WO2024089598A1

WO2024089598A1 - Omnidirectional mobility device for people with reduced motorial function

Info

Publication number: WO2024089598A1
Application number: PCT/IB2023/060722
Authority: WO
Inventors: Giuseppe Quaglia; Luigi TAGLIAVINI
Original assignee: Politecnico Di Torino
Priority date: 2022-10-27
Filing date: 2023-10-24
Publication date: 2024-05-02

Abstract

The invention relates to a mobility device for people with reduced motorial function, such as a motorized wheelchair and the like, equipped with a locomotion system that permits in-plane omnidirectional mobility, i.e. providing independent translation and rotation control. The device uses conventional wheels and a system for controlling the rotation and steering of the active wheels.

Description

DESCRIPTION

The invention generally concerns the mobility of people suffering from reduced motorial function because of lower-limb disorders.

As is known, people who are unable to walk because of leg injuries or nervous-system damages affecting the lower limbs (due to accidents or the like), or for other reasons, are forced to use mobility assistance devices such as, for example, wheelchairs.

The latter, as their name implies, are essentially carriages movable on wheels, castors or the like, which are available in models having different shapes and dimensions.

Motorized models exist through which the user can move autonomously by operating controls (e.g. push-buttons, joystick-type levers, and the like), while manual models have to be pushed by another person or by the arms of the person sitting in the wheelchair.

Whether manual or motorized, wheelchairs generally have wheels turning about a fixed rotation axis relative to the frame, as well as directional or steering wheels, just like most mobile vehicles.

In some cases, the fixed-axis wheels are the rear ones, upon which the person acts manually to cause the wheelchair to move; for this reason, such wheels are much bigger than the directional front wheels.

The latter are small orientable or pivoting castors that make it possible to direct the wheelchair in the desired direction.

One example of this state of the art is shown, for clarity, in the first figure of the annexed drawings.

One limitation of prior-art wheelchairs is that they do not allow for transversal movements, i.e. movements in a direction parallel to that of the fixed axis of the main wheels. Ing. Filippo Ferroni

In fact, when one wants to make a 90-degree direction change, the only possibility is to impart a counter-rotation to the main wheels (turning one wheel clockwise and the other wheel counterclockwise, or vice versa), so that the wheelchair will make a rotation about a vertical axis V passing substantially through the intermediate point between the main wheels.

Such a manoeuvre is not always feasible, especially in tight spaces like those that can be found in homes or health centres that have not been specifically designed for wheelchair use. Figure 2 of the drawings shows some situations in which a wheelchair needs to make this manoeuvre within a home environment.

This is true for all so-called differential wheelchairs, i.e. wheelchairs equipped with a differential mechanism, system or logic that permits curvilinear trajectories by moving the internal and external wheels at different rotation speeds.

In the figure one can identify a number of problems connected to the use of a wheelchair within a home environment.

Indeed, houses not specifically designed for such needs are typically characterized by small areas allowing access to the various rooms (e.g. corridors, hallways, anterooms, or the like), with insufficient manoeuvre space and sometimes with floor discontinuities.

As aforementioned, common wheelchairs usually have two rear or central main wheels with a coinciding axis which have to be operated by the user (by hand or by means of an electric motor) and two pivoting front wheels.

Such wheelchairs are structurally simple and robust, and are therefore widely used, also because they can be produced in foldable or motorized configurations. Ing. Filippo Ferroni

However, they cannot move omnidirectionally, in particular transversally, i.e. along an axis T parallel to that of the fixed rear main wheels (see Figure 1) and perpendicular to the vertical axis V.

Transversal mobility would make it possible to, in fact, overcome the limitations caused by insufficient room, and would improve the omnidirectional mobility of wheelchairs in comparison with the above-described known ones.

To the Applicant’s knowledge, some solutions exist which aim at fulfilling this requirement, which can be briefly grouped into a first category of wheelchairs using special wheels, such as those called Omni-Wheels or Mecanum Wheels, i.e. wheels with idle rollers installed on their outer circumference to provide the wheel with a free direction of translation. By appropriately combining 3 or 4 wheels of this kind, it is possible to obtain an omnidirectional base. Some examples of such solutions are described in patent publications CN 113440345; CN 20256866; ES 2331554; US 223753; US 2021/12111648.

By appropriately combining multiple wheels of this kind it is possible to obtain an omnidirectional base.

A second category, which is a variant of the first one, uses spherical wheels actuated by two or more motors and a transmission system, consisting of a special chain, also referred to as “omnichain”.

