TECHNICAL FIELD

The invention relates to a vehicle which comprises a downward facing sensor. The invention also relates to a method performed by a control unit for processing measurement data from a downward facing sensor of a vehicle and/or for controlling the vehicle, a control unit, a computer program and a computer readable medium.

The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. Although the invention will be described with respect to a truck trailer, the invention is not restricted to this particular vehicle, but may also be used in other vehicles such as work machines, for example dump trucks, wheel loaders, excavators etc.

BACKGROUND

Modern vehicles are typically equipped with different kinds of driver assistance systems. For example, commercial vehicles may use systems for localizing the vehicle when reversing towards a stop position, such as a docking station, ledge, or any other position where the vehicle needs to stop with high precision. The localizing of the vehicle with respect to the stop position may for example be done by use of a Global Navigation Satellite System (GNSS). As another example, an ultrasonic sensor system may be used for determining a distance to the stop position.

Such systems may also be used for autonomous or semi-autonomous vehicles, where the localizing may be used as input to an automatic motion control system of the vehicle.

Even though the above-mentioned systems can be used for localizing a vehicle with respect to a stop position, there is still a strive to develop further improved technology for such purpose, or at least to develop a suitable alternative and/or complement for providing redundancy.

SUMMARY

In view of the above, an object of the invention is to provide an improved vehicle which enables the vehicle to stop at a stop position with high precision, or at least to provide a suitable alternative/complement to already known technology. Another object of the invention is to provide an improved method performed by a control unit for processing measurement data from a downward facing sensor of a vehicle and/or for controlling the vehicle, or at least to provide a suitable alternative/complement to already known technology.

According to a first aspect, at least one of the objects is achieved by a vehicle according to claim 1. Thus, there is provided a vehicle which extends in a height direction, a longitudinal direction and a transverse direction, the vehicle comprising:

- a downward facing sensor which is configured to measure a height distance from the sensor to a ground surface supporting the vehicle,

- a control unit configured to compare the measured height distance with a predefined reference distance, wherein the predefined reference distance represents a reference height indicative of a predefined height distance from the sensor to a ground surface supporting the vehicle.

The height direction, the longitudinal direction and the transverse direction are perpendicular to each other. For example, the directions may be defined according to x, y and z directions in a Cartesian coordinate system. The flat extending surface is defined by a plane which extends in the longitudinal and the transverse direction of the vehicle.

The measured height distance may in one example embodiment be referred to as a vertical distance, as seen when the vehicle is provided on a flat horizontally extending surface.

By the provision of the vehicle as disclosed herein, the vehicle will be possible to stop at a specific stop position with high precision. More specifically, the present invention is based on a realization that it is advantageous to measure the height distance as disclosed herein to thereby be able to determine when a change in height is occurring which is indicative of the stop position. Thereby, when a change in height is determined, the vehicle can be allowed or prompted to stop. The use and implementation of a downward facing sensor as disclosed herein further implies a robust and cost-efficient configuration.

Optionally, the reference height represents an installation height of the sensor with respect to a flat extending surface when the vehicle is supported on the flat extending surface. Comparing the measured height distance with a reference height which represents the sensor’s installation height implies a reliable, robust and efficient comparison, e.g. it may require less processing power.

Optionally, the reference height represents a previously measured height distance to the ground surface measured by the sensor.

Optionally, the vehicle extends in the longitudinal direction between a front end and a rear end of the vehicle, wherein the sensor is associated with one of the ends. Being associated with one of the ends implies that the sensor is adapted to be used for allowing the associated end of the vehicle to be stopped at, or close to, the stop position.

Optionally, the vehicle comprises an outermost set of ground engaging means with respect to the end which the sensor is associated with, and the sensor is configured to measure the height distance at a ground surface position which is provided outside of the outermost set of ground engaging means, as seen in the longitudinal direction. This implies that the vehicle more easily can be allowed or prompted to stop before the outermost set of ground engaging means reaches a non-drivable portion of the ground surface, such as a hole or a ledge.

