Vehicle with an optimized omnidirectional drive

Abstract

Vehicle, - wherein the vehicle has a chassis (2), - wherein a plurality of base wheels (3) are arranged on the chassis (2), on which the vehicle can be moved on a level surface (4), - wherein the base wheels (3) are not driven and are mounted on the chassis (2) in such a way that the vehicle, as far as the base wheels (3) are concerned, can be moved on the ground (4) in any direction regardless of the orientation of the vehicle on the ground (4) and can also be rotated on the ground (4) about a first vertical axis (6) oriented orthogonally to the ground (4), - wherein a support element (9) is arranged on the chassis (2) and is rotatable relative to the chassis (2) about the first vertical axis (6), - wherein the vehicle has a holding arrangement (11) by means of which a rotational position of the support element (9) about the first vertical axis (6) relative to the chassis (2) can be fixed, - wherein two additional wheels (12) are arranged on the support element (9), so that the two additional wheels (12) can rotate about a respective axis of rotation (13) and roll on the ground (4), - wherein the axes of rotation (13) of the additional wheels (12) extend in a lower plane (14) orthogonal to the first vertical axis (6) and parallel to one another there, - wherein each of the additional wheels (12) is assigned its own wheel drive (15), so that the additional wheels (12) can be driven independently of one another, - wherein the additional wheels (12) are rigidly arranged on the support element (9) so that an orientation of the axes of rotation (13) of the additional wheels (12) within the lower plane (14) with respect to the support element (9) is unchangeable, - wherein a transverse axis (16) of the support element (9) extending in the lower plane (14) and intersecting the first vertical axis (6) runs parallel to the axes of rotation (13) of the additional wheels (12), - wherein, viewed in the direction of the transverse axis (16) of the support element (9), the two additional wheels (12) are offset from one another and - wherein the base wheels (3) are arranged directly, ie not via the supporting element (9), on the chassis (2).

Description

[0001] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0002] Regardless of the grammatical term usage, individuals with male, female or other gender identities are included within the term.

[0003] The present invention is based on a vehicle, - the vehicle having a chassis, - wherein several base wheels are arranged on the chassis, on which the vehicle can be moved on a level surface, - wherein the base wheels are not driven and are mounted on the chassis in such a way that the vehicle, as far as the base wheels are concerned, can be moved on the ground in any direction regardless of the orientation of the vehicle on the ground and can also be rotated on the ground about a first vertical axis oriented orthogonally to the ground.

[0004] The specification of the wheels as "base wheels" serves to linguistically distinguish them from other wheels introduced later, which - depending on the type of wheel - are referred to as additional wheels or additional wheels. The specification of the wheels as "base wheels" has no further significance.

[0005] Many vehicles are constructed in this way. Generally speaking, examples in the household sector include a so-called rolling container for office use or an office swivel chair. A rolling container typically has four such wheels, while an office swivel chair has five. However, similar vehicles can also be found in other areas. Examples include hospital beds and mobile medical equipment, such as mobile CT systems. Hospital beds and mobile medical equipment typically have four such wheels.

[0006] Such vehicles have the advantage that they can be rotated on-site around their first vertical axis as needed and can be moved in any direction, regardless of the vehicle's orientation on the flat surface. Therefore, the vehicle does not need to be aligned in a specific direction prior to moving. This freedom of movement is often referred to as omnidirectional movement.

[0007] These features are often desirable. In a relatively small and lightweight vehicle, they can easily be achieved using non-driven wheels, because such vehicles can easily be propelled by muscle power.

[0008] For a relatively large and heavy vehicle—a hospital bed, including the patient lying in it, can weigh several hundred kilograms; a mobile CT scanner can be even heavier—moving the vehicle using muscle power reaches its limits. In such cases, a (usually electric) drive is required to move the vehicle.

[0009] In the typical case of four base wheels located at the corners of the chassis, it is possible, for example, to design the two front or the two rear base wheels as driven wheels, which, however, are not mounted for free rotation about a respective first vertical axis oriented orthogonally to the ground. Rather, the two driven wheels are fixed in such a way that their axes of rotation are oriented orthogonally to a longitudinal direction of the vehicle. In this case, the vehicle can be driven similarly to a typical car. However, the possibility of omnidirectional movement is no longer available.

