Wheelchair comprising a propulsion assistance system, and related method of providing propulsion assistance to a wheelchair

Abstract

The present invention relates to a wheelchair (1) comprising: - a frame (10); - a pair of traction wheels (30), wherein each traction wheel (30) is rotatably connected to the frame (10) and is configured to be manually operated by the user, - a propulsion assistance system (100). The peculiar feature of the present invention lies in the fact that said propulsion assistance system (100) comprises: - at least one force sensor (110) associated with each traction wheel (30) and configured to detect a first piece of information about at least one force being applied by the user to at least one traction wheel (30), and to generate at least one electric signal representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel (30), - a central control unit (120) operatively connected to said at least one force sensor (110) and configured to receive said at least one electric signal generated by said at least one force sensor (110) and representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel (30), - a traction device (130) provided with a structure (131) configured to be connected to the frame (10) of the wheelchair (1), wherein said traction device (130) comprises a traction motor (133) associated with a drive wheel (134), and wherein said traction device (130) comprises a steering motor (135) associated with the drive wheel (134) through a steering system (136) that allows said drive wheel (134) to change its steering angle, wherein the central control unit (120) is operatively connected to said traction motor (133) for controlling said traction motor (133) in such away as to provide the drive wheel (134) with a degree of propulsion assistance that depends on the electric signal generated by said at least one force sensor (110) and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel (30), and wherein said central control unit (120) is operatively connected to said steering motor (135) for controlling the steering angle of the drive wheel (134) as a function of the electric signal generated by said at least one force sensor (110) and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel (30).

Description

[0001] WHEELCHAIR COMPRISING A PROPULSION ASSISTANCE SYSTEM, AND RELATED METHOD OF PROVIDING PROPULSION ASSISTANCE TO A WHEELCHAIR

[0002] DESCRIPTION

[0003] The present invention relates to a wheelchair comprising a propulsion assistance system according to the preamble of claim 1. In particular, disclosed herein are a wheelchair propulsion assistance system and an associated method of providing propulsion assistance to a wheelchair, wherein said system and method operate as a function of at least one force being applied by a user to the traction wheels of said wheelchair.

[0004] It is known in the art that wheelchairs are the most common means of transportation for persons with reduced mobility (also referred to as “PRMs”).

[0005] A PRM may have difficulty in moving because of a physical disability, which may be either temporary, e.g. caused by accident or surgery, or chronic, e.g. caused by a neurodegenerative disease or age. Therefore, a PRM may need to use mobility assistance devices such as a wheelchair, crutches, or a walker. Gaining access to buildings and means of transport may be a challenge for persons with reduced mobility, requiring solutions like ramps, lifts or accessible seats. In spite of such challenges, persons with reduced mobility can still live a full and active life with the aid of inclusive communities and assistance technologies.

[0006] For a wheelchair user, regular physical activity is important for a number of reasons. First of all, physical exercise is useful to maintain muscular force and flexibility, contributing to preventing complications associated with long-term immobility. Secondly, physical activity can increase cardiovascular strength, improve mental health, and reduce nervous stress. Lastly, regular training may also improve the wheelchair pushing technique, making daily activities easier and reducing the risk of lesions caused by repeated efforts. Several solutions are currently known in the art which concern wheelchair propulsion assistance systems.

[0007] In this respect, a first solution comprises a pair of wheels with a motor mounted on the wheel axle, said pair of wheels being intended to replace the wheels of a traditional wheelchair in order to assist the user’s pushing action. This solution still requires the user to perform some physical activity to push the wheelchair, which is very important to maintain the user’s psychophysical health. However, this first solution suffers from a number of criticalities reported by wheelchair users, including a difficult autonomous installation, difficult in-car transportation, and excessive weight added to the wheelchair (estimated to be approximately twenty additional kilograms).

[0008] Another solution provides a steering motorized wheel to be installed in the front part of the wheelchair. By lifting the two pivoting front wheels, the device converts the wheelchair into a sort of tricycle; the means of transportation resulting from the union of the wheelchair and the steering motorized wheel can be controlled by the user through a steering handlebar equipped with an accelerator grip and brake levers. The advantage of this solution lies in the fact that it is practical and user-friendly. However, the total dimensions of the wheelchair with the steering motorized wheel make this device totally unsuitable for indoor use and for use in narrow spaces, in addition to not requiring an active propulsive contribution from the user.

[0009] A further type of propulsion assistance device consists of a single propulsion wheel to be connected to the rear frame of the wheelchair. Such devices provide continuously all the thrust necessary to move the wheelchair at a constant speed. Usually, the reference speed is set by the user on a control panel. Compared with the other solutions described above, this further solution offers the advantage that less weight is added to a traditional wheelchair, without changing its overall dimensions; moreover, it is also easier to install than those solutions which utilize motorized wheels.

[0010] Nevertheless, also this solution has some criticalities.

[0011] A first drawback of this solution is that the direction of the thrust exerted by the device follows the longitudinal axis of the wheelchair; in this respect, any manoeuvre requiring the wheelchair to make a bend has to be totally managed by the user, who will have to intervene by manually braking either wheel, with controlled intensity, in order to properly steer the wheelchair. In this case, the user contribution is essentially contrary to the propulsion action, resulting in a poorly ergonomic gesture that requires training and non- intuitive ability. Further criticalities of this solution are the absence of thrust directionality, poor wheelchair handling, and the substantial absence of an active propulsive contribution from the user.

