Arrangement for Gait Training

[0001] The present invention relates to an arrangement for training the gait.

[0002] Apparatus for the detection of pressure and force distributions are known per se, for example, from DE 36 42 088 C2 and DE 25 29 475 C3.

[0003] Many of the prior apparatus can be employed as platforms for the biomechanical gait analysis, which examine and analyze the gait of a vertebrate, especially of a human being, but also of a horse or dog etc., if necessary. There is the drawback, however, that only one single step and one single flexing action of the foot can be recorded. To obtain a natural gait behavior it is necessary, however, to record the gait over a longer time period.

[0004] Therefore, apparatus and methods for the gait analysis using a treadmill have already been proposed. Reference is here made, for example, to DE 40 27 317 C1 or U.S. Pat. No. 6,010,465 A.

[0005] Moreover, a measuring device is described as being known in R. Kram and A. J. Powell: “A treadmill-mounted force platform” Appl. Physiol. 67 (4): 1692-1698 (1989), wherein a treadmill belt is drawn over a measuring platform or measuring surface, respectively, thereby permitting a continuous detection of forces.

[0006] The first one of these publications describes a treadmill formed of a plurality of members, each of which comprises pressure or force sensors, respectively, which are arranged in a matrix, while the second publication describes a treadmill comprising a measuring plate disposed underneath the belt surface with pressure or force sensors, respectively, arranged in a matrix. Both publications teach that an analyzing unit is connected to the respective sensor system, and U.S. Pat. No. 6,010,465 describes relatively detailed the construction and the operating mode of the analyzing unit, for example, for analyzing the position and an associated force quantity when stepping onto the treadmill belt, e.g. for determining torsional moments and loads exerted on the joints, as well as specific gait parameters.

[0007] The international patent application PCT/EP2006/01 04 71 of the applicant deals with improvements of said prior solutions as far as the derivation of differentiated medical and sports-physiological information is concerned. This patent application particularly discloses means and methods for the precise and differentiated detection of the actual speed of the treadmill based on the time and position dependence of pressure distribution images recorded on it as a subject is walking or running.

[0008] Further known is the use of display devices, such as display screens, in treadmill systems.

[0009] Known from EP 1 145 1682 A2 are a rehabilitation apparatus and method based on the treadmill technology, wherein an adaptation of the function of the treadmill to the current status of a patient's walking or running ability to be restored is provided. Specifically, the speed of the treadmill is adapted to a personal step cycle of the user and, at the same time, the apparatus is to give the user a feedback. In a specific embodiment, also the detection of pressure forces exerted during a step as well as the analysis thereof are provided as part of an overall program. The publication also describes the use of a display screen in connection with a keyboard, to display the footprints generated on the treadmill belt and to adjust treadmill belt parameters on the basis of this display.

[0010] U.S. Pat. No. 6,231,527 B1 likewise discloses the use of a display screen in a treadmill apparatus for use in sports medicine and rehabilitation, wherein the images of different cameras can be displayed, which record the movements of the sportsman/patient on the treadmill.

[0011] Also the unpublished European patent application no. 08001950.8 of the applicant describes a treadmill system for use in sports medicine and rehabilitation based on an image display technology, which additionally allows that pressure distribution patterns generated by a person walking on the treadmill are recorded and analyzed synchronously with the displayed images.

[0012] The invention is based on the object to provide a further improved apparatus of the last-mentioned type, which is particularly suited for sports-medical and rehabilitation purposes. It is one aim to develop the system further to obtain a flexibly usable training/therapy apparatus while simultaneously increasing the user acceptance.

[0013] This object is achieved with an arrangement according to the features of claim 1. Useful improvements of the inventive thought are each defined in the dependent claims.

[0014] In order to develop the aforementioned unpublished European application further, the invention is based on the idea to display an image associated with rehabilitation or training purposes directly within the area of the walking surface, i.e. on the upper surface of the treadmill belt or, if a transparent material is used for the treadmill belt, also on a display surface underneath the upper section of the treadmill belt. Furthermore, the invention is based on the idea to display in particular images or image elements, which the person doing the workout should touch with his feet or—on the contrary—should avoid and which are provided by suitable image signal generating means along with an adequate control of the display process. Finally, the invention is based on the idea to synchronize the analysis of the pressure distribution patterns generated by the feet of the person doing the workout with the image display in the area of the treadmill or make an adaption to the effect that an analysis of the gait or walking motion becomes possible as a direct reaction of the person doing the workout to images displayed to him.