[0010] In the typical case of four base wheels located at the corners of the chassis, it is still possible to design all four base wheels as driven wheels, each of which is additionally motor-driven to rotate about a second vertical axis oriented orthogonally to the ground. In this case, the possibility of omnidirectional movement is retained. However, this solution is very expensive because it requires multiple drives: one drive per base wheel to drive the respective base wheel and another drive to adjust the orientation of the respective base wheel relative to the respective second vertical axis.

[0011] As an alternative to designing the base wheels as driven wheels, in which the orientation of the respective base wheel relative to the respective second vertical axis is adjusted by means of a respective additional drive, it is possible to use so-called Mecanum wheels as the base wheels. Even in this case, the possibility of omnidirectional movement is retained. However, Mecanum wheels are complex and expensive. The costs are further increased by the fact that four such wheels are usually required, because the use of only three wheels would be unstable in practice. Furthermore, the control system is highly complex. Mecanum wheels also have other disadvantages.

[0012] The object of the present invention is to provide possibilities by means of which a vehicle can be created in a simple and cost-effective manner that enables omnidirectional movement.

[0013] The object is achieved by a vehicle having the features of claim 1. Advantageous embodiments of the vehicle according to the invention are the subject of dependent claims 2 to 12.

[0014] According to the invention, a vehicle of the type mentioned at the outset is designed in such a way that - that a support element is arranged on the chassis which is rotatable relative to the chassis about the first vertical axis, - that the vehicle has a holding arrangement by means of which a rotational position of the support element about the first vertical axis can be fixed relative to the chassis, - that two additional wheels are arranged on the support element, so that the two additional wheels can rotate about a respective axis of rotation and roll on the ground, - that the axes of rotation of the additional wheels run in a lower plane orthogonal to the first vertical axis and parallel to each other there, - that each additional wheel is assigned its own wheel drive so that the additional wheels can be driven independently of each other, - that the additional wheels are rigidly arranged on the support element, so that the orientation of the axes of rotation of the additional wheels within the lower plane with respect to the support element is unchangeable, - that a transverse axis of the support element running in the lower plane and intersecting the first vertical axis runs parallel to the axes of rotation of the additional wheels, - that the two additional wheels are offset from each other in the direction of the transverse axis of the support element and - that the base wheels are arranged directly on the chassis, i.e. not via the supporting element.

[0015] The vehicle is generally designed to operate on a nearly perfectly level surface, i.e., a smooth surface such as the floor inside a building. The contact points where the base wheels and the auxiliary wheels rest on the surface are therefore generally on the same level.

[0016] Where the term "axis" is used in the context of the present invention, it does not refer to a physically existing element, but merely to the definition of a direction. This applies equally to the first vertical axis, the rotational axes, and the transverse axis, as well as to the second vertical axes introduced later. Likewise, a plane is not a physically existing element, but rather a definition of two linearly independent directions. This applies equally to the lower plane and the longitudinal plane.

[0017] The specification of the wheels as "additional wheels," as already explained in connection with the base wheels, serves to linguistically distinguish them from other wheels. The specification of the wheels as "additional wheels" has no further significance.

[0018] Although the auxiliary wheels can be driven independently of one another, the drive of the auxiliary wheels is coordinated in such a way that the desired movement of the supporting element on the ground is achieved. Depending on the specific situation, this may also be linked to a desired movement of the vehicle on the ground. This will become clearer in later explanations. The specification of the auxiliary wheel drives as wheel drives serves to distinguish them from an element drive, which will be introduced later. The specification as "wheel drives" has no further significance.

[0019] The vehicle's weight can be supported—at least partially, and often even significantly—by the base wheels. Therefore, the additional wheels don't have to bear the entire weight of the vehicle.

[0020] Often, four base wheels are present, located at the corners of the vehicle or chassis. However, this is not mandatory. More than four base wheels can also be present. However, at least three base wheels are present as a minimum. It is crucial that the base wheels are positioned at a sufficient distance around the vehicle's center of gravity when the vehicle is on a horizontal, level surface, so that they can support the vehicle stably and securely.

