Abstract. This paper presents the design of a controltechnique applied to the pneumaticactivesuspension system of a quartercar model using controller with fuzzy logic embedded in the activeforcecontrol component. The overall control system is decomposed into two loops. In the main loop the desired force signal is calculated using an activeforcecontrol strategy with a sugeno fuzzy logic element which is being employed to estimate the mass needed to feed the control loop. A Mamdani fuzzy logic controller is implemented in the outer loop to design a force controller such that the desired force signal is achieved in a robust manner. The resulting control strategy known as fuzzy – activeforce controller (FLC-AFC) is used to control a nonlinear actuator attached between the sprung mass and the unsprung mass of the quartercar model. The performances of the proposed control method were evaluated and later compared to examine the effectiveness in suppressing the vibration effect of the suspension system. Resulting fuzzy activeforcecontrol gives better results if compared to the fuzzy logic and the passive suspension system. Keywords: pneumaticactuator, fuzzy logic controller, quartercarsuspension, activeforcecontrol. 1. Introduction
stiffness of the car body spring, 𝑘 𝑡 stiffness of car tyre, and 𝐶 𝑑 damper coefficient. Other than that 𝑋 𝑠 , 𝑋 𝑢 , and 𝑋 𝑟 are state variables for sprung mass, unsprung mass, and road profile. Generally, the frequency of the unsprung mass lies in the range of 10-15 Hz, while the frequency of the sprung mass lies in the range of 1-2 Hz. (Xue et al. 2011, Appleyard and Wellstead 1995). Moreover, active suspensions commercially implemented in automobiles today are based on hydraulic or pneumaticactuator, Appleyard and Wellstead (1995). Figure 1.2 shows the schematic diagram of the MacPherson strut suspension system applied in modern automotive activesuspension system. (Hong et al. 1999). The 𝑓 𝑑 is a body force of
inputs which are the body acceleration, body velocity, body deflection and one input, which is the desire actuatorforce. The designed Fuzzy Logic controller had been compared with the PID controller. There were two type road conditions that used as the road disturbance input, the smooth road and the real road roughness. For the smooth road condition, the proposed Fuzzy Logic controller had given the reduction in percentage in body acceleration, suspension working space and dynamic tire load amplitudes less than the PID controller by 65%, 19.35% and 30.43% respectively. For the real road roughness condition, the proposed Fuzzy Logic controller also gives the percentage in the body acceleration, suspension working space and dynamic tire load amplitudes less than the PID controller by 61.3%, 6.9% and 24.24% respectively. Therefore, the proposed Fuzzy Logic controller for the activesuspension system had improved the stability of the quartercar model.
This activesuspension system is different from passive suspension system in term of having a pneumaticactuator to support force for the activesuspension system. The pneumaticactuator will be control by a controller that will be created and test in this project. The control that will be evaluated in this project is the Proportional-Integral Sliding Mode Control. This technology allows car manufacturers to achieve a higher degree of both ride quality and car handling by keeping the tires perpendicular to the road in corners, allowing for much higher levels of grip and control.
Mohammad, Mahir and IyadEt.al  gives new control strategy for activesuspensionusing modified fuzzy and PID controllers. In this they proposed controlled strategy to control the suspension system by means of electro- hydraulic actuator. The passive suspension is replaced by low frequency activesuspension. The quartercar model tested under rolling effect, cornering and pitching effect at different speeds and road profiles. The reduction in body acceleration by 60% gives better road holding and car stability. There are two types of active suspensions which are commonly recognized that are low bandwidth and high bandwidth. Non-linear controllers are more capable to handle high bandwidth activesuspension because they show good capability at worst road condition. Researchers give the linear controller over activesuspension of low bandwidth new PID with fuzzy switch which improve the performance of suspension. The design of suspension is concern with three main parameter; car body acceleration for ride comfort, the tire deflection for road holding and the suspension travel. The ideal suspension system would minimize these three quantities for any road and operating condition, which is not achievable for suspension having constant spring stiffness and damping. This can be achieved by activesuspension system. But this needed high external energy. Hence it is not widely used. The alternative solution is to use of semi-activesuspension. It reduces car body resonance without compromising road holding. But this solution gives disturbance like jerk, rattling noise etc.
