Field of the invention

[0001] The present invention relates to an active walking platform and a system for keeping a walking or running person on a spot on the platform. The active walking platform may be used as an input device in training simulators, computer games and other similar applications.

Background art

[0002] In background art there has been numerous attempts trying to solve the problems of providing a moving surface that is able to keep a walking or running person in place, independent of the speed of the person on the surface. This means that the speed of the person has to be detected, and that the surface has to move in the opposite direction of the person at the same speed as the person.

[0003] One solution to this problem is a treadmill with a speed detector and a control system for controlling the speed of the treadmill. When the person

accelerates its speed in a forward direction, the treadmill will accelerate the belt speed in the backward direction, and decelerate when the person decelerates.

However, the movement here is only one-dimensional and mechanics are becoming much more complex when the person is allowed to move in two directions.

[0004] Ball decks or caster decks with rolling balls are used to transport heavy loads on flat surfaces. To keep a moving object steady, this same principle has been reversed to make the rolling balls active by placing a conveyor belt under the rolls. One problem that has been encountered with this solution, is that the conveyor belt has to rotate about a vertical axis relative the ball deck, and due to the mass of the conveyor belt, such a rotation will usually have a certain delay with regard to the changing direction of the person.

[0005] German patent application DE 10 2004 016 429 Al shows such a device with multiple rolling bodies (2), which together form a contact surface for placing a conveying-object. The rolling bodies are fixedly arranged in several directions of rotation in a pivoting manner, to move the object in different conveying directions. A driving belt is arranged at a lower surface of the roll bodies, and turns the bodies with respect to the directions of rotation.

[0006] Some platforms use moving tiles to keep the person in place.

[0007] One such platform is disclosed in German patent application DE 10149491 Al showing a device for walking or running in place, in which two transport elements crossing each other at a right angle are provided, which together form a walkable central surface (4), on which a user (13) walks forward, whereas, under him, the transport elements move at the same speed. It is essential that the transport elements (1, 2) consist of rows of square plates or tiles (5), which can be moved in rows in the X and Y directions, where at all times a row of tiles is removed by a transfer device (9, 10, 28, 17) and then shifted by 90 degree or 180 degree .

[0008] Yet another solution is to use two belts, where a second belt belt is placed perpendicularly inside a first belt that provides a walking surface.

[0009] US patent application US6152854 shows a treadmill (1) having a track assembly that allows a user (3) to walk or run in any arbitrary direction. A movable user support has a plurality of rotatable members that rotate about axes normal to the direction of movement of the user support (2). Separate power drive mechanism (7) (8) concurrently move the user support (2) and rotate the members to omnidirectional user movement. A control (4) for the power driven mechanism (7) (8) is responsive to the directional orientation of the user on the user support (2) to cause the user support (2) to operate in the direction of the orientation of the user (3).

[0010] As a natural development from a one-directional to a two-directional treadmill, it has been proposed to add trapezoidal treadmill segments together to form a platform with a center where all the trapezoidal treadmill segments originate. Due to the trapezoidal shape of the segments, parallel rollers with increasing length away from the center are used instead of a belt.

[0011] International Patent application WO 96/35481 A2 shows a device for walking or running on the spot, comprising transport devices 21 that together form a platform. In the example shown, there are 16 of these transport devices 21, where each of these transport devices 21 comprises a number of mutually parallel rollers 23 that are aligned tangentially to circles concentric to the standing surface 17. The bearing 25 of the individual rollers 23 occurs at the circle segment boundaries, that is, to the side of each transport device 21.

[0012] A similar trapezoidal platform is shown in international patent application

WO2010/089618 A2 and European patent application 2522403 Al .

[0013] All of the solutions described above require a complex implementation with a large number of individual parts. Especially the drive trains become complex due to the number of individual parts forming the walking surface.

[0014] A problem with some of the prior art is that response is slow due to large mechanical constructions that have to be turned parallel to the walking direction of the user before the surface is ready to take the user back towards a reference point.

If e.g. a person makes a sudden turn, the platform will not be able to keep up with the user, and the user may have run to the end of the surface before the surface has been turned into the correct direction.

[0015] Another problem with background art is that the person walking or running on the platform may find that the movements of the surface are unnatural. If the platform is used in a simulator, it is important that the user can concentrate on solving the tasks of the simulator without having to concentrate on keeping the balance due to strange surface movements. E.g . the user may experience an abrupt change of surface speed direction at the adjacent edge of two adjacent trapezoidal segments according to prior art.

Short summary of the invention

[0016] A main object of the present invention is solve the problems described above, and disclose an active walking platform that has a minimum number of mechanical parts, has a sudden response to the users movements, both in speed and direction, and provide the user with an experience as close to walking or running on a natural surface as possible.

