Sensorized handle for controlling motorized devices

Abstract

The invention relates to a control device (10) for motorized systems (1) having up to three degrees of freedom, such as wheelchairs, handling trolleys, or the like. The device comprises a handle (11) associated with sensor means (40, 41, 42) for force detection, so that the forces and / or torques applied to the handle (11) by a user can be measured and transformed into reference signals for controlling the motorized system (1). In accordance with the invention, the device uses uniaxial force sensors (40, 41, 42) only for measuring the forces applied to the handle (11) by the user. To this end, the handle (11) is supported by a mechanism with nn degrees of freedom, equal to those of the motorized system (1) to be controlled.

Description

[0001] Description of patent for industrial invention entitled:

[0002] “SENSORIZED HANDLE FOR CONTROLLING MOTORIZED DEVICES”

[0003] Applicant: Politecnico Torino - (Torino)

[0004] Filed on No.

[0005] Appointed inventors:

[0006] QUAGLIA Giuseppe (c / o: Politecnico di Torino - DIMEAS Dept.)

[0007] TAGLIAVINI Luigi (c / o: Politecnico di Torino - DIMEAS Dept.)

[0008] DESCRIPTION

[0009] In general, the invention relates to control devices for motorized systems.

[0010] In the last decades, technology development has led to widespread use of motorized systems such as motorized trolleys, lifters and wheelchairs. These devices are designed to assist people in performing activities that would otherwise be difficult, physically demanding, or, in some cases, wholly impossible. All such motorized systems must include a suitable control peripheral allowing users to control the motorized device.

[0011] The invention concerns, in particular, control devices for motorized systems providing assistance to people with reduced motor function.

[0012] The interface must meet several requirements, such as: drivability: through the interface, the user must have full control over the motorized device; ergonomics: the interface must be comfortable to use, avoiding problems due to improper driver posture; easiness of use: the interface must be easy and intuitive to use; ideally, no specific training should be necessary; safety: the interface must be able to discern whether the received command has been intentionally issued by the user or has been caused by shock or accidental contact.

[0013] The interface which is most commonly used for controlling motorized mobile devices is the joystick, or control lever (see example in Figure 1). This type of peripheral comprises a lever that can be rotated from its starting configuration (maintained by a return spring). The lever can be tilted about one or more axes, where angular position transducers measure the lever angle. From a functional viewpoint, a joystick is an interface that generates reference signals as a lever is rotated. Such control peripherals make it possible to generate reference signals in a simple and robust manner. They are particularly suited for use in virtual environments (gaming or simulators), for remotely controlling mobile devices (drones, mobile robots for search and rescue applications, lifting systems, etc.), or for controlling motorized systems for user transportation (electric wheelchairs). In other words, not considering virtual environment applications, lever-type joysticks are particularly suitable for controlling any motorized device where the joystick base is fixed relative to the user. This is due to the fact that it is difficult to accurately control the angular position of a lever when the base to which it is hinged can move relative to the user. In the field of motorized wheelchair controljoystick-type interfaces prove very effective for a user sitting in a wheelchair, but are much less convenient to use for a caregiver (operator) accompanying a care-dependent person sitting in a wheelchair. Aiming at solving this problem, control interfaces have been proposed which are based on the principle of reading the forces applied to the device by the operator.

[0014] Such peripherals are typically handles equipped with force sensors interposed between the element being gripped by the operator and the motorized device. In this way it is possible to measure the forces and torques that the user is applying to the device, which are then transformed into reference signals for controlling the motorized system.

[0015] Most of these solutions adopt six-axis force sensors, i.e. sensors capable of measuring all components of the resultant of the actions exerted on the sensor. One drawback of such solutions is the cost of the six-axis sensors, which very much affects the total cost of such systems, thus limiting the proliferation thereof. Some applications, only intended to control motorized devices with two degrees of freedom in a plane, employ two uniaxial load cells interposed between the handle and the frame of the motorized system. Lastly, some fieldspecific scientific research studies have proposed the use of matrices of touch sensors for measuring the resultant of the contact pressures exchanged between the operator’s hands and the handle.

[0016] In light of the above analysis of the state of the art, it can be stated that the technical problem at the basis of the invention is to provide a control device for motorized systems, in particular, without however being limited to, those providing assistance to people with reduced motor function, which has structural and functional characteristics that make it possible to overcome the above-mentioned limitations of the prior art.