accurately control the position of a pneumatic cylinder using pulse width modulation (PWM) technique. A fuzzy PI controller is designed and implemented to overcome the nonlinearity inherited in the system due to air compressibility, dry friction and the nature of the digital valves. The actuator under control is a vertical double-acting single-rod pneumatic cylinder of 158 mm stroke and 20 mm bore diameter. Four one way digital valves are employed in such a way that two valves supply the pressurized air to the cylinder while the others are used to exhaust the outlet air. The fuzzy controller is designed in Labview environment and coded by the graphical language. The fuzzy rules along with the membership functions are carefully adjusted to produce a satisfactory fuzzy surface capable of controlling the system non- linearities. Results of the open loop experiments showed a considerable delay at the starting of the piston motion associated with a non-linear behaviour which are dependent on the duty cycle (signal ON time over cycle time). Also the valve operating range is found to be between 12.5% and 60% cycle duty at 95 Hz. The gain selection of the fuzzy PI parameters (K e , K ∆e , K ∆u ) is
In vehicle suspension system ride comfort used for studying the performance of suspension system. For investigating the performance of semi-activesuspension system a quartercar model with two degree of freedom has been used. Many analytical and experimental studies on semi-activesuspension have been performed to improve ride comfort. Skyhook control strategies and PID controller now widely applied to vehicle suspension system.
Based on all that mentioned before it can be learnt that pneumatics are a qualified alternative over hydraulics and electromechanical systems if there is a solution to tackle with its high nonlinearity characteristics. Thus, controller design and its implementation for pneumatic servo actuators is one of the challenging problems in control engineering.
This research paper will discuss the study of a two degree-of-freedom quartercar model passive suspension system. Vehicle suspension system are rated by the ability to provide good vehicle handling and passenger comfortability. However, these are two conflicting criteria for a passive suspension system. This can be improved by introducing actuators to the system, transforming it into an activesuspension system. In this research, the main objectives are to study the motion characteristics of the passive suspension system of a quartercar model. Apart from that, a controller is designed to control platform 1, which represents the road profile of the quartercar model. The setup of the whole research is discussed and illustrated with details. Calibration of the IR sensors used in the research have been carried out. The setup and steps for calibration is included. The calibration results showed the relationship between IR sensor output voltage and measured distance, which output voltage decreases with increasing distance. Besides that, an experiment to determine the effects of tilting the IR sensor is also completed. The results show greater tilt angle decreases IR sensor output voltage at a fixed distance. The output voltage of the IR sensor is converted using a polynomial equation generated from the calibration of sensor. Next, experiments such as open loop characteristics testing using system identification method is carried out to determine the transfer function of the passive suspension system. Once these steps are completed, a closed loop uncompensated system is designed to determine the error between the output and desired input. Then, a proportional-integral-derivative (PID) controller is designed by using manual tuning method. The K p value is first varied, followed by varying K i and then K d . A
A suspension system connects the wheel of the car to the body. In such a way that the body is cautioned from jolts resulting from driving on uneven road surfaces. The suspension affects a car’s comfort and performance. The suspension system must also keep tyres firmly in contact with the ground and to provide a comfortable ride for the passengers. The suspension also prevents the car form shaking itself and without the suspension the ride will be so harsh and inconvenient.
Pneumatic Muscle Actuators (PMA) or Pneumatic Artificial Muscle (PAM) is one of the few pneumatics actuators that are currently being sought after and applied in various fields. Pneumatic muscle actuator is a contractile device manufactured with the inflaTable pneumatic bladder of usually long synthetic or natural neoprene tube wrapped inside artificial mesh at a pre-defined angle . Figure 1.4 shows a variation of PMA namely the fluidic muscle developed by FESTO corporation.
The dynamic load and vibration caused by landing impact and the unevenness of runway will result in airframe fatigue, discomfort of crew/passengers and the reduction of the pilot’s ability to control the aircraft. The semi-activesuspension system can provide good performance of both landing impact and taxi, and has the ability for adapting to various ground and operational conditions. This current paper designs Proportional Integral Derivative controller based on Bees Intelligent Algorithm as the optimization technique for nonlinear model of semi-active landing gear system that chooses damping performance of system at touchdown as object function. Optimal setting of controller parameters to achieve favorable time response using numerical software method based on Bees Algorithm is more simple and more effective than other traditional methods such as Ziegler-Nichols and experimental because it does not need high experience and complex calculations and leads to better results. This research develops nonlinear two-dimensional mathematical model to describe landing gear system with oleo- pneumatic shock absorber and linear tire. Based on this model, the dynamic equations are used to investigate the behavior of an aircraft semi-active landing gear system subject to runway disturbance excitation and the stability conditions of the landing system around static equilibrium position is studied. SIMULINK simulation software is applied to validate the theoretical analysis of system stability. Results of system numerical Simulation with optimized controller using Bees Algorithm in MATLAB software shows that the transmitted impact load to airframe, the vertical vibration of aircraft and time to return static equilibrium position at touchdown are significantly improved.
