NL2015695B1 - A laser scanner vehicle for mapping the surrounding environment of said vehicle during a travelled route, as well as a corresponding method. - Google Patents

Abstract

A laser scanner vehicle for mapping the surrounding environment of said vehicle during a travelled route, said vehicle comprising a global positioning system arranged for providing positioning data by determining an absolute geographical position of said vehicle during said travelled route, an inertial navigation system arranged for providing inertial data by determining a relative position, relative orientation and/or relative velocity of said vehicle during said travelled route, at least three separate laser scanner devices, each of which arranged to provide laser data by laser scanning said surrounding environment of said vehicle during said travelled route and by determining direction information and distance information of individual points in said surrounding environment, a computer system for mapping the surrounding environment of said laser scanner vehicle using said positioning data, said inertial data and said laser data, wherein said computer system is further arranged to detect, in real-time, abnormalities in said inertial data by comparing a geographical position of said vehicle obtained by only said provided positioning data with a geographical position of said vehicle obtained by only said provided inertial data.

Description

Title: A laser scanner vehicle for mapping the surrounding environment of said vehicle during a travelled route, as well as a corresponding method.

Description

The present invention relates to a laser scanner vehicle for mapping the surrounding environment of said vehicle during a travelled route.

Conventionally, a laser scanner vehicle comprises a global positioning system arranged for providing positioning data by determining an absolute geographical position of said vehicle during said travelled route, an inertial navigation system arranged for providing inertial data by determining a relative position, relative orientation and/or relative velocity of said vehicle during said travelled route and a laser scanner device arranged to provide laser data by laser scanning said surrounding environment of said vehicle during said travelled route and by determining direction information and distance information of individual points in said surrounding environment.

The obtained positioning data, inertial data and the laser data is then used for mapping the surrounding environment of the vehicle during its route travelled.

One of the drawbacks of the known laser scanner vehicle is that the construed map of the surrounding environment does not accurately resemble the actual surrounding environment. That is, as the different aspects of the laser scanner vehicle all, inherently, have certain inaccuracies which all add up and lead to a degree of inaccuracy of the construed map of the surrounding environment which is not acceptable.

It is therefore an object of the present invention to provide for a laser scanner vehicle which is able to more accurately construe a map of the surrounding environment.

The object is achieved in that the invention, in a first aspect, provides in a laser scanner vehicle for mapping the surrounding environment of said vehicle during a travelled route, said vehicle comprising: a global positioning system arranged for providing positioning data by determining an absolute geographical position of said vehicle during said travelled route; an inertial navigation system arranged for providing inertial data by determining a relative position, relative orientation and/or relative velocity of said vehicle during said travelled route; at least three separate laser scanner devices, each of which arranged to provide laser data by laser scanning said surrounding environment of said vehicle during said travelled route and by determining direction information and distance information of individual points in said surrounding environment, a computer system for mapping the surrounding environment of said laser scanner vehicle using said positioning data, said inertial data and said laser data, wherein said computer system is further arranged to detect, in realtime, abnormalities in said inertial data by comparing a geographical position of said vehicle obtained by only said provided positioning data with a geographical position of said vehicle obtained by only said provided inertial data.

It was the insight of the inventors that the inaccuracies of the map of the surrounding environment are at least made clear in case abnormalities in the inertial data are detected. The inventors found that the abnormalities can be detected by comparing the geographical position of the vehicle obtained by only the provided positioning data with a geographical position of the vehicle obtained by only the provided inertial data.

That is, the computer system is able to detect abnormalities caused by the inertial navigation system using the positioning data provided by the global positioning system.

As defined above, the inertial navigation system is arranged to provide relative differences in position, orientation and/or velocity of the vehicle. Based on an arbitrary, but known, starting position, the position of the vehicle can be determined using the inertial navigation system only. As the starting position is known and based on the relative information provided by the inertial navigation system, the geographical location of the vehicle can be determined at any position without assistance from the global positioning system. The determined position using the inertial navigation system only, as explained above, can then be compared with the position determined only by the global positioning system. In case the difference between the two above reference positions exceeds a certain predetermined threshold, it is assumed that abnormalities in the inertial data exist.