While in terms of omnidirectional mobility these solutions appear to be valid, the same cannot be said as regards movement command and control. Moreover, some drawbacks can be found in terms of user comfort, efficiency, ability to move on unlevel ground, the ability to overcome small obstacles, and vibrations induced by the rolling action of the small-diameter rollers. Ing. Filippo Ferroni

It can be understood, in fact, that the wheelchairs described in the above-mentioned publications (CN 113440345; CN 20256866; ES 2331554; US 223753; US 2021/12111648), which utilize special wheels, require drive wheels that can be activated when it is necessary to make a movement in a transversal direction.

In other words, the special wheels must be complemented with drive wheels that are activated during transversal manoeuvres: this requires the use of reversible engagement mechanisms to engage the drive wheels with the ground.

Furthermore, wheelchairs equipped with mecanum wheels or omniwheels, in a number greater than three, always require a complex control system that, in compliance with the kinematic constraints and characteristics, defines the revolution speed of each wheel to obtain the desired and/or requested omnidirectional motion.

Spherical wheels may perhaps be better from this point of view, but they are also more complex in terms of actuation and control.

In conclusion, it can be stated that the need is felt for omnidirectional wheelchairs offering improved performance over those considered above.

The technical problem at the basis of the invention is, therefore, to provide an omnidirectional mobility device for people with reduced motorial function, such as a wheelchair or the like, with such structural and functional characteristics that it can overcome the above-mentioned limitations and contraindications of the prior art.

The idea that solves this problem is to provide a mobility device comprising locomotion or motor assemblies which can be controlled independently. Ing. Filippo Ferroni

Preferably, the locomotion assemblies comprise respective wheels and have two actuated degrees of freedom: rotation of a wheel about a steering axis and rotation of the wheel about its rotation axis.

Device stability is ensured by the use of at least one passive pivoting wheel or another device performing the function of providing at least three surfaces of transmission of normal contact forces to ground.

The features of the invention are more specifically set out in the appended claims.

The effects and advantages resulting from the invention will become more apparent from the following description of a preferred but non-limiting embodiment, as shown in the annexed drawings, wherein:

Figs. 1 and 2 show a wheelchair according to the prior art and its limited mobility within a home environment;

Fig. 3 shows a user sitting in a mobility device according to the invention;

Figs. 4(a), 4(b), 4(c) show respective views of a first example of a mobility device according to the invention;

Figs. 5(a), 5(b), 5(c) show respective views of a second example of a mobility device according to the invention;

Figs. 6(a) and 6(b) schematically show the arrangement of the wheels of respective examples of mobility devices according to the invention;

Fig. 7 shows a detail of the mobility device of the preceding figures;

Fig. 8 schematically shows the control variables of the device according to the invention;

Fig. 9 is a flow chart that illustrates the control process of the device according to the invention; Ing. Filippo Ferroni

Fig. 10 shows the movements of the device of the invention within the home environment of Fig. 2.

With reference to the above-listed figures, and particularly to Figs. 3 to 9, a mobility device for people with reduced motorial function according to the invention is designated as a whole by reference numeral 10.

This applies to both the first example of such a device, shown in Figures 4(a)-4(c), and the second example shown in Figures 5(a)-5(c), which differ in the number and arrangement of the wheels, as will be further detailed hereinafter.

However, the following description may apply to both examples based on their compatibility or anyway according to the context. For simplicity, those elements which are structurally or functionally common to both examples will be indicated with the same reference numerals.

Therefore, the features and elements of these examples may be combined mutually or with other examples, depending on the implementable variants of the invention, in light of the teachings that will result from the following description.

The device 10 comprises a seat 11 for accommodating a user U, which seat may be configured as deemed most appropriate depending on the model of the device 10.

In the examples shown in the drawings, the seat 11 comprises a back 12 and armrests 13, thus being similar to an armchair supported by a base or platform 20 through a central stem or column 14 or any other element performing the same function.

The base or platform 20 is motorized and, according to a preferred embodiment of the invention, is provided with a plurality (two in this case) locomotion or actuation assemblies 29, 30 controlled independently to permit in-plane omnidirectional motion, as will be further explained below.

- 7 - Ing. Filippo Ferroni

The locomotion assemblies 29, 30 can be controlled by the user U through any appropriate system, taking also into account the different abilities of the people using the mobility device 1. Thus, there may be controls manually operable by the user (e.g. levers, push-buttons, steering wheels or the like, or controls that can be operated remotely (by means of remote controls, radio controls, video controls with cameras, etc.), or even controls using sensors of various kinds, e.g. sensors that make it possible to control the device 1 by means of movements of the user’s hands or eyes, accelerometric sensors, telemetry sensors, and so forth.