In this paper, the mathematical model of the nonlinear activesuspension system and the nonlinear hydraulic actuator was developed successfully. Matlab/Simulink model was designed for the NARMA-L2 , model reference and predictive controllers and comparisons of this proposed controllers have been done for the control targets (suspension deflection, body acceleration and body travel) using bump and sine pavement road profiles. The simulation results prove that the nonlinear activesuspension system with NARMA-L2 controller shows a good response in minimizing the body acceleration and adjusting the suspension deflection and body travel vertical amplitude in both the road disturbances input. Finally, that the nonlinear activesuspension system with NARMA-L2 controller shows a good improvement in ride comfort and road handling.
The forceactuator is controlled by various descriptions of controller determined by the designer. The rectify control strategy will provide better compromise between comfort and vehicle stability . Therefore, activesuspension system offers better riding relief and vehicle handling for the passengers. Figure 3 shows simple plain diagram to clarify how the activesuspension can attain better performance. Figure 4 describe essential component of activesuspension. In this type of suspension, the controller can qualify the system dynamics by activating the actuators . All these three descriptions of suspension systems have its own advantages and disadvantages. However, researchers are focus on the activecarsuspension and it is because the performance obtained is better than the other two types of suspension systems as mentioned before .
Figure 13 shows the experimental setup designed and developed for dynamic response analysis of the SDOF quartercarsuspension system model (refer also plate 2). The set up consists of a cam operated mechanism to pro- vide sinusoidal base excitation of the desired amplitude and excitation frequency. The time dependant motion of both the base excitation u(t) and the sprung mass re- sponse x 1 (t) are sensed and processed by the sensors
̇ Vehicle Velocity At Front-Left Corner ms -1 ̇ Vehicle Velocity At Front-Right Corner ms -1 ̇ Vehicle Velocity At Rear-Left Corner ms -1 ̇ Vehicle Velocity At Rear-Right Corner ms -1 ̈ Vehicle Acceleration At Front-Left Corner ms -2 ̈ Vehicle Acceleration At Front-Right Corner ms -2 ̈ Vehicle Acceleration At Rear-Left Corner ms -2 ̈ Vehicle Acceleration At Rear-Right Corner ms -2
Electro-Hydraulic actuator is common tools used in the industries. This is due to accurate positioning toward the load and fast response make it as major instruments for the industries process. This paper presents experimental work on non-recursive identification of electro-hydraulic actuator system that represented by a discrete-time model in open-loop configuration. A least square method is used to estimate the unknown parameters of the system based on auto regression with exogenous input (ARX) model. The plant mathematical model was approximated using system identification by aid of System Identification Toolbox of Matlab from open-loop input-output experimental data. These models have been validated by R 2 or best fitting criterion, root mean square error and correlation analysis to determine the adequate model for
Optimal vehicle handling, good driving pleasure, best comfort for passengers, effective and efficient isolation of road noise and vibration in suspension systems has been a key research area .This paper presents the application of different controllers to control the vibration occurred in the carsuspension system. When the suspension system is designed, a ¼ model of car is used to simplify the problem to a one dimensional mass spring- damper system. Its open-loop performance on the basis of time response is observed which depicts that the carsuspension has oscillations with large settling time. To overcome this problem, closed-loop system is used. Despite continuous advancement in control theory, Proportional –Integral (PI), Proportional-Integral- Derivative (PID) and H Infinity Control method are the popular technique to control any process. In this paper, Proportional-Integral (PI) , Proportional-Integral-Derivative (PID) and H infinity controllers are used to control the vibrations to give smooth response of the Carsuspension system and carry-out their comparison on the basis of time and frequency using Matlab environment.
Motivation : - The use of pneumatic muscle technology has spread into many different fields including robotics, human power and mobility assistance, therapy and rehabilitation. The design and development of this project will help in the research of applicability/effectiveness of pneumatic muscle actuator positioning system in robotics applications; especially for a set- up with very non-linear characteristics and very difficult to be controlled.