In the context of the present invention, a global positioning system is a space-based navigation system that provides location and time information anywhere on the Earth where there is an unobstructed line of sight to at least three Global Positioning System satellites.

The inertial navigation system is a system based on the relative position, relative orientation and/or relative velocity of the vehicle. The inertial navigation system may use motion sensors, for example in the form of accelerometers, and rotation sensors, for example in the form of gyroscopes, to continuously determine the position, orientation and/or velocity of a moving object. Other term often used to refer to inertial navigation systems or closely related device include inertial guidance system, inertial instrument, inertial measurement units, etcetera.

The laser scanner devices are arranged to send a laser beam in a certain direction and to receive a reflected laser beam to determine the distance to a certain point or object. In the present case, each of the laser scanner devices are arranged to send laser beams in any direction in a single plane. Typically the actual laser scanner rotates very quickly within the plane, i.e. having a rotating axis perpendicular to that plane, such that the laser beam exiting the scanner also rotates about the same rotating axis. As, according to the invention, at least three separate laser scanner devices are used, a three dimensional map of the surrounding environment of the vehicle can be construed.

In an embodiment of the invention, the computer system is further arranged to output, in real-time, any detected abnormalities in said inertial data such that a driver of said vehicle is made aware of inaccuracies in said mapped surrounding environment during said travelled route.

The advantage hereof is that the driver is notified that the provided inertial data is not correct, such that the driver can travel that same route, or a part of the route, again. The driver can, for example, decide to only travel that part of the route in which it was indicated that the abnormalities in the inertial data existed.

In a further embodiment, the route is travelled at least three times, and said computer system is further arranged to determine height levels of said vehicle during each travelled route based on said provided inertial data, and wherein, for determining said mapped surrounding environment, an average of said determined height levels is taken into account.

The same route may be travelled, for example, six or seven times. Each time the route is travelled, the height level of the vehicle, and thus also the height level of the road, is determined. The six or seven determined height levels are averaged in order to obtain a single accurate value of the height level of the road along the route.

The inventors further found that not all of the six or seven determined height levels should be taken into account. It may be the case that at least one of these determined height levels differs a lot from the other determined height levels. This deviating determined height level may simply be based on erroneously based inertial data. In such a case, that specific determined height level may be ignored and only the other determined height levels are taken into account for establishing the average height level.

In another embodiment, the computer system is further arranged to detect road surface markings in said mapped surrounding environment, and said computer system is arranged to horizontally align said positioning data, said inertial data and/or said laser data based on said detected road surface markings.

The inventors found that it may be beneficial to use road markings for aligning purposes as road markings are typically always present on a road. As such, the probability that the obtained positioning data and inertial data are correctly aligned to one another is improved.

Here, the computer system may also be arranged to determine a quality of said detected road markings by determining reflection coefficients of said detected road surface markings on said travelled route using said laser data.

Conventionally, the quality of road markings is determined based on images captured by conventional cameras, and image processing of said images. The process is typically cumbersome and costs a lot of time. The inventors found that the quality of the road markings may also be determined using the laser scanner vehicle. The reflection coefficient of each of the laser beams send to road markings is a measure for the actual quality of the road markings. As such, a driver only needs to travel a certain road once to determine the quality of each of the road markings present on that route.

The computer system may also be arranged to determine surface areas of said detected road surface markings in said mapped surrounding environment.

The advantage hereof is that this information may be used for, for example the government, determining how much paint or the like is to be reserved for repainting the road markings.

In another embodiment, the computer system is further arranged to detect deformations in the road during said travelled route using said inertial data, wherein said deformations are any of surface milling, rutting and road subsidence.

