Hybrid Motor System for High Precision Position Control of a Heavy Load Plant

The lift up or press process with high precision position control is an important application in industries. An example of the process lift up and press is the process of a machine tool for drilling, milling, or injection. It is difficult to design the mechanism and controller to control the position of the base table accuracy because it needs to control the base position of the system with the weight varying in a large range. Also, the friction in the system would vary in a large range. This lead to low performance of the system in some range of load. Therefore, the new design system utilizes a DC motor and ball screw and pneumatic actuator to create the hybrid motor system for applying to the lift up and press system. The pneumatic actuator is designed to support the heavy load and the DC motor and ball screw is designed to control the position. Then, the developed hybrid motor can be used to improve the performance of the system. The simulation and experiment results show that the developed system can improve the rise time, setting time, and steady state error. Then, the time response of the system with heavy load look similar to the time response of the system with light load. Moreover, the developed hybrid motor technique can apply to the applications such as to control the 3D powder painter tank base position, and the silicon injection system, the 3D print head, which is a challenge system due to the high friction in tube

Review On Controller Design In Pneumatic Actuator Drive System

A pneumatic actuator is a device that converts compressed air into mechanical energy to perform varieties of work. It exhibits high nonlinearities due to high friction forces, compressibility of air and dead band of the spool movement which is difficult to manage and requires an appropriate controller for better performance. The purpose of this study is to review the controller design of pneumatic actuator recommended by previous researchers from the past years. Initially, the basic views of the pneumatic will be presented in terms of introduction to the pneumatic actuator and its applications in industries. At the end of this review, discussions on the design of the controllers will be concluded and further research will be proposed along with the improvement of control strategies in the pneumatic actuator systems

Experimental Evaluation of A Cylinder Actuator Control Using McKibben Muscle

There has been an increased interest in applying pneumatic muscle actuator (PMA) in robotic systems because of its low weight and high compliant characteristics. On the other hand, pneumatic muscle actuator (PMA) is gaining attention in robotic applications because of its low weight and high compliant characteristics. It is known that the McKibben muscle is different from the fluidic cylinder actuator in that the cylinder was unstable in its position and in its velocity in an open-loop system unlike the McKibben that is stable in its position. The modeling and control of McKibben muscle as the actuator for the cylinder are crucial because it is known to have non-linear response, hysteresis and small stroke. In this project, a single acting cylinder model which would have uncontrolled extension to push direction by compressed air, is actuated and controlled using a PMA. The system is designed with two 1.3mm-diameter McKibben muscles attached to the cylinder. Open loop control was used and the result shows that the PMA is able to control the cylinder with good performance

Modeling and control of a pneumatic muscle actuator

This thesis presents the theoretical and experimental study of pneumatic servo position control systems based on pneumatic muscle actuators (PMAs). Pneumatic muscle is a novel type of actuator which has been developed to address the control and compliance issues of conventional cylindrical actuators. Compared to industrial pneumatic cylinders, muscle actuators have many ideal properties for robotic applications providing an interesting alternative for many advanced applications. However, the disadvantage is that muscle actuators are highly nonlinear making accurate control a real challenge. Traditionally, servo-pneumatic systems use relatively expensive servo or proportional valve for controlling the mass flow rate of the actuator. This has inspired the research of using on/off valves instead of servo valves providing a low-cost option for servo-pneumatic systems. A pulse width modulation (PWM) technique, where the mass flow is provided in discrete packets of air, enables the use of similar control approaches as with servo valves. Although, the on/off valve based servo-pneumatics has shown its potential, it still lacks of analytical methods for control design and system analysis. In addition, the literature still lacks of studies where the performance characteristics of on/off valve controlled pneumatic systems are clearly compared with servo valve approaches. The focus of this thesis has been on modeling and control of the pneumatic muscle actuator with PWM on/off valves. First, the modeling of pneumatic muscle actuator system controlled by a single on/off valve is presented. The majority of the effort focused on the modeling of muscle actuator nonlinear force characteristics and valve mass flow rate modeling. A novel force model was developed and valve flow model for both simulation and control design were identified and presented. The derived system models (linear and nonlinear), were used for both control design and utilized also in simulation based system analysis. Due to highly nonlinear characteristics and uncertainties of the system, a sliding mode control (SMC) was chosen for a control law. SMC strategy has been proven to be an efficient and robust control strategy for highly nonlinear pneumatic actuator applications. Different variations of sliding mode control, SMC with linear model (SMCL) and nonlinear model (SMCNL) as well as SMC with integral sliding surface (SMCI) were compared with a traditional proportional plus velocity plus acceleration control with feed-forward (PVA+FF) compensation. Also, the effects of PWM frequency on the system performance were studied. Different valve configurations, single 3/2, dual 2/2, and servo valve, for controlling a single muscle actuator system were studied. System models for each case were formulated in a manner to have a direct comparison of the configuration and enabling the use of same sliding mode control design. The analysis of performance included the sinusoidal tracking precision and robustness to parameter variations and external disturbances. In a similar manner, a comparison of muscle actuators in an opposing pair configuration controlled by four 2/2 valves and servo valve was executed. Finally, a comparison of a position servo realized with pneumatic muscle actuators to the one realized with traditional cylinder was presented. In these cases, servo valve with SMC and SMCI were used to control the systems. The analysis of performance included steady-state error in point-to-point positioning, the RMSE of sinusoidal tracking precision, and robustness to parameter variations