[0012] In this context, it is the main object of the present invention to provide a wheelchair propulsion assistance system so conceived as to overcome the drawbacks of prior-art solutions.

[0013] In particular, it is one object of the present invention to provide a wheelchair propulsion assistance system which still requires an active contribution from the user for moving the wheelchair, and which can be easily installed on a traditional manual wheelchair without excessively increasing the weight of said wheelchair.

[0014] It is another object of the present invention to provide a wheelchair propulsion assistance system so conceived as to not alter, or at least not increase, the total dimensions of the wheelchair, and which is suitable for both outdoor use and indoor use in narrow and crowded spaces.

[0015] It is a further object of the present invention to provide a wheelchair propulsion assistance system so conceived as to require substantially the same natural pushing action as required by common manual wheelchairs, thus beneficially exploiting the user’s motory functions and putting the user into a cognitive condition of active presence when propelling and manoeuvring the wheelchair.

[0016] It is yet another object of the present invention to provide a wheelchair propulsion assistance system which can direct the propulsion assistance action, thus also reducing the efforts necessary for manoeuvring the wheelchair along non-rectilinear trajectories, particularly within indoor environments and narrow and / or crowded spaces.

[0017] Further objects, features and advantages of the present invention will become apparent in light of the following detailed description and of the annexed drawings, which are provided herein merely by way of non-limiting explanatory example, wherein:

[0018] - Fig. 1 is a perspective view of a wheelchair comprising a propulsion assistance system according to the present invention;

[0019] - Fig. 2a is a perspective view of a component of the propulsion assistance system according to the present invention;

[0020] - Fig. 2b is a perspective view of the component of Fig. 2a and of a traction wheel of the wheelchair of Fig. 1;

[0021] - Figs. 3a and 3b are, respectively, a front view and a perspective view of the traction wheel of the wheelchair of Fig. 1;

[0022] - Fig. 4 is an illustrative block diagram of a wheelchair comprising a propulsion assistance system in accordance with one embodiment of the invention;

[0023] - Fig. 5 is an illustrative flow chart of a method of providing propulsion assistance to a wheelchair according to the present invention.

[0024] Describing now the annexed drawings, in Fig. 1 reference numeral 1 designates as a whole a wheelchair comprising a propulsion assistance system (designated as a whole by reference numeral 100) according to the present invention.

[0025] The wheelchair 1 comprises a frame 10 having a seat 20 configured to receive a user, wherein said seat 20 may comprise, in particular, a seat cushion 21 and a backrest 22, and a pair of traction wheels 30 rotatably connected to the frame 10 and configured to be manually operated by the user, in particular when the user is sitting in the seat 20, for (manually) propelling the wheelchair 1.

[0026] As is known in the art, the traction wheels 30 are connected to the frame 10 on opposite sides of the seat 20.

[0027] Furthermore, each one of the traction wheels 30 preferably comprises a handrim (or pushrim) 31 integral with the traction wheel 30 itself, wherein said handrim 31 is not in contact with the surface of the traction wheel 30 that touches the ground, and thus allows the user to move the traction wheels 30 to propel the wheelchair 1 without soiling his / her hands; in addition to this, as is known, the handrim 31 also provides better grip to transfer the thrust force to the traction wheel 30. In this regard, each handrim 31 may be connected to a respective traction wheel 30 through one or more connection plates (not shown in the annexed drawings, since they are per se known) at least partly oriented in the axial or substantially axial direction relative to the respective traction wheel 30.

[0028] The frame 10 may then comprise at least one handle 12, preferably arranged behind the backrest 22 of the seat 20, to allow an attendant to move the wheelchair 1.

[0029] The wheelchair 1 may then comprise further accessory elements, such as armrests 13 and at least one footrest 14, whereon the user can lay his / her arms and legs, and a parking brake (not shown in the annexed drawings) for locking the traction wheels 30.

[0030] The wheelchair 1 may then comprise at least one driven wheel 40 associated with the frame 10 in such a way as to be able to pivot relative thereto, usually in a position ahead of the traction wheels 30 and smaller in diameter than the latter.

[0031] As previously explained, the wheelchair 1 comprises also a propulsion assistance system 100.

[0032] In accordance with the present invention, said propulsion assistance system 100 comprises at least one force sensor 110 associated with each traction wheel 30 and configured to detect a first piece of information about at least one force being applied by the user to at least one traction wheel 30, and to generate at least one electric signal, whether analogue or digital, representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel 30. In accordance with one embodiment, the system 100 comprises a plurality of force sensors 110 associated with each traction wheel 30, wherein said force sensors 110 are arranged at regular intervals on the respective traction wheel 30. For example, according to Figures 1, 2b, 3a and 3b, the system 100 comprises four force sensors 110 arranged at intervals of approximately 90°; in other embodiments, the system 100 may comprise three force sensors 110 arranged at intervals of approximately 120°. It is nonetheless clear that, in other embodiments of the invention, a different number of force sensors 110 may be used (e.g. a number greater than three or four), preferably arranged at regular intervals on the traction wheel 30. Therefore, when the user applies, by acting upon the handrim 31, one or more thrusts to at least one traction wheel 30, corresponding forces are applied by the user to the traction wheel 30 through the respective handrim 31 and are transmitted to the force sensors 110, which detect a first piece of information about at least one force being applied by the user to at least one traction wheel 30 through said handrim 31 and generate at least one electric signal representative of said first piece of information.

