WO2020190218A1

WO2020190218A1 - Apparatus and method for decelerating, stopping and propelling movement of various body segments during human walking on a treadmill

Info

Publication number: WO2020190218A1
Application number: PCT/SI2020/050008
Authority: WO
Inventors: Zlatko MATJAČIĆ; Matjaž ZADRAVEC
Original assignee: Univerzitetni Rehabilitacijski Inštitut Republike Slovenije – Soča
Priority date: 2019-03-15
Filing date: 2020-02-27
Publication date: 2020-09-24
Also published as: SI25803A; EP3938059A1

Abstract

The object of the invention is an apparatus and a method for decelerating, stopping and propelling movement of various body segments during human walking on a treadmill. The method and the apparatus of the invention allow an individual who has successfully completed an early stage of rehabilitation and has his stepping function re-established to continue his walking training with a focus on some other aspects such as movement of a leg in a swing, symmetry of walking, coordination of movement, and training balance. The apparatus for decelerating, stopping and propelling movement of various body segments during human walking on a treadmill of the invention is represented by a braking mechanism (A) that is fastened at one side with its connecting means - a cable (1) to a human body segment under exercise and is provided at its other side by a weight (5) or a constant force spring that serves to bias the connecting means. When turned on, the braking mechanism that is optionally an electromagnetic brake/clutch either decelerates or completely and almost instantly stops the movement of the connecting means - the cable (1). The braking mechanism (A) has a measuring means (7) for measuring movement (position and velocity) of the connecting means - the cable (1), which measuring means together with an algorithm for identifying various sub-phases of a walking cycle manages the braking mechanism (A).

Description

APPARATUS AND METHOD FOR DECELERATING, STOPPING AND PROPELLING MOVEMENT OF VARIOUS BODY SEGMENTS DURING HUMAN WALKING ON A TREADMILL

The object of the invention is an apparatus and a method for decelerating, stopping and propelling movement of various body segments during human walking on a treadmill. The method and the apparatus of the invention allow an individual who has successfully completed an early stage of rehabilitation and has his stepping function re-established to continue his walking training with a focus on some other aspects such as movement of a leg in a swing, symmetry of walking, coordination of movement, and training balance.

The technical problem that is successfully solved by the proposed apparatus and method is enabling the application of force or force impulses to various body segments (pelvis, thigh, shank and foot) during treadmill walking in a desired portion of a walking cycle with a minimal mechanical impact on walking exerted by the apparatus/mechanism (low mechanical impedance) when said forces or force impulses are not applied.

Rehabilitation robots for walking normally have a limited number of mechanical degrees of freedom thus limiting the scope of walking training to practicing stepping movement. This type of training in an early rehabilitation phase is of benefit to people with diminished walking ability due to a neurological disease or injury (like stroke due to a cerebro-vascular incident). Such robots (for example LOKOMAT, G-EO, Lyra, Well-Walk 1000) are either in the form of exoskeletons or in the form of mechanisms interacting with feet. These robots are complex and expensive mechanisms and their ability to haptically interact with lower limbs is considerably limited due to their limited number of mechanical degrees of freedom and substantial mechanical inertia.

With the early stage of rehabilitation successfully completed when stepping movement has been re-established in a trainee, walking training should continue with the focus being on some other aspects such as movement of a leg in a swing, symmetry of walking, coordination of movement, and training balance - the above-indicated devices are not suitable for this due to said disadvantages. For example, following a cerebro-vascular incident a swing of a leg is often impaired and it would be beneficial if kinematics and kinetics of the movement of various body segments (pelvis, thigh, shank and foot) could be appropriately modified only in the part where necessary while a human would walk on a regular treadmill. This is currently done manually by a number of physiotherapists simultaneously.

The proposed solution to the set technical problem relates to an apparatus, i. e. a braking mechanism that allows for the application of force or force impulses to various body segments (pelvis, thigh, shank and foot) during treadmill walking in a desired portion of a walking cycle with a minimal mechanical impact on walking exerted by the apparatus/mechanism (low mechanical impedance) when said forces or force impulses are not applied, and to the related method. The main innovative feature of the mechanism and the method proposed is that the forces or force impulses are not generated actively by for example an electrical actuator but are achieved by decelerating the movement of non-elastic or elastic cables that are attached to a certain body segment, thus achieving a short-term mechanical stop or a slow-down of movement. The timing of applying said forces or force impulses within a walking cycle is such that various mechanical effects can be achieved. For instance, when exerting force to the pelvis in a frontal plane, a prolongation of a stance phase on the impaired leg can be achieved thus promoting equal loading of both legs and the symmetry of walking. Moreover, an almost instant stop of the pelvis movement may create a perturbation that induces a human’s reaction to adequately change the location of a next step. Another example is application of a short force impulse to the foot during a swing phase that mimics tripping that needs to be appropriately handled by a walking subject by appropriately changing the location of a next step. Yet another example is timely application of forces to the thigh and shank in order to modify a trajectory of a swinging leg.

