Patent Publication Number: US-6669215-B2

Title: Steerable locomotion device for sport or leisure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a locomotion device for sport or leisure intended to be used for moving over ground, preferably sloping ground. 
     2. Description of the Related Art 
     In the domain of winter sports, it is known to use a snowboard for moving over a snow-covered slope, the user guiding the board by the positioning of his/her body above the board, this inducing variations of the centre of gravity of the assembly formed by the surfer and the board. In practice, the use of a snowboard is limited to the winter season in the majority of regions. 
     Furthermore, it is known, for example by WO-A-99/48750, to produce a locomotion device which comprises an elongated chassis on which is mounted a pivoting sub-assembly for steering adapted to be manoeuvred by a seated user with his feet. The sensation of piloting is similar to that felt with a go-kart. 
     Other devices such as summer sledges are controlled like a skate board, i.e. by inclining a chassis on which the user places his feet with respect to an axis of a steering axle. The sensation of piloting is close to that obtained with a skate board. 
     SUMMARY OF THE INVENTION 
     The invention aims at proposing a novel locomotion device structure which makes it possible to feel new sensations of piloting, including over ground not covered with snow, these sensations of piloting being closer to those usually obtained with a snowboard. 
     In this spirit, the invention relates to a locomotion device for sport or leisure comprising a chassis adapted to accommodate at least one user and resting on the ground via engaging members, of the wheel or runner type, at least one of these members being mounted on a steering column articulated, with respect to the chassis, about an axis of rotation. This device is characterized in that it comprises a frame kinematically connected to the steering column, mobile with respect to the chassis and adapted to come into contact with the ground, this frame making it possible, by its movements with respect to the chassis, during abutments on the ground, to control rotation of the steering column about its axis. 
     Thanks to the invention, the frame capable of coming into abutment against the ground is used as the means for controlling the steering wheel or wheels or the or steering runner or runners. It therefore suffices for the user to incline the device in the direction of the ground for the frame to interact with the ground and consequently control the rotation of the steering column. Abutment of the frame on the ground may be obtained by the user modifying the position of his centre of gravity with respect to the device, similarly to that used with a snowboard. Change of direction is obtained by modifying the inclination of the chassis with respect to the frame. When the latter is in contact with the ground, the degree of inclination of the chassis may be modified by the user with his feet, without necessarily offsetting his centre of gravity, which makes it possible to vary the radius of curvature of the trajectory of the device. 
     According to advantageous but non-obligatory aspects of the invention, the locomotion device incorporates one or more of the following characteristics: 
     It comprises a single ground-engaging member disposed at one end, front or rear, of the chassis and a single ground-engaging member disposed at the other end, rear or front, of the chassis. In that case, each ground-engaging member may be provided to be mounted on a steering column articulated with respect to the chassis and kinematically connected to the frame, the frame being adapted to control rotation of each steering column about its own axis of rotation. 
     The axis of rotation of the steering column is inclined with respect to the vertical when the device rests on horizontal ground. This inclination of the steering column corresponds to the notion of steering error angle which may be defined over a cycle and the non-zero nature of the steering error angle of the steering column improves the stability of the device. However, this non-zero nature is optional. 
     Means are provided for returning the frame towards a position with respect to the chassis such that the ground-engaging member mounted on the steering column is oriented so that the device can move substantially in a straight line. These return means allow the device to advance in a straight line by default. These return means may be provided to be elastic and with adjustable elasticity. 
     Means are provided for damping vibrations between the ground and a user in place on the chassis, these means comprising wheels having low-pressure pneumatic tyre or elastic tyre, at least one telescopic damping fork, shock absorbers integrated in the chassis and/or a chassis with elastic memory. 
     The steering column bears a catch extending in a substantially radial direction with respect to its axis of rotation, while the frame is fast with a fork adapted to interact with this catch in order to control rotation of the column about this axis. 
     The frame is articulated on the chassis about an axis substantially parallel to the direction of displacement of the device in a straight line. 
     The means for connection between the frame and the steering column, the geometry of the frame and/or the geometry of the chassis are adjustable, which makes it possible to modify the conditions of piloting of the device and the sensations experienced. This also allows the conditions of piloting to be adapted to the morphology and/or athletic ability of the user. 