[0033] In addition to this, and in accordance with one embodiment of the present invention, each force sensor 110 consists of an extensimetric load cell.

[0034] Preferably, the system 100 comprises an anchoring element 110A configured to connect the traction wheel 30 to the handrim 31, wherein each anchoring element 110A is configured for housing at least one force sensor 110, in particular said at least one force sensor 110 being housed in the anchoring element 110A in such a way as to sense an action being exerted by the user in a direction tangential to the handrim 31; thus, each force sensor 110 will measure the forces acting perpendicular to a radius of the traction wheel 30 and parallel to a plane (not shown in the accompanying drawings) in which said traction wheel 30 lies, so that said forces acting parallel to the radius of each traction wheel 30 and parallel to the plane in which the handrim 31 lies can be determined with higher precision.

[0035] In accordance with the present invention, said propulsion assistance system 100 comprises a central control unit 120 (e.g. a Single Board Computer Rock PI 4) operatively connected to said at least one force sensor 110 and configured to receive at least one electric signal, whether analogue or digital, generated by said at least one force sensor 110 and representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel 30.

[0036] In this regard, it should be noted that said central control unit 120 can be operatively connected to said at least one force sensor 110 by means of either a wired interface, e.g. a USB interface, or a wireless interface, e.g. a Bluetooth interface.

[0037] In a preferred embodiment (as shown in the block diagram of Figure 4), the system 100 also comprises, in addition to said central control unit 120, a peripheral control unit 121 (e.g. based on an ESP32 development board) associated with each traction wheel 30, operatively connected (preferably via a wireless interface) to said at least one force sensor 110 and configured to receive from the force sensor 110 said at least one electric signal representative of the first piece of information about said at least one force. Each peripheral control unit 121 is also operatively connected (again, preferably via a wireless interface) to the central control unit 120 in order to transmit thereto the electric signal received from the force sensor 110 and representative of said first piece of information.

[0038] In this context, the electric signal generated by said at least one force sensor 110 may be an analogue signal, in which case each peripheral control unit 121 comprises also an analogue-to-digital converter (in particular, a 24-bit analogue-to-digital converter, such as, for example, an electronic board equipped with an HX711 chip) configured to convert (and, preferably, amplify) said analogue electric signal into a digital electric signal and send the latter to the central control unit 120.

[0039] In accordance with the present invention, said propulsion assistance system 100 further comprises a traction device (designated as a whole by reference numeral 130 in Fig. 2a) provided with a structure 131 configured to be connected to the frame 10 of the wheelchair 1.

[0040] In the embodiment shown in Figures 2a and 2b, said structure 131 comprises a mounting support 132 configured to connect the structure 131 to the frame 10 while allowing said structure 131 a passive degree of freedom of rotation relative to the frame 10, in particular a passive degree of freedom of rotation about a longitudinal axis of said mounting support 132; such features permit an optimal adaptation of the traction device 130 to the surface supporting the wheelchair 1, i.e. the surface whereon the wheelchair 1 is being moved.

[0041] In one embodiment of the present invention (visible in Figures 2a and 2b), the mounting support 132 is positioned in alignment with the axles of the traction wheels 30 by means of pins 11 inserted in the hubs 32 of the traction wheels 30.

[0042] Furthermore, in one embodiment of the present invention, the central control unit 120 is preferably housed in the structure 131 of the traction device 130 (as shown in Fig. 2a).

[0043] In accordance with the present invention, the traction device 130 comprises a traction motor 133 associated with a drive wheel 134, wherein the central control unit 120 is operatively connected to said traction motor 133 for controlling said traction motor 133 (and hence said drive wheel 134) in such a way as to provide the drive wheel 134 with a degree of propulsion assistance that depends on the electric signal generated by said at least one force sensor 110 and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel 30.

[0044] It is therefore clear that the propulsion assistance system 100 according to the present invention makes it possible to obtain an estimate of the actions performed by the user of the wheelchair 1 and, accordingly, to control the traction motor 133 and the drive wheel 134 as a function of said estimate of the user’s actions.

[0045] Preferably, the traction motor 33 is an electric motor (e.g. a 250W BLDC motor) and is positioned inside the drive wheel 134 (which is, therefore, of the “in-wheel motor” type, as shown in Figures 2a and 2b); such a solution proves particularly advantageous due to its compactness and optimal interaction with the geometry of the traction device 133. Though less efficient, a solution may also be conceived wherein the drive wheel 134 is controlled by a traction motor 133 arranged along its axis, but not integrated into said drive wheel 134, or a solution wherein the drive wheel 134 is controlled by a traction motor 133 not arranged along the wheel axis and connected to a hub of the drive wheel

[0046] 134 by a transmission system (gears, belt, or the like).

[0047] In accordance with one embodiment, the traction device 130 comprises a steering motor

[0048] 135 associated with the drive wheel 134 through a steering system 136 allowing said drive wheel 134 to change its own steering angle (i.e. allowing said drive wheel 134 to rotate with a substantially vertical steering shaft 136A, as shown in Fig. 2a), wherein the central control unit 120 is operatively connected to said steering motor 135 to control the steering angle of the drive wheel 134 (i.e. to control the rotation of the drive wheel 134 with said steering shaft 136A) as a function of the electric signal generated by said at least one force sensor 110 and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel 30.