In addition to being operable by the user with reduced motorial function, the device may also be operable by an external operator in the event that the user does not have the necessary physical or mental abilities, or when the intention is to create a remotely operated system for human transportation.

More generally, those skilled in the art will be able to provide all electronic, electromechanical, etc. means necessary for controlling the mobility device 1 as needed.

In the examples shown in the drawings, reference is made, for simplicity, to a 3-axis joysticktype lever control 15, through which the user can impart the desired motion.

The motor unit of the mobility device 1 is electric, and hence it comprises a battery 16 and an electronic control unit 17.

Each locomotion assembly 29, 30 comprises a respective wheel 31, 32 having two actuated degrees of freedom: rotation of each wheel 29, 30 about the corresponding steering axis AS1, AS2 and rotation of the wheel 29, 30 about its rotation axis ARI, AR2.

For this reason, pairs of motors 33, 34 and 35, 36 are associated with each wheel 31, 32 for their respective rotations about the axes AS1, AS2 and ARI, AR2. Ing. Filippo Ferroni

Stability of the platform 20 is ensured through the use of at least one idle pivoting wheel 37, i.e. a castor free to orientate itself about a pivot. In principle, the pivoting wheel may be replaced with a passive spherical support, a bearing, or other similar elements, although these solutions may not turn out to be cost-effective or optimally efficient from a technical viewpoint.

By mounting the locomotion assemblies 29, 30 and the pivoting wheel(s) 37 in different ways, it is possible to obtain different architectures of the motorized platform 20.

Fig. 6 schematically shows some different configurations of the motorized platform 20 for the device 1; for example, diagrams I and II correspond, respectively, to the devices of Figures 4(a)-4(c) and Fig. 5(a)-5(c), while the other diagrams III, IV, V, VI correspond to as many other possible variants.

According to a preferred embodiment of the invention, the steering axes AS1, AS2 of the drive wheels and the orientation axes of the pivoting wheel(s) 37 are arranged on an ellipse or anyway on a generic closed curved line.

More generally, unlike the solutions currently known in the art, the mobility device 1 according to the invention is characterized in that the plan projection of the centre of gravity of the system (which may be considered to approximately coincide with the vertical axis Z passing through the column 14) lies substantially on, or in close proximity to, the line that connects the two points of contact with the ground of the locomotion assemblies 29, 30.

Because of this characteristic, it is possible to adjust the forces normal to ground, unloading the pivoting wheels 37 to reduce the level of disturbance. In addition, the steering axis of the pivoting wheels 37 is closer to the vertical axis Z of the wheelchair than the steering axis AS1, AS2 of the traction wheels 31, 32, and this assists the actuation system in overcoming the disturbances induced by the pivoting wheels. Ing. Filippo Ferroni

Each locomotion assembly 29, 30 comprises a motor wheel 31, 32, i.e. a motorized wheel equipped with a gear reducer 35, 36 installed in or connected to the hub, a fork 39, 40, an axial- radial support 41, 42 that constitutes the steering kinematic pair, a sliding collector 43, 44 for connecting the cables of the in-hub gear reducer 35, 36 in such a way as to allow the wheel 31, 32 to rotate limitlessly about the steering axis AS1, AS2, a belt transmission 45, 46 that comprises a motor 33, 34 for actuating the steering axis AS1, AS2, an angular position sensor 47, 48 for reading the angular position 5i, 62 of the steering axis.

Commands are imparted to the mobility device 10 by means of the three-axis joystick-type lever 15, the output variables of which are read by an on-board microcontroller included in the unit 17, which is the most important component of the wheelchair’s control electronics.

Through a suitable push-button panel, preferably located on the armrest 13 near the lever 15, the user can select different maps for controlling the wheelchair. One of the selectable maps associates the longitudinal linear speed, transversal linear speed and yaw angular speed of the wheelchair or device 10 with the three degrees of freedom of the joystick-type lever 15.

In this mode, the linear speeds are controlled through the main lever, whereas the yaw speed is controlled by the rotation of the knob relative to the base.

Using the nomenclature presented in Figure 8, the relation between the four reference variables of the locomotion system, i.e. two angular positions 8^82 of the steering axes AS1, AS2 and two angular speeds 0₂ for the traction motors 35, 36, and the linear speeds v_x, v_y of the platform 20 can be written in vector form as follows:

- 10 - Ing. Filippo Ferroni

By inverting this relation it is possible to find the relation between the platform speeds (control system input) and the actuated degrees of freedom.

