Desain dan Simulasi Kontrol Elektropneumatik Pada Mesin Sealer Cup Semi Otomatis

Identification of viscous friction coefficients for a pneumatic system model using optimization methods

This project aims to develop a novel large stroke asymmetric pneumatic servo system of a hardware-in-the-loop for path tracking control under variable loads based on the MATLAB Simulink real-time system. High pressure compressed air provided by the air compressor is utilized for the pneumatic proportional servo valve to drive the large stroke asymmetric rod-less pneumatic actuator. Due to the pressure differences between two chambers, the pneumatic actuator will operate. The highly nonlinear mathematical models of the large stroke asymmetric pneumatic system were analyzed and developed. The functional approximation technique based on the sliding mode controller (FASC) is developed as a controller to solve the uncertain time-varying nonlinear system. The MATLAB Simulink real-time system was a main control unit of a hardware-in-the-loop system proposed to establish driver blocks for analog and digital I/O, a linear encoder, a CPU and a large stroke asymmetric pneumatic rod-less system. By the position sensor, the position signals of the cylinder will be measured immediately. The measured signals will be viewed as the feedback signals of the pneumatic servo system for the study of real-time positioning control and path tracking control. Finally, real-time control of a large stroke asymmetric pneumatic servo system with measuring system, a large stroke asymmetric pneumatic servo system, data acquisition system and the control strategy software will be implemented. Thus, upgrading the high position precision and the trajectory tracking performance of the large stroke asymmetric pneumatic servo system will be realized to promote the high position precision and path tracking capability. Experimental results show that fifth order paths in various strokes and the sine wave path are successfully implemented in the test rig. Also, results of variable loads under the different angle were implemented experimentally.

This paper demonstrates the effectiveness of applying constraints in a controller algorithm as a strategy to enhance the pneumatic actuator system’s positioning performance. The aim of the present study is to reduce the overshoot in the pneumatic actuator positioning system’s response. An autoregressive with exogenous input (ARX) model structure has been used to model the pneumatic system, while a model predictive control (MPC) has been employed as a control strategy. The input constraint has been applied to the control signals (on/off valves signals) to ensure accurate position tracking. Results show that the strategy with constraint effectively reduced overshoot by more than 99.0837 % and 97.0596 % in simulation and real-time experiments, respectively. Moreover, the performance of the proposed strategy in controlling the pneumatic positioning system is considered good enough under various loads. The proposed strategy can be applied in any industry that used pneumatic actuator in their applications, especially in industries that involved with position control such as in manufacturing, automation and robotics. The strategy proved to be capable of controlling the pneumatic system better, especially in the real-time environment.

This paper presents an approach for torque error compensation in an oscillating rotary pneumatic actuator. It is difficult to control the output torque of a pneumatic actuator precisely because of typical non-linear factors such as dead zone and pressure fluctuations in a pneumatic system. Thus, we proposed a hybrid actuator system which is integrated with an oscillating rotary pneumatic actuator and a voice coil motor (VCM) so as to compensate torque error in the pneumatic system by the VCM. Driving experimental results confirmed that the torque error in the pneumatic system is compensated by the VCM. Consequently, the hybrid actuator achieves high driving accuracy.

This work discusses the power transmitted by flowing compressed air, called air power in this study. Two processes are discussed to clarify the energy conversion in pneumatic systems. One is air compression where mechanical work is required for compressing air, and another is actuation of an actuator where compressed air is supplied and mechanical work is outputted. It is concluded that air power can be represented by the work-producing potential of compressed air. Furthermore, it is clear that air power consists of two parts. One is transmission power which represents pushing power from the upstream to the downstream of flowing air, and another is expansion power from the work ability of air expansion. It can be seen that expansion power should exist in any compressible fluid. With the success in determining air power, an energy consumption comparison between pneumatic and electric actuator systems is made. It is clear that a pneumatic system is not always less efficient. When holding a load for a long time, a pneumatic system is more efficient.