[0049] It is therefore apparent that the traction device 130 according to the present invention makes it possible to generate a thrust action (by means of the drive wheel 134) with such intensity (via the operative connection between the central control unit 120 and the traction motor 133) and direction (via the operative connection between the central control unit 120 and the steering motor 135) that will depend on the interpretation of the actions exerted by the user on at least one traction wheel 30 of the wheelchair 1, wherein said interpretation of the actions exerted by the user is obtained as a function of the detection of at least one force being applied by the user to at least one traction wheel 30, in particular said detection being made by the force sensors 110 associated with the traction wheels 30.

[0050] In the embodiment shown in Fig. 2a, the steering motor 135 comprises a servo motor, in particular a 2Nm 7V servo motor; in this context, the steering system 136 preferably comprises a gear transmission acting as a speed reducer between the servo motor and the steering shaft 136A, wherein said speed reducer is selected in a manner such as to effectively associate the adopted servo motor with the required steering function. It should be noted, however, that a wholly equivalent function may employ a steering motor 135 directly engaged with the steering shaft 136A, or a steering motor 135 connected to the steering shaft 136A through a different type of transmission, e.g. a belt transmission.

[0051] In addition, the traction device 130 may comprise power supply means 137 adapted to supply electric power to the central control unit 120 and / or to the traction motor 133 and / or to the steering motor 135; such power supply means 137 may comprise, for example, lithium-ion batteries, nickel -cadmium batteries, and power supply circuits to be connected to the electric grid.

[0052] In accordance with one embodiment, the propulsion assistance system 100 comprises detection means 141, 142 associated with the wheelchair 1 and configured to detect at least one kinematic parameter of said wheelchair 1 and to send to the central control unit 120 at least one electric signal representative of said at least one kinematic parameter, wherein said central control unit 120 is configured to control the traction motor 133 and / or the steering motor 135 also as a function of said kinematic parameter.

[0053] In this context, said detection means 141, 142 comprise at least one speed sensor 141 associated with each traction wheel 30, wherein the speed sensor 141 of each traction wheel 30 is configured to detect at least one second piece of information about an angular speed of the respective traction wheel 30, wherein the central control unit 120 is operatively connected to said at least one speed sensor 141 and is configured to:

[0054] - receive at least one electric signal (whether analogue or digital) generated by said at least one speed sensor 141 and representative of the second piece of information, and

[0055] - control the traction motor 133 and / or the steering motor 135 as a function of the electric signal generated by said at least one speed sensor 141 and representative of the second piece of information.

[0056] In particular, each speed sensor 141 is configured to detect a second piece of information about an angular speed of the respective traction wheel 30.

[0057] Preferably, each speed sensor 141 is installed on the respective traction wheel 30 by means of a support (not shown in detail in the accompanying drawings) so configured as to align said speed sensor 141 with an axis of rotation of the traction wheel 30; as can be inferred from the annexed figures, each speed sensor 141 is installed on a hub 32 of the respective traction wheel 30.

[0058] As already described above with reference to the force sensor 110, and as shown in Fig. 4, the speed sensor 141 is also, preferably, operatively connected to the peripheral control unit 121, wherein said peripheral control unit 121 is configured to receive from the speed sensor 141 (which may be, for example, a GY521 module incorporating a mpu6050™ six-axis sensor including a three-axis gyroscope and a three-axis accelerometer) at least one electric signal representative of said second piece of information, and to transmit said electric signal to the central control unit 120.

[0059] In this case as well, the electric signal generated by the speed sensor 141 is an analogue one, and the analogue-to-digital converter of each peripheral control unit 121 converts (and, preferably, amplifies) said analogue electric signal into a digital electric signal, which is then sent to the central control unit 120, which will in turn control the traction motor 133 and / or the steering motor 135 as a function of the electric signal, concerning the second piece of information, generated by said at least one speed sensor 141.

[0060] In this context, said detection means 141, 142 comprise at least one inclination sensor 142 (schematically shown in Fig. 4), in particular associated with the frame 10 of the wheelchair 1, wherein said at least one inclination sensor 142 is configured to detect at least one third piece of information about an inclination of the wheelchair 1, and wherein the central control unit 120 is operatively connected to said at least one inclination sensor 142 and is configured to:

[0061] - receive at least one electric signal (whether analogue or digital) generated by said at least one inclination sensor 142 and representative of the third piece of information, and

[0062] - control the traction motor 133 and / or the steering motor 135 as a function of the electric signal generated by said at least one inclination sensor 142 and representative of the third piece of information. Preferably, as shown in Fig. 4, the inclination sensor 142 is operatively connected to a further peripheral control unit 122, wherein said further peripheral control unit 122 (e.g. based on an ESP32 development board) is configured to receive from the inclination sensor 142 (which may be, for example, a GY521 module incorporating an mpu6050™ six-axis sensor) at least one electric signal representative of said third piece of information, and to transmit said electric signal to the central control unit 120.

[0063] In this case as well, the electric signal generated by the inclination sensor 142 is an analogue one, and said further peripheral control unit 122 comprises an analogue-to- digital converter that converts (and, preferably, amplifies) said analogue electric signal into a digital electric signal, which is then sent to the central control unit 120, which will in turn control the traction motor 133 and / or the steering motor 135 as a function of the electric signal, concerning the third piece of information, generated by said at least one inclination sensor 142.