Through this analytical relation, the control algorithm implemented in the on-board controller of the unit 17 evaluates reference quantities for the locomotion system in order to obtain the motion desired by the user, as shown in the flow chart in the last figure.

When the device is turned on, a procedure for zeroing the steering axes AS1, AS2 is initialized. From this configuration, the angular position of the steering axes is measured by reading the sensors 47, 48 installed on the locomotion assemblies 30.

With an omnidirectional vehicle available, the critical situations presented in Figure 2 can be faced more easily, as shown in Figure 10.

As can be understood, this eliminates the need for making complex manoeuvres in order to move within tight spaces.

By means of this locomotion architecture, the invention makes it possible to follow in-plane trajectories without binding the orientation of the user to the direction of motion. Let us assume that a user U of the mobility device 1 is interacting with a person standing in front of him/her. According to the prior art, a user wanting, for any reason, to translate laterally would have to make a 180° rotation when using a common wheelchair.

With the present invention, on the contrary, the user can make the same lateral translation while still facing the interlocutor, so that the interaction will not be interrupted.

This very simple practical case is representative of a whole category of cases of daily discomfort or difficulty that, if avoided, would result in improved personal and social life. This feature of the wheelchair proposed herein turns out to be particularly important for people Ing. Filippo Ferroni affected by motorial function disability, who cannot move their head and cannot, therefore, overcome the mobility limitations of common wheelchairs by turning their head in the desired direction.

The configuration of the mobility device 1 also permits the installation of additional equipment in the seat to which further improve the safety and reliability of the latter.

One example of such equipment is a vertical joint installed in the column 14, for orientating the user on the platform as required.

The column 14 is telescopic, so that its height and the height of the seat 11 can be adjusted, and preferably comprises also an incorporated locking system for securing the seat after choosing the desired orientation.

A system for tilting the seat may also be provided to improve the comfort and versatility of the device 1. Such system may be further modified to permit setting the seat into a horizontal position, which configuration can used for transferring the user from the wheelchair to the bed, and vice versa, thereby considerably facilitating the operations and reducing the risk of falling. All these features fall within the scope of the following claims.

Claims

Ing. Filippo Ferroni CLAIMS

1. Omnidirectional mobility device for people with reduced motorial function, comprising a seat (11, 12, 13) in which a person can sit, a base or platform (20) supporting the seat (11, 12, 13), a plurality of wheels (31, 32, 37) associated with the base (20), including at least two drive wheels (31, 32), to allow the omnidirectional movements of the device, means (15, 17) for commanding and/or controlling the movements of the device, characterized in that it comprises at least one pair of independently controlled drive wheels (31, 32) that can be steered about respective steering axes (AS1, AS2).

2. Device according to claim 1, wherein said drive wheels (31, 32) rotate about respective rotation axes (ARI, AR2) at independently controlled speeds (0- 62).

3. Device according to claims 1 or 2, wherein said drive wheels can be steered by angles (61, 62) of 360° or more.

4. Device according to any one of the preceding claims, comprising a sliding electric collector (43, 44) at the steering axis (AS1, AS2), for connecting the power cables of the drive wheels (31, 32) in such a way as to allow them to rotate limitlessly about the steering axis (AS1, AS2), without any differential actuation mechanisms.

5. Device according to any one of the preceding claims, wherein the steering axis (AS1, AS2) of the drive wheels (31, 32) passes through their point of contact with the ground.

6. Device according to any one of the preceding claims, comprising an angular position sensor (47, 48) for reading the angular position (<?-£, <5₂) of the steering axis (AS1, AS2).

7. Device according to any one of the preceding claims, wherein drive commands are imparted by means of a lever or the like (15) with three axes or degrees of freedom, the Ing. Filippo Ferroni output variables of which are read by an on-board microcontroller included in an electronic control unit (17) of the wheelchair.

8. Device according to claim 7, wherein the lever (15) can select different maps to be used for controlling the wheelchair.

9. Device according to claim 8, wherein one of the selectable maps associates the longitudinal linear speed, transversal linear speed and yaw angular speed of the device (10) with the three degrees of freedom of the lever (15).

10. Device according to any one of the preceding claims, wherein the wheels (31, 32, 37) are arranged in such a way that the projection to ground of the system’s centre of gravity lies substantially on, or in close proximity to, the line that connects the points of contact with the ground of both drive wheels (31, 32).

11. Device according to any one of the preceding claims, comprising one or more of: autonomous navigation means; control user interfaces; remote control systems; third- party control and command systems.