SAFETY DEVICE FOR ASSISTED CLIMBING

Description

[0001] The present invention relates to the field of climbing as a sporting or leisure physical activity.

[0002] It relates in particular to a belay brake type device having increased functions compared to devices known in the state of the art.

[0003] Climbing as a sport is currently gaining popularity among the general public. In order to practice this activity safely, equipment has been developed that allows climbers to be secured in a simple and effective manner.

[0004] It is well known that a climber is commonly belayed while climbing with a rope "in a pulley workshop" also called "top rope" using a rope passing through a pulley installed at the top of the route or block being climbed. One or two belayers are responsible for belaying the climber in the event of a fall or, if necessary, during their descent. The rope is inserted into a belay brake connected to a harness worn by the belayer. The belay brake allows the belayer to release slack while climbing and to brake or even block the rope in the event of a fall or descent by the climber.

[0005] Other known devices, called automatic reels, allow the belaying of a climber. Very generally, automatic reels are so-called rope distribution means and serve to protect a climber against falls by retracting the slack present in the rope into the reel when the rope is not under load and by providing a braking force when the rope is loaded, so that the weight at the end of the rope is reduced with a safety objective (typically, to prevent or brake a fall).

[0006] To provide the braking force, several systems such as a friction brake or a hydraulic damping mechanism have been used in automatic reel-type rope distribution devices. Furthermore, the known devices are distinguished by the presence or absence of a clutch to engage the braking system and conversely to disengage it when the rope is not under load, devices employing a device that does not require a clutch may prove safer.

[0007] For example, document US2014048639 discloses an automatic reel combining a rope return spring and a non-contact eddy current braking system, operating on the principle that when an electrically conductive element passes through a magnetic field (or vice versa), the relative movement induces a flow of electric currents in the conductor, which in turn induce a magnetic field that opposes the magnetic field that is applied. Another belaying device is known from WO 2010 / 133876 A1.

[0008] This type of device is simple, effective and safe. However, in the context of the development of climbing as a physical activity accessible to many audiences, or as a fun leisure activity, the Applicant has discovered that it could be advantageous to propose an automatic belaying device offering new functions. Thus, the invention relates to a belaying device for climbing comprising an automatic winder comprising a pulley and a rope. The device is configured so that the rope is wound or unwound according to the progress of a climber belayed by said belaying device. The belaying device comprises an electric motor configured so as to be able to apply a torque to the pulley and an encoder coupled to the pulley, the motor being controlled by an electronic control circuit using the encoder as a function of the rotation of the pulley so as to modulate said torque applied to the pulley according to at least: an assistance mode in which the torque applied by the motor to the pulley causes a pull on the rope which assists the climber in his climbing; and a fall mode in which the torque applied by the motor to the pulley stops a fall of the climber or slows it down to maintain it at a speed of less than 3 m / s.

[0009] The motor is servo-controlled so that the torque driving traction in the assist mode is only applied when the encoder detects a rotation of the pulley which translates into a decrease in the force applied by the rope on the pulley

[0010] The device thus proposed in the invention makes it possible to secure a climber, while offering an assistance function. In particular, the device makes it possible to manage both the climber's ascent or "climb", and his fall, using a simple and unique system based on a motor controlled by an encoder capable of characterizing the rotation of the pulley. The motor control is implemented in at least two modes depending on whether the climber is climbing or falling. The device makes it possible in particular to manage the climber's fall reliably, without resorting to a mechanical, electromagnetic or hydraulic clutch, as is the case in most known belaying systems, and also offers a climbing assistance function. This opens the practice of sport climbing to a wide audience, or allows for recreational climbing.A simple device, based on a servomotor, which can correspond to a servomotor, is also particularly well suited to the free climbing centers which are developing nowadays.

[0011] In addition, a climbing aid is thus obtained, which is only active when the climber is actively climbing a wall or a block. In other words, it is not a question of continuously and fixedly reducing the user's weight during the climb, but of proposing a device which adapts to the climb carried out, for example according to the efforts made by the climber, or according to the dynamism of this climb.

[0012] Of course, permanent assistance is not excluded from the invention, and can be applied in certain embodiments.

[0013] The value of the torque applied by the motor to the pulley in the assistance mode may be a function of the value, rate, or speed of the decrease in the force applied by the rope to the pulley. It may be a function of a predefined device calibration value.