[0064] In light of the above, the system 100 according to the present invention has been so conceived that the central control unit 120 analyses in real time the information about at least one force being applied by the user to each traction wheel 30 (such information being acquired by the force sensors 110 associated with each traction wheel 30) and the information about the kinematic parameters of the wheelchair 1 (such information being acquired by the detection means 141, 142) in accordance with a predefined algorithm; such predefined algorithm can be implemented through a computer program product, comprising portions of software code, which can be loaded into a memory of the central control unit 120.

[0065] Thus, the central control unit 120 will process said force and kinematic-parameter information in order to generate reference signals for controlling the traction motor 133 and / or the steering motor 135 as a function of said information.

[0066] In particular, by using the various data available, the central control unit 120 can provide dynamic control capable of adapting to different conditions of use of the wheelchair 1.

[0067] In this context, starting from the force-related information, the central control unit 120 can make an estimate of the actions being exerted by the user on the wheelchair 1, but cannot estimate detailed information about the user’s manoeuvring intentions, which are dependent on the kinematic conditions of the wheelchair 1; in this regard, it should be noted that, as a matter of fact, the user’s intention is not solely a function of the actions performed on the traction wheels 30 because, the exerted forces being equal, the user’s intention may be different depending on whether the wheelchair 1 is stationary or moving at constant speed, or anyway in non-null speed conditions. The availability of information about kinematic parameters results in the possibility of creating a logic capable of actively adapting to the actual conditions of use of the wheelchair 1.

[0068] Therefore, starting from the information available to the central control unit 120, “machine learning” algorithms can be integrated into said predefined algorithm in order to interpret the user’s intention.

[0069] Moreover, since two degrees of freedom can be controlled directly by the traction device 130 (i.e. the rotary motion of the drive wheel 134, via the traction motor 133, and the steering angle of the drive wheel 134, via the steering motor 135), the system 100 according to the present invention can be so implemented as to comprise an external terminal (not shown in the accompanying drawings, but consisting of, for example, a smartphone, a tablet, a laptop, or a computer) comprising input means (e.g. a joystick, voice commands, mobile applications, and so forth) allowing for remote management of the wheelchair 1, thus making it easier to move and manage the wheelchair 1 during the user’s movements.

[0070] Essentially, therefore, the present invention concerns a kit for providing propulsion assistance to a wheelchair 1, wherein said kit comprises:

[0071] - at least one force sensor 110 associated with each traction wheel 30 and configured to detect a first piece of information about at least one force being applied by the user to at least one traction wheel 30, and to generate at least one electric signal, whether analogue or digital, representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel 30;

[0072] - a central control unit 120 operatively connected to said at least one force sensor 110 and configured to receive said at least one electric signal, whether analogue or digital, generated by said at least one force sensor 110 and representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel 30;

[0073] - a traction device 130 provided with a structure 131 configured to be connected to the frame 10 of the wheelchair 1, said traction device 130 comprising a traction motor 133 associated with a drive wheel 134, wherein the central control unit 120 is operatively connected to said traction motor 133 to control said traction motor 133 (and hence said drive wheel 134) in such a way as to provide the drive wheel 134 with a degree of propulsion assistance that depends on the electric signal generated by said at least one force sensor 110 and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel 30.

[0074] In particular, the traction device 130 may comprise a steering motor 135 associated with the drive wheel 134 through a steering system 136 allowing said drive wheel 134 to change its own steering angle, wherein the central control unit 120 is operatively connected to said steering motor 135 to control the steering angle of the drive wheel 134 as a function of the electric signal generated by said at least one force sensor 110 and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel 30.

[0075] Furthermore, the kit may comprise detection means 141, 142 associated with the wheelchair 1 and configured to detect at least one kinematic parameter of said wheelchair 1 and to send to the central control unit 120 at least one electric signal representative of said at least one kinematic parameter, wherein said central control unit 120 is configured to control the traction motor 133 and / or the steering motor 135 also as a function of said kinematic parameter.

[0076] In particular, said detection means 141, 142 may comprise at least one speed sensor 141 associated with each traction wheel 30, wherein the speed sensor 141 of each traction wheel 30 is configured to detect at least one second piece of information about an angular speed of the respective traction wheel 30, and wherein the central control unit 120 is operatively connected to said at least one speed sensor 141 and is configured to:

[0077] - receive at least one electric signal (whether analogue or digital) generated by said at least one speed sensor 141 and representative of the second piece of information, and

[0078] - control the traction motor 133 and / or the steering motor 135 as a function of the electric signal generated by said at least one speed sensor 141 and representative of the second piece of information.

[0079] In addition, said detection means 141, 142 comprise at least one inclination sensor 142 (schematically shown in Fig. 4), in particular associated with the frame 10 of the wheelchair 1, wherein said at least one inclination sensor 142 is configured to detect at least one third piece of information about an inclination of the wheelchair 1, and wherein the central control unit 120 is operatively connected to said at least one inclination sensor 142 and is configured to:

[0080] - receive at least one electric signal (whether analogue or digital) generated by said at least one inclination sensor 142 and representative of the third piece of information, and

[0081] - control the traction motor 133 and / or the steering motor 135 as a function of the electric signal generated by said at least one inclination sensor 142 and representative of the third piece of information.

[0082] With reference to Figure 5, the following will describe a method (designated as a whole by reference numeral 200) of providing propulsion assistance to a wheelchair 1 according to the present invention, said wheelchair 1 comprising a frame 10 and a pair of traction wheels 30 rotatably connected to the frame 10 and configured to be manually operated by the user.