Optionally, the sensor is adapted so that the ground surface position is further provided inside of the end which the sensor is associated with, as seen in the longitudinal direction. Preferably, the sensor is adapted so that the ground surface position is further provided inside of the end which the sensor is associated with, as seen when the vehicle is provided on a flat extending surface. By conducting the height measurement in an area delimited by the outermost set of ground engaging means and the end which the sensor is associated with, as seen in the longitudinal direction, a reliable and efficient measurement can be conducted. This implies that the vehicle can be allowed to stop before the outermost set of ground engaging means reaches a non-drivable portion of the ground surface, such as a hole or a ledge. Thus, the vehicle is allowed to stop with high precision.

Optionally, the vehicle comprises an overhang portion extending in the longitudinal direction between the outermost set of ground engaging means and the end which the sensor is associated with, wherein the sensor is mounted on a downward facing surface of the overhang portion. Thereby, the sensor may be efficiently protected from debris, rain, snow, sun-glare etc. Accordingly, this implies a more robust configuration.

Optionally, the sensor is adapted so that the ground surface position at which the sensor is configured to measure the height distance is provided a predefined longitudinal distance from a ground surface contact point of the set of ground engaging means. Thereby, for example, the predefined longitudinal distance, together with other vehicle state information, such as vehicle speed, may be used to determine a required brake torque for stopping the vehicle before the set of ground engaging means reaches a non- drivable portion of the ground surface.

Optionally, the predefined longitudinal distance is at least 0.5 m.

Optionally, the predefined longitudinal distance is less than 5 m, such as less than 4 m, 3.5 m, 3 m, 2.5 m, or 2 m.

Optionally, the control unit is further configured to control the vehicle to drive at a maximum allowed vehicle speed so that the vehicle can stop within a maximum stopping distance which is equal to or smaller than the predefined longitudinal distance. Thereby, the ground engaging means can be efficiently prevented from reaching a non-drivable area.

Optionally, the control unit is further configured to issue a warning signal and/or to automatically stop the vehicle when the comparison of the measured height distance with the predefined reference distance indicates a difference therebetween which fulfils a predetermined condition. This implies that the vehicle can be allowed or prompted to stop with high precision before reaching a non-drivable portion of the ground surface.

Optionally, the predetermined condition comprises at least one of a maximum and a minimum threshold value, wherein the maximum threshold value represents a height distance from the sensor to the ground surface which is larger than the predefined reference distance and the minimum threshold value represents a height distance from the sensor to the ground surface which is smaller than the predefined reference distance. Still optionally, the maximum threshold value is indicative of a downhill slope or hole with respect to the ground surface and the minimum threshold value is indicative of a protruding portion from the ground surface, such as a ledge, or an uphill slope.

For example, the maximum threshold value and/or the minimum threshold value may be used during a reversing operation of the vehicle, wherein the warning signal is issued and/or the vehicle is automatically stopped when the comparison of the measured height distance with the predefined reference distance indicates a difference therebetween which fulfils the predetermined condition.

A vehicle as used herein may be a vehicle comprising a propulsion unit, but it may also be a vehicle without any propulsion unit, such as a trailer. According to one example embodiment, the vehicle is a vehicle combination comprising a towing vehicle and at least one connected trailer.

According to a second aspect of the invention, at least one of the objects is achieved by a method according to claim 12. Thus, there is provided a method performed by a control unit for processing measurement data from a downward facing sensor of a vehicle and/or for controlling the vehicle, wherein the vehicle extends in a height direction, a longitudinal direction and a transverse direction, and wherein the downward facing sensor is configured to measure a height distance from the sensor to a ground surface supporting the vehicle. The method comprises:

- obtaining a measured height distance from the sensor, and

- comparing the measured height distance with a predefined reference distance, wherein the predefined reference distance represents a reference height indicative of a predefined height distance from the sensor to a ground surface supporting the vehicle.