[0014] The motor can be controlled so that, in assistance mode, the climbing speed, corresponding to the speed of winding the rope onto the pulley, is substantially constant.

[0015] The device thus allows in particular an adaptation to the wishes or morphology, in particular the weight, of the climber. The device can thus be adapted for example to a specific training program, providing for example a progression of the climber in his practice by reducing the level of assistance little by little. The device can be adapted to a more playful practice of climbing, by providing a very high level of assistance allowing the user to climb almost effortlessly, to jump from one hold to another, or even from one wall to another, etc.

[0016] The motor can be controlled so that in the fall mode the torque applied to the pulley essentially ensures a substantially constant predefined fall speed, independently of the force applied by the rope (3) on the pulley.

[0017] The motor can be controlled so that in fall mode the torque applied to the pulley allows for progressive braking of the climber before ensuring a substantially constant fall speed.

[0018] The motor, as a controlled device, makes it possible to directly manage a situation in which the climber falls. In particular, the fall speed can be limited to a speed that avoids any risk of injury. It is accepted that a speed of less than 3 m / s, in particular a speed of approximately 2 m / s, is compatible with a safe descent. Furthermore, in certain embodiments of the invention, the control of the motor can be programmed to ensure dynamic belaying of the climber, which is more comfortable and safer than sudden braking.

[0019] The motor can be directly connected to the pulley or can be connected through a synchronous mechanical transmission.

[0020] Thus, no clutch-type device is used in the invention in its nominal operating mode. A mechanical clutch or brake-type device is only implemented, if applicable, in an optional degraded mode implemented, for example, in the event of a power supply failure to the device. The motor and the pulley are connected together so that the motor causes direct drive of the pulley, or with a gear ratio, in order to apply an assistance or resistance torque to it.

[0021] The device may further comprise a disc brake configured to be actuated automatically in the event of a power failure of said device.

[0022] By its configuration alone, the device can thus, in a degraded operating mode corresponding for example to a power cut to the motor, ensure the safety of the climber in the event of a fall. The disc brake ensuring the safety of the climber in the event of a power failure to the device is engaged in the absence of a power supply, and released when the device is powered on.

[0023] The motor may be of the brushless type and comprise a rotor carrying a series of permanent magnets and a stator carrying a set of windings.

[0024] Such an engine is reliable, not prone to wear, and allows for significant mechanical torque.

[0025] The device may comprise a mechanical system allowing movement of the automatic reel, in a so-called transverse direction, perpendicular to the general direction of extension of the rope outside the automatic reel, this direction being said to be vertical. For example, the automatic reel is mounted on a rail extending in the transverse direction so as to be able to be translated freely along said rail, or on a pivoting arm along an axis extending substantially in the vertical direction.

[0026] A transverse movement of the automatic reel, which includes in particular the pulley, allows it to follow the climber's movement laterally. This increases user comfort, prevents the climber from swinging in the event of a fall, and makes the device compatible with very wide climbing walls.

[0027] The invention also relates to a fun climbing system comprising a climbing structure, a virtual reality device such as a headset or glasses, a computer system adapted to project into the virtual reality device an image applied to the structure to be climbed, and a belay device for climbing as described previously.

[0028] The invention also relates to a fun climbing system comprising a climbing structure, an augmented reality device, a computer system adapted to project an image onto the structure to be climbed, and a belay device for climbing as described previously.

[0029] In a fun climbing system according to the invention, a sensor can be configured to determine the position and attitude of a climber using said fun climbing system, so as to vary the image projected in the virtual reality device or on the structure to be climbed.

[0030] The device proposed in the invention, which not only allows for belaying a climber but also for assistance in climbing, makes it possible to envisage a recreational use that differs from the common practice of climbing. By coupling the device to a virtual environment, whether generated using a virtual reality device or an augmented reality device, a new experience can be offered to the user. For example, a child or an adult evolving in this environment may have the impression of climbing a tree or a building recreated virtually in correspondence with the holds available on a wall or another climbing structure. This recreational activity is then carried out effortlessly, or even in the manner of a superhero, the belaying device according to the invention being able to achieve performances inaccessible to a human.For example, it is possible to climb at high speed, jump from hold to hold, or any other climbing experience with a reduced feeling of gravity.

[0031] Other features and advantages of the invention will become apparent in the description below.