In a second aspect, there is provided a method for mapping the surrounding environment of a vehicle during a travelled route using a laser scanner vehicle according to any of the previous claims, said method comprising the steps of: travelling said route by said vehicle; during said route, providing said positioning data by said global positioning system, during said route, providing said inertial data by said inertial navigation system, providing laser data by laser scanning said surrounding environment of said vehicle during said travelled route using said at least three separate laser scanner devices, mapping, by said computer system, said surrounding environment of said laser scanner vehicle using said positioning data, said inertial data and said laser data, and detect, in real-time, abnormalities in said inertial data by comparing a geographical position of said vehicle obtained by only said provided positioning data with a geographical position of said vehicle obtained by only said provided inertial data.

In an embodiment hereof, the route is travelled at least three times, and wherein said method further comprises the steps of: determining height levels of said vehicle during each travelled route based on said provided inertial data, and wherein said step of mapping said surrounding environment comprises: mapping said surrounding environment based on an average of said determined height levels.

In a further embodiment, the method further comprises the steps of: detecting, by said inertial navigation system, at least one bump in said route and providing said inertial data comprising data related to said detected at least one bump; detecting, by said computer system, abnormalities in said provided inertial data related to said detected at least one bump by laser scanning, by at least one of said at least three laser scanner devices, an position of said detected at least one bump.

The basic idea behind this embodiment is that the inertial navigation system is able to detect bumps in the road by the relative position change of the vehicle. That is, a bump will cause a sudden vertical displacement of the vehicle which is tracked by the inertial navigation system. At least one of the three laser scanner devices can then, subsequently, double check whether the inertial navigation system has detected the bump correctly. To do so, the at least one laser scanner device can laser scan the bump detected by the inertial navigation system. The computer system assumes that the bump is actually present in the road in case the at least one laser scanner device is also able to detect that same bump. An abnormality is detected in the provided inertial data in case the at least one laser scanner device is not able to detect that same bump. In such a case, it is assumed that the inertial data is faulty.

As such, the laser scanner devices are arranged to correct, or at least indicate, faulty inertial data.

The expressions, i.e. the wording, of the different aspects comprised by the laser scanner vehicle according to the present invention should not be taken literally. The wording of the aspects is merely chosen to accurately express the rationale behind the actual function of the aspects.

In accordance with the present invention, different aspects applicable to the above mentioned examples of the vehicle, including the advantages thereof, correspond to the aspects which are applicable to the method, according to the present invention.

The above-mentioned and other features and advantages of the invention will be best understood from the following description referring to the attached drawings. In the drawings, like reference numerals denote identical parts or parts performing an identical or comparable function or operation.

The invention is not limited to the particular examples disclosed below in connection with a particular type of laser scanner vehicle.

Figure 1 is an overview of a laser scanner vehicle according to the present invention.

Figure 2 discloses a same overview of the laser scanner vehicle as in figure 1 but it includes a visualisation of the laser beams.

Figure 3 is rear view of a laser scanner vehicle according to the present invention.

Figure 4 discloses certain aspects of the laser scanner vehicle according to the present invention in more detail.

Figure 1 is an overview of a laser scanner vehicle 1 for mapping the surrounding environment of the vehicle 1 during a travelled route. The vehicle 1 may be any type of vehicle 1 such as a car, bus, etc.

The vehicle 1 comprises a global positioning system (GPS), the antenna of which is referenced to with reference numeral 4, which global positioning system is arranged for providing positioning data by determining an absolute position of said vehicle 1 during the travelled route.

The antenna 4 is in connection with a couple of different satellites for determining its location. In accordance with the present invention, the location of the vehicle 1 is determined. In more detail, the location of any of the aspects of the vehicle 1, or an imaginary point coupled to the vehicle 1 may be determined.

An inertial navigation system 8 is provided, which is arranged for providing inertial data by determining a relative position, relative orientation and/or relative velocity of the vehicle 1 during the travelled route.