     The frame may be substantially in the form of a closed loop. It may also be formed by two half-frames kinematically connected to a front steering column and to a rear steering column, respectively, of the device. According to another approach, the frame may be substantially in S or Z form, having its respective ends kinematically connected to a front steering column and to a rear steering column, respectively, of the device. 
     The frame is equipped with at least one removable runner provided to come into contact with the ground. Such a runner protects the frame from shocks and may be changed as a function of its wear. The frame may also be equipped with a removable device incorporating caster(s) or roller(s) performing the same function. 
     An elastic net is provided between the chassis and the frame. 
     The chassis comprises a cradle substantially in the form of a loop and covered with a board adapted to support a user. According to another approach, the chassis comprises a cradle formed by two half-cradles each fast with a steering column and connected by a tie-piece. In that case, these half-cradles are advantageously articulated with respect to the tie-piece, with possibility of limited rotation, which makes it possible to dampen the shocks and/or vibrations. These two half-chassis may also be covered with a board adapted to support a user. 
     In the case or a supporting board being used, damping means may be arranged between the cradle and this board. 
     The means for connection between the frame and the steering column include means for returning the frame towards a position with respect to the chassis such that the ground-engaging member mounted on the steering column is oriented so that the device can move substantially in a straight line. 
     According to a first form of embodiment, the connection means comprise an element made of supple plastics material forming a sleeve adapted to surround an arm for controlling the steering column in rotation, this element forming at least one housing for receiving part of the frame. 
     According to another form of embodiment, an elastic member is adapted to slide on an arm controlling the steering column in rotation, this elastic member being fast with an element connected to a shank of the steering column. In that case, a fork fast with the element connected to the shank may be provided, adapted to alternately compress the elastic member against the arm controlling the steering column. 
     According to another form of embodiment, the connection means comprise a member articulated on an arm controlling the steering column and forming a fork adapted to cooperate with a shaft fixed with respect to the shank of the column. 
     According to another form of embodiment, the connection means comprise an elastically deformable endpiece, mounted on an arm controlling the steering column and connected to the frame by connecting rods or cables. 
     Means are provided for compensating the necessary clearance between the frame and the chassis in order to allow deformations of the cradle of this chassis. In that case, these compensation means advantageously include a compression spring disposed inside a sleeve fast with the frame, this spring surrounding a pin and exerting on part of it a clearance-compensating force. 
    
    
     BRIEF DESCRITPION OF THE DRAWINGS 
     The invention will be more readily understood and other advantages thereof will appear more clearly in the light of the following description of seven forms of embodiment of a locomotion device in accordance with its principle, given solely by way of example and made with reference to the accompanying drawings, in which: 
     FIG. 1 is a side view of a locomotion device according to a first form of embodiment of the invention. 
     FIG. 2 is a plan view of the device of FIG.  1 . 
     FIG. 3 is an end view, from the front, of the device of FIGS. 1 and 2. 
     FIG. 4 is a partial section of the device of FIGS. 1 to  3  along line IV—IV of FIG.  3 . 
     FIG. 5 schematically shows the device of FIGS. 1 to  4  in the course of being used along a rectilinear trajectory. 
     FIG. 6 is a view similar to FIG. 5 when the device is used in a bend. 
     FIG. 7 is a view similar to FIG. 3 when the device is in the configuration of use of FIG.  6 . 
     FIG. 8 is a plan view of the device alone in the configuration of FIGS. 6 and 7. 
     FIG. 9 is a view similar to FIG. 5 while the user is in another position. 
     FIG. 10 is a view similar to FIG. 6 while the user is in the position of FIG.  9 . 
     FIG. 11 is a side view of a device in accordance with a second form of embodiment of the invention. 
     FIG. 12 is a plan view of the device of FIG.  11 . 
     FIG. 13 is an end view, from the front, of the device of FIGS. 11 and 12. 
     FIG. 14 is a view in perspective of the device of FIGS. 11 to  13 . 
     FIG. 15 is a view in perspective of a device in accordance with a third form of embodiment of the invention. 
     FIG. 16 is a view similar to FIG. 15, while certain elements of the device have been omitted in order to render the drawing clearer. 
     FIG. 17 schematically shows a longitudinal section of the device of FIGS. 15 and 16. 
     FIG. 18 is a section on a larger scale of part of the device of FIGS. 15 and 17. 
     FIG. 19 is a view in perspective of a device in accordance with a fourth form of embodiment of the invention. 