[0021] Often, the support element has no other wheels besides the two additional wheels. In this case, in particular, the rotational axes of the two additional wheels are preferably aligned with each other, and the transverse axis is also aligned with the rotational axes of the additional wheels. This design enables, in particular, a compact design of the support element and simple control of the wheel drives. Furthermore, it facilitates rotating the vehicle around the first vertical axis on the spot, i.e., without intentionally or inadvertently causing the vehicle to move.

[0022] However, it is also possible that other wheels are present on the support element. These wheels are referred to below as additional wheels. Similar to the base wheels and additional wheels, the specification of these wheels as "additional wheels" serves to linguistically distinguish them from the other wheels. The specification of the wheels as "additional wheels" has no further significance.

[0023] The additional wheels, if present, are preferably functionally similar to the auxiliary wheels. They can rotate about a respective axis of rotation and roll along the ground. Furthermore, they are each assigned their own wheel drive so that the additional wheels can be driven independently of one another and independently of the auxiliary wheels. Furthermore, the axes of rotation of the additional wheels also run in the lower level and there parallel to one another and also parallel to the axes of rotation of the auxiliary wheels. Finally, the additional wheels are rigidly mounted on the support element so that the orientation of the axes of rotation of the additional wheels with respect to the support element is unchangeable.

[0024] If additional wheels are present, they can be arranged next to the auxiliary wheels so that the axes of rotation of the additional wheels are aligned with the axes of rotation of the auxiliary wheels. However, the additional wheels can also be arranged in front of or behind the auxiliary wheels so that the axes of rotation of the additional wheels run parallel to the axes of rotation of the auxiliary wheels, but are offset within the lower plane in a longitudinal direction of the support element that is orthogonal to the transverse axis.

[0025] As a rule, the auxiliary wheels are arranged on either side of a longitudinal plane that runs orthogonally to the transverse axis and contains the first vertical axis. While this configuration is not the only possible one, it is certainly the standard one. This configuration not only facilitates maintaining a stable direction of travel, but also facilitates turning the vehicle as a whole or the supporting element relative to the vehicle about the first vertical axis. This is especially true when the two auxiliary wheels are not only arranged on either side of the longitudinal plane, but are also equally spaced from the longitudinal plane.In this case in particular, as long as the orientation of the support element relative to the vehicle remains fixed by the holding arrangement, a similar control of the wheel drives (i.e., rotation in the same direction of rotation and over the same circumferential lengths) causes the vehicle to move in a straight line, with the vehicle's direction of travel still being determined by the rotational position of the support element. As long as the orientation of the support element relative to the vehicle remains fixed by the holding arrangement, a rotation of the vehicle as a whole around the first vertical axis is still caused by opposing control of the two wheel drives (i.e., rotation in opposite directions of rotation and over the same circumferential lengths).If, however, the orientation of the support element relative to the vehicle is not fixed by means of the holding arrangement, only the support element, but not the vehicle as a whole, is rotated about the first vertical axis by controlling the two wheel drives in opposite directions.

[0026] Preferably, the support element is not arranged completely rigidly toward the chassis in the direction of the first vertical axis, but is resiliently supported by a spring device. This spring device results in a substantially constant contact pressure of the auxiliary wheels against the ground. This makes the load on the auxiliary wheels essentially independent of the mass of the vehicle as a whole, while still ensuring sufficient contact pressure and thus adequate traction.

[0027] Preferably, the spring force of the spring device is adjustable. This allows the contact pressure of the auxiliary wheels against the ground to be adjusted as needed, for example, to a slightly higher value for a large vehicle mass and a slightly lower value for a small vehicle mass. A simple implementation can be achieved, for example, with pneumatic suspension. In this case, the spring force of the spring device can be varied by adjusting the pressure of the pneumatic suspension.