The innovative aspect of the proposed apparatus and method is a possibility to follow, measure, assist and perturb movement of various body segments during walking on a treadmill in a way that minimally impedes movement while also allowing for modifying a movement pattern of these segments and enabling application of perturbations like tripping or frontal plane perturbation of pelvis when non-elastic cables are used.

The apparatus for decelerating, stopping and propelling movement of various body segments during human walking on a treadmill of the invention is represented by a braking mechanism that is fastened at one side with its connecting means to a human body segment under exercise and is provided at its other side by a weight or a constant force spring that serves to bias the connecting means. When turned on, the braking mechanism that is optionally an electromagnetic brake/clutch either decelerates or completely and almost instantly stops the movement of the connecting means. The braking mechanism has a measuring means for measuring movement (position and velocity) of the connecting means, which measuring means together with an algorithm for identifying various sub-phases of a walking cycle manages the braking mechanism.

The invention will be explained in more detail on the basis of an embodiment and the belonging drawings, in which

Figure 1 is a schematic illustration of an apparatus for an efficient application of the method of the invention;

Figure 2 is a structural embodiment of the braking mechanism of the apparatus of the invention;

Figure 3 illustrates the method of the invention that enables tripping while walking on the treadmill;

Figure 4 illustrates the method of the invention allowing the application of lateral perturbation to the pelvis while walking on a treadmill;

Figure 5 illustrates the method of the invention allowing the application of swing leg kinematics modulation;

Figure 6 illustrates a situation when two additional braking mechanisms of the apparatus are used on the posterior side of the leg.

The apparatus of the invention is represented by a braking mechanism A provided with a measurement means 7 having an algorithm for identifying particular sub-phases of a gait cycle which is used to control the braking mechanism A.

Figure 1 is a schematic illustration of an embodiment of the apparatus for an efficient application of the method of the invention and the utilization of the apparatus of the invention. A human subject walking on a treadmill has one end of a cable 1 attached to the lower end of his shank. In the braking mechanism A, this cable 1 is fastened at its other end to a pulley 3 that is stiffly connected to a pulley 4, to which a weight 5 is fastened by way of a cable 2, said weight having a mass that provides an appropriate tension of the cable 2 and also of the cable 1. The rotation of the pulleys 3, 4 and consequently the movement of the cables 1 , 2 can be either stopped or slowed down by the operation of the braking mechanism A. Information on a current position and velocity of the ankle and thus also information on the current sub-phase of a gait cycle is provided for by a measurement means 7 modifying the rotation of the pulleys 3, 4. The whole system is simple, light-weight and minimally impedes the movement of the leg when the braking mechanism is not engaged.

Figure 2 illustrates an embodiment of the proposed braking mechanism A. The braking mechanism A consists of two pulleys 3, 4 which may have different diameters, are stiffly connected to each other and firmly attached to a mechanical axle 5 that is mounted on a stationary base 6. On one side of the mechanical axle 5 the measurement means 7 is appropriately fastened to measure rotation and angular velocity, while on the other side of the mechanical axle 5 a friction wheel 8 is fastened, which is acted upon by a braking disk 9 by way of an electromagnet 10 which, depending on the applied voltage, provides an adequate braking moment on the mechanical axle 5. On the first pulley 3, one end of the first cable 1 is firmly attached to the pulley 3, the cable 1 is wound with a sufficient number of loops onto the pulley 3 to provide a sufficient total length of the cable 1 , while the other end of the cable 1 is attached to a cuff arranged on a certain body segment of a human walking on the treadmill. On the second pulley 4, one end of the second cable 2 is firmly attached to the pulley 4, the cable 2 is wound with a sufficient number of loops onto the pulley 4 to provide a sufficient total length of the cable 2, while the other end of the cable 2 is provided with a weight 11 having an appropriate mass and a constant force spring. Such arrangement represents low impedance to the movement of a given body segment when the braking mechanism A is not engaged. The force exerted by the weight 1 1 or the constant force spring onto this body segment while the braking mechanism A is not engaged mainly depends on the mass of the weight 1 1 which can in turn be very low (less than 5 N).

The connecting means, the cables 1 , 2, can be stiff/non-elastic or flexible/elastic cables, the weight 1 1 can be a weight with a mass that provides for an adequate tension of the cables 1 , 2 or can be formed as a constant force spring that provides for a pretension of the cables 1 , 2, while the braking function in the braking mechanism A can be successfully performed by an electromagnetic brake/clutch or the like.