In equipment manufacturing processes, pneumatic systems are commonly used because of their relatively simple design, high power-to-weight ratio, clean power source, safety, zero heat generation, and easy maintenance. Pneumatic systems contain devices such as linear actuators that convert air pressure and create straight-line motion and are widely used in industrial automation, robotics, and machinery. However, these pneumatic actuators are susceptible to frictional forces and difficult to control owing to their inherent air pressure characteristics. They therefore lack the precision and accuracy of electric actuators. Precision motion systems have become increasingly popular in manufacturing equipment, and this industrial revolution has led to the reduction of pneumatic systems adopted in precision motion systems. Many special type pneumatic servo systems have, through years of research and engineering efforts, been designed to meet special requirements such as precision and speed. However, these involve high investment and engineering time to adopt. Hence, this paper presents a novel compensator-based control system that uses a standard type linear pneumatic actuator to achieve ultra-high precision positioning control. The ultra-high-precision control feature, endowed with the inherent benefits of pneumatic systems such as safety, provides an all-around approach for future industrial automation. The research methodology involves the design of a control system with a novel compensator algorithm to address friction interference in pneumatic actuators, which is the primary causation factor of poor positioning accuracy in pneumatic servo systems. Moreover, the compensator can be easily integrated into any main control system, allowing easy adoption in any industrial field. The experimental results prove that high accuracy in the steady-state position can be achieved by this proposed algorithm. A steady-state accuracy of ±1 nm was obtained. Compared to previous studies in which accuracies of approximately 5 nm were obtained, the compensator-based control system achieves a considerably higher accuracy than the previously reported accuracies, matching that of electric actuators. The final section of this paper will present potential directions for future work.

In this paper, we analyzed the stability of a wave-variables-based bilateral control system driven by pneumatic actuators. A pneumatic system is generally a third-order lag system due to the compressibility of gas. Frequency domain passivity of the system is evaluated using scattering matrix. The passivity is numerically confirmed when an appropriate control gain is given. The pneumatic system is nonlinear and can be unstable if the stability analysis is based on frequency domain passivity condition. The simulation results show that the pneumatic bilateral control system is passive.

The paper combines computer vision technology and pneumatics, and designs pneumatic proportional position system based on computer vision technology. In order to realize automatic location of pneumatic system actuator, the paper studies preprocessing technique of image including gray scale conversion of image, image enhancement, smooth, improving image quality and highlighting objective features. And the paper researches image segmentation approach, and applies mathematical morphology to process binary images, which makes image quality better. Introduction In recent years, with the development of computer technology, especially the development of multi media, digital image preprocess and analysis theory, and rapid development and application of large-scale integrated circuit, computer vision technology is widely applied and studied. This paper applies computer vision technology to study the location of objects, which provides the position information of the objects for pneumatic position system, for achieving automatic location of pneumatics, which not only makes pneumatic system have object recognition ability, but also constructs the system of object automatic recognition and location. The paper realizes the application of computer vision technology to pneumatic system, constructs a computer vision pneumatic positioning system, and realizes the function of object recognition and location, which provides reference for real production application. Above al, studying computer vision, especially studying the application of it to industry, has great importance to improve production technology and develop industry. Image gray processing In order to accelerate the processing speed of images, the acquired color images need to be converted into gray images, which is called gray processing. It makes R,G and B of RGB model equal. Gray processing is the process that color images with light and color are converted into gray images. The graying result is the basis of processing the subsequent images. In general, each pixel of color image is represented by three bytes. Each byte corresponds to the light (red, green and blue) of R, G and B component. The pixel of the black-and-white image after conversion uses one byte to represent the gray value which is between 0 and 255. The greater the value is, the whiter the point is. The transformational relation is: ( , ) 0.299 ( , ) 0.587 ( , ) 0.114 ( , ) Gray i j R i j G i j B i j = + + (1 ) ( , ) Gray i j is the gray value of black-and-white image after transformation on point ( , ) i j In formula (1), green has the largest proportion, so G value can be used to be as the gray after transformation. Gray processing has the other methods such as taking the maximum, minimum and average value of three components. The purpose is to make the values of R, G and B component equal. For gray-scale images, each pixel value can be represented by one byte or eight bits, which can show 256 ( 8 2 ) levels. It means that gray-scale images only can show 256 colors, and the gray-scale images only have gray level and have no color. International Conference on Automation, Mechanical Control and Computational Engineering (AMCCE 2015) © 2015. The authors Published by Atlantis Press 331 Image Segmentation and Location After the image receives gray-scale conversion, histogram equalization and smooth, the image is segmented. The objects of the image are separated from the background, which forms a binary image. Based on the image, morphological processing is made to make the centroid coordinates calculation accurate, which realizes pixel coordinates location of object image centroid. Segmentation based on regions. Selecting gray threshold for binarization processing on object image is one of the most typical, simple and effective image segmentation methods. Before taking out geometric features of gray scale images, the images must receive threshold processing, which means the process of taking out the part above or below the gray value. An acquired image includes object, background and noise. The most common method for how to take out the required object image from many-valued images is to suppose a threshold value t, and t divides the data of the image into two parts, the pixel which is greater than t and the pixel which is less than t. If the input image is gray scale image ( , ) f i j ,and the output image is ( , ) g i j , 1 ( , ) ( , ) 0 ( , ) f i j t g i j f i j t ≥  =  <  ,

