Device for determining the driver's steering torque

Description

[0001] The invention relates to a device and an associated method for determining the driver steering torque.

[0002] The steering torque, and in particular the driver's steering torque, is a particularly relevant input variable for driver assistance systems in both single-track and dual-track motor vehicles. The driver's steering torque is defined as the torque applied by the driver via the handlebars or handlebars of the motorcycle around the vehicle's steering axis.

[0003] Various methods for determining driver steering torque are known in the state of the art. However, these are mostly designed specifically for two-track motor vehicles and are not applicable to single-track motor vehicles such as motorcycles. For example, for two-track vehicles, the driver steering torque is calculated using physical models and known input variables. This is possible because various dynamic influencing factors, such as body movement of the driver or vehicle occupants, are negligible, which is not the case, however, especially for motorcycles. In addition, the driver's weight, or the ratio of the driver's weight to the vehicle's weight, has a much greater influence on the driving dynamics of motorcycles than in cars.However, these influencing factors, such as weight ratio and body movement, cannot be described using a physical model, or can only be described with great effort, making it impossible or very difficult to determine the driver's steering torque using conventional methods. In addition, other driving dynamics influences relevant to determining the driver's steering torque, such as motorcycle inclination and, for example, a curve radius when cornering, cannot usually be taken into account using the methods known in the state of the art. Known devices for determining the driver's steering torque are predominantly only applicable to two-track vehicles and are optimized for these vehicles or are comparatively expensive.

[0004] Devices for determining steering torque for single-track motor vehicles are known, for example, from documents EP 3 290 318 A1, which discloses all features of the preamble of independent claim 1, JP 2008 068734 A, JP 2011 046342 A, EP 2 436 586 A1, and US 2011 / 239786 A1. Furthermore, document DE 10 2013 220 696 A1 teaches a device by which a force applied axially around a steering rod for controlling the speed of a vehicle can be detected using strain gauges.

[0005] The invention is therefore based on the object of overcoming the aforementioned disadvantages and of providing a device and an associated method for determining the steering torque on single-track motor vehicles, by means of which the steering torque can be determined cost-effectively and with little space requirement.

[0006] This object is achieved by the combination of features according to patent claim 1.

[0007] According to the invention, a device for determining steering torque on a single-track motor vehicle is proposed. The device comprises a handlebar mounted for rotation about a steering axis, a fork bridge mounted for rotation about the steering axis, and a coupling device arranged between the handlebar and the fork bridge and connected to them. The coupling device is designed to transmit a steering movement directed about the steering axis from the handlebar to the fork bridge. Furthermore, a grip section is provided on the handlebar, into which a steering force causing the steering movement can be introduced, wherein the steering force is applied to the grip section in particular by the vehicle driver or the driver of the single-track motor vehicle.Between the grip section of the handlebar and the fork bridge, a deformation measuring element is provided on the handlebar, which is designed to measure a deformation of the handlebar to determine the steering torque, wherein the handlebar or the coupling device forms a hollow space at least in sections and the deformation measuring element is arranged on an inner side of the handlebar or the coupling device facing the hollow space.

[0008] The steering torque introduced by the steering force leads to a minimal, invisible deformation of the steering rod, which can, however, be measured by the deformation measuring element.

[0009] The positioning of the deformation measuring element is crucial, as it allows only deformations that directly correlate with the rider's steering torque to be determined. Both the deformations and the rider's steering torque are caused by the steering forces applied to the grip section. Interference can occur on components located downstream of the grip section, such as the fork legs, in the direction of force flow from the grip sections, which can distort the measurement. If multiple fork clamps are present, the deformation measurement should be performed in front of the topmost fork clamp, which is located farthest away from any potential interference.In addition, deformation measurements at free ends, for example at the free ends of the handlebar, or at force-free sections, for example on the handlebar between two handlebar clamps, do not lead to any usable measurement result, which is why the measurement must be carried out by the deformation measuring elements between the handle section and the coupling device or along a force flow from the handle section to the fork bridge.

