Control method for self-balancing vehicles and respective self-balancing vehicle

Abstract

The present invention relates to a self-balancing vehicle (1), which uses a gyrostabiliser (5) to keep itself balanced, specifically when the vehicle (1) is stationary or at low speed.

Description

[0001] CONTROL METHOD FOR SELF-BALANCING VEHICLES AND RESPECTIVE SELF-BALANCING VEHICLE

[0002] DESCRIPTION

[0003] Technical field of the invention

[0004] The present invention relates to a control method for self-balancing vehicles such as, for example, Segway® two-wheelers, single-wheeled vehicles or other similar single-axle vehicles and respective self-balancing vehicle.

[0005] Known prior art

[0006] Self-balancing vehicles have been widespread in recent years, both because they are practical and convenient to use and because they facilitate individual transportation in urban areas. The operation of these single-axle vehicles is known and, generally, is based on a control system connected to a series of inertial sensors, such as gyroscopic sensors and / or accelerometers, which are able to detect vehicle's balance with the user on board. When the sensors detect a user's inclination relative to an equilibrium configuration, the control system imparts acceleration to the single-axle vehicle's wheels, which is proportional to the inclination and in the same direction as the inclination. Similarly, when the user decreases the inclination, bringing the center of gravity back toward the equilibrium configuration, the system imparts deceleration. This way, the user can move forward by simply unbalancing his / her weight in the desired forward direction.

[0007] For example, a known type of self-balancing vehicle provides a seat mounted on a platform provided with two side wheels. Two electric motors move the wheels independently. The control system is connected to the wheels and is provided with inertial sensors that allow the machine's balance to be detected. When the user leans forward or backward, the control system reacts by applying torque to the motors, which tends to restore the balanced attitude of the seat. Under normal conditions, the wheels are free to move, consequently, positive or negative acceleration will respectively correspond to the applied torque. This particular type of vehicles is preferably provided with a handlebar and / or a control lever, bywhich the control system can be prompted to perform a steering action through the application of differential torque between the two motors.

[0008] This latter type of vehicle, sometimes referred to as a motorized self-balancing chair, is preferably used to transport people with walking problems, such as for example those with limited or no mobility in their lower limbs, like a wheelchair. These vehicles can indeed allow the user greater freedom of movement, since a forward direction change can occur more quickly and easily than with a conventional wheelchair, and they generally allow a user to keep his / her body in a higher position compared to the ground, than with a conventional wheelchair. The main disadvantage of self-balancing devices is the difficulty in maintaining a stable position when the vehicle is stationary or at low speed. Typically, some sensors detect a vehicle imbalance and correct this imbalance by small movements of the wheels.

[0009] However, especially in case of users with reduced mobility, these corrections can be annoying, especially considering that these users can unintentionally cause the vehicle to continually lose its balance, leading to a continuous need for corrections by the vehicle. In order to avoid this abnormal behavior, in case of stationary vehicle, parking feet are used that rest on the ground and are raised when the vehicle is moved.

[0010] Furthermore, in case of self-balancing motorized wheelchairs for people with even partially reduced mobility in their lower limbs, there is the additional disadvantage that, in the event of uphill or downhill slopes, the vehicle may malfunction, given the difficulty for the user to adequately unbalance him / herself with respect to the vertical line.

[0011] Also, in case of an uneven distribution of masses on the platform, for example due to the presence of a suitcase, this vehicle may not function properly.

[0012] Summary of the invention

[0013] Therefore, the technical problem posed and solved by the present invention is to provide a control method for self-balancing vehicle and respective self-balancing vehicle that allow overcoming the above mentioned drawbacks with reference to the known art.Specifically, object of the present invention is to implement a method for controlling self-balancing vehicles that allows better balancing of the vehicle, specifically when the vehicle is stationary or at low speed, and / or in case of uphill or downhill slopes, which is effective and comfortable for the user.

[0014] These and other objects are achieved by the present invention according to one or more of the attached claims.

