Device for measuring forces exerted during ambulatory exercise

Details Device for measuring forces exerted during ambulatory exercise Device for measuring forces exerted during ambulatory exercise

1997-10-03

2001-01-16

Williams, Hezron (Department: 2856)

Measuring and testing

Orthopedic pressure distribution

C600S595000

Reexamination Certificate

active

06173608

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to the technical field of analysis and measurement apparatus for biomechanical medical purposes, especially medical and sporting use.
BACKGROUND OF THE INVENTION
In the event of rehabilitation following any injury or simply in order to monitor and test an individual, it is important to ascertain the forces exerted by each of the legs when walking normally.
Apparatus is known which can be used to measure angular variations between the tibia and femur corresponding, in particular, to movements of flexion and extension when walking. In contrast, such apparatus provides no indication of the forces exerted by the foot.
In order to measure forces exerted by the foot, there are known systems which use a platform which rests on the floor and uses sensors. The platform is located along the path that is walked in order to obtain an image of the force exerted by a footstep. Nevertheless, it appears that such a solution is not satisfactory given the fact that the person has a natural tendency to pause before walking onto the platform so that the force which is exerted is not natural. This system can be duplicated for each leg. This system is not suitable for the measurement of several consecutive steps.
A proposal has also been made to equip endless belts in an attempt to measure the loads applied when an individual walks. This system involves fitting force meters between the base over which one side of the endless belt travels and the chassis. Such a solution has several drawbacks:
First the measurement cannot differentiate between the force exerted by each leg; this poses relatively few problems when analysing running motion because both feet practically never touch the ground simultaneously since contact is essentially one-footed but it is an important shortcoming when the individual is walking because both feet always touch the ground since contact is two-footed,
Second it is impossible to measure tangential forces.
Patent EP-A-0603115 and the Publication BIOMEDIZINISCHE TECHNIK, Volume 32, No. 10, October 1987 disclose solutions whereby the endless belt consists of two separate parts. In Patent EP-A-0603115, separation is transversal whereas in the Publication BIOMEDIZINISCHE TECHNIK, separation is longitudinal. This being so, in both cases the sensors are placed between the belt and the base, i.e. the part over which the belts travel. It therefore seems that these solutions cannot be used to measure tangential forces taking into account the friction of the belts on the base.
The invention aims to overcome these drawbacks in a simple, safe, effective and rational manner.
The problem which the invention aims to solve is to provide physiologists and orthopaedists with a solution capable of measuring vertical and horizontal forces, i.e. tangential forces of footsteps, especially for several successive steps by advantageously, but not exhaustively, differentiating between the forces exerted by the right leg and those exerted by the left leg.
SUMMARY OF THE INVENTION
In order to solve this problem, a device for measuring the forces exerted by each leg in particular when walking has been devised and perfected which comprises at least one assembly equipped with a motor-driven endless belt installed in a chassis consisting of a rigid structure that accommodates the various drive elements of the belt, said structure being supported by force meters that are physically connected to a common floor support plate in order to measure the vertical and tangential forces.
The vertical and tangential forces are therefore measured given the fact that friction is totally eliminated because the part that accommodates the endless belt is isolated from the floor.
Under these conditions, the friction forces of the belt on its mounting and of all the elements that drive the belt are internal forces and are not applied to the force meters that support the structure under any circumstances.
In order to solve the problem of measuring the various forces exerted by each of the legs during several consecutive steps while walking, the device comprises two independent assemblies arranged in parallel side by side corresponding to each leg, each of the assemblies being separately monitored by force meters supported by the common floor support plate.
Advantageously, each of the structures comprises an upper part in the form of a straight beam designed for mounting an endless belt installed in combination with drive rollers fixed at each of the ends of said beam, said structures being placed opposite each other so as to position the belts so that they almost abut but prevent any contact between the two belts.
In order to solve the problem of measuring vertical and tangential forces straightforwardly and obtaining precise access to rapid variation of these forces, the force meters can be crystal-type force meters capable of measuring the three orthogonal components of a dynamic force acting in any direction.
Advantageously the force meters are attached to each of the ends of each chassis.


REFERENCES:
patent: 5229454 (1993-07-01), Weichmann
patent: 5299454 (1994-04-01), Fuglewicz et al.
patent: 5360015 (1994-11-01), Heurte
patent: 5475087 (1995-12-01), Nashner
patent: 5476013 (1995-12-01), Nashner
patent: 5623944 (1997-04-01), Nashner
patent: 90 17 709 (1991-09-01), None
patent: 0603115A2 (1994-06-01), None
patent: 93/06779 (1993-04-01), None
patent: WO 93/06779 (1993-04-01), None

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