A drive system for rotating a first device relative to a second device about an axis of rotation.

Abstract

A drive system for a vehicle that rotates a first device relative to the vehicle about a rotation axis (2). The system includes a support (3), a support (6) that is movable relative to the first support (3), and a piezoelectric element (7) fixed to the second support (6), with the second support (6) and / or the piezoelectric element (7) fixed to the first device (D1). The system further includes a friction surface (4) and at least one tip (8) fixed to the piezoelectric element (7). The piezoelectric element (7) is configured to impart movement to the tip(s) (8) when a voltage is supplied to the piezoelectric element (7). The tip(s) (8) are configured such that one end of the tip (8) contacts the friction surface (4) during at least a portion of the movement to enable relative movement between the first support (3) and the second support (6) about the rotation axis (2).

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates to the orientation of a vehicle device, and more particularly to an apparatus for changing the orientation of a vehicle device relative to the vehicle. [Background technology]

[0002] When driving a vehicle, the vehicle's attitude may change, for example due to the roughness of the ground on which the vehicle is traveling or as a result of driving phases such as braking, accelerating or turning.

[0003] However, some optical devices mounted on a vehicle, such as headlights or sensors, are sensitive to this change in attitude.

[0004] For example, a vehicle's headlights usually illuminate the area the vehicle is facing, and when the vehicle changes attitude, the headlights, which follow the change in attitude, may illuminate areas other than the area the vehicle is facing.

[0005] The same is true for autonomous vehicles. An autonomous vehicle corresponds to a vehicle that can travel without the intervention of a driver. Typically, autonomous vehicles are equipped with sensors that detect obstacles on the path to travel safely. In general, the larger the detection angle of the sensor, the shorter the detection distance. The detection distance must allow the autonomous vehicle to detect obstacles early enough to avoid them when moving at normal speed. For example, at speeds of 80km / h to 90km / h, the required detection distance can be 100m to 300m. To achieve this detection distance, sensors such as LIDAR (Laser Detection and Ranging) sensors have a detection angle of 2° to 3°. The direction of orientation must therefore be accurate to allow the detection of possible obstacles. During vehicle travel on rough roads or during driving phases that change the vehicle's attitude, the detection orientation of the sensor may change, thereby affecting the detection of obstacles. For this reason, it is necessary to correct the detection orientation of the sensor so that it remains stable regardless of the roughness of the road and the driving phase. Correcting the orientation may require an accuracy of only 1 / 100th of a degree.

[0006] Actuators exist that can correct the orientation of the device, however these actuators are imprecise and bulky. Summary of the Invention [Problem to be solved by the invention]

[0007] The aim of the present invention is to overcome these drawbacks by proposing a system that allows correcting the orientation of the sensor with sufficient precision. [Means for solving the problem]

[0008] To this end, the invention relates to a drive system for rotating a first device for a vehicle relative to a second device integrated in the vehicle about an axis of rotation.

[0009] According to the invention, the system comprises at least - a first support; - a friction surface; - a second support movable relative to the first support; - a piezoelectric element fixed to a second support, the second support and / or the piezoelectric element being fixed to the first device, - further comprising at least one tip secured to the piezoelectric element; The piezoelectric element is configured to impart movement to the tip when a voltage is supplied to the piezoelectric element, and the tip is configured such that one end of the tip contacts the friction surface during at least a portion of the movement to enable relative movement between the first support and the second support about the axis of rotation.

[0010] Thus, the system is capable of obtaining relative rotational motion with an accuracy of one hundredth of a degree as a result of a dynamic and compact drive system.

[0011] In one embodiment, the first support remains fixed relative to the vehicle whilst the second support rotates about an axis of rotation.

[0012] In another embodiment, the second support remains fixed relative to the vehicle while the first support rotates about the axis of rotation.

[0013] Additionally, the system includes at least one position sensor configured to measure a relative angle between the first support and the second support.

[0014] Also, at least one tip has a first end fixed to the piezoelectric element and a second end, and the friction surface and the axis of rotation are separated by a fixed distance such that a torque generated by a friction force caused by contact of the second end of the tip on the friction surface corresponds to a torque required for relative motion to have a predetermined speed and a predetermined acceleration when the second device is fixed to the first support and the first device is fixed to the second support.