Modeling and control of a pneumatic muscle actuator

This thesis presents the theoretical and experimental study of pneumatic servo position control systems based on pneumatic muscle actuators (PMAs). Pneumatic muscle is a novel type of actuator which has been developed to address the control and compliance issues of conventional cylindrical actuators. Compared to industrial pneumatic cylinders, muscle actuators have many ideal properties for robotic applications providing an interesting alternative for many advanced applications. However, the disadvantage is that muscle actuators are highly nonlinear making accurate control a real challenge. Traditionally, servo-pneumatic systems use relatively expensive servo or proportional valve for controlling the mass flow rate of the actuator. This has inspired the research of using on/off valves instead of servo valves providing a low-cost option for servo-pneumatic systems. A pulse width modulation (PWM) technique, where the mass flow is provided in discrete packets of air, enables the use of similar control approaches as with servo valves. Although, the on/off valve based servo-pneumatics has shown its potential, it still lacks of analytical methods for control design and system analysis. In addition, the literature still lacks of studies where the performance characteristics of on/off valve controlled pneumatic systems are clearly compared with servo valve approaches. The focus of this thesis has been on modeling and control of the pneumatic muscle actuator with PWM on/off valves. First, the modeling of pneumatic muscle actuator system controlled by a single on/off valve is presented. The majority of the effort focused on the modeling of muscle actuator nonlinear force characteristics and valve mass flow rate modeling. A novel force model was developed and valve flow model for both simulation and control design were identified and presented. The derived system models (linear and nonlinear), were used for both control design and utilized also in simulation based system analysis. Due to highly nonlinear characteristics and uncertainties of the system, a sliding mode control (SMC) was chosen for a control law. SMC strategy has been proven to be an efficient and robust control strategy for highly nonlinear pneumatic actuator applications. Different variations of sliding mode control, SMC with linear model (SMCL) and nonlinear model (SMCNL) as well as SMC with integral sliding surface (SMCI) were compared with a traditional proportional plus velocity plus acceleration control with feed-forward (PVA+FF) compensation. Also, the effects of PWM frequency on the system performance were studied. Different valve configurations, single 3/2, dual 2/2, and servo valve, for controlling a single muscle actuator system were studied. System models for each case were formulated in a manner to have a direct comparison of the configuration and enabling the use of same sliding mode control design. The analysis of performance included the sinusoidal tracking precision and robustness to parameter variations and external disturbances. In a similar manner, a comparison of muscle actuators in an opposing pair configuration controlled by four 2/2 valves and servo valve was executed. Finally, a comparison of a position servo realized with pneumatic muscle actuators to the one realized with traditional cylinder was presented. In these cases, servo valve with SMC and SMCI were used to control the systems. The analysis of performance included steady-state error in point-to-point positioning, the RMSE of sinusoidal tracking precision, and robustness to parameter variations

A nonlinear controller for pneumatic servo systems: Design and experimental tests

International audienceThis paper is dedicated to the problem of pneumatic cylinder control without pressure measurement. Based on the theory of homogeneous, finite time stable, ordinary differential equations, a state feedback nonlinear controller is proposed. The closed loop system stability is proved and an attraction domain of the controller is given. The performances and the effectiveness of the proposed controller are illustrated against an experimental setup consisting of a pneumatic cylinder controlled by dSPACE dS1103 microcontroller

Model Identification And Controller Design For An Electro-Pneumatic Actuator System With Dead Zone Compensation

Pneumatic actuator system is inexpensive, high power to weight ratio, cleanliness and ease of maintenance make it’s a choice compared to hydraulic actuator and electromagnetic actuator. Nonetheless, the steady state error of the system is high due to the dead zone of the valve. In this paper, an Auto-Regressive with External Input (ARX) model structure is chosen to represent the pneumatic actuator system. The recursive least square method is used to estimate the model parameters. The pole-assignment controller is then developed for position tracking. To cater the problem of high in steady state error, the dead zone compensation is added to the system. The dead zone controller was designed based on the inverse dead zone model and the dead zone compensation designed based on the desired error. The proposed method is then experimentally with varies load and compares with Nonlinear PID controller. The result shows that the proposed controller reduced the overshoot and steady state error of the pneumatic actuator system to no overshoot and 0.025mm respectively. Index terms: System identification, recursive least square, ARX, dead zone compensator, pneumatic actuato