[0010] An advantageous further development provides for a deformation measuring element to be provided along each force flow path that transmits the steering movement from the handlebar to the fork bridge. In order to determine the driver's steering torque from the measured deformation, there must be no undetectable force shunts or force tributaries that would prevent unknown components of the forces or the deformation caused by the forces from being recorded.

[0011] An advantageous variant of the device provides that the deformation measuring element comprises at least one strain gauge.

[0012] A further advantageous embodiment is one in which the deformation measuring element comprises four strain gauges arranged to form a full bridge, which are arranged to measure the strain in one plane or along one direction. The bridge circuit is preferably implemented using active strain gauges.

[0013] A full bridge for measuring strain in a plane is understood here to be a bridge circuit in which preferably two first strain gauges are connected in series, which are arranged in parallel with two second series-connected strain gauges on a voltage source. A change in resistance at the strain gauges caused by strain is detected by a voltage measurement between the series-connected strain gauges, and the strain and compression or deformation is calculated from the measured voltages. Furthermore, the series-connected strain gauges are arranged on opposite surfaces of a component, so that when the component is deformed, two strain gauges can detect a strain and two strain gauges a compression.

[0014] Due to the arrangement on opposite surfaces, the strain and compression on both sides of the component are measured. With knowledge of the component properties and appropriate calibration, the acting force can be determined and, from the force together with the position of the deformation measuring element on the component, the steering torque can be determined.

[0015] The full bridge with four preferably active strain gauges, which measure the strain along one direction or in one plane, has the advantage that temperature influences, which can distort the measurement, and mechanical interference are compensated as best as possible.

[0016] In order to measure exclusively the deformation resulting from the driver's steering torque and subsequently infer the driver's steering torque, an advantageous development of the device provides that the deformation measuring element is designed to measure the deformation of the handlebar in a single plane. In the single plane or along the single direction in which the deformation measurement is performed, the respective component on which the measurement is performed is deformed exclusively by the steering torque, so that the magnitude or value of the steering torque can be inferred from the deformation.

[0017] Preferably, the deformation measuring element is configured and aligned on the handlebar to measure the deformation of the handlebar in a steering plane orthogonal to the steering axis. According to the invention, the handlebar or the coupling device forms a cavity at least in sections. The deformation measuring element is arranged on an inner side of the handlebar or the coupling device facing the cavity.

[0018] A first particularly advantageous embodiment of the device provides that the coupling device has at least one handlebar clamping device designed as a support for the handlebar, with which the handlebar is fixed directly to the fork bridge. A deformation measuring element is arranged between each handlebar grip section and a nearest handlebar clamping device on the handlebar. A steering force acting on the handle section and the steering torque acting about the steering axis can be determined from the deformation of the handlebar measured by the respective deformation measuring element.

[0019] Preferably, the deformation or strain is detected by the deformation measuring element at two positions arranged symmetrically to each other around the steering axis in order to be able to detect asymmetric loads and to be able to determine steering forces from a difference between the forces acting on both sides.

[0020] A further aspect of the invention relates to a method for determining the steering torque using a device according to the invention. In the method, the deformation of the handlebar or the coupling device is measured by the deformation measuring element, and the steering torque acting about the steering axis is determined from the measured deformation and a position of the deformation measuring element on the handlebar or the coupling device.

[0021] The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

[0022] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. They show: Fig. 1 shows a first embodiment of a device for determining steering torque; Fig. 2 shows a second embodiment of a device for determining steering torque; Fig. 3 shows a third embodiment of a device for determining steering torque;

[0023] The figures are schematic examples. Like reference numerals in the figures indicate like functional and / or structural features.

[0024] The Figures 1 to 3 Each shows a different design variant of the device, which depends in particular on the structural design of the single-track vehicle and the steering force transmission. Figures 1 to 3 The variants shown do not correspond to the device according to the invention.