[0083] At step 210 an initialization phase is carried out, wherein:

[0084] - at least one force sensor 110 is associated with each traction wheel 30,

[0085] - a structure 131 of a traction device 130 is connected to the frame 10 of the wheelchair 1, said traction device 130 comprising a traction motor 133 associated with a drive wheel 134,

[0086] - a central control unit 120 (preferably housed in the structure 131 of the traction device 130) is operatively connected to the force sensor 110 associated with each traction wheel 30.

[0087] During the initialization phase 210, further detection means 141, 142 may be associated with the wheelchair 1 to detect at least one kinematic parameter of said wheelchair 1, wherein said further detection means 141, 142 are operatively connected to the central control unit 120 to send thereto at least one electric signal representative of said at least one kinematic parameter.

[0088] In particular, during the initialization phase 210 at least one speed sensor 141 may be associated with each traction wheel 30, and at least one inclination sensor 142 may be associated with the frame 10 of the wheelchair 1.

[0089] Furthermore, during the initialization phase 210 said central control unit 120 may calibrate the force sensors 110 and / or the detection means 141, 142 in accordance with a predefined calibration procedure. For example, the calibration phase may determine a null value of the information acquired by said sensors 110, 141, 142 when the user is not acting upon the traction wheels 30 and the wheelchair 1 is stationary on a horizontal surface.

[0090] At step 220 an acquisition phase is carried out, wherein the user operates at least one traction wheel 30, the force sensors 110 detect a first piece of information about at least one force being applied by the user to at least one traction wheel 30, and the central control unit 120 receives at least one electric signal (in particular, via peripheral control units 121) generated by said at least one force sensors 110 and representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel 30.

[0091] During the acquisition phase 220, said detection means 141, 142 associated with the wheelchair 1 may detect one or more kinematic parameters of the wheelchair 1, and the central control unit 120 receives respective electric signals representative of said kinematic parameters.

[0092] In particular, during the acquisition phase 220 said at least one speed sensor 141 associated with each traction wheel 30 detects at least one second piece of information about an angular speed of the respective traction wheel 30, and the central control unit 120 receives (in particular, from peripheral control units 121 associated with each speed sensor 141) at least one electric signal generated by said at least one speed sensor 141 and representative of the second piece of information about said angular speed of the respective traction wheel 30.

[0093] Furthermore, during the acquisition phase 220 said at least one inclination sensor 142 associated with the frame 10 of the wheelchair 1 detects at least one third piece of information about an inclination of the wheelchair 1, and the central control unit 120 receives (in particular, from a further peripheral control unit 122 associated with the inclination sensor 142) at least one electric signal generated by said at least one inclination sensor 142 and representative of the third piece of information about the inclination of the wheelchair 1.

[0094] At step 230 an actuation phase is carried out, wherein the central control unit 120 controls the traction motor 133 associated with the drive wheel 134 in such a way as to provide the drive wheel 134 with a degree of propulsion assistance that depends on the electric signal generated by said at least one force sensor 110 and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel 30.

[0095] During the actuation phase 230, the central control unit 120 may also control a steering motor 135 of the traction device 130 in order to change a steering angle of the drive wheel 134 as a function of the electric signal generated by said at least one force sensor 110 and concerning a first piece of information about said at least one force being applied by the user to at least one traction wheel 30.

[0096] It should be noted that, during said actuation phase 230, the central control unit 120 may control the traction motor 133 and / or the steering motor 135 as a function of said respective electric signals representative of said kinematic parameters.

[0097] In particular, during the actuation phase 230 the central control unit 120 may control the traction motor 133 and / or the steering motor 135 as a function of the electric signal generated by said at least one speed sensor 141 and representative of the second piece of information about the angular speed of the traction wheels 30.

[0098] Furthermore, during the actuation phase 230 the central control unit 120 may control the traction motor 133 and / or the steering motor 135 as a function of the electric signal generated by said at least one inclination sensor 142 and representative of the third piece of information about the inclination of the wheelchair 1.

[0099] At step 240 a verification phase is carried out, wherein the central control unit 120 verifies if, e.g. during a predefined acquisition period, said at least one force sensor 110 and / or said at least one speed sensor 141 and / or said at least one inclination sensor 142 generate a respective electric signal concerning a force being applied by the user to at least one traction wheel 30 and / or an angular speed of each traction wheel 30 and / or an inclination of the wheelchair 1. If so (i.e. if at least one of said sensors 110, 141, 142 generates a respective electric signal before said predefined acquisition period expires), then step 220 will be executed again; otherwise (i.e. if none of said sensors 110, 141, 142 generates a respective signal before said predefined acquisition period expires), then step 250 will be executed as described below.

[0100] At step 250 a termination phase is carried out, wherein the central control unit 120 performs all necessary operations for terminating the previous phases. During this termination phase 250, the central control unit 120 may signal its inoperative state, e.g. by means of luminous and / or audible indicators.

[0101] The advantages of the present invention are apparent from the above description.

[0102] Indeed, the peculiar features of the present invention make it possible to provide a wheelchair propulsion assistance system 100 which has been so conceived as to still require an active contribution from the user for moving the wheelchair 1, and which can be easily installed on a traditional manual wheelchair without excessively increasing the weight of said wheelchair 1.