[0015] Objects of the present invention specifically are a vehicle and a respective controlling method according to the attached independent claims. Preferred features of the present invention are the subject matter of the dependent claims. In particular, an object of the present invention is a self-balancing vehicle comprising: a base frame, at least one wheel, which can be rotated about a main axis, the main axis being perpendicular to the rectilinear forward direction of the vehicle; inertial sensors connected to said base frame, which are suitable to detect, under condition of use, the angle of inclination of the frame with respect to the ground; at least one motor configured to move and / or brake the vehicle by acting on said at least one wheel; a gyrostabiliser; a central control unit connected to the inertial sensors, to the at least one motor and to the gyrostabiliser. The control unit is configured to operate the gyrostabiliser depending at least on the angle of inclination.

[0016] The gyrostabiliser comprises a flywheel, a container element containing the flywheel configured to allow the rotation of the flywheel within the container element about a first axis of rotation, the container element being hinged on said frame, so as to allow the rotation of the container element about a second axis of rotation with respect to the frame, a first motor device configured to allow the rotation of the flywheel within the container element about the first axis of rotation, and a second motor device configured to rotate the container element about the second axis of rotation. The first axis of rotation is perpendicular to the second axis of rotation and is integral with the rotation of the container element rotating the second axis of rotation, and the second axis of rotation is perpendicular to the main axis.

[0017] In other words, the rotation of the axis of rotation of the flywheel causes torquethat counteracts the vehicle's imbalance, that is, torque opposite to the one which caused a difference between the measured angle and the pre-set angle, so as to keep the two values identical (or at least substantially identical, up to a threshold). This increases the stability of the vehicle, can reduce or prevent vehicle malfunctions in case of uphill or downhill slopes, especially in the case of vehicles suitable for people with reduced mobility, and can allow a vehicle to be made without stabilizing feet.

[0018] According to an aspect, the vehicle comprises exactly two wheels.

[0019] Typically, the two wheels have the same axis of rotation. The axis of rotation of the wheels is perpendicular to the rectilinear forward direction of the vehicle. According to a possible aspect, the control unit is configured to operate the gyrostabiliser depending on the rotation speed of said at least one wheel, in addition to the data obtained from the sensors. For example, the stabilizer can only be used when the device is stationary or at low speed, that is when all the wheels of the device rotate at a speed lower than a certain threshold. The rotation speed can be measured directly (for example, by encoders or the like), or indirectly, for example, by checking the control given by the motor to the wheels themselves. As discussed, the stabilizer preferably acts when the vehicle is stationary or at low speed, and / or in case of uphill or downhill slopes, as well as in case additional masses are present other than that of the user. However, using the gyrostabiliser also during normal vehicle movement, so as to assist self-balancing functions thereof, is not excluded.

[0020] According to a possible aspect, the container element has a substantially spherical shape.

[0021] According to another possible aspect, the second motor element rotates the container element by means of a pinion-rack system, and the rack is arranged on the outer surface of the container element.

[0022] According to a further possible aspect, the vehicle comprises at least one seat integral with the base frame.

[0023] According to a possible aspect, the vehicle comprises at least one control handlebar integral with the base frame.The present invention also relates to a controlling method for a self-balancing vehicle according to one or more of the preceding aspects, comprising the following steps: a) detecting, by means of inertial sensors, the angle of inclination of the frame with respect to the ground; b) by means of the control unit, comparing the value of the angle of inclination detected with respect to the value of a pre-set angle; c) when the detected angle of inclination differs from the preset angle, operating the gyrostabiliser by rotating the flywheel about said first axis of rotation and rotating the container element about the second axis of rotation, so as to create a gyroscopic torque suitable to rotate said vehicle about the main axis so as to reduce or cancel the difference between the value of the detected angle of inclination and the pre-set value.

[0024] Other advantages, characteristics and ways of using the present invention will be evident from the following detailed description of some embodiments proposed for illustrative and non-limiting purpose.