[0017] The idea that solves this problem is based on the provision of a flat mechanism isostatically constrained by three uniaxial cells. The mechanism is arranged into a particular configuration that improves the quality of the measurements of the forces applied by the user, while at the same time reducing the sensitivity of the device to assembly errors;

[0018] When considered without load cells, the mechanism on which the patent idea of the sensorized handle is based allows the handle to move only in the degrees of freedom of interest, corresponding to the degrees of freedom of the motorized system to be controlled. Thus, any forces or torques applied in directions that are not of interest will be transmitted to the structure of the mechanism, without altering the readings of the forces applied to the handle by the operator.

[0019] In a preferred embodiment, the device of the invention makes exclusive use of unidirectional load cells, which are much less expensive and much more easily available than the multiaxial cells employed by most other solutions known in the art.

[0020] The features of the invention are specifically set out in the claims appended to this description. Such features, as well as the effects deriving therefrom and the advantages achieved by the invention, will become more apparent in light of the following description of a preferred, but non-limiting, example of embodiment of the invention, as shown in the annexed illustrative, but non-limiting, drawings, wherein:

[0021] - Fig. 1 shows a conventional joystick-type control device;

[0022] - Fig. 2 shows a person sitting in a mobile chair comprising a control device according to the invention;

[0023] - Fig. 3 is a top view of the person sitting in the chair in the preceding figure;

[0024] - Fig. 4 shows a detail of the control device of the chair of Figures 1 and 2;

[0025] - Figs. 5 and 6 show respective variant embodiments of a handle employed in the device of the invention shown in the preceding figures; Fig. 7 is a block diagram of the measurement system of the sensorized handle of Fig. 6.

[0026] With reference to the above-listed figures, numeral 1 designates as a whole a motorized system with multiple degrees of freedom controlled by a control device 10 in accordance with the invention.

[0027] In the preferred example considered herein, the motorized system 1 consists of a wheelchair designed to assist people with reduced motor function; as aforesaid, the invention is also applicable to other motorized systems, not necessarily intended for people assistance or mobility purposes (e.g. handling of objects).

[0028] It should also be pointed out that any reference to an “implementation”, an “embodiment”, a “variant embodiment”, or any other similar expressions that are typical of patent documents, will indicate that a particular configuration, structure, action, operating phase or other feature is comprised in at least one example of the invention.

[0029] Therefore, such expressions, which may be present in different parts of this description, will indicate elements not necessarily referring to a single implementation or embodiment.

[0030] In addition, those skilled in the art will recognize that the individual configurations, structures or features considered herein may be combined with each other in several appropriate ways to attain the described results of the invention.

[0031] Lastly, in compliance with an established practice in the patent field, the numerical or alphabetical references used in the drawings are provided for clarity only, without limiting the protection scope or extension of the invention.

[0032] With this in mind, the wheelchair 1 comprises a structure 2 acting as a seat for the person P; as can be observed, in this case the structure 2 of the wheelchair is of the type comprising a backrest 3 and armrests 4 due to the reasons that will be further explained below; nonetheless, the structure 2 may also be different, e.g. resembling a stool, or with two or more seats for other people.

[0033] The wheelchair 1 comprises a base or platform 5 that supports the seat structure 2 through a vertical column or post 6 extending from the base; also as concerns this feature, other solutions are also possible for supporting the structure 2 over the base 5, e.g. legs, rods, suspensions, etc. The base 5 is movable on wheels 7 positioned under it, which allow the wheelchair 1 to move in any direction in a plane; to this end, some wheels 7 are driving and steering wheels, while others are idle wheels; also, some wheels may be pivoting wheels adopting different design solutions. The movable base may also employ mecanum wheels, omniwheels or the like for omnidirectional mobility.

[0034] Preferably, the configuration and arrangement of the wheels 7 are similar to those described in Italian patent application no. 102022000022155, filed on 27.10.2022 by the present Applicant, in that the control device 10 of the present invention is well suited for application to a wheelchair like the one described in said prior application.

[0035] The wheelchair described in said application is, in fact, equipped with a locomotion system providing it with omnidirectional mobility in a plane, i.e. with the possibility of independently controlling the translation and rotation of the chair, thus also allowing movements in tight spaces within home environments.

[0036] Said wheelchair makes use of conventional wheels, some steering ones and some driving ones, which are controlled by an active-wheel rotation and steering control system.

[0037] Nevertheless, any other type of wheel 7, different from those of Italian patent application no. 102022000022155, may also be used for the present invention; what matters is that the wheels

[0038] 7 must allow the chair 1 to move in all directions in a plane. For this purpose, the wheelchair 1 comprises a battery-powered electric motor 8 associated with at least one driving wheel 7, the operation of which can be managed through the control device 10.