[0103] Another advantage of the system 100 according to the present invention lies in the fact that it has been conceived in such a way that the total dimensions of the wheelchair 1 are not altered, or at least not increased, and that it can be used both outdoors and in closed, narrow and crowded indoor spaces. Unlike prior-art devices, and particularly unlike those devices having a single rear drive wheel that cannot be actively oriented, the solution proposed by the present invention includes an active steering system that directs the propulsion assistance action, thereby also reducing the effort necessary for manoeuvring the wheelchair 1 along non-rectilinear trajectories, particularly when used indoors and in narrow spaces.

[0104] A further advantage of the present invention lies in the fact that the system 100 has been so conceived as to require substantially the same natural pushing action as required by common manual wheelchairs, thus beneficially exploiting the user’s motory functions and putting the user into a cognitive condition of active presence when propelling and manoeuvring the wheelchair 1.

[0105] The system 100 according to the present invention can direct the propulsion assistance action, thereby also reducing the effort necessary for manoeuvring the wheelchair 1 along non-rectilinear trajectories, particularly when used indoors and in narrow and / or crowded spaces. In this respect, as far as control practicality is concerned, the system 100 of the present invention does not require the installation of any additional controller on the wheelchair 1, since it can directly interpret the user’s manoeuvring intentions by estimating the forces that the user applies to the wheels. Controlling the wheelchair 1 comprising the system 100 is thus very intuitive, because the system 100 requires the same pushing gesture as required by common manual wheelchairs.

[0106] The wheelchair 1 and the associated system 100 described herein by way of example may be subject to many possible variations without departing from the novelty spirit of the inventive idea; it is also clear that in the practical implementation of the invention the illustrated details may have different shapes or be replaced with other technically equivalent elements.

[0107] It can therefore be easily understood that the present invention is not limited to the abovedescribed wheelchair 1 and associated system 100, but may be subject to many modifications, improvements or replacements of equivalent parts and elements without departing from the inventive idea, as clearly specified in the following claims.

Claims

CLAIMS1. A wheelchair (1) comprising:- a frame (10);- a pair of traction wheels (30), wherein each traction wheel (30) is rotatably connected to the frame (10) and is configured to be manually operated by the user,- a propulsion assistance system (100), said wheelchair (1) being characterized in that said propulsion assistance system (100) comprises:- at least one force sensor (110) associated with each traction wheel (30) and configured to detect a first piece of information about at least one force being applied by the user to at least one traction wheel (30), and to generate at least one electric signal representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel (30),- a central control unit (120) operatively connected to said at least one force sensor (110) and configured to receive said at least one electric signal generated by said at least one force sensor (110) and representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel (30),- a traction device (130) provided with a structure (131) configured to be connected to the frame (10) of the wheelchair (1), wherein said traction device (130) comprises a traction motor (133) associated with a drive wheel (134), and wherein said traction device (130) comprises a steering motor (135) associated with the drive wheel (134) through a steering system (136) that allows said drive wheel (134) to change its steering angle, wherein the central control unit (120) is operatively connected to said traction motor (133) for controlling said traction motor (133) in such away as to provide the drive wheel (134) with a degree of propulsion assistance that depends on the electric signal generated by said at least one force sensor (110) and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel (30), and wherein said central control unit (120) is operatively connected to said steering motor (135) for controlling a steering angle of the drive wheel (134) as a function of the electric signal generated by said at least one force sensor (110) and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel (30).

2. Wheelchair (1) according to claim 1, characterized in that said traction motor (33) is an electric motor, in particular of the type positioned inside the drive wheel (134).

3. Wheelchair (1) according to one or more of the preceding claims, characterized in that said propulsion assistance system (100) comprises detection means (141, 142) associated with the wheelchair (1) and configured to detect at least one kinematic parameter of said wheelchair (1) and to send to the central control unit (120) at least one electric signal representative of said at least one kinematic parameter, wherein said central control unit (120) is configured to control the traction motor (133) and / or the steering motor (135) as a function of said kinematic parameter.

4. Wheelchair (1) according to claim 3, characterized in that said detection means (141, 142) comprise at least one speed sensor (141) associated with each traction wheel (30), wherein the speed sensor (141) of each traction wheel (30) is configured to detect at least one second piece of information about an angular speed of the respective traction wheel (30), wherein the central control unit (120) is operatively connected to said at least one speed sensor (141) and is configured to:- receive at least one electric signal generated by said at least one speed sensor (141) and representative of the second piece of information, and- control the traction motor (133) and / or the steering motor (135) as a function of the electric signal generated by said at least one speed sensor (141) and representative of the second piece of information.

5. Wheelchair (1) according to one or more of the preceding claims, characterized in that said system (100) comprises a peripheral control unit (121) associated with each traction wheel (30), operatively connected to said at least one force sensor (110) and configured to receive from the force sensor (110) said at least one electric signal representative of the first piece of information about said at least one force, wherein each peripheral control unit (121) is operatively connected to the central control unit (120) in order to transmit thereto the electric signal received from the force sensor (110) and representative of said first piece of information.

6. Wheelchair (1) according to claims 4 and 5, characterized in that said at least one speed sensor (141) is operatively connected to the peripheral control unit (121), wherein said peripheral control unit (121) is configured to receive from the speed sensor (141) at least one electric signal representative of said second piece of information and to transmit said electric signal to the central control unit (120).