     FIG. 20 is a partial view in perspective of a device in accordnce with a fifth form of embodiment of the invention. 
     FIG. 21 is a view similar to FIG. 20 for a device in accordance with a sixth form of embodiment of the invention, and 
     FIG. 22 is a view in perspective of a device in accordance with a seventh form of embodiment of the invention. 
    
    
     DESCRITPION OF THE PREFERRED EMBODIMENTS 
     The locomotion device  1 , shown in the Figures and in accordance with the invention, comprises a chassis  2  including a tubular cradle  21  and a supporting board  22  mounted on this cradle. The cradle  21  comprises two tubes  23  and  24  which are substantially parallel and rectilinear, the ends  23   a ,  23   b ,  24   a  and  24   b  of these tubes being curved upwardly and joining at the level of two shanks  26  and  27 . 
     X-X′ denotes a longitudinal axis of the chassis  2 . This axis is parallel to the tubes  23  and  24  in their central parts and traverses the shanks  26  and  27 . This axis corresponds to the direction of advance of the device  1  in a straight line. 
     Y-Y′ denotes an axis transverse to the chassis  2 , this axis being perpendicular to axis X-X′ and parallel to the median plane of the board  22 . Finally, Z-Z′ denotes a central vertical axis of the device  1  when the latter rests on horizontal ground S, axis Z-Z′ being perpendicular to axes X-X′ and Y-Y′. 
     A 26  denotes the central axis of the shank  26 , A 27  denotes the central axis of the bush  27 . 
     Axis A 26  is included in a plane defined by axes X-X′ and Z-Z′ and inclined, in this plane, with respect to axis Z-Z′ by an angle α equal to about 30°. Similarly, axis A 27  is included in the plane defined by axes X-X′ and Z-Z′ and inclined by an angle β of about 30° with respect to axis Z-Z′. Axes A 26  and A 27  are convergent in the direction of axis Z-Z′ opposite the ground S, i.e. upwardly in FIG.  1 . 
     The device also comprises two steering columns  3  and  4  respectively engaged inside the shanks  26  and  27 . 
     As is particularly visible in FIG. 4, the column  3  comprises a shaft  31  aligned on axis A 26  and connected to a fork  32  in which a wheel  5  is mounted. On the shaft  31  is likewise mounted a shank  33  fast with the fork  32  and provided with a curved finger  34  projecting in a substantially radial direction with respect to the shaft  31  and represented by axis A 34 . 
     The column  4  is similar to column  3  and likewise comprises a fork  42  in which a wheel  6  is mounted. 
     By hypothesis, it is considered that column  3  is mounted at the front of the device  1  while column  4  is mounted at the rear thereof, the direction of displacement of the device  1  in FIG. 1 being from left to right. However, this is pure convention, insofar as the device  1  is symmetrical with respect to the plane defined by axes Y-Y′ and Z-Z′ and it also allows a displacement towards the left in FIG.  1 . 
     The shank  26  forms a concave housing  26   a  for receiving a shaft  28  extending along an axis X 28  parallel to axis X-X′ and coplanar to axes X-X′ and Z-Z′. 
     In the same way, bush  27  forms a housing for receiving a shaft  29  extending along the same axis X 28 . 
     A frame  7  is articulated on chassis  2 , being mounted to pivot about shafts  28  and  29 . The frame  7  comprises a tubular structure formed by two tubes  71  and  72  substantially parallel to the tubes  23  and  24  and located on either side of the chassis  2 . The tubes  71  and  72  are respectively connected to the front and to the rear of the device  1  by upwardly curved tubes  73  and  74 . 
     The tube  73  is also connected to two struts  75  which join at the level of a shank  76  intended to be disposed around the shaft  28 . Similarly, the tube  74  is connected by two struts  75 ′ to a shank  77  disposed around the shaft  29 . In this way, the frame  7  may pivot about axis X 28  with respect to the rest of the device  1 . 
     The shank  76  is equipped with two clips  76   a  and  76   b  between which the finger  34  is engaged, the clips  76   a  and  76   b  forming a sort of fork for receiving the finger  34 . 
     Similarly, the shank  77  is equipped with two clips forming a fork for receiving a finger  44  belonging to the column  4 . 
     Two elastic members  81  and  82  are respectively disposed between the fork  32  and the ends  73   a  and  73   b  of the tube  73 , while other two elastic members  83  and  84  are disposed between the fork  42  and the ends  74   a  and  74   b  of the tube  74 . 