[0015] The image display in the area of the treadmill, which is an important aspect of the invention, may be accomplished in different ways and with known display devices. In a first embodiment the display means comprise an image projector for the projection of images onto the walking surface of the treadmill, specifically a laser beamer which is connected as an image or video source to a small computer (PC, laptop, PDA . . . ). If necessary, the projected images have to be subjected to a distortion correction, as the projector should not be mounted directly from above but, for example, from an inclined front direction in order to prevent the projected image from being covered by the feet. Moreover, in order for the walking environment to be as natural as possible the projection surface may be drawn slightly upwardly in the front so that the patient's head need not be bowed downwardly too much.

[0016] According to an alternative embodiment it is provided that the image display surface is formed of at least one display screen of an electro-optical display device, specifically of the LCD, plasma or OLED type. This requires, of course, that the treadmill belt is made of a transparent material so that the image display surface can be disposed statically underneath the section of the treadmill belt that moves on the top (in use). This embodiment with a transparent material (at least section-wise) is not necessarily associated with the last-mentioned embodiment of the optical display means, however, but, in certain circumstances, it may also be sensible in combination with a projection technology.

[0017] The display means project, for example, steps having the shape of circular surfaces or footprints onto the treadmill belt. The subject or the person doing the workout is asked to place his feet onto the projected surfaces. By this, the patients can be encouraged to observe specific step widths or step breadths. If footprints are projected onto the treadmill belt instead of circular surfaces, also the angle where the feet should be placed may be predefined. The pressure sensor matrix is spatially calibrated with the projected surfaces, so that it can be checked directly whether the feet were correctly placed. If necessary, a feedback signal may request the patient to adopt his steps to the defaults. Also, a therapy or success control may be carried out.

[0018] Deviating from predefined surfaces for placing the feet, of course, also obstacles may be projected, which should not be stepped on so that the patient has to jump or climb over the prohibited surfaces, thereby training his coordination. These obstacles can be, for example, objects or puddles which, when being stepped on, likewise trigger a feedback signal or lead to a loss of points.

[0019] In another embodiment the arrangement comprises additional optical display means for displaying images on another image display surface, outside of the walking surface and especially at eye level of the person doing the workout, wherein the additional display means are likewise connected to the image signal generating means and the display process controller, and are specifically used for an additional visualization of the walking surface and/or the walking environment. Preferably, the patterns projected onto the treadmill belt are additionally displayed on this screen. These patterns are now overlapped with the virtual footprints of the sensor matrix. Thus, the patient has the choice to look at his own feet on the belt or at the virtual feet or footprints on the screen and can position them correctly.

[0020] In another embodiment it is provided to instal either stationary elevations or recesses or actuators in or underneath the walking surface, by means of which raised areas can be realized on the walking surface, or specifically also walking surface areas that are locally perceived as resilient and elastic or also as particularly hard. This could be realized, for example, with a matrix of air- or liquid-filled chambers which, like the components for analyzing the pressure distribution images and for the synchronization with the displayed images, are controlled by a common control unit and may be used for provocation tests.

[0021] In the first modification it is particularly expedient if the endless belt, which has a gait-effectively structured surface, is provided with a position coding to assign the position of surface elements, if the processing unit comprises profile storage means for storing the profile of the gait-effectively structured surface and is assigned a position signal receiver for addressing the profile storage means, and if a processing algorithm is implemented in the processing unit, by means of which the pressure distribution images are assigned to the surface elements of the walking surface.

[0022] An advantageous embodiment of the second modification is characterized in that the array of actuators is assigned a profile control unit, which outputs control signals for actuating the actuators in order to form a predetermined dynamic profile (conventional surface profile and/or elasticity or hardness profile) of the walking surface, that the processing unit comprises a control signal receiver for receiving the control signals, outputted by the profile control unit, as position assignment signals, and that a processing algorithm is implemented in the processing unit, by means of which the pressure distribution images are assigned to the dynamic profile of the walking surface. It will be appreciated that, appropriately, image elements are projected along with local areas of different elasticity or hardness, which make this differentiation also visually perceivable to the person doing the workout (subject).