[0025] At the Figure 1 In the embodiment shown, the handlebar 10 is fixed directly to the fork bridge 30 by two handlebar clamping devices 22, so that the coupling device 20 in the Figure 1shown variant is essentially formed by the two handlebar clamping devices 22. The handlebar clamping devices 22, which are spaced apart along the longitudinal axis X of the handlebar 10, divide the handlebar 10 into three sections: a section on the left and right in the image plane, each of which is adjacent to a clamping device 22, and a central section located between the two clamping devices 22. At the free ends of the handlebar 10 along its longitudinal axis X, a handle with a handle section 11 is arranged, which are intended to transmit steering forces from the driver to the handlebar 10. Steering forces introduced into the handle sections 11 together lead to a steering torque about the steering axis Z via the lever determined by the handlebar 10. The handlebar 10 transmits the steering forces, resulting in an elastic and reversible deformation of the handlebar 10 that is imperceptible to the driver.In the steering plane, which is orthogonal to the steering axis Z and corresponds to the image plane in the illustration shown, the handlebar 10 has a central neutral fiber and a tensile and a compressive fiber on its outer circumference, wherein the deformation on the outer circumference or on the tensile and compressive fibers can be measured in the form of an extension or compression. In order to be able to measure a deformation of the handlebar 10 due to a steering force applied to the grip section 11, a deformation measuring element 40 is arranged between the grip section 11 and the coupling device 10 or the handlebar clamping device 22 closest to the respective grip section 11.In order to be able to determine the actual steering force and the resulting driver steering torque in the case of an asymmetrical steering force application, for example a steering force on only one handle section 11, or in the case of supporting forces, for example with forces directed in the same direction on the handle sections 11, two symmetrically arranged deformation measuring elements 40 are provided in the embodiment shown. The deformation measuring element 40 is formed by four strain gauges connected to form a full bridge, two of which are provided on a first surface and two on an opposite second surface of the handlebar 10, wherein the surfaces are each arranged orthogonally to the steering plane, so that a strain and a compression can be measured by two strain gauges at a time. In the embodiment shown in . Figure 1In the embodiment shown, the steering axis Z is determined by an axis 32, about which the fork bridge 30 with the fork legs 31 fixed thereto and the handlebar 10 fixed by the handlebar clamping devices 22 can be rotated or steered.

[0026] In Figure 1An exemplary loading case is shown in which a first steering force F1 is applied to a handle section 11 and a second steering force F2 is applied to an opposite handle section 11. The steering forces F1, F2 deform the handlebar 10 minimally, so that the longitudinal axis X or the neutral fiber of the handlebar 10 is deformed, shown greatly exaggerated, into a new longitudinal axis X' or new neutral fiber. As a result, an elongation of the tensile fiber and a compression of the compression fiber can be measured at the deformation measuring elements 40. From the measured values, the position of the deformation measuring elements 40 on the handlebar 10, the dimensions and arrangement of the handlebar 10 and the steering axis Z can be used to determine the driver's steering torque as well as the steering forces F1, F2.

[0027] At the Figure 2In the embodiment shown, the coupling device additionally comprises a handlebar bridge 21, to which the handlebar 10 is fixed with two handlebar clamps 22, as well as two coupling rods 23. The coupling rods 23 connect the handlebar bridge 21 to the fork bridge 30, wherein the steering movement from the handlebar bridge 21 or the handlebars 10 is transmitted to the fork bridge 30 via the coupling rods 23. The embodiment corresponds schematically, for example, to the structure of a Duolever front wheel suspension. In an ideal system in which the coupling rods 23 transmit the steering movement without play, a deformation measuring element 40 can alternatively be provided on only one of the coupling rods 23, wherein in the embodiment shown, a deformation measuring element 40 is provided on each coupling rod 23. The steering bridge 21 is mounted so as to be rotatable about the steering axis Z, whereby no steering moments can be transmitted via the bearing, so that the steering forces orRider steering torques can be transmitted exclusively through the coupling rods 23 to the fork bridge 30 and the fork legs 31 attached thereto or to the front wheel. The coupling rods 23 experience compression and / or expansion due to the transmitted steering forces or rider steering torques, which are measured by deformation measuring elements 40. Since the coupling rods 23 also move depending on spring movements of the chassis or the fork bridge, the plane in which the measurement takes place also shifts, so that in the case of the in . Figure 2In the embodiment shown, the deformation measurement does not take place in a plane orthogonal to the steering axis. However, since the coupling rods 23 only transmit steering torques and, for example, supporting forces on the handlebar sections 11 are compensated by the mounting of the handlebar bridge 21 or opposing forces, the steering forces and the resulting driver steering torque can be determined by measuring the compression and expansion of the coupling rods 23.