[0015] Advantageously, the system further comprises at least one stopper fixed to the first support, the stopper being configured to limit relative movement of the second support with respect to the first support.

[0016] Further, the friction surface has a shape including a cylindrical cross-section having a pivot axis parallel to the rotation axis, the pivot axis and the rotation axis being coincident, the tip is a rigid tip, the friction surface is fixed to the first support, the piezoelectric element is configured to impart periodic elliptical motion to a second end of the rigid tip when a voltage is supplied to the piezoelectric element, and the rigid tip is configured such that the second end periodically contacts the friction surface during at least a portion of the elliptical motion to enable relative motion between the first support and the second support about the rotation axis.

[0017] The invention also relates to an equipment unit for a vehicle.

[0018] According to the present invention, the sensor unit comprises: - a drive system as defined above; - a first device; - a control module configured to supply a voltage to the piezoelectric element, wherein the second device corresponds to a part of the vehicle, and the signal is a function of a control command received by the control module.

[0019] According to a first embodiment, the first device includes a sensor.

[0020] According to one embodiment, the sensor is a LIDAR.

[0021] According to a second embodiment, the first device comprises a headlight.

[0022] According to a third embodiment, the first device includes an image acquisition module.

[0023] The invention also relates to a vehicle, in particular an autonomous vehicle, equipped with an equipment unit as described above.

[0024] The invention, its features and advantages will become more apparent upon reading the description and upon reference to the accompanying drawings, in which: [Brief description of the drawings]

[0025] [Figure 1] FIG. [Diagram 2] FIG. 2 is a top view of the drive system with the first support and the second support in a first relative position. [Diagram 3] FIG. 13 is a top view of the drive system with the first support and the second support in a second relative position. [Figure 4a] FIG. 3 is a schematic enlarged view of FIG. 2. [Figure 4b] FIG. 4 is a schematic enlarged view of FIG. [Diagram 5] 1 is a schematic front view of a vehicle having a vehicle equipment unit including a drive system; [Figure 6] 1 is a schematic diagram of a drive system with a fixed first device for a vehicle and a second device integrated in the vehicle; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] 1 to 3 show a drive system 1.

[0027] The drive system 1 is arranged to rotate a first device D1 for a vehicle VH about a rotation axis 2 relative to a device D2 integrated with the vehicle VH.

[0028] The device D1 may correspond to an optical device or an orientable device.

[0029] According to a first embodiment, the device D 1 includes a sensor 13 .

[0030] According to a second embodiment, the device D1 comprises a vehicle headlight (headlamp).

[0031] According to a third embodiment, the device D1 comprises an image acquisition module.

[0032] The drive system 1 comprises a support 3 intended to be fixed to a device D2 and a support 6 intended to be fixed to a device D1. The support 3 and the support 6 are each capable of rotating about a rotation axis 2. Figure 6 is a schematic diagram of the devices D1 and D2 fixed to the respective supports 3 and 6.

[0033] The drive system 1 can be configured to rotate the support 3 relative to the support 6 about the axis of rotation 2. The drive system 1 can also be configured to rotate the support 6 relative to the support 3 about the axis of rotation 2.

[0034] The drive system 1 also includes a friction surface 4 having the shape of a cylindrical cross section with a pivot axis 5 substantially parallel to the axis of rotation 2 .

[0035] According to one variant, the pivot axis 5 and the rotation axis 2 can substantially coincide.

[0036] According to another variant, the pivot axis 5 is close to the axis of rotation 2. Without being limiting, by the pivot axis close to the axis of rotation it is meant that the distance between the pivot axis 5 and the axis of rotation 2 is equal to or less than 2 mm.

[0037] The friction surface 4 can be fixed to the support 3. The cylindrical shape of the cylindrical part of which the friction surface 4 is formed corresponds to a straight cylinder. The friction surface 4 can correspond to the inner surface of a part of a tube in the form of a cross section of a straight cylinder.

