Gravity balanced orthosis apparatus

Two Degrees of Freedom

[0024] The two degrees of freedom apparatus described is for use in full or partial support of a paretic limb i.e. a leg or a trunk, to help reduce the effect of gravity on the patient's motion. The present invention overcomes the problem of supporting the weight of the afflicted member during a dynamic activity like walking here the weight of the leg continuously shifts by balancing the weight of the leg in all configurations, thereby putting the leg in, so to speak, a state of neutral equilibrium.

[0025] We will use FIGS. 1, 2a and 2b to demonstrate the calculation of the COM and the parallelogram structure as well as the selection of springs and their points of attachment for a system comprising two articulated members. The described system provides the design for an exoskeleton device for attachment to a patient's leg to assist such patient in walking.

[0026] Referring to FIG. 1 there is schematically illustrated a basic system according to the present invent

Three Degrees of Freedom

[0046] More than two articulated members are also within the scope of this invention. The calculation of the COM and the selection of spring constants will next be illustrated in connection with the design of a 3 degree of freedom system for supporting and training device impaired subjects in sitting and getting up from a chair, with reference to FIGS. 4, 5 and 6.

[0047] The term three degrees-of-freedom is used to refer to the motion of the body at the hip, knee, and ankle. In the present design, the device is an orthosis device with straps or other convenient attachments between the corresponding moving segments of the machine and the patient's leg. In this example, the following assumptions are made:

(i) the motion of the body is in sagittal plane;

(ii) both legs have the same motion during the sit to stand cycle (STS) motion; and

(iii) the device links are lightweight and do not add significant mass to the moving.

[0048] The human body can be modeled dur