     The function of the members  81  and  84  is to return the frame  7  and the forks  32  and  42  by default in the median position shown in FIGS. 1 to  4 , i.e. in a position such that the respective axis of rotation of the wheels  5  and  6  is parallel to the axis Y-Y′, which allows advance of the device  1  in a straight line. 
     When, due to an inclination of the device  1 , one of the tubes  71 ,  72  comes into contact with the ground S, this has the effect of causing the frame  7  to pivot about axis X 28 , which induces the transmission of an effort by one of the clips  76   a  or  76   a  to the finger  34 . This induces a pivoting of the shaft  31  of the column  3  about the axis A 26 . This results in a modification of the direction of the wheel  5  leading to a change in direction of the device  1  in the course of displacement. 
     Referring to FIGS. 5 and 6, it will be understood that, when a user wishes to advance in a straight line, including on sloping ground as shown in FIG. 5, it suffices for him to maintain his centre of gravity G in the plane defined by the axes X-X′ and Z-Z′, in which case the device  1  and its occupant move in the direction X-X′ which is perpendicular to the plane of FIG.  5 . Imagining that the user wishes to turn towards the left in FIG. 5, it suffices for him to lean over in order to displace his centre of gravity towards the side where he wishes to turn, which has the effect of bringing the tube  71  into contact with the ground S. Due to the force of reaction exerted by the ground, this induces a pivoting of the frame  7  about axis X 28  with respect to the chassis  2 . Such pivoting induces a corresponding pivoting of the branches  76   a  and  76   b  of the shank  76  about axis A 28 , in the direction of arrow F 1  in FIG. 7, this having the effect of pivoting the finger  34  about axis A 26  as represented by arrow F 2 , the pivoting of the finger  34  inducing a corresponding pivoting of the column  3  and a change in orientation of the wheel  5 . This pivoting of the column  3  is represented by arrow F 3  in FIG.  8 . 
     In the same way, the pivoting of the frame  7  induces, thanks to the finger  44  and to the fork formed on the shank  77 , a corresponding pivoting F 3  of the column and of the wheel  6 , which makes it possible to attain the configuration shown in FIG. 8 or the trajectory T of the device  1  is substantially circular with a centre of curvature located on the left-hand side of FIG.  8 . 
     If a lesser radius of curvature is to be attained, the user may accentuate the offset of his centre of gravity, which increases the pivoting of the frame  7  with respect to the chassis  2  and the rotation of the steering columns  3  and  4 . He may also modify the position of the chassis  2  with respect to the frame in abutment on the ground by a bending movement of the ankles, inducing a variation of the angle of rotation of the columns  3  and  4 . 
     It is also possible to use the device  1  in the manner shown in FIGS. 9 and 10 where the user is sitting on the board  22  of the chassis  2  and where it suffices for him to maintain his centre of gravity G aligned with the longitudinal axis X-X′ of the device  1  in order to move in a straight line, as shown in FIG. 9, and to lean over to the side where he wishes to turn to bring the frame  7  into contact with the surface of the ground S and thus provoke rotation of the wheels  5  and  6 , as shown in FIG.  10 . 
     The invention has been shown with a device  1  equipped with two guiding wheels. However, it is applicable to the case of only one wheel being guiding, this guiding wheel being able to be the front wheel or the rear wheel of the device. 
     The frame  7  is not necessarily of continuous and closed form, it may take any geometry adapted to its function of abutment on the ground. The zone of contact between this frame and the ground may be equipped with casters or runners in order to limit the decelerations upon impact of the frame on the ground. The frame  7  is not necessarily completely rigid. For example, the struts  75  and  75 ′ may be articulated with return into position by an elastic system in order to absorb the possible irregularities of the ground. 
     The definition of the value of the degrees of lock of the device  1  is obtained by the adjustment in longitudinal position of the clips  76   a ,  76   b  and equivalent with respect to the axis of rotation A 26  and equivalent of the steering columns  3  and  4 . The degree of lock, which is therefore adjustable, may be identical or different for the two wheels  5  and  6  when the two wheels are guiding. 
     In order to improve the comfort of use of the device  1 , the wheels may be wheels incorporating low pressure pneumatic tyre or rubber tyre. In a variant, one or more telescopic damping forks may be used. It is possible also to provide for the chassis  2  to have elastic memory. 