[0023] In combination therewith, or also as an alternative, an embodiment is provided according to which the treadmill as a whole is mounted on actuators for generating a global resilience and elasticity of the entire walking surface. Instead of simulating local defects of the ground, this embodiment permits the simulation of a large-surface elasticity and resilience of the ground.

[0024] Other useful embodiments of the invention relate to providing the image signals. In one embodiment it is provided that the image signal generating means comprise an image element storing unit for storing a plurality of predefined image elements and, optionally, an image element mixer for mixing image elements retrieved from the storing unit according to a plurality of predetermined mixing programs. According to a particular advantage it may be additionally provided that the image signal generating means comprise a video memory for storing image sequences and, optionally, a video image element mixer for mixing image sequences read out from the video memory optionally with image elements read out from the image element storing unit. These means allow a realistic visual and (by using corresponding actuators, as was mentioned above) also tactile simulation of a natural ground, and images or image elements may be inserted into this ground which impose certain requirements on the person doing the workout, thereby allowing a particularly efficient workout.

[0025] A user guide provided by the arrangement, with a visual and/or audible output of display-accompanying instructions, serves the realization of training and rehabilitation programs. This may take place as follows: Initially, the patient walks in accordance with his accustomed walking style. By means of the pressure sensor matrix integrated in the treadmill the characteristic gait parameters are detected, especially the length of the steps, the track width, the foot rotation angle or applied force values. These parameters may then be used as starting values for the training. Based on this setting, the patterns projected onto the treadmill belt are then automatically adapted to the target value desired by the therapist within one training process. The alteration of the values may be linear, exponential or be accomplished with any other mathematical function. Subsequently, an automatic analysis based on a target-performance comparison can be performed, i.e. it is checked how good the patient was at complying with the defaults. If the patient is to vary the applied force in partial regions of the foot or of the whole foot he is instructed by an acoustic signal or a voice output, for example, an instruction to put more or less weight on a foot.

[0026] In a specific embodiment predefined step widths or breadths can be steadily varied (e.g. increased) during a training process so as to make the patient slowly approach the training goals. This is accomplished by an embodiment in which the display process controller comprises a program memory for storing a plurality of predetermined display processes and/or speed and/or relative position adjusting means for adjusting the speed of a display process and for predefining relative positions between image elements of a display. Also, it is possible to permanently vary by a random generator the symbols for setting the steps so as to train the coordination of the patient and turn away from ingrained gait patterns in order to improve the success of the therapy. In addition to step placement patterns the random generator can also present other image elements (e.g. obstacles) in a stochastically varied form, thereby further raising the coordination requirements for the person doing the workout.

[0027] The above description already shows that the proposed arrangement is expediently provided with a user guide unit for the visual and/or audible output of display-accompanying instructions, particularly by means of earphones and/or text insertions in the area of the walking surface.

[0034] FIG. 1 shows a treadmill training system 1, comprising a treadmill belt 2b running over two rollers 2a, underneath the upper surface of which, which is used by the user as walking surface 2c, a pressure detection plate 3 with a high spatial resolution and having a plurality of (not individually designated) pressure sensors is provided, which pressure sensors are arranged in a matrix-type manner and detect pressure detection images generated by the user as he steps on the treadmill. One of the two rollers 2a is driven and pulls the treadmill belt 2b at a predetermined speed, which is adjusted by a processing and control unit 4 of the arrangement and by a speed controller 5. Moreover, it is possible to adjust an inclination of the treadmill as a whole according to need or, optionally, slightly raise only the front portion thereof by means of a suited inclination actuator 6, which can likewise receive interference signals from the processing and control unit 4 (this is merely symbolically illustrated in the figure).

[0035] In the embodiment illustrated in FIG. 1, which is strongly simplified, signals characterizing the adjusted speed value of the treadmill are reported back from the speed controller 5 to the processing and control unit 4, where they serve the synchronization of an image displayed on the walking surface 2c by means of a projector (laser beamer) 7, the image being generated from prestored image elements and/or image sequences (see below).