[0025] Brief description of the figures

[0026] Reference will be made to the figures of the attached drawings, in which:

[0027] ■ Figure l is a side view of a vehicle according to an embodiment of the present invention;

[0028] ■ Figure 2 is a perspective view of the lower portion of a vehicle according to an embodiment of the present invention;

[0029] ■ Figure 3 is a perspective view of a gyrostabiliser usable in embodiments of the present invention;

[0030] ■ Figure 4 is a plan and partial sectional view of the gyrostabiliser of figure 3;

[0031] ■ Figures 5a and 5b are simplified figures of the rotation of the gyrostabiliser container element of Figure 3 under condition of use.

[0032] The thicknesses and curvatures depicted in the figures set forth above should be intended as purely illustrative and not necessarily shown to scale.

[0033] Detailed description of preferred embodiments

[0034] A vehicle 1 according to the invention comprises a base frame 2 and at least one wheel 20, typically two wheels 20, mounted to the frame so as to be rotatableabout a main axis MA.

[0035] The main axis MA is perpendicular to the rectilinear forward direction D of the vehicle 1, considered under condition of use of the device.

[0036] The device further comprises inertial sensors S connected to the base frame 2, which are suitable to detect, under conditions of use, the angle of inclination (a) of the frame 2 itself with respect to the ground.

[0037] Inertial sensors S for detecting the inclination a of the vehicle 1, such as gyroscopes and accelerometers, are known in the art and are not discussed in detail here. Such inertial sensors S, shown only schematically in the figures, are configured to detect the angle of inclination a of the frame 2 with respect to the ground G, or in any case with respect to a horizontal axis (considered under condition of use). Specifically, the angle a measures the rotation of the base frame 2 about the main axis MA. Generally, an angle of inclination a of 0° defines a perfectly horizontal condition of the base frame 2.

[0038] Generally, any convention can be chosen for measuring the angle a, and specifically any convention for defining when the angle a is equal to 0. For example, the angle of inclination can be measured with respect to a vertical axis. However, as discussed, typically an angle a equal to 0 denotes a condition in which the base frame 2 is horizontal, in use, or however is in the desired position for the base frame 2 when the vehicle 1 is stationary.

[0039] The vehicle 1 also comprises at least one motor M configured to move and / or brake the vehicle 1. Motors M configured to this purpose are known in the art and are not discussed in detail here.

[0040] The vehicle 1 can thus brake by the action of the motor M but it can also be provided with additional braking devices, for example acting on the wheels, so as to reduce, and if necessary cancel, the forward speed of the vehicle 1.

[0041] As discussed, the vehicle 1 preferably comprises two wheels 20. In this case it is preferable to have two motors M, i.e. one motor M for each wheel 20, which can be controlled independently of the other motor M.

[0042] In the figures, for simplicity’s sake, only one motor M is shown schematically, although the preferred embodiment shown herein has two distinct motors.Preferred motors M are electric motors.

[0043] The vehicle 1 also comprises a gyrostabiliser 5 and a central control unit CPU connected to the inertial sensors, to the at least one motor M and to the gyrostabiliser 5. Typically, the central control unit CPU is able to detect, directly or indirectly, the rotation speed of the wheels and / or the speed of the forward motion of the vehicle.

[0044] The central control unit CPU is typically a logic control unit known in the art and not described in detail here.

[0045] Note that the term “connected” means that the control unit CPU can send and / or receive signals to and from these elements, for example via cables or wirelessly. The gyrostabiliser 5 comprises a flywheel 51, a container element 52 containing the flywheel 51 and configured to allow the rotation of the flywheel within the container element 51 about a first axis of rotation Al.

[0046] The flywheel 51 is typically, but not necessarily, made of metal material and typically has protrusions 51a, configured to engage within respective seats 52a of the container element 52, so as to act as pivot pins of the flywheel 51 within the container element 52.

[0047] The stabilizer 5 comprises a first motor element Ml typically made at least in part within the container element 52, configured to rotate the flywheel 51 about the first axis of rotation Al.

