508 research outputs found

    Fuzzy PD-Type Iterative Learning Control of a Single Pneumatic Muscle Actuator

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    Pneumatic muscles actuator (PMA) is widely used in the field of rehabilitation robot for its good flexibility, light weight and high power/mass ratio as compared to traditional actuator. In this paper, a fuzzy logic-based PD-type iterative learning controller (ILC) is proposed to control the PMA to track a predefined trajectory more precisely during repetitive movements. In order to optimize the parameters of the learning law, fuzzy logic control is introduced into ILC to achieve smaller errors and faster convergence. A simulation experiment was first conducted by taking the PMA model fitted by support vector machine (SVM) as controlled target, which showed that the proposed method achieved a better tracking performance than traditional PD-type ILC. A satisfactory control effect was also obtained when fuzzy PD-type ILC was applied to actual PMA control experiment. Result showed that it takes 25 iterations for the maximum error of trajectory converges to a minimum of about 0.2

    Positioning Control Of A 1-DOF Pneumatic Muscle Actuator (PMA) System With Modified PID Plus Feedforward Controller

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    The pneumatic muscle actuator (PMA) is a novel actuator which carries numerous advantages such as high strength and power/weight ratio, low cost, compact, clean and easy to maintain features. However, pneumatic muscle actuator has notable nonlinear characteristics, which makes it difficult to control. The purpose of this research is focused on experimental system development and parameter characterization of phenomenological modelling for commercially available Festo Fluidic Muscle Actuator. The model and parameters obtained from the characterization are validated in simulation and experimental platform. The major part of the research is focused on the framework of the modified PID plus feedforward control system, and its effectiveness in a 1 degree-of-freedom PMA system is experimentally demonstrated in comparison with a classical PID controller. The overall control system comprises of a feedforward controller and a modified PID controller in the feedback loop which designed based on the exact PMA system characteristics. The design procedure of the modified PID plus feedforward controller is practical and features easy design procedures. The usefulness and advantages of the proposed controller are shown via positioning and tracking motion experimental studies. Besides, this study also highlights the robustness of the modified PID plus feedforward controller by examining its performance in point-to-point and tracking motions in the presence of extra mass. In the robustness performance, the modified PID plus feedforward controller is compared with a classical PID control systems. The comparative experiments results illustrate that modified PID plus feedforward controller shows the significant motion performances as compared to the PID controller by maintaining steady state error between ±50μm. The framework used to develop the proposed controller is generally enough for further investigation in PMA motion control system, further improvement in terms of positioning accuracy and tracking motion could extend th

    Sampled Data Control of a Compliant Actuated Joint Using On/Off Solenoid Valves

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    This paper proposes a new control system design method for a compliant actuated joint using on/off solenoid valves. Themathematical modelling and the system’s hardware are described in detail. The control design method is presented in ageneral manner so it could be applied for any other similar system. For the present system, the designed controller is implementedvia a digital computer and it is characterised by very good performance and simplicity. The success of the proposedmethod is validated via simulations and experiment

    Sliding Mode Control

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    The main objective of this monograph is to present a broad range of well worked out, recent application studies as well as theoretical contributions in the field of sliding mode control system analysis and design. The contributions presented here include new theoretical developments as well as successful applications of variable structure controllers primarily in the field of power electronics, electric drives and motion steering systems. They enrich the current state of the art, and motivate and encourage new ideas and solutions in the sliding mode control area

    Design of an active orthotic device for joint management.

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    Existing treatment programs and procedures are incapable of addressing the complications encountered with patients who experience spasticity and hypertonia related joint contractures. Current passive therapy procedures and devices are only capable of managing the extent of joint contractures on patients with chronic and acute onset severe neurological disorders. The project was conceived as a means to develop an active device that is capable of adapting to the state of the joint to mange the extent of contractures and to permit consideration for the prevalence of spastic activity episodes and hypertonia. The project focused on the design of the physical prototype and the controller software in order to regulate the operation of such a device. Additionally, the signal conditioning and sensor package was developed as determined to be appropriate for the requirements of the device. The operation of the device was verified in the bench-top environment in the laboratory and on human subjects in order to qualify, verify, and tune the position tracking capability of the device, spastic activity detection and rejection capability of the device, and the operation of patient controlled devices. The overall operation of the device was evaluated on a group of human subjects. Using simulated contractures and spastic activity episodes, the validity of the preliminary deterministic test data was confirmed as was the appropriate operation of the device. The end prototype devices are capable of responding to a spastic activity episode by maintaining a constant load in addition to mimicking the passive extension behavior of conventional commercial devices

    Development of a Hybrid Powered 2D Biped Walking Machine Designed for Rough Terrain Locomotion

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    Biped robots hold promise as terrestrial explorers because they require a single discrete foothold to place their next step. However, biped robots are multi-input multi-output dynamically unstable machines. This makes walking on rough terrain difficult at best. Progress has been made with non-periodic rough terrain like stairs or inclines with fully active walking machines. Terrain that requires the walker to change its gait pattern from a standard walk is still problematic. Most walking machines have difficulty detecting or responding to the small perturbations induced by this type of terrain. These small perturbations can lead to unstable gait cycles and possibly a fall. The Intelligent Systems and Automation Lab at the University of Kansas has built a three legged 2D biped walking machine to be used as a test stand for studying rough terrain walking. The specific aim of this research is to investigate how biped walkers can best maintain walking stability when acted upon by small perturbations caused by periodic rough terrain. The first walking machine prototype, referred to as Jaywalker has two main custom actuation systems. The first is the hip ratchet system. It allows the walker to have either a passive or active hip swing. The second is the hybrid parallel ankle actuator. This new actuator uses a pneumatic ram and stepper motor in parallel to produce an easily controlled high torque output. In open loop control it has less than a 1° tracking error and 0.065 RPM velocity error compared to a standard stepper motor. Step testing was conducted using the Jaywalker, with a passive hip, to determine if a walker with significant leg mass could walk without full body actuation. The results of testing show the Jaywalker is ultimately not capable of walking with a passive hip. However, the walking motion is fine until the terminal stance phase. At this point the legs fall quickly towards the ground as the knee extends the shank. This quick step phenomenon is caused by increased speeds and forces about the leg and hip caused by the extension of the shank. This issue can be overcome by fully actuating the hip, or by adding counterbalances to the legs about the hip

    Design, Manufacturing, and Control of a Pneumatic-Driven Passive Robotic Gait Training System for Muscle-Weakness in a Low Limb

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    [[abstract]]We designed and manufactured a pneumatic-driven robotic passive gait training system (PRPGTS), providing the functions of body-weight support, postural support, and gait orthosis for patients who suffer from weakened lower limbs. The PRPGTS was designed as a soft-joint gait training rehabilitation system. The soft joints provide passive safety for patients. The PRPGTS features three subsystems: a pneumatic body weight support system, a pneumatic postural support system, and a pneumatic gait orthosis system. The dynamic behavior of these three subsystems are all involved in the PRPGTS, causing an extremely complicated dynamic behavior; therefore, this paper applies five individual interval type-2 fuzzy sliding controllers (IT2FSC) to compensate for the system uncertainties and disturbances in the PRGTS. The IT2FSCs can provide accurate and correct positional trajectories under passive safety protection. The feasibility of weight reduction and gait training with the PRPGTS using the IT2FSCs is demonstrated with a healthy person, and the experimental results show that the PRPGTS is stable and provides a high-trajectory tracking performance.[[notice]]補正完
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