The inertial navigation system 8 uses, for example, accelerometers to determine whether the vehicle 1 is accelerating or de-accelerating. The relative position of the vehicle 1 can then be determined using this information. The system 8 further uses gyroscopes to determine the orientation, angular position, or attitude of the vehicle 1, i.e. how it is placed on the road.

The embodiment shown in figure 1 comprises three separate laser scanner devices 2, 3, of which only two are visible. A first laser scanner device 2 is placed in such a way that the laser beams 2a sent from that first laser scanner device 2 are directed differently from the laser breams 3a, 11a sent from the second laser scanner device 3 and the third laser scanner device 11.

Each of the laser scanner devices 2, 3, 11 is arranged to provide laser data by laser scanning the surrounding environment of the vehicle 1 during the travelled route and by determining direction information and distance information of individual point in the surrounding environment.

That is, the laser scanning devices 2,3,11 are arranged to transmit a laser beam in a particular direction, and to receive a reflected beam in that same direction. Based on the time difference between the transmitted laser beam and the received reflected laser beam a distance to a certain object can be determined.

The energy received from the reflected laser beam may be used to determine the material type of the object. Based on the received energy, and the determined distance, a reflection coefficient may be established which is a measure for the type of material of the object. As such, the computer system according to the present invention may also determine whether the object is the road, a tree, a lamppost, another car, etc. A computer system 5 is comprised in the vehicle 1, which computer system 5 is arranged for mapping the surrounding environment of the laser scanner vehicle 1 using the positioning data, the inertial data and the laser data.

One of the aspects of the present invention is that the computer system 5 is arranged to detect, in real-time, abnormalities in the inertial data by comparing a geographical position of the vehicle 1 obtained by only the provided positioning data with a geographical position 4 of the vehicle 1 obtained by only the provided inertial data. A concrete example hereof is explained in more detail below.

Assume that the vehicle 1 is actually travelling a certain route. The global positioning system is arranged to determine, in a continuous matter, the actual geographical position of the vehicle 1. Over time, the geographical position of the vehicle 1 changes as the vehicle 1 is travelling, i.e. riding, over the road. The inventors found that the actual geographical position of the vehicle 1 may also be calculated using the inertial navigation system 8 only.

That is, the geographical position of the vehicle, for example determined by the global positioning system 4, may be used as an input to the inertial navigation system 8. Based on such an initial position, the inertial navigation system 8 is able to update that position, over time, using information from the accelerometers only. This updated position is then compared with an actual position of the vehicle 1 determined by the global positioning system 4 only. In case the accelerometers were operating accurately, and in case the global positioning system was working accurately, the position determined by the inertial navigation system and the position determined by the global positioning system should match. In case these two determined positions do not match, or differ too much, it is concluded that an abnormality is detected.

The inventors found that a time period of 1 - 5 seconds, more preferably 1 - 3 seconds, is efficient for determining whether the inertial data from the inertial navigation system is “drifting” away from the positioning data from the global positioning system, or whether inertial data from the inertial navigation system can not be fully trusted. As such, the real-time character of the claim is actually in the order of a couple of seconds.

In addition to the above, the laser scanner vehicle 1 may comprise a camera 6 for capturing images in a 360 degree view from the vehicle 1. These captured images do not need to be used to map the surrounding environment. However, these images may be useful to double check the data from the laser scanner devices 2, 3, 11, or to supplement the data from the laser scanner devices 2, 3, 11. For example, the computer system 5 may be arranged to determine that some sort of pole is present besides the road. What kind of pole it exactly is, may then be derived from images captured from the camera 6. As the camera is able to provide visual, colored, images which may thus contribute to the mapped surrounding environment as established by the laser scanner vehicle 1.