Advantages and effects of the second aspect of the invention are analogous to the advantages and effects of the first aspect of the invention. It shall be noted that all embodiments of the second aspect of the invention are combinable with all embodiments of the first aspect of the invention, and vice versa.

Optionally, the reference height represents an installation height of the sensor with respect to a flat extending surface when the vehicle is supported on the flat extending surface. Optionally, the reference height represents a previously measured height distance to the ground surface measured by the sensor.

Optionally, the vehicle extends in the longitudinal direction between a front end and a rear end of the vehicle, wherein the sensor is associated with one of the ends.

Optionally, the vehicle comprises an outermost set of ground engaging means with respect to the end which the sensor is associated with, and wherein the sensor is configured to measure the height distance at a ground surface position which is provided outside of the outermost set of ground engaging means, as seen in the longitudinal direction.

Optionally, the sensor is adapted so that the ground surface position is further provided inside of the end which the sensor is associated with, as seen in the longitudinal direction.

Optionally, the vehicle comprises an overhang portion extending in the longitudinal direction between the outermost set of ground engaging means and the end which the sensor is associated with, wherein the sensor is mounted on a downward facing surface of the overhang portion.

Optionally, the sensor is adapted so that the ground surface position at which the sensor is configured to measure the height distance is provided a predefined longitudinal distance from a ground surface contact point of the set of ground engaging means.

Optionally, the predefined longitudinal distance is at least 0.5 m.

Optionally, the predefined longitudinal distance is less than 5 m, such as less than 4 m, 3.5 m, 3 m, 2.5 m, or 2 m.

Optionally, the method further comprises:

- controlling the vehicle to drive at a maximum allowed vehicle speed so that the vehicle can stop within a maximum stopping distance which is equal to or smaller than the predefined longitudinal distance. Thereby, it can be efficiently prevented that the ground engaging means will reach a non-drivable area. Optionally, the method further comprises:

- issuing a warning signal and/or automatically stopping the vehicle when the comparison of the measured height distance with the predefined reference distance indicates a difference therebetween which fulfils a predetermined condition.

Optionally, the predetermined condition comprises at least one of a maximum and a minimum threshold value, wherein the maximum threshold value represents a height distance from the sensor to the ground surface which is larger than the predefined reference distance and the minimum threshold value represents a height distance from the sensor to the ground surface which is smaller than the predefined reference distance.

Optionally, the maximum threshold value is indicative of a downhill slope or hole with respect to the ground surface and the minimum threshold value is indicative of a protruding portion from the ground surface, such as a ledge, or an uphill slope.

According to a third aspect, at least one of the objects is achieved by a control unit according to claim 24. Thus, there is provided a control unit for controlling a downward facing sensor of a vehicle and/or for controlling the vehicle, wherein the control unit is configured to perform the steps of the method according to any one of the embodiments of the second aspect of the invention.

According to a fourth aspect, at least one of the objects is achieved by a computer program according to claim 25. Thus, there is provided a computer program comprising program code means for performing the steps of the method according to any one of the embodiments of the second aspect when said program is run on a computer, such as on the aforementioned control unit.

According to a fifth aspect, the object is achieved by a computer readable medium according to claim 26. Thus, there is provided a computer readable medium carrying a computer program comprising program code means for performing the steps of the method according to any one of the embodiments of the second aspect when said program product is run on a computer, such as on the aforementioned control unit.

Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

In the drawings:

Fig. 1 is a side view of a vehicle according to an example embodiment of the present invention,

Fig. 2 is a side view of the vehicle as shown in fig. 1 ,

Fig. 3 is a flowchart of a method according to example embodiments of the present invention, and

Fig. 4 is a schematic view of a control unit and a downward facing sensor according to an example embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Fig. 1 depicts a vehicle 1 according to an example embodiment of the present invention. The vehicle 1 as shown is a truck trailer, such as a heavy-duty trailer. It shall however be understood that the invention is not only applicable for such a vehicle, but may advantageously be used for other vehicles, including trucks, buses and construction equipment. In particular, the invention has shown to be useful for commercial vehicles, such as trucks, trailers, vehicle combinations, dump trucks, wheel loaders etc., where it is important to stop the vehicle close to a stop position with high precision. For example, the present invention has shown to be advantageous when unloading or loading a vehicle, such as when dumping material into a pit or when docking with a docking station at a terminal.