[0039] With reference to Figures 2-6, in this exemplary embodiment of the invention the device 10 comprises a handle 11 configured essentially as a crossbar, which is supported by a mechanism allowing it to translate in the horizontal plane defined by the axes X-Y and to rotate about the vertical axis Z.

[0040] The handle 11 is positioned on the backrest 3 of the chair 1 to allow a user to push it and steer it; as an alternative, a similar handle may be provided in a front position, facing the person P sitting in the wheelchair 1, to allow them to drive it autonomously.

[0041] The handle 11 makes it possible to transmit the necessary drive commands, in any direction, to the motor means 8.

[0042] To this end, it measures the components XX and YY of the resultant of the system of forces applied to the handle 11 and the resulting moment of the system of forces about the vertical axis ZZ. Such input parameters of the control system 16 of the device 10 have been chosen to make the handle 11 more intuitive to use.

[0043] In light of the above considerations, the principle of operation of the handle 11 is based on an articulated support mechanism 12 with a number riri of degrees of freedom, preferably 3, such as, for example, an articulated hexagon; the functional diagram of the mechanism is shown in Figure 4.

[0044] Considering the sensorized handle 11 without load cells, its support 12 consists of an articulated system with three degrees of freedom. It can, in fact, translate in the plane X-Y and rotate about the vertical axis Z of the reference system of the handle, considering the axes shown in Figs. 2- 4.

[0045] The articulation of the support mechanism of the handle 11 comprises six elements (articulated hexagon), one of which is the handle 11 itself, while a first element is fixed and constitutes the frame 20 that is integral with the structure 2 of the motorized system to be controlled, i.e. the wheelchair 1 in this case.

[0046] Two rocker-arm elements 21 and 22 are connected to the fixed frame 20 through respective rotoidal pairs (i.e. real or virtual hinges) 23 and 24.

[0047] In turn, the rocker arms 21 and 22 are connected to respective connecting rods 25 and 26 through rotoidal pairs 27 and 28; the connecting rods 25, 26 are articulated to the ends of the handle 11 through rotoidal pairs 29 and 30.

[0048] According to Griibler’s formula, this articulated polygon 12 would be labile with a number of degrees of freedom equal to nn = 3(m — 1) — 2C — C2= 3 • (6 — 1) - 2 - 6 — 0 = 3. Where m = 6 is the number of members of the mechanism, C1= 6 is the number of kinematic pairs of class “1”, and C2= 0 is the number of kinematic pairs of class “2”. In order to make the structure isostatic, it is constrained by three load cells 40, 41 and 42.

[0049] The installation of the three load cells 40, 41 and 42 is preferably carried out by means of ball joints, and isostatically constrains the articulated mechanism 12.

[0050] Due to such characteristics, only those components of the resultant of the forces which belong to the plane X-Y and the component of the resulting moment about the axis Z are read by the three uniaxial force sensors. All the other components are transmitted to the frame 20, and hence to the structure of the wheelchair 1, through the articulated mechanism 12. Moreover, the special configuration of the mechanism that supports the handle 11 makes the measurements of the load cells 40-42 more accurate by decoupling the readings.

[0051] In point of fact, a force applied to the handle 11 along the axis Y will be measured as the sum of the forces read by the load cells 41 and 42, and a force applied to the handle 11 along the axis X will be recorded by the load cell 40 only, while a moment about the axis ZZ will be read as the difference between the forces read by the load cells 41 and 42 multiplied by half the distance between the axes of the load cells 41 and 42.

[0052] According to a preferred implementation of the invention, in order to guarantee safety of use, the sensorized handle 11 must be able to discern whether the received command has been intentionally issued by the operator or has been caused by an accidental shock undergone by the handle.

[0053] To provide this functionality, the sensorized handle 11 uses a plurality of sensors, preferably contact sensors, integrated in the valleys of the ergonomical gripping zones 13, 14 or 15 of the handle. These sensors 45, 46, . . . . N are used as series switches. It is thus possible to ascertain whether the operator is gripping the handle 11 or not. The control logic will only activate the system if the grips 13 and 14, or 15, are being correctly gripped.

[0054] Figures 5 and 6 show two detailed construction examples of the sensorized handle 11.

[0055] The first construction solution (Fig. 5) is designed for use with both hands on the respective grips 13 and 14, while the second solution is designed for use with just one hand, and is therefore equipped with a single grip 15.

[0056] In both cases, a plurality of contact sensors are installed within the ergonomical grips 13-15. Lastly, the load cells 40-42 and the contact sensors 45 are read by a central microcontroller 18, which then processes such data through suitable mapping functions conceived to facilitate the use of the handle 11.

[0057] One example of the control system 16 of the sensorized handle 11 is shown in the diagram of Figure 7.