[0017] In an embodiment the invention is an active walking platform comprising;

- two or more bent rods arranged to transfer rotary motion, wherein the two or more bent rods are arranged adjacent each other, together constituting at least a part of a walking surface of the walking platform, and

- one or more motors arranged to rotate the two or more bent rods about their longitudinal axis.

[0018] In an embodiment the invention is a system for walking in place, wherein the system comprises;

- an active walking platform according to any of the embodiments described above,

- a movement sensor arranged to continuously detect a position of a human on the active platform,

- a control system arranged to receive a position signal from the position sensor and calculate one or more control signals to control a speed of the one or more motors of the active walking platform.

Figure captions

[0019] The attached figures illustrate some embodiments of the claimed invention.

[0020] Figure 1 illustrates in an isometric view an embodiment of the active walking platform according to the invention

[0021] Figure 2 illustrates a sectional view of the active walking platform shown in Figure 1.

[0022] Figure 3 illustrates in an exploded view a drivetrain of the walking platform according to an embodiment of the invention. [0023] Figure 4 illustrates in a perspective view a walking detection system according to an embodiment of the invention.

[0024] Figure 5 illustrates in a schematic view training in remote locations and the trained persons perception of their relative position.

[0025] Figure 6 illustrates an embodiment of the active walking platform (10) where the bent rods are spiral arms.

Embodiments of the invention

[0026] The invention will in the following be described and embodiments of the invention will be explained with reference to the accompanying drawings.

[0027] Fig. 1 illustrates an embodiment of the active walking platform (10) according to the invention, and will in the following be described in more detail.

[0028] The active walking platform (10) comprises two or more bent rods (110) arranged to transfer rotary motion, wherein the two or more bent rods (110) are arranged adjacent each other, together constituting at least a part of a walking surface of the walking platform (10). The active walking platform (10) also comprises one or more motors (120) arranged to rotate the two or more bent rods (110) about their longitudinal axis.

[0029] In an embodiment two or more bent rods are arranged in adjacent circular sections, as can be seen in Figure 1, and a drivetrain (130) is connected to at least a first end (110) of each of the two or more bent rods (110), wherein the one or more motors (120) are arranged to drive the drivetrain (130). The one or more motors (120) may in an embodiment be arranged in the center of the active walking platform as illustrated in Fig. 1, but may also be arranged along the perimeter of the walking platform as illustrated in Figure 4.

[0030] Figure 1 illustrates circular sections that fills the whole circle, e.g. close to 360°, meaning that the two ends (111, 112) of each of the bent rods (110) end up in the same place. In this embodiment one motor (120) is sufficient to drive, or rotate the bent rods (110).

[0031] A drivetrain (130) is responsible for transferring the rotational energy from the motor (120) to the bent rods (110). All the bent rods (110) have to collaborate to move a person trying to escape back to the center of the platform, and the bent rods (110) must therefore rotate in the same direction, e.g. in a direction where the walking surface constituted by the top of the bent rods (110) moves towards the center of the platform. In an embodiment, illustrated in Fig. 3 the drivetrain (130) comprises a series of meshing cog wheels (131, 132) where every second cog wheel (131) is connected to one or both ends (111, 112) of the bent rods (110) so that they rotate in the same direction. [0032] In another embodiment a chain wheel is connected to each of the bent rods (110), i.e. one or both ends (111, 112) where the chain wheels are driven by a chain driven by the one or more motors (110).

[0033] The drivetrain (130) can also be implemented by any equivalent means as will be understood by a person skilled in the art.

[0034] According to an embodiment the drivetrain (130) is arranged to drive all the bent rods (110) with the same rotational speed, e.g . all the cog wheels or chain wheels are the same size. By varying the motor speed the person on the platform can be brought back to the center, or kept in one place.

[0035] In another embodiment the drivetrain (130) is arranged to drive the bent rods (110) with a rotational speed increasing from the center of the platform, e.g. decreasing gear ratio away from the center. In this embodiment the motor speed may remain more constant while still keeping the person on the platform (10).

[0036] The bent rods (110) should preferably rest on a stable platform as illustrated in Figure 2, showing supporting rollers (151) in roller frames (151), where the supporting rollers (151) supports the bent rods (110). The distance between the rollers (151) in the longitudinal direction of the bent rods (110) will depend on the stiffness of the bent rods (110) in their lateral direction in a specific implementation.

[0037] According to an embodiment, the center portion of the active walking platform (10) comprises a fixed center plate (160), partly illustrated in Figure 2. Since the intention is to restrict or counteract any movement away from the center, there is no need to take any action when the person on the platform stands in the middle. Therefore, no bent rods are necessary in the middle.

[0038] In an embodiment the center plate (160) is made of a material with little friction with respect to the shoes of the person walking on the active walking platform, to allow the person to glide in and out of center plate (160). In an embodiment the center plate (160) is made in a plastic material.