The vehicle 1 extends in a height direction h, a longitudinal direction L and a transverse direction w. The vehicle 1 comprises,

- a downward facing sensor 100 which is configured to measure a height distance hi from the sensor 100 to a ground surface GS supporting the vehicle 1 ,

- a control unit 20 (not shown in fig. 1) configured to compare the measured height distance hi with a predefined reference distance href, wherein the predefined reference distance href represents a reference height href indicative of a predefined height distance from the sensor 100 to a ground surface GS supporting the vehicle 1.

In the shown embodiment, the ground surface GS corresponds at least partly to a flat extending surface. In other words, the predefined reference distance href is as shown a distance from the sensor 100 to the flat extending surface GS. Accordingly, the reference height href may represent an installation height of the sensor 100 with respect to a flat extending surface GS when the vehicle 1 is supported on the flat extending surface GS. Alternatively, the reference height may represent a previously measured height distance to the ground surface GS measured by the sensor 100.

The downward facing sensor 100 may be any kind of sensor which can measure a distance from the sensor 100 to a ground surface. By downward facing may herein mean that the sensor 100 can emit a sensor signal and/or receive a reflected sensor signal which has/have a direction being aligned with the height direction h. For example, the downward facing sensor 100 may use light, laser, radio waves, ultrasonic waves or any other sensor technique for measuring the height distance.

Fig. 4 depicts a schematic view of a downward facing sensor 100 and a control unit 20 which are communicatively connected (indicated by a dashed line). The control unit 20 is an electronic control unit and may comprise processing circuitry which is adapted to run a computer program as disclosed herein. The control unit 20 may comprise hardware and/or software for performing the method according to the invention. In an embodiment the control unit 20 may be denoted a computer. The control unit 20 may be constituted by one or more separate sub-control units. In addition, the control unit 20 may communicate with the sensor 100 by use of wired and/or wireless communication means. For example, the control unit 20 may be part of the vehicle 1 as shown in fig. 1. Alternatively, the control unit 20 may be part of another vehicle entity, such as a towing vehicle (not shown) for towing the trailer 1. Still further, even though the control unit 20 preferably is a vehicle onboard control unit 20, it shall be noted that the control unit may additionally or alternatively be a vehicle off-board control unit, such as a control unit being part of a computer cloud system.

The vehicle 1 may extend in the longitudinal direction L between a front end 10 and a rear end 12 of the vehicle 1, wherein the sensor 100 is associated with the rear end 12. Accordingly, the sensor 100 is adapted to be used for allowing the rear end 12 of the vehicle 1 to be stopped at, or close to, a stop position. In an alternative embodiment not shown, the sensor may be associated with the front end 10.

In the shown embodiment, the vehicle 1 comprises an outermost set of ground engaging means 14 with respect to the rear end 12 which the sensor 100 is associated with. The outermost set of ground engaging means 14 are here in the form of wheels. The sensor 100 is configured to measure the height distance hi at a ground surface position GS1 which is provided outside of the outermost set of ground engaging means 14, as seen in the longitudinal direction L. In the shown embodiment, the sensor 100 is located between the rear end 12 and the outermost set of ground engaging means 14.

As further shown, the sensor 100 may be adapted so that the ground surface position GS1 is further provided inside of the rear end 12, as seen in the longitudinal direction L. Thereby, the height distance hi will be measured in an area delimited by the outermost set of ground engaging means 14 and the rear end 12. In the shown embodiment, the downward facing sensor 100 is substantially directed downwardly in the height direction h of the vehicle 1. As such, for example, when the vehicle 1 is provided on a flat horizontally extending surface, the sensor 100 may be substantially directed downwardly in a vertical direction h, such as ±5 degrees with respect to the vertical direction h.