[0028] Preferably, the support element is extendable and retractable relative to the chassis in the direction of the first vertical axis. This configuration can be advantageous when only the support element is to be rotated about the first vertical axis, but the vehicle as a whole is to reliably maintain its current orientation. Furthermore, this configuration can also be advantageous when the vehicle is to be moved alternatively by motor or muscle power, for example, in emergency operation, for example, in the event of a power failure of the vehicle.

[0029] Retraction and extension can be achieved, for example, by pneumatic cylinders or by blowing air into an expandable element between the chassis and the support element or by releasing air from the expandable element. Whether blowing air into the expandable element causes the support element to retract or extend, and consequently whether releasing air from the expandable element causes the support element to extend or retract, can be determined by the design and arrangement of the expandable element or the arrangement and design of the pneumatic cylinder.

[0030] A combination of a "normal" spring element (e.g., a coil spring) and an air spring is also possible. For example, the normal spring element can push the support element upwards, causing the auxiliary wheels to lift off the level ground. The setting of the air spring then determines whether (with a weak air spring setting) the support element remains pushed upwards or (with a strong air spring setting) the support element is lowered downwards. Of course, the reverse configuration is also possible. In both cases, the strength of the air spring can be varied by adjusting the air pressure in the air spring.

[0031] The holding arrangement preferably comprises an element drive, by means of which a torque can be exerted on the support element, causing the support element to rotate about the first vertical axis. This configuration has the advantage that, with appropriate control of the element drive during control of the wheel drives by means of the holding arrangement, the direction of movement of the vehicle can be changed even during movement of the vehicle as a whole, without simultaneously having to change the orientation of the vehicle.

[0032] Preferably, the holding arrangement comprises—alternatively or in addition to the element drive—a brake by means of which, depending on the control of the brake, rotation of the support element about the first vertical axis is blocked or released, but by means of which no torque can be exerted on the support element, due to which the support element would be rotated about the first vertical axis. This configuration has the advantage that the orientation of the support element relative to the vehicle can be reliably fixed in a particularly simple manner. This configuration is also energy-efficient, since blocking often requires considerably less energy than would be required for active holding by means of an element drive.

[0033] It is possible to have both the element drive and the brake. However, at least one of these two elements – that is, the element drive and the brake – is usually present. If only the brake is present, and as long as the brake blocks the rotation of the support element about the first vertical axis, the wheel drives can only be used to drive the vehicle in a specific direction while maintaining a constant orientation of the vehicle on the ground, or to rotate the vehicle as a whole on the spot about the first vertical axis. If the brake allows the rotation of the support element about the first vertical axis, the orientation of the support element about the first vertical axis can be changed without moving the vehicle on the ground and without rotating the vehicle as a whole.If, however, the element drive is present (exclusively or additionally), the orientation of the support element around the first vertical axis and thus also on the ground can be changed by appropriately coordinated control of the element drive and the wheel drives even while the vehicle is moving on the ground, without simultaneously changing the orientation of the vehicle around the first vertical axis and thus also on the ground.

[0034] Preferably, the brake blocks rotation of the support element about the first vertical axis when not being supplied with energy. It may also be possible to manually release this block, for example, to change the orientation of the support element about the first vertical axis relative to the chassis in the event of a power failure of the vehicle.

[0035] Preferably, the first vertical axis passes through the vehicle's center of gravity. This design results in particularly stable operation. If the vehicle's center of gravity can change due to a "variable payload" (i.e., the patient in the case of a hospital bed), for example, this statement applies to the unloaded state.

[0036] Preferably, an electrically operated medical device is mounted on the chassis. This approach represents a particularly preferred application.

[0037] Preferably, the base wheels are mounted on the chassis so they can rotate freely about second vertical axes oriented orthogonally to the ground. This configuration allows for simple omnidirectional movement of the base wheels, while also allowing the base wheels to bear a heavy load. The free rotation of the base wheels means that the base wheels align themselves automatically as required by the movement of the vehicle as a whole. However, the orientation of the base wheels is not actively adjusted—for example, via a steering system or the like.

[0038] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of the embodiments, which are explained in more detail in conjunction with the drawings. Herein, in schematic representation: Fig. 1 a vehicle from the side, Fig. 2 the vehicle from Fig. 1 from the front, Fig. 3 relevant parts of a vehicle chassis from above, Fig. 4 a possible driving curve of the vehicle of the Fig. 1 to 3, Fig. 5 another possible driving curve of the vehicle of the Fig. 1 to 3 and Fig. 6 a part of a chassis and a supporting element.

