This article presents a wearable lower extremity exoskeleton (LEE) developed to enhance the ability of a human’s walking while carrying heavy loads. The ultimate goal of the current research work is to design and control a power assist system that integrates a human’s intellect for feedback and sensory purposes. The exoskeleton system in this work consists of an inner exoskeleton and an outer exoskeleton. The inner exoskeleton measures the movements of the wearer and provides these measurements to the outer exoskeleton, which supports the whole exoskeleton system to walk following the wearer. A special footpad, which is designed and attached to the outer exoskeleton, can measure the zero moment point (ZMP) of the human as well as that of the exoskeleton in time. Using the measured human ZMP as the reference, the exoskeleton’s ZMP is controlled by trunk compensation so that the exoskeleton can walk stably. A simulation platform has first been developed to examine the gait coordination through inner and outer exoskeletons. A commercially available software, xPC Target, together with other toolboxes from MATLAB, has then been used to provide a real-time operating system for controlling the exoskeleton. Real-time locomotion control of the exoskeleton is implemented in the developed environment. Finally, some experiments on different objects showed that the stable walking can be achieved in the real environment.

Категория: Ищем научные статьи | Нет комментариев »

In this study, the sliding mode approach is applied to the tracking control problem of a planar arm manipulator system driven by a new type of actuator, which comprises a pneumatic muscle (PM) and a torsion spring. Unlike the traditional agonist/antagonist PM actuator, the PM is arranged in place of bicep and the torsion spring provides opposing torque in the presented actuator. The dynamic model is derived for this system and a sliding mode controller is designed to make the joint angle track a desired trajectory within a guaranteed accuracy even there are modelling uncertainties. A selection method is also proposed to obtain an appropriate spring coefficient, which plays an important role in the tracking control task. The effectiveness of the proposed method is confirmed by simulations. The differences between the control results of using our new actuator and that of using the traditional PM actuator in opposing pair configuration are also compared.

Категория: Ищем научные статьи | Нет комментариев »

The torques at the first and second joints of a test subject are measured, which may be generated simultaneously by the coordinate action of the antagonistic mono- and bi-articular muscles. A hexagonal diagram of the output distribution is formulated on a plane formed by two axes corresponding to torques at the first and second joints as. Based on the diagram, the muscular force of the subject, changing through training, may accurately be evaluated, without the necessity of specifying the force of individual function-based muscles of praxis, even if the subject changes his or her position or joint angle. The torques at the first and second joints are measured, which are generated simultaneously by the coordinate action of the antagonistic mono- and bi-articular muscles. The muscular force of the bi-articular link mechanism of the subject is thus measured by the diagram.

(далее…)

Категория: Патенты | Нет комментариев »