The vehicle 1 comprises an overhang portion 16 extending in the longitudinal direction L between the outermost set of ground engaging means 14 and the end 12 which the sensor 100 is associated with, wherein the sensor 100 is mounted on a downward facing surface 160 of the overhang portion 16. Thereby, the sensor 100 will be protected from e.g. debris, rain, snow, sun-glare etc. during use. According to an example embodiment, the downward facing surface 160 may be denoted a bottom surface of the vehicle 1.

The sensor 100 may as shown be adapted so that the ground surface position GS1 at which the sensor 100 is configured to measure the height distance hi is provided a predefined longitudinal distance L1 from a ground surface contact point 141 of the outermost set of ground engaging means 14. The ground surface contact point 141 is preferably an outermost ground surface contact point 141 being closest to the rear end 12. The predefined longitudinal distance L1 is preferably defined with respect to a flat extending surface when the vehicle 1 is supported by such a surface. Additionally, or alternatively, the sensor 100 may be mounted on the downward facing surface 160 at a mounting position which is provided a predefined longitudinal distance (corresponding to L1 in the shown embodiment) from the ground surface contact point 141 of the outermost set of ground engaging means 14.

For example, the predefined longitudinal distance L1 may be at least 0.5 m. Additionally, or alternatively, the predefined longitudinal distance L1 may be less than 5 m, such as less than 4 m, 3.5 m, 3 m, 2.5 m, or 2 m.

The control unit 20 may further be configured to issue a warning signal and/or to automatically stop the vehicle 1 when the comparison of the measured height distance hi with the predefined reference distance href indicates a difference therebetween which fulfils a predetermined condition.

By way of example, the predetermined condition may comprise at least one of a maximum and a minimum threshold value, wherein the maximum threshold value represents a height distance from the sensor 100 to the ground surface GS which is larger than the predefined reference distance href and the minimum threshold value represents a height distance from the sensor 100 to the ground surface GS which is smaller than the predefined reference distance href.

Fig. 1 depicts a downhill slope 200 at the rear of the vehicle 1. Thus, the maximum threshold value may be indicative of the downhill slope 200 or a hole with respect to the ground surface GS.

Fig. 2 depicts the vehicle 1 as shown in fig. 1 when its rear end 12 is close to a ledge 210. Accordingly, the minimum threshold value may be indicative of a protruding portion from the ground surface GS, such as the ledge 210, or an uphill slope. Fig. 3 depicts a flowchart of a method according to an example embodiment of the invention. The boxes with dashed lines indicates optional steps of the method. The method, performed by a control unit, is a method for processing measurement data from a downward facing sensor of a vehicle and/or for controlling the vehicle.

The vehicle may for example be the vehicle 1 as shown in figs. 1-2.

The method comprises:

S10: obtaining a measured height distance hi from the sensor 100, and

S20: comparing the measured height distance hi with a predefined reference distance href, wherein the predefined reference distance href represents a reference height indicative of a predefined height distance from the sensor 100 to a ground surface GS supporting the vehicle 1.

For example, as mentioned in the above, the reference height href may represent an installation height of the sensor 100 with respect to a flat extending surface GS when the vehicle 1 is supported on the flat extending surface GS. Alternatively, the reference height may represent a previously measured height distance to the ground surface GS measured by the sensor 100.

The method may further comprise:

SO: controlling the vehicle 1 to drive at a maximum allowed vehicle speed so that the vehicle 1 can stop within a maximum stopping distance which is equal to or smaller than the predefined longitudinal distance L1.

Furthermore, the method may further comprise:

S30: issuing a warning signal and/or automatically stopping the vehicle 1 when the comparison of the measured height distance hi with the predefined reference distance href indicates a difference therebetween which fulfils a predetermined condition.

It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.