Review on controller design in pneumatic actuator drive system

This paper presents a model and controller design for a pneumatic actuator system. Three control strategies of position, force and compliance control are proposed. From the compliance control, stiffness characteristic of the pneumatic actuator will be presented in real-time system. Model of the pneumatic actuator system (transfer function) is obtained from System Identification (SI) method. Next, Predictive Functional Control (PFC) with observer design is selected as the control strategy for the pneumatic system. Performance assessment of the controller is performed in MATLAB and validated through real-time experiment. Result shows that the PFC controller is adapted to the system and able to control successfully in both simulation and experiment.

Practical and intuitive controller design method for precision positioning of a pneumatic cylinder actuator stage

Loop shaping is the principle step for synthesising the quantitative feedback theory (QFT) based robust controllers. The controller assures performance robustness in the presence of plant uncertainties. This paper explores a template and bounds free approach for the automated synthesis of low order fixed structure QFT controller for a highly uncertain pneumatic servo actuator system. In this work, the loop-shaping problem has been posed as a multi-objective optimisation problem and solved using the multi-objective variant of the genetic algorithm. At the end of the design process, a set of Pareto optimal solutions (POS) are obtained, to aid the decision maker in choosing an ideal solution from the POS, use of level diagrams has been explored. The simulation of the results and time and frequency domain analysis has been carried out using MATLAB and the results obtained clearly unveil that the designed QFT controller offers robust behaviour over a range of plant's parametric uncertainty.

Pneumatic actuators are preferred for low to medium power requirements due to their desirable features like large power to weight ratio, low cost and safe working medium. Position control of pneumatic actuators is however difficult due to inherent nonlinearity-contributing factors. Therefore, position control of pneumatic actuators have been found to be a challenging task using fixed gain controllers. Sliding mode control can be used to overcome this difficulty. Further, the nonlinear response of pneumatic actuators under variable loading conditions makes it a fit case for using heuristic control based on the knowledge of the system behaviour. This may be done by using fuzzy logic based control approach. In the present work, a hybrid controller was synthesized using fuzzy logic control and sliding mode control for position control of a pneumatic actuation system. The quantitative results emphasized that hybrid FLC-SMC controller exhibited effective position control for pneumatic actuation system as fuzzy logic control was effective for combinations of lower payloads and smaller piston displacements, whereas sliding mode controller was effective for combinations of higher payloads and larger piston displacements.

This paper describes the application of system identification techniques and robust control strategies to a pneumatic muscle actuator system. Due to the inherent nonlinear and time-varying characteristics of this system, it is difficult to achieve excellent performance using conventional control methods. Therefore, we apply identification techniques to model the system as linear transfer functions and regard the un-modeled dynamics as system uncertainties. Because robust control is well-known for its capability in dealing with system uncertainties, we then apply robust control strategies to guarantee system stability and performance for the system. This work is carried out in three parts. First, the pneumatic muscle actuator system was modeled as linear transfer functions. Second, robust control theorem were utilized to design a Hinf robust controller to deal with system uncertainties and performance requirements. Finally, the designed controller was implemented for experimental verifications and compared with a conventional PID controller. From the experimental results, the proposed Hinf robust controller is deemed effective.

Abstract: This paper work deals with the Compressed- air vehicle as a pneumatic actuator that converts one form of energy into another. The Air Driven Vehicle is an eco-friendly vehicle which operates with compressed air. This Vehicle uses the expansion of compressed air to drive the pistons of the vehicle. An Air Driven Vehicle is a pneumatic actuator that creates useful work by expanding compressed air. There is no mixing of fuel with air as there is no combustion. An Air Driven Vehicle makes use of Compressed Air Technology for its operation The Compressed Air Technology is quite simple. If we compress normal air into a cylinder the air would hold some energy within it. This energy can be utilized for useful purposes. When this compressed air expands, the energy is released to do work. So this energy in compressed air can also be utilized to displace a piston. Compressed air propulsion may also be incorporated in hybrid systems, e.g., battery electric propulsion and fuel tanks to recharge the batteries. This kind of system is called hybrid-pneumatic electric propulsion. Additionally, regenerative braking can also be used in conjunction with this system

This paper presents the detailed analysis of a pneumatic clutch actuator with an artificial intelligence control algorithm. The low cost of pneumatic actuator makes it an advantage in automotive applications, but fast and precise control is difficult on account of its time-varying and nonlinear character. In order to achieve good performance and save cost, the development of a fast, accurate, and inexpensive automatic pneumatic actuator clutch system for a single-axle parallel hybrid electrical is important. Targeted for the working principle of electric-drive automated mechanical transmission parallel hybrid system for shifting and clutch dynamic control during operation mode switch course, the design adopts single neuron-adaptive PID-based clutch operation process, proposed the clutch actuator piston non-contact cylinder lock control method to overcome time-varying and nonlinear characteristics’ impact present in the pneumatic actuator closed-loop control, and through the effective control of segment displacement self-diagnosis during the clutch operation process, performs variable clutch control and improve the actuator fault tolerance. Experiments show that the proposed control algorithm is feasible, which has effectively reduced the torque shock and clutch friction work during clutch engaging process.