[0039] According to the Fig. 1 to 3, a vehicle 1 has a chassis 2. Several base wheels 3 are arranged on the chassis 2. The base wheels 3 are arranged directly on the chassis 2.

[0040] The number of base wheels 3 is typically four, with the base wheels 3 being arranged at the corners of the chassis 2. However, both the exact number of base wheels 3 and the exact arrangement of the base wheels 3 are of secondary importance.

[0041] The vehicle 1 can be moved on a level surface 4 on the base wheels 3. The base wheels 3 are not driven, but - of course - are pivotally mounted so that they can roll on the surface 4. The base wheels 3 are mounted on the chassis 2 in such a way that the vehicle, as far as the base wheels 3 are concerned, can be moved in any direction on the surface 4, regardless of the orientation of the vehicle on the surface 4. Fig. 3, purely by way of example, some possible directions are indicated by arrows 5. Furthermore, the vehicle 1, as far as the base wheels 3 are concerned, can not only be moved on the ground 4 in any direction, but can also be rotated on the ground 4 about a first vertical axis 6, i.e., rotated on the spot, so to speak. This is shown in Fig. 3 is indicated by a double arrow 7. The first vertical axis 6 is oriented orthogonally to the ground 4. To enable the omnidirectional movement explained above, the base wheels 3 can, for example, be freely rotatably mounted on the chassis 2 about second vertical axes 8 oriented orthogonally to the ground 4. The second vertical axes 8, like the first vertical axis 6, are oriented orthogonally to the ground 4. However, other designs are also possible, for example, as so-called ball rollers, which inherently enable this degree of freedom.

[0042] A support element 9 is also arranged on the chassis 2. The support element 9 can, for example, be designed as a round disc. The support element 9 is, as shown in Fig. 3 by a double arrow 10, is rotatable relative to the chassis 2 about the first vertical axis 6. However, the vehicle 1 also has a holding arrangement 11, by means of which a rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 can be fixed. If and as long as the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 is fixed by means of the holding arrangement 11, a rotational position of the support element 9, once set, remains unchanged. If and as long as the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 is not fixed by means of the holding arrangement 11, the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 can be changed. How this can be done will become clear from later explanations. The above-mentioned arrangement of the base wheels 3 directly on the chassis 2 refers in particular to the support element 9.This is because the base wheels 3 are not arranged on the support element 9. This would be an indirect arrangement on the chassis 2. Rather, the base wheels 3 are arranged directly on the chassis 2.

[0043] Two additional wheels 12 are arranged on the support element 9. The two additional wheels 12 are rotatable about a respective axis of rotation 13. As a rule (possible exception: when lifted off the ground), they roll on the ground 4. The axes of rotation 13 of the additional wheels 12 run in a lower plane 14 and parallel to one another within the lower plane 14. The lower plane 14 is oriented orthogonally to the first vertical axis 6. In contrast to the base wheels 3, the additional wheels 12 are rigidly arranged on the support element 9, so that the orientation of the axes of rotation 13 of the additional wheels 12 within the lower plane 14 with respect to the support element 9 is unchangeable. The orientation of the axes of rotation 13 relative to the chassis 2 can therefore only be changed by rotating the support element 9 relative to the chassis 2.

[0044] Each additional wheel 12 is assigned its own wheel drive 15. The additional wheels 12 can be driven independently of each other by means of the wheel drives 15. Therefore, depending on the control of the wheel drives 15, it is possible - to turn both additional wheels 12 forwards by the same distance, - both additional wheels 12 are to be turned forward, but to different extents, - to turn one additional wheel 12 forward and not to turn the other additional wheel 12, - to rotate one auxiliary wheel 12 forward and to rotate the other auxiliary wheel 12 backward, whereby the extent to which the other auxiliary wheel 12 is rotated backward can be smaller, equal to or greater than the extent to which the one auxiliary wheel 12 is rotated forward, - both additional wheels 12 are to be turned backwards, but to different degrees and - turn both additional wheels 12 backwards by the same distance.