[0048] The first motor element Ml is preferably configured so as not to contact the flywheel 51, for example by causing the latter to rotate by electromagnetic induction.

[0049] The container element 52 is typically hinged to the base frame 2a, for example to protrusions 21 of the base frame 2a. The container element 52 typically has a substantially spherical shape.

[0050] The container element is thus rotatable with respect to the base frame 2, about a second axis of rotation A2.

[0051] In this regard, the gyrostabiliser 5 comprises a second motor element M2 configured to rotate the container element 52 about the second axis of rotation A2. This second motor element M2 is typically electric. Preferably, the rotation of thecontainer element 52 is controlled by the second motor element M2 by means of a pinion-rack system, in which a rack 521 is arranged on the outer surface of the container element 52, and a pinion 522 is arranged on a rotating shaft 523 of the second motor element M2.

[0052] Using different solutions for rotating the container element 52 is however not excluded. For example, the container element could be connected directly or indirectly (for example by means of reduction gears) to a drive shaft of the second motor element M2. In general, the second motor element M2 is configured to rotate the container element 52.

[0053] Note how the first axis of rotation Al is integral with the container element 5 in its rotation about the second axis of rotation A2, as schematically shown in figures 5a and 5b. In other words, when the container element 5 rotates about the second axis of rotation A2, which in the art is known as the gyroscope precession axis, the first axis of rotation Al of the flywheel 51 rotates about the axis of rotation A2.

[0054] As known from gyroscope theory, since the first and second axes of rotation Al, A2 are perpendicular to each other, this causes torque T on the gyrostabiliser 5 about an axis perpendicular to both axes Al, A2. Since the second axis of rotation A2 is perpendicular to the main axis MA and is parallel to the rectilinear forward direction D, and since the gyrostabiliser 5 is constrained to the base frame 2, the torque is transmitted to the base frame 2, and thus to the vehicle 1. This torque T causes a rotation of the base frame 2, and thus of the vehicle 1, about the main axis MA.

[0055] By exploiting the gyroscope theory, it is thus possible to direct this torque, by selecting the direction of rotation of the flywheel 51 and / or the container element 52, so as to counteract an imbalance of the vehicle 1, i.e. the base frame 2 with respect to the ground G.

[0056] In this regard, the mass of the gyrostabiliser 5, and in particular of the flywheel 51, is sized so that the torque T can effectively balance the vehicle.

[0057] Indeed, the flywheel preferably has mass greater than 3 kg, more preferably 5 kg. The vehicle 1 further preferably comprises a seat 3 and a control handlebar 4 thatare able to allow a user to proceed to move while seated. The control handlebar 4 is constrained to the base frame, as well as the seat 3 is also constrained to the base frame 2.

[0058] It should be noted, however, that even a self-balancing vehicle 1 without a seat would still fall within the scope of protection of the present solution. Different embodiments may provide control elements other than the handlebar 4.

[0059] Thus, in use, the inertial sensors S detect an imbalance of the vehicle 1 about the main axis MA, i.e. detect that the rotation angle a of the base frame with respect to the ground G is different from a pre-set value ao. For example, in reference to the embodiment of the figures, the value of the reference angle ao corresponds to 0°, that is, a condition in which the frame is parallel to the ground. When the value of a is different from 0, the central control unit CPU controls the activation of the gyrostabiliser 5.

[0060] Specifically, while the flywheel 51 is rotating, its axis of rotation Al is rotated about the second axis of rotation A2 so as to generate, on the base frame 2, the torque T being configured so as to take the angle of inclination a back to the preset value ao.

[0061] The control unit can further be programmed so as to set threshold values within which the gyrostabiliser is activated. In other words, the control unit can be programmed so that the gyrostabiliser 5 is activated only when the difference a -ao exceeds a certain threshold value. Similarly, the gyrostabiliser can stop generating the torque T when this difference returns to below a certain threshold value.