In this study, we propose a novel micro valve usingPluronic^[○!R] F127 as thermally responsive solution. It was hard to integrated conventional micro valves into micro devices because of their complicated composition. Thus, we propose novel micro valve to be integrated with pneumatic micro actuator. The thermally responsive solution valve was designed and fabricated by using micro channel containing thermally responsive solution with micro heater. The micro valve can be reversibly driven by heating and gellirig of thermally responsive solution. Furthermore,we integrated the micro valve topneumatic balloon actuator and successfully controlled its actuation by developed micro valve. Integration of a valve into pneumatic actuator allows designing compact pneumatic actuator system.

Pneumatic servo positioning systems have been in use for long time and subject to wide spectrum of studies due to their numerous advantages: inexpensive, clean, safe and high ratio of power to weight. However, the compressibility of air and the inherent non-linearity of these systems continue to make achieving accurate position control a real challenge. Conventional pneumatic servo systems are based on cylinder actuators that are difficult to control precisely due to the aforementioned nonlinearities as well as the nonlinear behavior of the air flow through the valve, the friction between the cylinder and the piston, and the stick slip effect at the low velocity of the system. In this paper, a position servo control system using a pneumatic muscle actuator is studied. Pneumatic muscle actuator is a novel type of actuator which has even higher force to weight ratio than the cylinder. In addition, muscle actuator introduces a stick slip free operation giving an interesting option for positioning systems. However, significant hysteresis and position dependant force result in a highly nonlinear system, a real challenge for good control performance. In this paper, pneumatic muscle actuator is controlled by a low-cost on/off valve with PWM-strategy instead of costly servo or proportional valve. The main processes of the system, including flow dynamics, pressure dynamics, force dynamics and load dynamics are derived to provide a full nonlinear model that captures all the major nonlinearities of the system. This model is used for analyzing and tuning the controller performances by simulations before implementing in the real system. In addition, a recently introduced method of using bipolynomial functions to model the valve flow rate is utilized to provide a continuous and invertible description of flow for controller designs. A proportional plus velocity plus acceleration controller with feed-forward component (PVA+FF) is designed based on the linearized system model. For a comparison, a sliding mode controller (SMC) based on linear as well as non-linear system model are designed. The performance of the designed controllers is studied by simulations. The stability and performance analysis includes the effects of friction modeling error and valve modeling error. The robustness of the controllers is tested by varying the payload mass of the system.

Previous works about robotic arm for the automatic harvesting of an agricultural crop of quality small plants (red radicchio), were mainly concerned about the study of the control system for pneumatic actuators moving the robotic arm. The choice of pneumatic actuators was due to their physical favourable characteristics for positioning applications. The main problem of this choice was linked to non-linear behaviour of pneumatic systems. This non-linearity makes accurate position control of a pneumatic actuator difficult to achieve. A recent trend developed the use of inexpensive on/off solenoid valves to control pneumatic actuator systems. Furthermore, the use of pulse width modulated signals (PWM) across the power devices reduces control problems such as dead band and stiction. The results ensure the possibility of following a desired trajectory using potentiometer feedback and a PI controller with parameters tuned in an iterative way. This paper shows experimental results carried out considering a vision feedback obtained with a cheap cam mounted on the top of end-effector. This vision feedback is processed in order to localise the plant position along the movement plane of the robotic arm end-effector. A kinematical model of the robotic arm defines each actuator trajectory to lead end-effector to grasp the plant in the taking plane according to the vision feedback. All the control and localisation system was realised using a single commercial PC.

A speed controller's primary input, for an internal combustion engine-based vehicle, is the throttle angle. The most common way to adjust the throttle angle setting is with a pneumatic actuator. When a faster and more accurate throttle response is desired, the pneumatic based system is generally replaced with a stepping motor mounted directly on the throttle plate assembly. For controller design purposes that fit the physical situation, a model of the throttle actuator system has been developed that is comprised of two second-order linear systems. Using this variable structure model, a switching controller has been designed which has been verified, both theoretically and experimentally, to work satisfactorily. This paper provides an interesting example of designing a reference tracking controller for a real physical system by switching between its stable and unstable structures while achieving closed loop stability.