[0038] The actuator 1 further comprises a piezoelectric element 7 fixed to the support 6 and at least one tip 8. The tip(s) 8 have an end 91 fixed to the piezoelectric element 7 and an end 92 (Figures 4a and 4b).

[0039] The tip 8 may have the shape of a rod having an end 91 and an end 92 .

[0040] When a voltage is applied to the piezoelectric element 7, the piezoelectric element 7 is configured to impart a periodic elliptical motion to the end 92 of the tip(s) 8 by the inverse piezoelectric effect.

[0041] The piezoelectric element may have a generally rectangular shape.

[0042] A voltage is supplied to the piezoelectric element 7 via the electrodes 10 .

[0043] When a particular voltage is applied to the electrodes 10, vibrations occur according to a primary longitudinal vibration mode, in which the piezoelectric element 7 periodically expands and contracts along its longitudinal axis. In addition, vibrations occur according to a secondary transverse vibration mode, which has the effect of bending the piezoelectric element in a direction perpendicular to the longitudinal axis of the piezoelectric element. The combination of the two vibration modes can cause the entire piezoelectric element to vibrate, producing a periodic elliptical motion of the end 92 of one or more tips 8. The particular voltage has a frequency that can be substantially equal to the resonant frequency of the piezoelectric element 7.

[0044] The tip(s) 8 are configured such that end(s) 92 periodically contact the friction surface 4 during at least a portion of the elliptical motion. This contact of end(s) 92 of tip(s) 8 on friction surface 4 can result in relative motion between support 3 and support 6 about axis of rotation 2 through friction of end(s) 92 of tip(s) 8 on friction surface 4 (fixed to support 3). Advantageously, tip(s) 8 are hard tip(s) 8.

[0045] According to a first embodiment, the support 3 can remain fixed relative to the vehicle VH while the support 6 rotates about the rotation axis 2. According to a second embodiment, the support 6 can remain fixed relative to the vehicle VH while the support 3 rotates about the rotation axis 2.

[0046] The drive system 1 advantageously includes at least one position sensor (not shown) configured to measure the relative angle between the support 3 and the support 6 .

[0047] The friction surface 4 and the rotation axis 2 are separated by a distance D (FIG. 2). The distance D is the friction force caused by the contact of the end 92 on the friction surface 4. The torque generated by TIFF0007664901000001.tif6150 is defined to correspond to the torque required for the relative motion to have a predetermined speed and a predetermined acceleration when device D2 is fixed to support 3 and device D1 is fixed to support 6 (Figures 4a and 4b).

[0048] Therefore, the drive system 1 has a mechanism with no play between the two supports 3 and 6, thereby achieving high accuracy on the order of one hundredth of a degree. Furthermore, the drive system 1 occupies a small area and can be easily incorporated into an on-board system in the vehicle VH.

[0049] The drive system 1 may also include at least one stopper 11 fixed to the support 3. The stopper or stoppers 11 are configured to limit the relative movement of the support 6 with respect to the support 3.

[0050] For example, the drive system includes a single stopper 11 that limits the relative movement between the support 6 and the support 3 in one direction of relative movement. The drive system can also include two stops 11 that limit the relative movement between the support 6 and the support 3 in two opposite directions of relative movement.

[0051] The invention also relates to an equipment unit 14 for a vehicle VH.

[0052] The device unit 14 is - a drive system 1; a device D1, a control module 16 configured to supply a voltage to the piezoelectric element 7.

[0053] Thus, device D2 corresponds to part 17 of vehicle VH.

[0054] According to a first embodiment, the device D1 includes a sensor 13 for the autonomous vehicle VH (FIG. 5). The sensor 13 may be configured to detect obstacles likely to be present on the path of the vehicle VH. The sensor 13 may correspond to a LIDAR.

[0055] According to a second embodiment, the device D1 comprises a vehicle headlight (headlamp).

[0056] According to a third embodiment, the device D1 includes an image acquisition module, such as a camera. The camera may be a passive camera.

[0057] The control module 16 makes it possible to control the piezoelectric element 7 as a function of control commands received by the control module 16 .