[0032] In the attached drawings, given as non-limiting examples: there figure 1 represents, according to a schematic three-dimensional view, a belaying device in accordance with an embodiment of the invention; the figure 2 represents, in a three-dimensional exploded view, the device of the figure 1 ; there figure 3 represents, in a schematic view, a particular embodiment of the invention and its environment of use; the figure 4 represents, in a three-dimensional schematic view, another particular embodiment of the invention and its environment of use; the figure 5 represents, in a three-dimensional schematic view, a playful climbing system in accordance with an embodiment of another aspect of the invention.

[0033] There figure 1 represents an example of a belay device for climbing according to an embodiment of the invention. This device comprises an automatic reel 1, comprising a housing 2 inside which a rope 3, which may consist of a flat strap, is wound and unwound as required.

[0034] The reel comprises a fixing interface 4, adapted to be fixed to a mounting bracket 5. In the example shown here, the device comprises the mounting bracket 5, which constitutes a fixed point capable of reliably supporting a significant force, greater than the weight of a climber.

[0035] The connection between the mounting bracket 5 and the fixing interface 4 of the reel 1 is made in the example shown using two bolts 6.

[0036] Other mechanical connection means, for example tie rods or studs, are of course conceivable. For example, the device may be without a mounting bracket 5, so as to be fixed at the top of a climbing wall, for example using two carabiners.

[0037] Further, as further described with reference to figures 3 And 4 , the device can be configured to allow lateral movement of the reel, using a suitable mounting bracket which can have various configurations.

[0038] The device is provided with an electrical power socket 7, allowing the connection of a power cable 8. According to certain variants of the invention, the device can be equipped with a programming socket, which can be associated with or dissociated from the electrical power socket 7.

[0039] There figure 2 represents an exploded view of the belay device according to the embodiment shown in figure 1 , allowing in particular to see the internal elements of the housing 2 of the reel 1.

[0040] A frame 9, which in the example shown here comprises the fixing interface 4, constitutes the main structure of the belaying device. A pulley 10 allows the winding and unwinding of the rope 3, which here takes the form of a flat strap. A rope guide 11 allows the rope 3 to be guided, in particular for its correct winding on the pulley 10. The rope guide is typically a part, for example made of plastic material, comprising a slot allowing the guided passage of the flat strap constituting the rope 3.

[0041] The device comprises an electric motor 12 which comprises a rotor 14 and a stator 13. The operation of the motor is controlled by an electronic control circuit 15.

[0042] The rotor 14 essentially consists of a crown on an internal face of which permanent magnets 16 are fixed. The permanent magnets 16 are advantageously powerful magnets, for example made of neodymium. The stator 13 is positioned inside the crown of the rotor 14. The stator 13 comprises a set of windings 17. The rotor and the stator form a brushless motor, commonly referred to by the English term "brushless". This type of motor makes it possible to generate a significant torque, and is very reliable and not very subject to wear, in the absence of friction parts. The motor 12, and in particular the rotor 14, is directly connected to the pulley 10 for example by nuts distributed around the perimeter of the pulley 10 and the rotor 14. Thus, any rotational movement of the rotor 14 is transmitted directly to the pulley 10, and vice versa.

[0043] The shaft 18 is immobilized in rotation relative to the pulley 10 by means of a key. An encoder 24 is connected to the shaft 18, and thus makes it possible to characterize the rotation of the pulley 10.

[0044] The shaft 18 is advantageously mounted on bearings, in particular opposite the stator 13. For example, two ball bearings 19 allow the free rotation of the shaft (and therefore of the pulley 10 and the rotor 13) in the winder.

[0045] The reel further comprises a disc 21, rigidly connected to the pulley 10 by means of spacers 22.

[0046] The disc 21 constitutes, in cooperation with a caliper 23, a disc brake making it possible to brake or block the rotation of the pulley 10. This brake can be actuated as a safety measure, for example in the event of the power supply to the belay device being cut off, for example to brake the rotation of the pulley in the event of a fall of a climber secured by the belay device.

[0047] The assembly consisting of the motor 12, the armature 9, the pulley 10 and the disc 21, is included between two flanges 22 fixed together through spacers, which are for example distributed around the periphery of the flanges 22.