[0058] From the above description one can understand how the control device 10 and the associated handle 11 can solve the technical problem addressed by the invention.

[0059] This is due to the fact that the device 10 comprises a sensorized handle 11 for controlling a motorized apparatus 1, which in the example considered herein is a wheelchair, but which may also be a different device, having up to three degrees of freedom.

[0060] In order to avoid those problems which affect peripherals like joystick levers, the sensorized handle 11 measures the forces applied by the operator, which are then converted, through suitable mapping functions, into reference signals for controlling the movements of the motorized system 1.

[0061] The basic idea of the invention is to exclusively use uniaxial force sensors for measuring the forces applied by the user, preferably sensors selected according to their availability and cost. In general, the operator will apply to the handle a force and a moment in space.

[0062] Let us consider a handle for a motorized device with nn (nnE N, nn< 3) degrees of freedom in a plane. For preventing the 6 - nn components of the actions exerted by the user from disturbing the readings of the nn components of interest, the structure of the sensorized handle will be based on a mechanism having nn degrees of freedom. In order to read the nn components of interest, the handle will be equipped with nn uniaxial load cells, installed by means of ball joints to constrain the mechanism isostatically. In this way, the 6 - nn components not of interest will be transmitted to the structure of the mechanism, without affecting the readings of the nn components of interest.

[0063] The invention may be subject to many variations from the example taken into consideration herein.

[0064] For example, the control device may also be used on motorized systems other than the wheelchair 1, such as handling trolleys or lift trucks, floor processing machines (e.g. honing machines, polishing machines), or other similar machinery.

[0065] Applications are also possible for controlling electronic devices, even much smaller than the wheelchair taken into account in the example.

[0066] In this regard, the control device of the invention may be used as a replacement for joysticks in all electronic devices, including gaming devices.

[0067] In such situations, the handle 11 will be gripped with one hand and operated accordingly.

[0068] All such variants will still fall within the scope of the following claims.

Claims

CLAIMS1. Control device (10), in particular for motorized systems (1) having up to three degrees of freedom, such as wheelchairs, handling trolleys, or the like, comprising a handle (11) associated with sensor means (40, 41, 42) for force detection, so that the forces and / or torques applied to the handle (11) by a user can be measured and transformed into reference signals for controlling the motorized system (1), characterized in that it comprises only uniaxial force sensors (40, 41, 42) for measuring the forces applied to the handle (11) by the user.

2. Device according to claim 1, wherein the handle (11) is supported by a mechanism with a number of degrees of freedom (nn), equal to those of the motorized system (1) to be controlled.

3. Device according to claims 1 or 2, wherein the handle (11) is supported by a mechanism (12) with a number of degrees of freedom (nn), which only allow the handle (11) to move in the degrees of freedom of interest.

4. Device according to claim 3, wherein all forces and / or torques applied in directions that are not of interest are transmitted to the structure of the mechanism (12) without altering the readings of the forces applied to the handle (11).

5. Device according to any one of the preceding claims, wherein the handle (11) is supported by a mechanism (12) consisting of an articulated system.

6. Device according to any one of the preceding claims, wherein the force sensors (40, 41, 42) are load cells.

7. Device according to claim 6, wherein the installation of the load cells (40, 41 and 42) is preferably carried out by means of ball joints, and isostatically constrains the articulated mechanism (12).

8. Device according to any one of the preceding claims, wherein the handle (11) is configured substantially like a bar, which is supported at both ends by an articulated system (12), so that it can translate in the horizontal plane defined by the axes X-Y and rotate about the vertical axis Z.

9. Device according to any one of the preceding claims, comprising a frame (20, 31) integral with the structure (2) of the motorized system (1) to be controlled, which is adapted to substantially constitute a constraint for the movements in one direction (X) of the articulated support (12) of the handle (11), where at least one of said uniaxial force sensors (40) is active.

10. Device according to any one of the preceding claims, wherein the articulated system (12) that supports the handle (11) can be composed of members mutually connected by conventional rotoidal pairs or virtual hinges.

11. Device according to any one of the preceding claims, wherein the handle (11) comprises at least one grip or gripping zone (13, 14, 15) where contact sensors (45, 46) are arranged which are adapted to detect when a user is holding the handle (11) and consequently activate the control of the motorized system (1).

12. Device according to any one of the preceding claims, wherein the handle (11) is supported by a mechanism (12) with a number of degrees of freedom (nri), which, if not constrained through the sensors (40,41,42), would only allow the handle (11) to move in the degrees of freedom of interest.

13. Wheelchair comprising a device according to any one of the preceding claims.

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