Figure 3 illustrates the proposed method that enables tripping while walking on the treadmill by using the apparatus of the invention. The left column in Figure 3 shows four sub-phases of a gait cycle where the braking mechanism A is not engaged, while the right column shows a situation, in which the braking mechanism A is engaged for a short period of time (typically 100-200 ms) during the early swing phase. When the braking mechanism is engaged, the movement of the swinging leg is almost instantly stopped in a similar manner as when a human hits a curb or a tree root. As a consequence, the gait pattern changes causing an imbalance that needs to be adequately handled after the braking mechanism A is disengaged. This would typically cause an inclination of the body forward, an extension of the arms forward and prolongation of the step as depicted in Figure 3. Walking on a treadmill is a cyclic activity, this means that the position and velocity of movement of the ankle joint, measured by the measurement means 7 form a phase portrait which enables robust identification of various sub-phases of the gait cycle thus providing an opportunity to perform tripping perturbation at different sub-phases of a gait cycle.

Figure 4 illustrates the proposed method that enables performing lateral perturbation to the pelvis while walking on a treadmill by using the apparatus of the invention. The left column in Figure 4 shows five sub-phases of a gait cycle where the braking mechanism A is not engaged, while the right column shows a situation, in which the braking mechanism A is engaged for a short period of time (typically 100-200 ms) during the mid-stance phase. When the braking mechanism A is engaged, the movement of the pelvis is almost instantly stopped. As a consequence, the gait pattern changes causing an imbalance that needs to be adequately handled after the braking mechanism A is disengaged. Flere, a typical human reaction is to change the location of a next step as depicted in Figure 4. Walking on a treadmill is a cyclic activity, this means that the position and velocity of movement of the pelvis, measured by the measurement means 7 form a phase portrait which enables robust identification of various sub-phases of the gait cycle thus providing an opportunity to perform lateral perturbation at different sub-phases of a gait cycle.

Figure 5 illustrates the proposed method and system that allows modulation of swing leg kinematics by using the apparatus of the invention. Two braking mechanisms A, A’ as shown in Figure 5a are used, the first braking mechanism A being arranged on the thigh and the second braking mechanism A’ being arranged on the shank, both being arranged from the anterior aspect. A gait cycle starts with the right leg initial contact when both braking mechanisms A, A’ allow for a free movement of the leg. During the leg loading phase both braking mechanisms A, A’ are engaged. In subsequent sub-phases of the right stance phase the elastic portion B of the connecting means undergoes elongation due to the movement of the right leg on the motorized treadmill. After the right leg starts the swing phase, the potential energy stored in the elastic portion B of the cable 1 is being released thus modifying the movement of the thigh and the shank. In another variant, the connecting means would be attached to a shoe instead to the shank; this would not only facilitate knee extension but also foot clearance. Both braking mechanisms A, A’ can be disengaged either at the end of the swing phase or somewhat earlier, giving us control over the release of the amount of potential energy from the portion B of the connecting means into the adequately modified leg swing movement.

Figure 5 illustrates the method of the invention allowing the application of swing leg kinematics modulation and the timing of engagement/disengagement of the braking mechanism A, which is purely illustrative. Depending on the information from both measuring means 7 recording the kinematics of the swinging leg, the timing interval of the engagement/disengagement of the braking mechanism A can be adequately changed in subsequent steps in order to achieve the desired leg movement. Utilization of two or more proposed braking mechanisms A, A’ on the anterior side of the leg enables the modification of the leg movement forward.

Figure 6 illustrates a situation when two additional braking mechanisms A”, A’” are used on the posterior side of the leg, said mechanisms assisting in the movement of the thigh and the shank or leg backward. For example, it is important that the initial contact starts with the touch of the heel and with the extended knee joint. This can be achieved by timely engaging both braking mechanisms A”, A’” that act on the posterior side during the terminal swing phase. By combining the information from all four measuring means 7 the optimal timing of operation of all four braking mechanisms A, A’, A”, A’” can be determined in order to achieve the desired leg movement in the swing phase and the desired step length.

By utilizing the elastic connecting means in the proposed apparatus of the invention and by adequately operating (engagement/disengagement) the braking mechanism A or braking mechanisms A, A’, A”, A’”, a changed kinematics of the swinging leg can be achieved, wherein the treadmill drive is exploited as the source of energy which is stored in the portion B of the connecting means during the stance phase and the energy is then released in a controlled manner during the swinging leg phase by an adequate disengagement of the braking mechanism A.

Furthermore, the measurements of movement of various body segments can be used for real-time visual feedback that is forwarded to a walking subject.