[0048] In a variant, the disk 21 can serve as a coding wheel which makes it possible, using one or more optical sensors, to characterize the rotation (angle of rotation, and / or speed of rotation) of the pulley 10. The information on the rotation of the pulley 10 makes it possible to determine the winding or unwinding speed of the rope 3, in particular the linear speed of entry or exit of the rope into the winder housing.

[0049] The electronic circuit 15 is positioned outside the mechanical part of the system located between the two flanges 22, but could, according to other embodiments, be located differently, in particular between the flanges 22.

[0050] Unlike known belay devices, braking during a fall of a climber belayed by the device is achieved by applying a suitable torque to the pulley by the motor 12. In addition, the belay device allows assistance in climbing, also by applying a torque by the motor to the pulley.

[0051] The use of a motor makes it possible to precisely and dynamically control the torque applied to the pulley according to various operating modes of the device and according to the force exerted by the rope 3 on the belay device.

[0052] In a fall mode, the belay device must limit the climber's fall speed to a safe speed, i.e., a speed at which the climber can safely land on the ground. A speed of 1.8 m / s, or 6 feet per second, is considered suitable. The device can thus offer a fall speed, which can optionally be programmed, of 1 m / s, 1.8 m / s, 2 m / s, or 3 m / s, these values being given as non-limiting examples.

[0053] For this fall mode, the torque to be applied by the motor depends on the climber using the device as well as the geometry of the pulley, and in particular its diameter. To block the fall, a torque is applied to the rope, applying a force opposite and equal to the force exerted by the climber (typically his weight). For a given fall speed, the applied torque is modulated to maintain the desired maximum fall speed.

[0054] The servo-driven motor, by dynamically managing the torque applied to the pulley, can also allow dynamic belaying of the climber. Typically, beyond a certain climbed height, which can be determined by the quantity of rope 3 wound in the reel since the start of an ascent, it can be more comfortable and safer for the climber not to suddenly stop his fall, but to ensure progressive braking until an acceptable fall speed is reached. In the context of traditional belaying, carried out by a belayer located at the bottom of the wall, this is achieved by making a little slack in the rope before braking the climber's fall. Such behavior can be reproduced automatically, programmed, by the belaying device proposed in the invention.

[0055] A fall situation can be detected by the unwinding of the rope 3, which results in a given direction of rotation of the pulley 10. As an alternative, or in addition to this parameter, the acceleration of the rotation of the pulley and / or the torque or the variation of torque applied by the rope 3 on the pulley can be determined and used.

[0056] One of the primary functions of an automatic winding belay device is to allow the progressive winding of the rope as the climber ascends. The proposed device allows this basic function to be fulfilled without providing assistance, i.e. without applying a pulling force to the climber or at least without applying a significant pulling force to him. Typically, the servomotor can be programmed to wind the rope with a very low torque applied to the pulley, and / or be programmed to stop winding it as soon as the reaction of the rope 3 on the pulley 10 increases.

[0057] The belay device also provides climbing assistance, in an assistance mode, by pulling on the rope 3. Such traction reduces the climber's apparent weight; and facilitates his ascent. The motor can be controlled and programmed so as to dynamically adapt the assistance provided, according to various laws or parameters.

[0058] The climber may wish to have assistance as part of sports climbing training, for example to modulate the efforts in a training program, to work on their climbing technique without the constraint of significant efforts, or on physically demanding passages or sequences. In these cases and others, permanent traction on the rope may prove troublesome or unwanted. The device makes it possible to apply traction only as assistance to an effort, that is to say to ensure that the assistance is only offered in response to an effort from the climber, and modulated according to the detected effort.

[0059] For example, the application of traction to the rope by the motor may be limited to situations in which the servo device, via an encoder, detects a rotation of the pulley reflecting a reduction in the force applied by the rope to the pulley. The reduction, compared to an initial or reference situation, corresponds to the fact that while climbing, the climber applies part of his weight or more generally the weight he was exerting on the rope to the climbing holds, and therefore makes an effort tending to hoist it.

[0060] Since the force applied by the rope to the pulley is the resultant of the force exerted by the climber and the reaction of the rope to the force applied to it by the pulley, it corresponds at any time to the weight of the climber less the part of this weight supported at the level of the climbing holds, and can at any time be compared to a predefined value to determine whether the climber is climbing or not. Thus, assistance can only be provided when the climber produces an effort, just as, by analogy, the assistance devices of electric bicycles do, which only produce assistance when pedaling is detected.