[0045] The lower plane 14 is, as already mentioned, oriented orthogonally to the first vertical axis 6. Each axis running in the lower plane 14 which intersects the first vertical axis 6 therefore intersects the first vertical axis 6 orthogonally. One of these axes runs parallel to the axes of rotation 13 of the additional wheels 12. This axis is referred to below as the transverse axis 16 of the support element 9. The transverse axis 16 is therefore not related to the vehicle 1 or the chassis 2 as a whole, but to the support element 9. The orientation of the transverse axis 16 thus changes with the rotation of the support element 9. Viewed in the direction of the transverse axis 16, the two additional wheels 12 are according to the Fig. 2 and Fig. 3 offset from each other.

[0046] The Fig. Figures 1 to 3 illustrate not only the basic principle of the present invention, but also some embodiments. These embodiments can be implemented independently of one another. Thus, they can be implemented individually, in groups, or together, as needed.

[0047] For example, the rotation axes 13 of the additional wheels 12 are aligned according to the Fig. 1 to 3 with each other and the transverse axis 16 is also aligned with the rotation axes 13 of the additional wheels 12. Furthermore, the additional wheels 12 are according to the Fig. 2 and Fig. 3 are arranged on both sides of a longitudinal plane 17. Preferably, the two additional wheels 12 are even equidistant from the longitudinal plane 17. The longitudinal plane 17 is defined by the fact that it runs orthogonally to the transverse axis 16 and contains the second vertical axis 6. The longitudinal plane 17, like the transverse axis 16, is therefore related to the supporting element 9, but not to the chassis 2 as a whole.

[0048] Furthermore, in the (usual) case that the flat ground 4 runs horizontally, the first vertical axis 6 passes through the center of mass 18 of the vehicle 1.

[0049] Furthermore, an electrically operated medical device 19 is often arranged on the chassis 2, for example as shown in the Fig. 1 and Fig. 2 a mobile CT system.

[0050] The holding arrangement 11 can be designed as required, provided it offers the desired minimum functionality, i.e. the possibility of fixing the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 by means of the holding arrangement 11 and enabling a change of this rotational position. For example, the holding arrangement 11 can be designed for this purpose according to Fig. 3 comprise an element drive 20. By means of the element drive 20, the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 can be fixed. However, a torque can also be exerted on the support element 9, due to which the support element 9 is rotated about the first vertical axis 6. If the element drive 20 is present, it is as shown in Fig. 4, it is particularly possible to continuously change the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2, while the vehicle 1 is moved by corresponding, more or less similar, control of the wheel drives 15. The result is, as in Fig. 4, a method along a curve, wherein the orientation of the vehicle 1 or the chassis 2 is maintained during cornering. If necessary, changing the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 can be supported by slightly different control of the wheel drives 15. Fig. 4 only the chassis 2, the base wheels 3, the first vertical axle 6, the support element 9, the additional wheels 12 and the element drive 20 are shown. The simplified representation of Fig. 4 serves the purpose of Fig. 4 not to overload with details that are not necessary for understanding.

[0051] Alternatively, the holding arrangement 11 can be Fig. 3 may include a brake 21. By means of the brake 21, rotation of the support element 9 about the first vertical axis 6 can be blocked or released, depending on how the brake 21 is controlled. However, by means of the brake 21, no torque can be exerted on the support element 9, due to which the support element 9 is rotated about the first vertical axis 6. If the brake 21 is present, it is not possible to continuously change the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 while the vehicle 1 is moved by correspondingly controlling the wheel drives 15. However, it is possible to move the vehicle 1 in sections in a respective direction by similarly controlling the wheel drives 15 without changing the orientation of the vehicle 1. During these periods, the brake 21 blocks a change in the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2.However, at the transitions from one section to the other, the brake 21 can be released and, by controlling the wheel drives 15 in opposite directions, the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 can be changed. The result is, as shown in . Fig. 5, a method along straight sections, wherein the orientation of the vehicle 1 or the chassis 2 is maintained throughout the entire journey.