Pneumatic soft robotic systems show remarkable potentials in producing versatile locomotion and manipulations, owing to their flexibility in structural design and material selections. However, fabrication of pneumatic soft robotic systems with complex 3D structures and material distribution still remains elusive. Herein, a mode‐free fabrication approach, called planar laser cutting and stacking fabrication (PLCSF), is proposed to create pneumatic soft robotic systems with multi‐material and complex structure, which involves the following steps: 1) slicing the 3D model of desired pneumatic soft robotic systems into 2D layers; 2) fabricating each layer via laser cutting corresponding 2D membrane; 3) stacking all layers together to finish the fabrication. With the PLCSF approach, various prevalent pneumatic soft actuators are fabricated with complex structures (including fiber‐reinforced and pneu‐net) and different actuation modes (such as bending, elongation, twisting, abduction, contraction, and grabbing). The scalability of the PLCSF approach to fabricate multiple degrees‐of‐freedom (DOFs) pneumatic soft actuators with integrated structures, such as twisting‐bending pneumatic soft actuators for delivering and bending‐elongation‐bending pneumatic soft actuators for crawling, is also demonstrated. It is further demonstrated that the PLCSF approach also enables creating a bio‐inspired soft hand with nine DOFs, capable of various dexterous motions and manipulations.

A study is conducted on several paradigms to provide closed-loop position control of an actuator powered by a pneumatic muscle system. This actuator has many advantages including having extremely high power/weight and power/volume ratios, being light-weight, autonomous, and safe. An implementation as a tracking controller using a gain scheduling method is presented.

The manipulator robots have many applications, such as industrial process, objects translation, process automation, medicine process, etc. Therefore, these kind of robots are studied in many ways. However, most of the reported works use electrical or hydraulic actuators. These actuators have a linear behaviour and the control is easier than pneumatic actuators. The main disadvantages of electrical actuators are the low power-weight rate, the high current related with its load and its weight. The hydraulic actuators are not ecological, needs hydraulic oil which is feedback to the pump. On the other hand, the pneumatic actuators are lighter, faster, having a greater power-weight rate and air feedback is not needed. However, pneumatic actuators are not used into flexible manipulators developing, due to their highly non linear behaviour. In the case of robot dynamic analysis, other researchers have presented the following works. An equations and algorithms are presented in an easy way to understand for all practical robots (Featherstone, 1987), (Featherstone & Orin, 2000), (Khalil & Dombre, 2002). Also, a dynamic simulation is developed to investigate the effects of different profiles into the contact force and the joint torques of a rigid-flexible manipulator (Ata & Johar, 2004). A study of dynamic equations is developed for a robot system holding a rigid object without friction (Gudino-Lau & Arteaga, 2006). Furthermore, a dynamic modeling analysis is developed for parallel robots (Zhaocai & Yueqing, 2008). The link flexibility is considered for system performance and stability. Moreover, an innovative method for simulation is developed (Celentano, 2008) to allow students and researchers, to easily model planar and spatial robots with practical links. However, the reported works are developed using only electrical actuators, not pneumatic actuators. Therefore, this chapter presents how the pneumatic model is used with a two-link flexible robot and its dynamic analysis for the simplified system. Previous researches by the authors include: a simplified thermo-mechanical model for pneumatic actuator has been obtained (Ramos et al., 2006). For animation purposes, the 27

This study aims to develop a leveling position control of an active PWM-controlled pneumatic isolation table system. A novel concept using parallel dual-on/off valves with PWM control signals is implemented to realize active control and to improve the conventional pneumatic isolation table that supported by four pneumatic cushion isolators. In this study, the cushion isolators are not only passive vibration isolation devices, but also pneumatic actuators in active position control. Four independent closed-loop position feedback control system are designed and implemented for the four axial isolators. In this study, on/off valves are used, and PWM is realized by software. Therefore, additional hardware circuit is not required to implement PWM and not only cost down but also reach control precision of demand. In the controller design, the Fourier series-based adaptive sliding-mode controller with H∞ tracking performance is used to deal with the uncertainty and time-varying problems of pneumatic system. Finally, the experiments on the pneumatic isolation table system for synchronous position and trajectory tracking control, including no-load and loading conditions, and synchronous position control with master-slave method, are implemented in order to verify that the controller for each cushion isolator can realize good position and trajectory tracking performance.