Claims

1. An apparatus for decelerating, stopping and propelling movement of various body segments during human walking on a treadmill that allows for modification of kinematics of various body segments during walking on a treadmill,

characterized by

being represented by a braking mechanism (A) connected with a non-elastic or elastic connecting means to a cuff arranged on a certain body segment of a human walking on a treadmill and the braking mechanism (A) being provided with a measurement means (7) having an algorithm for identifying particular sub-phases of a gait cycle that enables a control of the braking mechanism (A) and when the latter is engaged, it either decelerates or completely and almost instantly stops the movement of the connecting means.

2. The apparatus according to claim 1 ,

characterized in that

the braking mechanism (A) consists of pulleys (3, 4) which may have different diameters and are firmly attached to a mechanical axle (5) that is mounted on a stationary base (6) and the measurement means (7) is appropriately fastened on one side of the mechanical axle (5), while a friction wheel (8) is fastened on the other side of the mechanical axle (5), said friction wheel being acted upon by a braking disk (9) by way of an electromagnet (10), wherein the non-elastic or elastic connecting means is a cable (1 ) wound on the first pulley (3) such that one end of the first cable (1 ) is firmly attached to the pulley (3) and the cable (1 ) is wound with a sufficient number of loops on the pulley (3), while the other end of the cable (1 ) is attached to a cuff arranged on a certain body segment of a human walking on the treadmill, and a cable (2) being wound on the second pulley (4), one end of the second cable (2) being firmly attached to the pulley (4), the cable (2) being wound with a sufficient number of loops on the pulley (4), while the other end of the cable (2) is provided with a weight (11 ).

3. A method for decelerating, stopping and propelling movement of various body segments during human walking on a treadmill that allows for modification of kinematics of various body segments during walking on a treadmill, used on the apparatus according to claim 1 and 2,

characterized by

including the utilization of the force of the braking mechanism (A), which is transferred to the body segment under exercise of a human via the non-elastic or elastic connecting means and a light cuff, wherein the connecting means follows the movement of the body segment when the braking mechanism (A) is disengaged, and when the movement of the elastic connecting means is impeded by using the braking force, i. e. the braking mechanism (A) is engaged, the braking force is transferred to the body segment under exercise.

4. The method according to claim 3,

characterized in that

the proposed method allows for tripping during a treadmill walk such that, when the braking mechanism (A) is engaged, the movement of the swinging leg is almost instantly stopped in a similar manner as when a human hits a curb or a tree root, and as a consequence, the gait pattern changes causing an imbalance that needs to be adequately handled after the braking mechanism (A) is disengaged and this normally causes an inclination of the body forward, an extension of the arms forward and prolongation of the step.

5. The method according to claim 3,

characterized in that

the proposed method enables performing lateral perturbation to the pelvis while walking on a treadmill by using the apparatus of the invention, wherein the braking mechanism (A) is engaged for a short period of time during the mid-stance, wherein, with the braking mechanism (A) being engaged, the movement of the pelvis is almost instantly stopped and as a consequence the gait pattern changes causing an imbalance that needs to be adequately handled after the braking mechanism (A) is disengaged.

6. The method according to claim 3,

characterized in that

the proposed method allows for the modification of the leg movement kinematics in the swing phase, wherein two braking mechanisms (A, A’) are used, the first braking mechanism (A) being arranged on the thigh and the second braking mechanism (A’) being arranged on the shank, both being arranged from the anterior aspect, a gait cycle starts with the right leg initial contact when both braking mechanisms (A, A’) allow for a free movement of the leg, while during the leg loading phase both braking mechanisms (A, A’) are engaged and in subsequent sub-phases of the right stance phase the elastic portion (B) of the connecting means undergoes elongation due to the movement of the right leg on the motorized treadmill and after the right leg starts the swing phase, the potential energy stored in the elastic portion B of the connecting means is being released thus modifying the movement of the thigh and the shank, wherein both braking mechanisms (A, A’) can be disengaged either at the end of the swing phase or somewhat earlier, giving us control over the release of the amount of potential energy from the portion B of the connecting means into the adequately modified leg swing movement.

7. The method according to claim 3,

characterized in that

the proposed method allows for a situation when two additional braking mechanisms (A”, A’”) are used on the posterior side of the leg, said mechanisms assisting in the movement of the thigh and the shank or leg backward, which can be achieved by timely engaging both braking mechanisms (A”, A’”) that act on the posterior side during the terminal swing phase, and by combining the information from all four measuring means (7) the optimal timing of operation of all four braking mechanisms (A, A’, A”, A’”) can be determined in order to achieve the desired leg movement in the swing phase and the desired step length.