     According to a variant of the invention (not shown), the device  1  may be motorized, with transmission of the movement to one or the two wheels in order to go up slopes. It is also possible to provide using the ski-lifts of a skiable area in order to climb up a slope. 
     Members  81  to  84  may be replaced by other means for elastically returning the wheels and frame into configuration of rectilinear advance. A damping device comprising one or more pads made of elastomer may be used. Pneumatic or hydraulic jacks may also be used. The means for returning the frame  7  with respect to the chassis  2  and/or the wheels  5  and  6  may be positioned at different spots of the device  1  and not simply between the forks  32  and  42  and the frame  7 . In particular, they may be integrated in the shanks  26  and  27  or  76  and  77 . In that case, they work in torsion. These return means may be adjustable, which makes it possible to modify the sensations of piloting. 
     Similarly, the steering error angle of the steering columns  3  and  4 , i.e. the value of the angles α and β may be adjustable over a wide range, these angles not necessarily being equal to each other. The centre distance of axes of the steering columns  3  and  4  may also be adjustable, in the same way as the centre distance of axes of the wheels. 
     Other adjustments may be envisaged, such as the width of the frame  7  or the height h of its lowermost part, in the present case the tubes  71  and  72 , with respect to the ground S in the configuration of FIGS. 1 and 3. The adjustment of this height determines the inclination necessary for starting a bend. 
     In the second form of embodiment of the invention shown in FIGS. 11 to  14 , the elements similar to those of the first form of embodiment bear identical references increased by  100 . The device  101  of this embodiment comprises a chassis  102  including a tubular cradle  121  and a supporting board  122  mounted on this cradle. The cradle  121  comprises two tubes  123  and  124  which are substantially parallel to a longitudinal axis X-X′ of the device  101 . 
     Two steering columns  103  and  104  are provided at the front and rear ends of the device  101  and are engaged inside shanks  126  and  127  forming shank for the columns. The columns  103  and  104  respectively comprise forks  132 ,  142  making it possible to control the orientation about two axes A 126  and A 127  of two wheels  105  and  106 . 
     A frame  107  is articulated with respect to the chassis  102  and is substantially in the form of a closed loop, formed by two tubes  171  and  172  substantially parallel to the tubes  123  and  124  and connected by curved tubes  173  and  174 . 
     A net  185 , shown partially in FIGS. 11 to  14 , is stretched between the frame  107  and the chassis  102  and avoids a user&#39;s feet sliding between the chassis  102  and the frame  107 . The net  185  is made of elastic threads  186  whose tension tends to return the frame  7  into a median position corresponding to a rectilinear advance of the device  101 . The elasticity of the net  185  may be adjusted by playing on the tension of the threads  186 . 
     Furthermore, the frame  107  is provided, in the vicinity of the tube  173 , with two extensions  178  and  179  formed by pieces of tube and projecting forwardly with respect to the tube  173 . The extensions  178  and  179  each comprise two parts  178   a ,  178   b ,  179   a ,  179   b , respectively, oriented in two directions substantially perpendicular with respect to each other. 
     A finger  134  for controlling the fork  132  is inserted in a sleeve  191  formed by a member  190  made of elastic plastics material, in which bores  192  for passage of parts  178   b  and  179   b  of the extensiosn  178  and  179  are also made. 
     The member  190  is made of supple plastics material, for example of synthetic or natural elastomer. 
     In this way, the member  190  constitutes an element for elastic connection between the frame  107  and the column  103 , the control in rotation of the column  103  about the central axis A 126  of the shank  26  being effected through this member. It will be understood that the elastic nature of the member  190  tends to return the finger  134  into a position such that the wheel  105  is oriented substantially in the direction of axis X-X′. 
     Similarly, an elastic member  190 ′ is provided to ensure the connection between the frame  107  and the column  104 . 
     The frame  107  is also equipped with runners  194  intended to come into contact with the surface of the ground when the frame  107  bears thereon. These runners  194  are mounted by means of straps  195  in median zones  107   a  and  107   b  of the frame  107 . On the left-hand side of FIG. 14, the straps  195  are shown in open configuration, before they are fastened in order to immobilize the corresponding runner  194  on the frame  107 . The material of the runners  194  may be chosen to give them a certain elasticity allowing part of the shocks resulting from the bearing of the frame  7  on the ground at relatively high speed to be absorbed. The runners  194  are wearing pieces which may be the object of one or more standard exchanges during the life of the device  101 . 