[0062] Moreover, the rotation speed of the flywheel and / or the amplitude of rotation of the container element 52 and / or the rotation speed of the container element 52 can be adjusted depending on the difference a - ao, i.e. depending on the unbalance of the vehicle 1, i.e. the inclination of the base frame with respect to the ground. As discussed, the gyrostabiliser 5 can be used to generate the torque T only when the vehicle 1 is stationary, or however moved at low speed.

[0063] Note that a counterclockwise imbalance of the vehicle 1, and therefore the generation of clockwise torque T (considering the orientation shown in thefigures) by means of the gyrostabiliser is shown in the figures, for the sake of simplicity. It is clear, however, how the gyrostabiliser is also able to generate torque in the opposite direction, if necessary.

Claims

CLAIMS1. Self-balancing vehicle (1) comprising:• a base frame (2);• at least one wheel (20), which can be rotated about a main axis (MA), said main axis (MA) being perpendicular to the rectilinear forward direction (D) of the vehicle (1);• inertial sensors (S) connected to said base frame (2), which are suitable to detect, under condition of use, the angle of inclination (a) of said frame (2) with respect to the ground;• at least one motor (M) configured to move and / or brake said vehicle (1);• a gyrostabiliser (5);• a central control unit (CPU) connected to said inertial sensors (S), to said at least one motor (M) and to said gyrostabiliser (5), said central control unit (CPU) being configured to operate said gyrostabiliser (5) depending on at least said angle of inclination (a);wherein said gyrostabiliser (5) comprises a flywheel (51), a container element (52) containing said flywheel (51) configured to allow the rotation of said flywheel (51) within said container element (52) about a first axis of rotation (Al), said container element (52) being hinged on said base frame (2) so as to allow the rotation of said container element (52) about a second axis of rotation (A2) with respect to said base frame (2), a first motor device (Ml) configured to allow the rotation of said flywheel (51) within said container element (52) about said first axis of rotation (Al), and a second motor device (M2) configured to rotate said container element (52) about said second axis of rotation (A2), the first axis of rotation (Al) being perpendicular to said second axis of rotation (A2) and being integral with the container element (52) rotating about the second axis of rotation (A2), said second axis of rotation (A2) being perpendicular to said main axis (MA).

2. Vehicle (1) according to claim 1, comprising exactly two coaxial wheels (20).

3. Vehicle (1) according to claim 1 or 2, wherein said central control unit (CPU) is configured to operate said gyrostabiliser (5) also depending on the rotation speed of said at least one wheel (20) and / or the forward speed of the vehicle (1).

4. Vehicle (1) according to one of the preceding claims, wherein said container element (52) has a substantially spherical shape.

5. Vehicle (1) according to one of the preceding claims, wherein said second motor element (M2) rotates said container element (52) by means of a pinion (522) - rack (521) system, said rack (521) being arranged on the outer surface of said container element (52).

6. Vehicle (1) according to one or more of the preceding claims, comprising at least one seat (3) integral with said base frame (2).

7. Vehicle according to one or more of the preceding claims, comprising at least one control handlebar (4) integral with said base frame (2).

8. Method of controlling a self-balancing vehicle (1) according to one or more of the preceding claims, comprising the following steps:a) detecting, by means of said inertial sensors, the angle of inclination (a) of said frame (2) with respect to the ground;b) comparing, by means of said control unit, the value of said angle of inclination (a) detected with respect to the value of a pre-set angle (ao);c) when said detected angle of inclination (a) differs from said pre-set angle (ao), operating said gyrostabiliser (5) by rotating said flywheel (51) about said first axis of rotation (Al) and rotating said container element (52) about said second axis of rotation (A2), so as to create a torque (T) suitable to rotate said vehicle about said main axis (MA) so as to reduce or cancel the difference between the value of said detected angle of inclination (a) and the value of said pre-set angle (ao).

9. Method according to claim 8, wherein said step c) is carried out only if the rotation speed of said at least one wheel (20) is lower than a pre-set value and / or if the forward speed of the vehicle (1) is lower than a pre-set value.

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