Disclosed herein is a control system for an exoskeleton haptic device, having: a frame structure, to be coupled to the body of a subject; actuators, carried by the frame structure and operable to cause movement of a number of joints of the body; and sensors, coupled to the body to detect first signals indicative of an intention of movement of the subject. The control system is provided with: a feedback stage, controlling a position of the joints based on a reference position; a feedforward stage, controlling a compliance presented by the exoskeleton haptic device to the subject based on the detected first signals; and a combining block, combining outputs from the feedback stage and feedforward stage in order to generate a driving signal for the actuators, thereby imposing a controlled position to the joints. This primary control action may also be integrated with a posture equilibrium control, for controlling postural equilibrium of the subject during the movement.

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Limited research has been done on exoskeletons to enable faster movements of the lower extremities. An exoskeleton’s mechanism can actually hinder agility by adding weight, inertia and friction to the legs; compensating inertia through control is particularly difficult due to instability issues. The added inertia will reduce the natural frequency of the legs, probably leading to lower step frequency during walking. We present a control method that produces an approximate compensation of an exoskeleton’s inertia. The aim is making the natural frequency of the exoskeleton-assisted leg larger than that of the unaided leg. The method uses admittance control to compensate for the weight and friction of the exoskeleton. Inertia compensation is emulated by adding a feedback loop consisting of low-pass filtered acceleration multiplied by a negative gain. This gain simulates negative inertia in the low-frequency range. We tested the controller on a statically supported, single-degree-of-freedom exoskeleton that assists swing movements of the leg. Subjects performed movement sequences, first unassisted and then using the exoskeleton, in the context of a computer-based task resembling a race. With zero inertia compensation, the steady-state frequency of the leg swing was consistently reduced. Adding inertia compensation enabled subjects to recover their normal frequency of swing.

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Limited research has been done on exoskeletons to enable faster movements of the lower extremities. An exoskeleton’s mechanism can actually hinder agility by adding weight, inertia and friction to the legs; compensating inertia through control is particularly difficult due to instability issues. The added inertia will reduce the natural frequency of the legs, probably leading to lower step frequency during walking. We present a control method that produces an approximate compensation of an exoskeleton’s inertia. The aim is making the natural frequency of the exoskeleton-assisted leg larger than that of the unaided leg. The method uses admittance control to compen-sate the weight and friction of the exoskeleton. Inertia compensation is emulated by adding a feedback loop consisting of low-pass filtered acceleration multiplied by a negative gain. This gain simulates nega-tive inertia in the low-frequency range. We tested the controller on a statically supported, single-DOF exoskeleton that assists swing movements of the leg. Subjects performed movement sequences, first unas-sisted and then using the exoskeleton, in the context of a computer-based task resembling a race. With zero inertia compensation, the steady-state frequency of leg swing was consistently reduced. Adding inertia compensation enabled subjects to recover their normal frequency of swing.

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The present invention describes, generally, a method and system for controlling the dynamics of an actuatable load functioning or operable within a servo or servo-type system, wherein the dynamics of the load are controlled by way of a unique pressure control valve configured to provide intrinsic pressure regulation. The pressure control valve, which may be referred to as a dynamic pressure regulator because of its capabilities, utilizes dual spools that are physically independent of one another and freely supported in the valve body to regulate the pressures acting within the overall system between the control or pilot pressure and the load or load pressure. The dual spools of the pressure control valve, although physically independent of one another, function in cooperation with one another in an attempt to maintain a state of equilibrium in the system, namely to keep pressure acting on or within the actuator (the load pressure), or the feedback force corresponding to the load pressure, the same as the control or pilot pressure. Moreover, pressure regulation and control is intrinsic to the pressure control valve because of the configuration and function of the dual spools and the mechanical feedback system acting on the spools, thus eliminating the need for electronically or mechanically user controlled systems.

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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.

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