biological Technology

This paper describes the servo pneumatic control technique, which is applied to the biomedical and biological technology. A cell micromanipulator is built by a 3-axes servo pneumatic micromanipulator system, which is set horizontally or vertically and driven by pneumatic cylinders. Due to the nonlinear characteristic of the air flow and the compressibility of air, the system is highly nonlinear system. Therefore, the compensators must be designed to reject those nonlinear effects and to improve the positioning precision. The dead-zone of the 3 axes pneumatic servo micromanipulator is measured, and the relation of velocity and voltage is plotted. Finally, a hybrid fuzzy controller, with dead zone, and velocity compensation, is designed to control the positioning precision of the 3 axes pneumatic servo micromanipulator. From the experimental results, the pneumatic servo micromanipulator has the positioning accuracy of 40 nm with different displacements. The system can be potentially used for the cell extraction, puncture, cutting and microinjection of the biological technology.Copyright