[0036] The image is controlled on the basis of the speed signals in such a way that—especially in connection with another specific embodiment described below—the user is presented an altogether harmonious simulation of a walking environment, preferably combined with the insertion of markings to be touched by the feet and/or with the simulation of obstacles to be climbed over or avoided. Diverging from the representation in the figure, the actual speed of the treadmill can also be detected by a suitable (non-illustrated) sensor system, and the measured value can be supplied to the processing and control unit 4 in order to obtain a (virtually feedback) process control of the image display and synchronized analysis of the pressure distribution patterns.

[0037] It is shown in the figure that the projector 7 is fixed to a wall holder 7a in an adjustable manner with respect to angles, so that the direction of the projection encloses with the plane of the treadmill a variable angle. In order to avoid distortions of the images or image elements, which are provided by the processing and control unit 4, due to the acute angle of projection an image signal distortion corrector 7b is connected upstream of the projector 7. This distortion corrector 7b can operate dependent on the actual angular position of the projector 7 in the holder 7a, which is not shown in the figures, however, for reasons of clarity. Moreover, in order to round up the user interface an audio stage 8 is provided (here symbolized as a loudspeaker), by means of which the person doing the workout can receive additional acoustic training instructions. The audio stage 8 can also be realized, for example, bidirectionally in form of a headset, so that the person doing the workout can give an acoustic feedback (e.g. an acknowledgment of received instructions or answers to questions he is asked).

[0038] For performing training tasks on the treadmill system it may be of interest to detect the lifting height of the feet from the belt, for example, when the subject is to climb over a virtual obstacle. In another embodiment the subject therefore has a sensor 9 attached to each of his feet, the signals of which can be detected by means of a (non-illustrated) position detection sensing system, which is known per se, so as to draw conclusions on the position or the height of the feet, respectively. Preferably, the sensors are operated time-synchronized with the sensors of the pressure distribution matrix. If appropriate, a precise time synchronization can be generated by means of an infrared or radio signal or by a detection of the moment when the feet contact the belt.

[0039] The sensors 9 may be designed as acceleration sensors or multi-axis acceleration sensors and, if appropriate, are wirelessly connected to the analyzing computer 4. The position of the feet can be calculated from the acceleration signals, especially if the time and position dependence of the pressure distribution patterns can be additionally included in the calculation. In extended arrangements, inertial sensor systems may be employed, in which gyroscopes or sensors for detecting the earth magnetic field are used additionally. Of course, such sensors can also be attached to other body sections, so that the movement of the complete lower extremities or of the whole body can be measured and represented. However, the sensors 9 may also be operated in accordance with other measuring principles, e.g. on the basis of active or passive light markers recorded by stationary cameras, magnetic field sensors, or sensors emitting or receiving ultrasonic waves to or from stationary receivers and determining the position of the feet from the propagation time of the sound.

[0040] The pressure sensors of the pressure detection plate may optionally be provided with an analog or—according to a simpler and more inexpensive embodiment—a digital response characteristic (on/off characteristic). Both options are eligible for certain applications, and the system designer will choose one of the options in accordance with the primary use requirements.

[0041] FIG. 2 shows a modification of the arrangement shown in FIG. 1 and described above. Insofar as the same components of the latter are employed, they are designated with the same reference numbers used in FIG. 1 and will not be explained again below.

[0042] The essential modification consists in using a large-surface electro-optical touchscreen 7′ as display device instead of a projector. The upper surface of the touchscreen defines a display surface 2c′ located, in use, underneath the upper section of the endless belt 2b. At the same time, the touchscreen defines a novel pressure detection plate 3′. According to a modified version of the touchscreen principle, and in the light of the actual costs for the arrangement, this combined display/pressure detection device may be replaced by a matrix-type alternating arrangement of a plurality of smaller electro-optical display elements (e.g. LCD displays) and respective adjacent smaller pressure detection plates, or a flexible display screen insensitive to pressure (e.g. of the OLED type) may be placed over a normal pressure detection plate.

[0043] In all cases the endless belt (2b) is to be formed of a transparent material, at least in the central portion of its lateral extension, in order to allow the person doing the workout a perception of the images displayed on the display surface 2c′.