Pneumatic actuators are capable of providing high power output levels at a relatively low cost. In addition, they are clean, lightweight, and can be easily serviced. The difficulty of achieving a high-bandwidth, stable, pneumatic control system has limited its use in robotic position control applications. For open-loop control applications, such as many robot grippers, pneumatic actuators are often used. In this paper, direct-drive pneumatic servo-actuators are examined for their potential use in robotic applications. A complete mathematical model of the actuator is derived, and several control algorithms are tested numerically and experimentally. Our analysis shows that pneumatic systems are practical for use in servo-control applications. The main limitation is that of the system response time, which is determined by the valve flow characteristics and supply pressure. Large output forces can be obtained and accurately controlled with the servo-valve and differential pressure transducer used in the experiments.

Energy efficiency is an important property in pneumatic systems. There are three approaches for evaluating the efficiency of pneumatic systems. The analysis shows that exergy-related analysis is the most suitable tool. In this study, exergy analysis is performed in a pneumatic line throwing system. The non-flow exergy based on the real gas equation is deduced and divided into the volume component and the non-volume component. The results show that the total exergy efficiency of the system fluctuates slightly between 16.29% and 16.86%. The exergy efficiency of the throttling decompression process decreases from 97.12% to 67.34% as the working pressure decreases. While the exergy efficiency of the pneumatic line-thrower part increases from 17.36% to 24.19% with the decreasing working pressure. Some practical measures are proposed to improve the efficiency of the system. Additionally, future work on this study and outlook for exergy analysis in pneumatic systems are discussed.

Feedback linearization for pneumatic actuator systems with static friction

Friction of plain slide valves

Report on the progress and present state of our knowledge of hydraulics as a branch of engineering

Pneumatic muscle actuators offer a higher force-to-weight ratio compared to traditional cylinder actuators, and introduce stick-slip-free operation that offers an interesting option for positioning systems. Despite several advantages, pneumatic muscle actuators are commonly avoided in industrial applications, mainly due to rather different working principles. Due to the highly nonlinear characteristics of the muscle actuator and pneumatic system, a reliable control strategy is required. Although muscle actuators are widely studied, the literature lacks detailed studies where the performance for servo systems is compared with traditional pneumatic cylinders. In this paper, a pneumatic servo actuation system is compared with a traditional cylinder actuator. As the overall system dynamics are highly nonlinear and not well defined, a sliding mode control (SMC) strategy is chosen for the control action. In order to improve the tracking performance, an SMC strategy with an integral action (SMCI) is also implemented. The control algorithms are experimentally applied on the pneumatic muscle and the cylinder actuator, for the purposes of position tracking. The robustness of the systems are verified and compared by varying the applied loads.

A software tool development for pneumatic actuator system simulation and design