7. Wheelchair (1) according to one or more of claims 3 to 6, characterized in that said detection means (141, 142) comprise at least one inclination sensor (142), in particular associated with the frame (10) of the wheelchair (1), wherein said at least one inclination sensor (142) is configured to detect at least one third piece of information about an inclination of the wheelchair (1), and wherein the central control unit (120) is operatively connected to said at least one inclination sensor (142) and is configured to:- receive at least one electric signal generated by said at least one inclination sensor (142) and representative of the third piece of information, and- control the traction motor (133) and / or the steering motor (135) as a function of the electric signal generated by said at least one inclination sensor (142) and representative of the third piece of information.

8. Wheelchair (1) according to claim 7, characterized in that the inclination sensor (142) is operatively connected to a further peripheral control unit (122), wherein said further peripheral control unit (122) is configured to receive from the inclination sensor (142) at least one electric signal representative of said third piece of information and to transmit said electric signal to the central control unit (120).

9. Wheelchair (1) according to one or more of the preceding claims, characterized in that said central control unit (120) is housed in the structure (131) of the traction device (130).

10. Wheelchair (1) according to one or more of the preceding claims, characterized in that said structure (131) comprises a mounting support (132) configured to connect the structure (131) to the frame (10) of the wheelchair (1) while allowing said structure (131) a passive degree of freedom of rotation relative to the frame (10), in particular a passive degree of freedom of rotation about a longitudinal axis of said mounting support (132).

11. A propulsion assistance system (100) adapted to be associated with a wheelchair (1) according to one or more of claims 1 to 10.

12. Method (200) of providing propulsion assistance to a wheelchair (1) comprising a frame (10) and a pair of traction wheels (30) rotatably connected to the frame (10) and configured to be manually operated by a user, said method (200) being characterized in that it comprises the following phases:- an initialization phase (210), wherein:- at least one force sensor (110) is associated with each traction wheel (30),- a structure (131) of a traction device (130) is connected to the frame (10) of thewheelchair (1), said traction device (130) comprising a traction motor (133) associated with a drive wheel (134),- a central control unit (120), in particular housed in the structure (131) of the traction device (130), is operatively connected to the force sensor (110) associated with each traction wheel (30);- an acquisition phase (220), wherein:- the user operates at least one traction wheel (30),- the force sensors (110) detect a first piece of information about at least one force being applied by the user to at least one traction wheel (30),- the central control unit (120) receives at least one electric signal generated by said at least one force sensor (110) and representative of the first piece of information about said at least one force being applied by the user to at least one traction wheel (30);- an actuation phase (230), wherein the central control unit (120) controls the traction motor (133) associated with the drive wheel (134) in such a way as to provide the drive wheel (134) with a degree of propulsion assistance that depends on the electric signal generated by said at least one force sensor (110) and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel (30), and wherein the central control unit (120) controls a steering motor (135) of the traction device (130) to change a steering angle of the drive wheel (134) as a function of the electric signal generated by said at least one force sensor (110) and concerning the first piece of information about said at least one force being applied by the user to at least one traction wheel (30) of the wheelchair (1).

13. Method (200) according to claim 12, characterized in that:- during said initialization phase (210), further detection means (141, 142) are associated with the wheelchair (1) to detect at least one kinematic parameter of said wheelchair (1), wherein said further detection means (141, 142) are operatively connected to the central control unit (120) to send to said central control unit (120) at least one electric signal representative of said at least one kinematic parameter;- during said acquisition phase (220), said detection means (141, 142) associated with the wheelchair (1) detect one or more kinematic parameters of the wheelchair (1), and the central control unit (120) receives respective electric signals representative of said kinematic parameters;- during said actuation phase (230), the central control unit (120) controls the traction motor (133) and / or the steering motor (135) as a function of said respective electric signals representative of said kinematic parameters.

14. Method (200) according to claim 13, characterized in that:- during said initialization phase (210), at least one speed sensor (141) is associated with each traction wheel (30) of the wheelchair (1);- during said acquisition phase (220), said at least one speed sensor (141) detects at least one second piece of information about an angular speed of the respective traction wheel (30), and the central control unit (120) receives at least one electric signal generated by said at least one speed sensor (141) and representative of the second piece of information about said angular speed of the respective traction wheel (30),- during said actuation phase (230), the central control unit (120) controls the traction motor (133) and / or the steering motor (135) as a function of the electric signal generated by said at least one speed sensor (141) and representative of the second piece of information about the angular speed of the traction wheels (30).

15. Method (200) according to one or more of claims 13 and 14, characterized in that:- during said initialization phase (210), at least one inclination sensor (142) is associated with the frame (10) of the wheelchair (1);- during said acquisition phase (220), said at least one inclination sensor (142) detects at least one third piece of information about an inclination of the wheelchair (1), and the central control unit (120) receives at least one electric signal generated by said at least one inclination sensor (142) and representative of the third piece of information about the inclination of the wheelchair (1);- during said actuation phase (230), the central control unit (120) controls the traction motor (133) and / or the steering motor (135) as a function of the electric signal generated by said at least one inclination sensor (142) and representative of the third piece of information about the inclination of the wheelchair (1).

16. Computer program product comprising a set of instructions which, when loaded into a memory of a central control unit (120) of a propulsion assistance system (100) operatively connected to a wheelchair (1), are adapted to implement the method according to one or more of claims 12 to 15.

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