[0061] The decrease in the force exerted by the rope on the pulley can be described by several parameters, including the absolute value of this decrease, by its rate compared to an initial value, or by its speed. These parameters can be determined by observing the rotation of the pulley. These parameters can also be combined, one with another or all three, to determine the level of assistance to be applied. The level of assistance is advantageously dynamically modulated according to the evolution of one or more of these parameters.

[0062] In particular, assistance may only be implemented when a sufficient, predefined gap between the force exerted by the rope on the pulley and a reference force is observed. This gap makes it possible to only assist the climber from a certain level of effort provided. This makes it possible to avoid untimely implementation of assistance. This can also make it possible to define, for example, a constant value of an effort to be produced by the climber, the difference between this value and the force necessary for climbing being provided by the assistance function of the belay device.

[0063] The assistance offered may also take into account a calibration value. This value may be fixed, by default, or programmed according to the user. For example, the user's weight, or a predefined fraction of the user's weight, may be taken as the calibration value.

[0064] Other motor control laws may be envisaged within the scope of the invention. For example, the motor may be controlled so that the climber's climbing speed is constant. This type of assistance is not well-suited to sport climbing, but may, in certain cases, be suitable for recreational climbing.

[0065] There figure 3 illustrates a belay device for climbing according to one embodiment of the invention. According to this embodiment, the reel can move laterally at the top of the climbing wall 25 to accompany a lateral movement of the climber who is being belayed.

[0066] The transverse direction T is defined as a direction perpendicular to the vertical V, that is to say the direction of application of gravity or the general direction of extension of the belay rope. The transverse direction extends in the general plane of extension of the climbing wall considered.

[0067] In the embodiment of the figure 3 , the automatic reel 1 is mounted via a mounting bracket 5 adapted on a rail 26 extending in the transverse direction T. The automatic reel moves freely on the rail 26, so that its movement accompanies the lateral movements of the climber.

[0068] There figure 4 illustrates a variation of the principle illustrated in figure 3 . In the embodiment of the figure 4 , the automatic reel 1 providing a climbing assistance function is mounted on a pivoting arm 27, which allows its transverse movement. Although the movement is not purely transverse, the device can be configured to allow adequate transverse movement, and has the advantage of great simplicity and reliability.

[0069] There figure 5 illustrates another aspect of the invention, according to which the belay device providing assistance in climbing is used in a virtual or augmented reality environment. Indeed, due to the assistance that can be provided, as well as the comfort and high level of safety offered, the proposed belay device is particularly suitable for more recreational uses than the traditional practice of climbing.

[0070] The invention thus also relates to a fun climbing system shown in the figure 5. In addition to the belay device comprising an automatic reel 1, the device comprises a computer system 28 programmed to apply a virtual environment to a climbing structure 29 (for example a climbing wall).

[0071] The virtual environment can be applied using a projector 30. This is called augmented reality.

[0072] The environment can be applied via a virtual reality headset 31, in which case we speak of virtual reality.

[0073] The projector and the virtual reality headset can be used as an alternative or in addition, for example to simultaneously allow the immersion of the climber in the virtual environment and a visualization by spectators of the virtual environment in which the climber is placed.

[0074] The virtual environment can be of any type, for example a natural environment (cliff, virtual tree 33, etc.) or an urban environment (facade of a building, monument, etc.).

[0075] The virtual environments are advantageously created so that the holds of the virtual environment correspond, in position and shape, to the actual holds of the climbing structure 29.

[0076] The assembly may include means for making the virtual environment dynamic, depending on the climber's actions. For this purpose, sensors are used to determine the climber's position and attitude. These may be sensors positioned on the climber, and / or one or more cameras associated with image processing software. It is thus possible to vary the environment, projected onto the climbing structure 29 or in a virtual reality headset, to adapt it to certain actions of the climber. It is also possible to provide the climber equipped with a virtual reality headset with visual feedback on the position of his own limbs in the virtual environment.

[0077] A fun climbing system as proposed according to this aspect of the invention makes it possible to offer a new climbing experience, fun or for educational purposes (for example for adaptation to the sensation of vertigo) or even a completely fun experience: effortless climbing in unusual virtual environments, jumping from virtual tree to tree, between virtual buildings, etc., for example in the manner of a superhero capable of superhuman physical feats.