[0052] Analogous to Fig. 4 are also in Fig. 5 only the chassis 2, the base wheels 3, the first vertical axle 6, the support element 9, the additional wheels 12 and the element drive 20 are shown.

[0053] In both cases, i.e., both in the case where the holding arrangement 11 comprises the element drive 20 and in the case where the holding arrangement 11 comprises the brake 21, cornering with a change in the orientation of the chassis relative to the ground 4 is still possible through appropriately coordinated control of the wheel drives 15. In this case, only the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 needs to be fixed by the holding arrangement 11.

[0054] Typically, the holding arrangement 11 comprises only either the element drive 20 or the brake 21. However, it is also possible for both the element drive 20 and the brake 21 to be present. For example, the brake 21 can be used for fixing, and the element drive 20 can be de-energized during this time. To change the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2, the brake 21 can be briefly released and the element drive 20 can be activated.

[0055] In addition to these advantageous embodiments, further embodiments are also possible. These embodiments can be implemented independently of one another and also independently of the advantageous embodiments explained above.

[0056] For example, the support element 9 can be resiliently supported towards the chassis 2 in the direction of the first vertical axis 6 by means of a spring device 22. For example, the support element 9 can be designed as shown in Fig. 6 be divided into an upper element 23 and a lower element 24, between which the spring device 22 acts.

[0057] It is possible that the spring device 22 is not adjustable. Alternatively, it can be adjustable. A simple adjustment option can be, for example, as shown in Fig. 6 can consist in that the spring device 22 comprises a number of non-adjustable coil springs 25 and a number of compressed air springs 26. In this case, the resulting effect of the spring device 22 can be adjusted by adjusting a working pressure p of the compressed air spring 26.

[0058] Furthermore, it is possible for the support element 9 to be retractable and extendable relative to the chassis 2 in the direction of the first vertical axis 6. For example, the compressed air spring 26 can be arranged in a telescopic cylinder 27, so that when the working pressure p increases, the telescopic cylinder 27 is extended, and when the working pressure p decreases, the telescopic cylinder 27 is retracted. In this case, for example, the coil springs 25 can be tension springs that pull the lower element 24 upwards. If the working pressure p has a relative value (for example, the usual air pressure of approximately 1 bar), the tensile force of the coil springs 25 predominates, so that the coil springs 25 lift the lower element 24 and the additional wheels 12 are no longer in contact with the ground 4. If the working pressure p is increased (for example, to a value of 2 bar), the force of the coil springs 25 can be compensated for the first time.As the working pressure p is further increased (for example, to a value of 3 bar), the lower element 24 is gradually lowered so that the additional wheels 12 rest on the ground 4 without pressure. By increasing the working pressure p (for example, to values ​​above 3 bar), the force with which the additional wheels 12 are pressed against the ground can then be adjusted.

[0059] Both the structural design and the values ​​given for the working pressure p are purely exemplary, but they show a simple possible principle.

[0060] If necessary, the brake 21 can also be constructed in a similar way. For example, the brake 21 can be designed as an annular hose arranged between the chassis 2 and the support element 9. If, in such a case, the hose is not pressurized with compressed air, the hose is slack and the brake 21 is thus deactivated. The rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 can be changed. If, on the other hand, the hose is pressurized, the hose rests against the chassis 2 and the support element 9. A change in the rotational position of the support element 9 about the first vertical axis 6 relative to the chassis 2 is thereby blocked. If the chassis 2 is arranged above the annular hose and the support element 9 is arranged below the annular hose, a spring effect can also be adjusted if necessary via the pressure applied to the hose.

[0061] Here, too, the structural design is only to be understood as an example, but it shows a simple possible principle.

[0062] The present invention has many advantages. From a mechanical and structural point of view, the structure is simple, robust, and reliable, as well as cost-effective. Although only the wheel drives 15 and the holding device 11 are required, omnidirectional movement of the vehicle 1 is possible. The travel movement can be carried out virtually smoothly in the vertical direction. With respect to the ground 4, smooth curves can be negotiated while maintaining the orientation of the vehicle 1, particularly when the holding arrangement 11 includes the element drive 20. Control is also very simple. Due to the base wheels 3, the additional wheels 12 only have to bear a relatively small proportion of the mass of the vehicle 1 and can therefore be designed to be relatively lightweight.