[0028] The two coupling rods 23 correspond to a schematic representation and can, for example, also be two connected wishbones arranged between the handlebar bridge and the fork bridge or fork and transmitting the handlebar movements. In a design with two wishbones, one or two deformation measuring elements 40 can be arranged on only one of the wishbones.

[0029] Figure 3illustrates another alternative embodiment of a device for determining the steering torque. The steering forces are transmitted from the steering bridge 21 in the form of the driver's steering torque to an axle 32 that determines the steering axis Z, which also corresponds to an axle rod 24 belonging to the coupling device 20. The driver's steering torque leads to a deformation on the axle rod 24 in the form of a torsion, which can be detected by a deformation measuring element 40 arranged on the axle rod 24, so that the driver's steering torque can be determined from the measured torsion.

[0030] The Figures 1 to 3 each show different embodiments of a device for determining the driver's steering torque, whereby the variants can be combined at least partially to increase accuracy. For example, on the handlebars 10 of the Figures 1 and 2 shown design variants each have deformation measuring elements 40 corresponding to the design variant of the Figure 1 be provided to determine the driver steering torque by two different measurements and thus exclude measurement errors, increase error tolerance and achieve higher measurement accuracy.

Claims

1. Device for determining the steering torque on a single-track motor vehicle, comprising a handlebar (10) rotatably mounted about a steering axle (Z), a fork bridge (30) rotatably mounted about the steering axle (Z), and a coupling device (20) which is arranged between the handlebar and the fork bridge and is connected to them, wherein the coupling device (20) is designed to transmit a steering movement, which is directed about the steering axle (Z), from the handlebar (10) to the fork bridge (30), on the handlebar (10) a gripping portion (11) is provided in which a steering force (F1, F2) causing the steering movement can be introduced, characterized in that between the gripping portion (11) of the handlebar (10) and the fork bridge (30), a deformation measuring element (40) is provided on the handlebar (10), said deformation measuring element being designed to measure a deformation of the handlebar (10) for determining the steering torque, wherein the handlebar (10) or the coupling device (20) at least in sections forms a cavity, and the deformation measuring element (40) is arranged on an inside of the handlebar (10) or of the coupling device (20), the inside facing the cavity.

2. Device according to the preceding claim, wherein a deformation measuring element (40) is provided along each force flux path transmitting the steering movement from the handlebar (10) to the fork bridge (30).

3. Device according to either of the preceding claims, wherein the deformation measuring element (40) comprises at least one strain gauge.

4. Device according to the preceding claim, wherein the deformation measuring element (40) comprises four strain gauges which are arranged to form a full bridge and are arranged to measure the strain in a plane.

5. Device according to any one of the preceding claims, wherein the deformation measuring element (40) is designed to measure the deformation of the handlebar (10) or of the coupling device (20) in a single plane.

6. Device according to any one of the preceding claims, wherein the deformation measuring element (40) is designed and aligned with the handlebar (10) or the coupling device (20) to measure the deformation of the handlebar (10) in a steering plane lying orthogonally to the steering axle (Z).

7. Device according to any one of the preceding claims, wherein the coupling device (20) has at least one handlebar clamping device which is designed as a support of the handlebar and with which the handlebar (10) is fixed directly to the fork bridge (30), wherein a deformation measuring element (40) is arranged between each gripping portion (11) of the handlebar (10) and a nearest handlebar clamping device on the handlebar (10), and a steering force (F1, F2) acting on the gripping portion (11) and the steering torque acting about the steering axle (Z) can be determined from a deformation of the handlebar (10) measured by the respective deformation measuring element (40).

8. Method for determining the steering torque with a device according to any one of the preceding claims, wherein the deformation of the handlebar (10) is measured by the deformation measuring element (40), and the steering torque acting about the steering axle (Z) is determined from the measured deformation and a position of the deformation measuring element (40) on the handlebar (10) or on the coupling device (20).