[0078] The climbing belay device developed in the invention thus proposes a simple and safe automatic reel belay device for climbing without a belayer. It makes it possible to achieve, by a single means, namely a motor controlled by an encoder coupled to the reel pulley, both a belay function in the event of a fall, and a climbing assistance function. The use of a controlled motor makes it possible to obtain the necessary torque to be applied to the pulley for these two functions, and to modulate this torque according to various motor control laws, in order to meet the uses and purpose of the device in the practice of climbing as a sport, leisure activity, or recreational activity.

[0079] Due to its very simple configuration and the functions it offers, the device is suitable for use in a fun climbing set allowing a virtual environment to be applied to a real climbing structure, to offer new and / or fun experiences to the climber.

Claims

1. A climbing belay device comprising an automatic winder (1) comprising a pulley (10) and a rope (3), the device being configured so that the rope (3) is wound or unwound according to the course of a climber belayed by said belay device, the belay device comprising an electric motor (12) configured so as to be able to apply a torque to the pulley (10) and an encoder coupled to the pulley, the motor being servocontrolled by an electronic control circuit using the encoder depending on the rotation of the pulley (10) so as to modulate said torque applied to the pulley according to at least: - an assist mode in which the torque applied by the motor to the pulley (10) causes traction of the rope (3) which assists the climber in their climbing; and - a fall mode in which the torque applied by the motor to the pulley (10) blocks fall of the climber or slows it down to keep it at a speed of less than 3 m / s, the belay device being characterized in that the motor (12) is servocontrolled such that the torque causing traction in the assist mode is applied only when said encoder detects rotation of the pulley which reflects a decrease in the force applied by the rope (3) on the pulley (10).

2. The device according to claim 1, wherein the value of the torque applied by the motor (12) to the pulley (10) in the assist mode is a function of the value, rate, or speed of the decrease in the force applied by the rope (3) on the pulley (10).

3. The device according to one of the preceding claims, wherein the value of the torque applied by the motor (12) to the pulley (10) in the assist mode is a function of a predefined calibration value of the device.

4. The device according to one of the preceding claims, wherein the motor (12) is servocontrolled such that, in the assist mode, the rise speed, corresponding to the speed of winding the rope (3) onto the pulley (10), is substantially constant.

5. The device according to one of the preceding claims, wherein the motor (12) is servocontrolled such that in the fall mode, the torque applied to the pulley (10) essentially ensures a substantially constant predefined fall speed, independently of the force applied by the rope (3) on the pulley (10).

6. The device according to claim 5, wherein the motor is servocontrolled such that in the fall mode, the torque applied to the pulley allows gradual braking of the climber before ensuring a substantially constant fall speed.

7. The device according to one of the preceding claims, wherein the motor (12) is directly connected to the pulley (10) or via a synchronous mechanical transmission.

8. The device according to one of the preceding claims, further comprising a disk brake (21) configured to be automatically actuated in the event of an electric power cut to said device.

9. The device according to one of the preceding claims, wherein the motor (12) is of the brushless type and comprises a rotor (14) carrying a series of permanent magnets and a stator (13) carrying a set of windings.

10. The device according to one of the preceding claims, characterized in that it comprises a mechanical system allowing the automatic winder to be moved, in a so-called transverse direction (T), perpendicular to the so-called vertical (V) general direction of extension of the rope (3) outside the automatic winder (1).

11. The device according to claim 10, wherein the automatic winder (1) is mounted to a rail (26) extending in the transverse direction (T) so as to be freely translatable along said rail (26), or to a pivot arm (27) along an axis extending substantially along the vertical direction (V).

12. A recreational climbing system comprising a climbing structure (29), a virtual reality device such as a headset (31) or eyeglasses, a computing system (28) adapted to project an image applied to the climbing structure (29) into the virtual reality device, and a climbing belay device according to one of the preceding claims.

13. A recreational climbing system comprising a climbing structure (29), an augmented reality device, a computing system (29) adapted to project an image onto the climbing structure, and a climbing belay device according to any one of claims 1 to 11.

14. The recreational climbing system according to claim 12 or claim 13, comprising a sensor configured to determine position and attitude of a climber using said recreational climbing system, so as to vary the image projected into the virtual reality device or onto the climbing structure (29).