     Runners similar to runners  194  may, of course, be used with the devices in accordance with the other forms of embodiment described. 
     According to a variant of the invention (not shown), the runners  194  may be replaced by devices comprising casters or rollers bearing on the ground. Such devices are particularly adapted for movement of the device  101  over hard ground, of the tarmac type, particularly in an urban setting. Devices incorporating caster(s) or roller(s) may, of course, be used with the other forms of embodiment. 
     In the third form of embodiment shown in FIGS. 15 to  18 , the elements similar to those of the first form of embodiment bear identical references increased by  200 . The device  201  of this embodiment comprises a chassis  202  including a tubular cradle  221  and a supporting board  222 . This board is equipped with retaining elements  222   a  in the form of an upturned U, under which the user can slide his feet with a view to a better hold on the board  222 . The cradle  221  is formed by two tubes  223  and  224  each forming a loop and of which the two ends are welded on a shank  226 ,  227  respectively. The two tubes  223  and  224  thus constitute half-cradles which are connected by a tie-piece  225  of which the ends are shaped to receive the tubes  223  and  224  respectively, with possibility of rotation. The cradle  221  is thus deformable under the effect of the user&#39;s weight P. 
     As previously, two steering columns  203  and  204  are provided on the device  201  and comprise forks  232  and  242  for controlling two wheels  205  and  206  in rotation. 
     A frame  207  formed by curved tubes  271 ,  272 ,  273  and  274  is mounted on the device  201  so as to be able to come into contact with the ground by the median zones  207   a  and  207   b.    
     A net  285  is stretched between the chassis  202  and the frame  107 , on either side of the board  222 . 
     Control of the fork  232  by the frame  207  is explained with reference to FIG. 18. A pin  251  is articulated with respect to the shank  226  by means of an articulation  252 . This pin traverses a sleeve  253  welded on the frame  207 . In fact, the sleeve  253  cuts the front part  273  of the frame  207  into two. The sleeve  253  is fast with a fork  254  of which the two branches  254   a  and  254   b  traverse an elastic member  255  mounted to slide with respect to a finger  234  for controlling the column  203  in rotation about the central axis A 226  of the shank  226 . The elastic member  225  is capable of moving along the finger  234 , as represented by double arrow F 4 . 
     A compression spring  256  is disposed inside the sleeve  253  and around the pin  251  and abuts on washers  257  defining its housing inside the sleeve  253 . 
     When the weight P of a user has the effect of deforming the cradle  221 , by pivoting of the tubes  223  and  224  in the tie-piece  225 , it is necessary to allow a relative movement of the frame  207 , which is rigid, with respect to the cradle  221 . This is possible, as the pin  251  may slide in the sleeve  253 . 
     The spring  256  exerts on the end head  251   a  of the pin  251  a force E 1  which opposes the penetration of the head  251   a  in the sleeve  253  and thus compensates the clearance provided for the stroke of the pin  251  in the sleeve  253  and necessary for the deformation of the cradle  221 . 
     The articulation  252  makes it possible to align the pin  251  and the sleeve  253 , including in the case of deformation of the cradle  221 . 
     The two branches  254   a  and  254   b,  which traverse the member  255  on either side of the finger  234 , alternately compress the member  255  against the finger  234 , depending on the direction of the bend to be effected. 
     A similar structure is provided at the level of the second steering column  204 . 
     Damping blocks  286  are interposed between the board  222  and the half-cradles  223  and  224 , in order to improve the comfort of use of the device  201 . 
     In the fourth form of embodiment of the invention shown in FIG. 19, the elements similar to those of the first form of embodiment bear identical references increased by  300 . The device  301  of this embodiment comprises a chassis  302  and two steering columns  303  and  304 . 
     It differs from the preceding ones essentially in that its frame  307  is formed by two half-frames  307 A and  307 B kinematically connected to the front steering column  303  and to the rear steering column  304 , respectively. 
     The half-frame  307 A is in the form of an upturned handlebar and comprises end parts, of which only one is visible with reference  307 A 1 , intended to come into contact with the ground. In the same way, the rear half-frame  307 B is provided with end parts, of which only one is visible with reference  307 B 1 , provided to come into contact with the ground. The respective end parts of the half-frames  307 A and  307 B are oriented rearwardly with respect to the zones of connection between these half-frames and the steering columns. 