[0039] The bent rods (110) may in an embodiment be coiled spring rods as illustrated in Figure 1, 2 and 4. Coiled spring rods can be bent in circular sections and transfer rotational motion and energy as required to give the person on the platform a safe walking and running experience.

[0040] In another embodiment each of the bent rods (110) are comprised of two or more universal joints. The universal joints will consist of a number of joints and intermediate shaft axles. A series of universal joints can also be bent in circular sections and transfer rotational motion and energy.

[0041] In an embodiment the supporting rollers (151) as described above, are arranged underneath said shaft axles between said joints. The joints will then be free to rotate without support, while the axle shafts between the joints is supported by the rollers.

[0042] In an embodiment the bent rods (110) have a center to center distance less than 35 mm. This gives the person walking on the walking platform the experience that the surface is smooth, while at the same time maintaining the advantages of the bent rods constituting the surface as described above.

[0043] In an embodiment, alternative to the circular sections, the bent rods may be arranged as spiral arms extending horizontally from the center of the walking platform (10) as illustrated in Figure 6. The drivetrain (130), which is not shown, may be arranged under the center plate (160) of the platform, and consist of e.g. bevel or hypoid gears to transfer the energy to the bent rods (110).

[0044] According to an embodiment the bent rods (110) are at least partly covered with a flexible hose. The hose will even out structures in the bent rods (110) that are necessary to perform the rotation, and the person on the platform may find the surface smoother and more attractive to walk on.

[0045] In an embodiment the invention is also a system (1) for walking in place as illustrated in Figure 4, wherein the system (1) comprises;

- an active walking platform (10) according to any of the embodiments described above,

- a movement sensor (20) arranged to continuously detect a position of a human on the active platform (10),

- a control system (30) arranged to receive a position signal (21) from the position sensor (20) and calculate one or more control signals (31) to control a speed of the one or more motors (120) of the active walking platform (10).

[0046] In this embodiment the position sensor (20) will continuously detect the position of the walking or running person relative to an initial position on the active walking platform (10) and send a position signal (21) to a control system (30). When the position signal (21) indicates that the person is outside the initial position, the control system (30) will send control signals to speed up the motors (120) to make the bent rods (110) rotate faster and bring the person back to the initial position.

[0047] The initial position may in an embodiment be the fixed center plate (160), where this is used. However, the initial position can be defined to be anywhere on the active walking platform (10), and the control system may be arranged to maintain the person in the initial wherever it is. The initial position may also change dynamically as the person is walking or running, depending on the purpose and the application of the system. E.g. if physical exercise is intended, it might be

appropriate to continuously change the initial position. [0048] The system comprises in an embodiment one or more screens (40), surrounding at least a sector of the active walking platform (10), wherein the screens (40) are arranged to show video pictures on the side of the screen facing towards the walking platform (10).

[0049] In Figure 4 a circular screen surrounding the entire active walking platform (10) is illustrated. The screen may be passive screens projected onto by one or more video projectors or be LED screens or any other active devices for showing video pictures. Depending on the content on the screen, the task of the person on the platform may be to walk towards a specific location in the video picture shown on the screen (40). As the person starts walking in the direction towards the location, he/she will walk away from the initial position. The control system (30) will detect this and bring the person back. If e.g. the person is to turn around a corner of a building on the screen, he will turn around to one side. This will also be detected by the control system (30) and the person is again taken back towards the initial position. It should be noted that the same control signal (31) can be used to bring the person back to the initial position independent of the walking direction.

[0050] Several active walking platforms and the systems according to the invention may be used to create a multi-user simulator or training filed as shown in Figure 5. In the example shown, three systems (1) are located in a first physical location (201), and three other systems (1) are located in a second physical location (202). In each of the six systems (1) there is a person (A, B) walking or running in the direction indicated. In this embodiment a computer implemented simulator controller (31) is arranged to control all the video projections on the screens of each system (1) and detect the movement, i.e. position and direction of each of the persons (A,B). Thus, a virtual training field (300) may be set up, where the persons (A, B) can see each other on the screens as if they were in the same location. In the virtual training filed (300) the trained persons (A, B) have a perception of their relative positions that is different from their real relative positions in the first and second physical locations (201, 202).

[0051] According to an embodiment of the invention the control system (30) calculates system output signals (32) arranged to control a simulator software or a game software. The position of the person on the platform, as well as the speed of the platform, or a speed equivalent value, may be used to control the software. Similarly, the control system (30) may in an embodiment receive system input signals (33) from the simulator software or a game software that may be used e.g. in the calculation of the motor speed. The system output and input signals (32, 33) may be sent over proprietary or standardized network protocols like UDP. The system output signals (32) may in an embodiment use the same format as regular computer mouse or joystick protocols.