[0044] FIG. 3 shows a detailed representation of essential components of the processing and control unit 4 of the arrangement illustrated in FIG. 1 or 2. Not included is here the image signal distortion corrector separately shown in FIG. 1, which is used only in an embodiment of the arrangement where the projector is inclined relative to the treadmill.

[0045] In a display control part 4a the processing and control unit 4 comprises an image element storing unit 41 and a video memory 42, with an image element mixer 43 and finally a video image element mixer 44 for generating image sequences with predetermined image element insertions being connected downstream thereof. In addition, it is symbolically shown that both mixers 43, 44 can moreover be influenced by control signals of a random generator 45. Also, a display process controller 46 is connected downstream of the second mixer 44, which is assigned a process program memory 47 and a speed controller 48. An image element position controller 49 is connected, in terms of control signals, to the image element mixer 43 and acts on the same so as to vary relative positions of image elements in the ultimate representation. The speed controller 48 can be influenced by signals of the speed controller 5 of the treadmill (not shown in this figure).

[0046] At the same time, these signals are supplied to a system control unit 50 of the arrangement, which synchronizes the different control procedures of the display and analysis functions and performs necessary adaptations of the data streams and data formats. In the figure this is symbolized by the double arrows pointing to the display control part 4A and the analyzing section 4B.

[0047] Moreover, the final image signal provided at the output of the display process controller and, on the other hand, the (space-time-resolved) output signal of the pressure distribution plate 3 are supplied to the analyzing section 4B. The output signal of the pressure distribution plate 3 is freed from interference signals and artefacts in a pressure signal preprocessing stage 51, is synchronized with the image signals in terms of time in a pressure signal time adaptation stage 52 and in terms of space in a pressure signal position adaptation stage 53, and is processed in a training analysis stage (main processing stage) 53 on the basis of a predetermined training analysis program, and the results are outputted on a separate display unit 10 of the therapist. Moreover, they can be processed—together with instructions inputted via an input unit 11 of the therapist—to instructions for the person doing the workout in a user guide stage 54, which instructions are outputted by the display unit 7 or 7′ assigned to the person doing the workout and, optionally, by the audio stage 8.

[0048] FIG. 4 shows in a sketch-like perspective representation (partially cut) a section of the walking surface according to an embodiment of the inventive arrangement, in which a regular array of actuators 12 is installed in a modified pressure detection plate 3″. The actuators 12 are individually controllable, and by the appropriate control of which a harder or softer ground, or a ground locally having a certain degree of elasticity, can be simulated. The contour of a heel of a foot f is shown on the endless belt 2b, which is projected onto the belt and is to instruct the person doing the workout to place his foot on this position. In this figure, the actuators are merely illustrated schematically. In the practical implementation they can be, for example, mechanical pistons or controllably fillable air or liquid chambers. The matrix-type arrangement of individual actuators in FIG. 4, too, is to be understood as an example only; instead, they may also be arranged in smaller groups, in rows or in columns. It is, at all events, important that a sufficient number of pressure sensors is provided in the environment of the actuators in order to obtain therewith an informative pressure distribution image of the subject placing his foot at this position.

[0049] Furthermore, it will be appreciated that the control of the actuators is accomplished by the processing and control unit of the arrangement in such a way that it corresponds to a specific training program and, where applicable, is accompanied by a user guide and, on the other hand, is adjusted to an image representation on the walking surface (e.g. the representation of a small stone or a puddle etc.) and is reliably synchronized with the image representation. Corresponding supplements to the embodiment of the processing and control unit 4 shown in FIG. 3 and described above are within the framework of the competent action of the skilled person and are, therefore, not explained in more detail.

[0050] Exemplifying an image to be provided for the person doing the workout on the walking surface FIG. 5 shows (in a simplified manner) a series of footprints f′, combined with ground features A (puddle or “soft” spot) and B (stone or hard elevation). It follows from the above explanations that the impression of these obstacles is not only conveyed by a visual perception, but in combination therewith also by a tactile perception, which is realized by means of an array of actuators in the walking surface of the type shown in FIG. 4.

[0051] The realization of the invention is not limited to the above-described examples, but is also possible in a plurality of modifications within the framework of the competent action of the skilled person.