[0058] The control commands are determined to predict changes in the attitude of the vehicle VH such that the attitude of the device D1 remains stable despite changes in the attitude of the vehicle VH. The control commands are determined, for example, by a computer on board the vehicle VH. The control commands are determined, for example, on the basis of current data relating to the driving phases of the vehicle VH and current data acquired by sensors characterizing the environment of the vehicle VH. The drive system 1 is thus a dynamic system which takes into account the behavior of the vehicle VH.

[0059] The invention also relates to a vehicle VH comprising at least one equipment unit 14. The orientation of the device(s) D1 of the vehicle VH can be corrected using a drive system 1 of the equipment unit 14 as a function of the road roughness or the driving phase. [Explanation of symbols]

[0060] 1. Drive system 2 Rotation Axis 3 Support 4 Friction surface 5 Swivel Axis 6 Support 7 Piezoelectric element 8 Tip 10 electrodes 11 Stopper

Claims

1. A drive system for rotating a first device (D1) for a vehicle relative to the vehicle about a rotation axis (2), comprising at least a first support (3), a second support (6) movable relative to said first support (3); a piezoelectric element (7) fixed to said second support (6), wherein the second support (6) and / or the piezoelectric element (7) are fixed to the first device (D1), and the drive system comprises: - a friction surface (4), at least one tip (8) fixed to said piezoelectric element (7); the piezoelectric element (7) is configured to impart a movement to the tip (8) when a voltage is supplied to the piezoelectric element (7), the tip (8) being configured such that one end of the tip (8) contacts the friction surface (4) during at least a portion of the movement to enable relative movement between the first support (3) and the second support (6) about the axis of rotation (2); the friction surface (4) has a shape including a cylindrical cross-section with a pivot axis (5) parallel to the rotation axis (2), the friction surface (4) corresponds to the inner surface of a portion of a tube in the form of a cross-section of a right cylinder, the friction surface (4) is fixed to the first support (3), the piezoelectric element (7) is configured to impart a periodic elliptical motion to a second end (92) of the tip (8) when a voltage is supplied to the piezoelectric element (7), the tip (8) is configured such that the second end (92) periodically contacts the friction surface (4) during at least a portion of the elliptical motion to enable a relative motion between the first support (3) and the second support (6) about the rotation axis (2). A system characterized by:

2. the first support (3) remains fixed relative to the vehicle (VH) while the second support (6) rotates about the rotation axis (2), The system of claim 1 .

3. the second support (6) remains fixed relative to the vehicle (VH) while the first support (3) rotates about the rotation axis (2); The system of claim 1 .

4. at least one position sensor configured to measure the relative angle between the first support (3) and the second support (6), The system of claim 1 .

5. The at least one tip (8) has a first end (91) fixed to the piezoelectric element (7) and a second end (92), the friction surface (4) and the rotation axis (2) are separated by a distance (D), and a friction force generated by the contact of the second end (92) of the tip (8) on the friction surface (4) is corresponds to a torque required for the relative movement to have a predetermined speed and a predetermined acceleration when the second device (D2) of the vehicle is fixed to the first support (3) and the first device (D1) is fixed to the second support (6), The system of claim 1 .

6. and at least one stopper (11) fixed to the first support (3), the stopper (11) being configured to limit the relative movement of the second support (6) with respect to the first support (3). The system of claim 1 .

7. The pivot axis (5) and the rotation axis (2) are coincident, and the tip (8) is configured to be a hard tip (8). The system of claim 1 .

8. A vehicle equipment unit, comprising at least: - a drive system (1) according to any one of claims 1 to 7, a first device (D1), a control module (16) configured to supply a voltage to said piezoelectric element (7); a second device (D2) corresponding to a part (17) of the vehicle (VH), the signal being a function of a control command received by the control module (16), A unit characterized by:

9. The first device (D1) includes a sensor (13), A unit as claimed in claim 8.

10. The sensor (13) is a LIDAR. A unit as claimed in claim 9.

11. said first device (D1) comprising a headlight, A unit as claimed in claim 8.

12. said first device (D1) comprising an image acquisition module; A unit as claimed in claim 8.

13. Equipped with at least one equipment unit (14) according to any one of claims 8 to 12, A vehicle characterized by:

Images