[0063] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

[1] Vehicle, - wherein the vehicle has a chassis (2), - wherein a plurality of base wheels (3) are arranged on the chassis (2), on which the vehicle can be moved on a level surface (4), - wherein the base wheels (3) are not driven and are mounted on the chassis (2) in such a way that the vehicle, as far as the base wheels (3) are concerned, can be moved on the ground (4) in any direction regardless of the orientation of the vehicle on the ground (4) and can also be rotated on the ground (4) about a first vertical axis (6) oriented orthogonally to the ground (4), - wherein a support element (9) is arranged on the chassis (2) and is rotatable relative to the chassis (2) about the first vertical axis (6), - wherein the vehicle has a holding arrangement (11) by means of which a rotational position of the support element (9) about the first vertical axis (6) relative to the chassis (2) can be fixed, - wherein two additional wheels (12) are arranged on the support element (9), so that the two additional wheels (12) can rotate about a respective axis of rotation (13) and roll on the ground (4), - wherein the axes of rotation (13) of the additional wheels (12) extend in a lower plane (14) orthogonal to the first vertical axis (6) and parallel to one another there, - wherein each of the additional wheels (12) is assigned its own wheel drive (15), so that the additional wheels (12) can be driven independently of one another, - wherein the additional wheels (12) are rigidly arranged on the support element (9) so that an orientation of the axes of rotation (13) of the additional wheels (12) within the lower plane (14) with respect to the support element (9) is unchangeable, - wherein a transverse axis (16) of the support element (9) extending in the lower plane (14) and intersecting the first vertical axis (6) runs parallel to the axes of rotation (13) of the additional wheels (12), - wherein, viewed in the direction of the transverse axis (16) of the support element (9), the two additional wheels (12) are offset from one another and - wherein the base wheels (3) are arranged directly, ie not via the supporting element (9), on the chassis (2). [2] Vehicle according to claim 1, characterized by that the axes of rotation (13) of the additional wheels (12) are aligned with each other and the transverse axis (16) is aligned with the axes of rotation (13) of the additional wheels (12). [3] Vehicle according to claim 1 or 2, characterized by that the additional wheels (12) are arranged on the two sides of a longitudinal plane (17) extending orthogonally to the transverse axis (16) and containing the first vertical axis (6). [4] Vehicle according to claim 1, 2 or 3, characterized bythat the support element (9) is resiliently supported towards the chassis (2) in the direction of the first vertical axis (6) by means of a spring device (22). [5] Vehicle according to claim 4, characterized by that a spring force of the spring device (22) is adjustable. [6] Vehicle according to one of the above claims, characterized by that the support element (9) can be retracted and extended relative to the chassis (2) in the direction of the first vertical axis (6). [7] Vehicle according to one of the above claims, characterized by that the holding arrangement (11) comprises an element drive (20) by means of which a torque can be exerted on the support element (9), due to which the support element (9) is rotated about the first vertical axis (6). [8] Vehicle according to one of the above claims, characterized byin that the holding arrangement (11) comprises a brake (21) by means of which, depending on the control of the brake (21), rotation of the support element (9) about the first vertical axis (6) is blocked or released, but by means of which no torque can be exerted on the support element (9) on the basis of which torque the support element (9) is rotated about the first vertical axis (6). [9] Vehicle according to claim 8, characterized by that the brake (21) blocks rotation of the support element (9) about the first vertical axis (6) in a state in which it is not subjected to energy. [10] Vehicle according to one of the above claims, characterized by that the first vertical axis (6) passes through the center of gravity (18) of the vehicle. [11] Vehicle according to one of the above claims, characterized by that an electrically operated medical device (19) is arranged on the chassis (2). [12] Vehicle according to one of the above claims, characterized bythat the base wheels (3) are mounted on the chassis (2) so as to be freely rotatable about second vertical axes (8) oriented orthogonally to the ground (4).

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