     As a function of the relief of the terrain over which the device  301  is moving, the front ( 305 ) and rear ( 306 ) wheels of the device  301  may be controlled independently thanks to the half-frames  307 A and  307 B. 
     In the fifth form of embodiment of the invention shown in FIG. 20, the elements similar to those of the first form of embodiment bear identical references increased by  400 . The device  401  of this embodiment also comprises a chassis  402  and steering columns of which only one is shown with reference  403 . A frame  407  is provided to come into abutment on the ground and control in rotation a wheel  405  adapted to pivot about a central axis A 426  of a shank  426  forming a shaft for the steering column  403 . 
     A ball-joint  451  is provided at the end of a finger  434  for controlling the fork  432  of the steering column  403  in rotation, this ball joint  451  allowing movements of pivoting of a fork  452  connected to an elastic member  453  similar to the member  255  of the third embodiment. The member  453  is mounted about a shaft  454  fixed with respect to the shank  426 . In this way, the frame  407  may move transversely with respect to the shaft  454 , as represented by the double arrow F 5 , which makes it possible to control rotation of the fork  432  and of the wheel  405  about axis A 426 . 
     In the sixth form of embodiment of the invention shown in FIG. 21, the elements similar to those of the first form of embodiment bear identical references increased by 500. The device  501  of this embodiment comprises a chassis  502  and a frame  507  intended to abut against the ground and articulated with respect to a shank  526  forming shank for a steering column  503  about an axis X 551  fixed with respect to the shank  526 . A finger  534  is provided for the control in rotation of a fork  532  belonging to the column  503  for controlling the orientation of a wheel  505  with respect to a central axis A 526  of the shank  526 . An elastically deformable cap  552  is provided to be mounted at the end of the finger  534  and connected to the frame  507  by two connecting rods  553  and  554 . 
     The orientation of the wheel  505  with respect to the axis A 526  is controlled by means of the connecting rods  553  and  554  and the cap  552  whose elasticity makes it possible to return the wheel  505  into a median position corresponding to a rectilinear advance of the device  501 . 
     In a variant, the connecting rods  551  and  554  may be replaced by cables stretched between the sleeve  552  and the frame  507 . 
     In the seventh form of embodiment of the invention shown in FIG. 22, the elements similar to those of the first form of embodiment bear identical references increased by  600 . The device  601  of this embodiment comprises a chassis  602  similar to those of the third and fourth embodiments. The frame  607  of this embodiment has a structure substantially in the form of an S and is kinematically connected by its respective ends  607 A and  607 B to means for controlling in rotation steering columns  603  and  604  provided respectively at the front and at the rear of the device  601  for controlling the position of two wheels  605  and  606 . 
     The invention has been shown with a device  1  equipped with wheels. However, it is applicable with a device equipped with runners, particularly with a view to moving over a snow-covered surface. In practice, a device with two types of dismountable ground-engaging members, wheels or runners, may be envisaged, the wheels being used in the absence of snow, while the runners are used over snow-covered ground. 
     The invention has been shown with a device  1  capable of being used by one person. Use by a plurality of persons may be envisaged, in which case the dimension of the chassis is adapted. 
     The invention has been shown with a device  1  comprising a single wheel at the front and a single wheel at the rear of the chassis. It is applicable with a device comprising a plurality of wheels or runners at the front and/or at the rear of the chassis, these ground-engaging members being guiding, or not. 
     The invention has been shown with a device  1  provided with identical wheels at the front and at the rear. However, these wheels may be of different diameters. 
     The invention has been shown with devices of which the steering columns are inclined with respect to the vertical and convergent opposite the surface of the ground, as indicated hereinabove with reference to axes A 26  and A 27 . However, it is possible to provide steering columns divergent opposite the surface of the ground, which increases the compactness of the device in length. 
     The means for immobilizing a user&#39;s feet, bearing reference  222   a  in FIG. 15, may be replaced by straps, cavities for accommodating the front part of the foot, or bindings of the type found on surfboards, or even alpine skis or sailboards. 
     The technical characteristics of the different forms of embodiment described may be combined together, and modifications may be made to the devices described without departing from the scope of the present invention as defined by the accompanying Claims.