One of the advantages of the laser scanner vehicle 1 according to the present invention is that the computer system is able to accurately determine, and recognize, objects in the surrounding environment. For example, the computer system may detect, recognize, guardrails, exits, trees, bicycle paths, bumps in roads, emergency lanes, etc. Based on the detected, recognized, objects, and their corresponding location, the computer system may automatically provide warning signals. For example, in case a tree trunk is oriented too close to the road, the computer system may issue a warning signal indicating that there is a possible safety issue.

Figure 2 discloses a same overview of the laser scanner vehicle as in figure 1 but it includes a visualisation of the laser beams. Here, it is shown that the laser beams 3 are comprised in a single plane. As such, the second laser beam 3 is able to detect any object in that single plane. The laser beams may, for example, have a frequency of 100 Hz or the like, such that every 1 /100th of a second a complete scan in that single plane is made.

Figure 3 is rear view of a laser scanner vehicle according to the present invention. Here it is made clear the laser beams 3a, 11a from the second laser device 3 and the third laser device 11 are directed differently.

Figure 4 discloses certain aspects of the laser scanner vehicle 1 according to the present invention in more detail. The inventors found that the antenna 4 of the global positioning system should be placed on the highest point of the vehicle 1 such that the likelihood that accurate data from the satellites is received is improved.

It will be clear to those skilled in the art, that the invention is described above by means of several embodiments. However, the invention is not limited to these embodiments. The desired protection is defined by the appended claims.

Claims (10)

A laser scanner vehicle for imaging the surrounding environment of the vehicle during a traveled route, the vehicle comprising: - a global positioning system adapted to provide positioning data by determining an absolute geographic position of the vehicle during the traveled route; - an inertia navigation system adapted to provide inertia data by determining a relative position, relative orientation and / or relative speed of the vehicle during the traveled route; - at least three separate laser scanner devices, each of which is adapted to provide laser data by laser scanning the surrounding environment of the vehicle during the traveled route and by determining the direction information and distance information of individual points in the surrounding environment, - a computer system for imaging surrounding environment of the laser scanner in the vehicle using the positioning data, the inertia data and the laser data, in which the computer system is further adapted to detect, in real-time, abnormalities in the inertia data by comparing a geographical position of the vehicle obtained by only the provided positioning data with a geographical position of the vehicle obtained by only the provided inertia data. A laser scanner vehicle according to claim 1, wherein the computer system is further adapted to perform, in real time, detected abnormalities in the inertia data such that a driver of the vehicle has become aware of imperfections in the depicted surrounding environment during the traveled route. A laser scanner vehicle according to any one of the preceding claims, wherein the route is traveled at least three times, and wherein the computer system is further adapted to determine height levels of the vehicle during each route traveled based on the inertia data provided, and wherein, for determining the surrounding environment depicted, an average of the determined elevation levels is taken into account. A laser scanner vehicle according to claim 3, wherein the computer system is further adapted to detect road surface markings in the surrounding environment depicted, and wherein the computer system is adapted to horizontally align the positioning data, the inertia data and / or the laser data based on the detected data road surface markings. The laser scanner vehicle according to claim 4, wherein the computer system is adapted to determine a quality of the detected road markings by determining reflection coefficients of the detected road surface markings on the traveled route using the laser data. A laser scanner vehicle according to any of claims 4 and 5, wherein the computer system is further adapted to determine surface areas of the detected road surface markings in the surrounding environment depicted. A laser scanner vehicle according to any one of the preceding claims, wherein the computer system is further adapted to detect deformations in the road during the traveled route using the inertia data, wherein the deformations are one of surface milling, track formation and road subsidence. A method of imaging the surrounding environment of a vehicle during a traveled route using a laser scanner in a vehicle according to any of the preceding claims, which method comprises the steps of: - traveling the route through the vehicle; - provide the positioning data by the global positioning system during the route, - provide the inertia navigation system during the route, - provide laser data from the surrounding environment of the vehicle during the route using the at least three separate routes laser scanner devices, - imaging, by the computer system, of the surrounding environment of the laser scanner vehicle using the positioning data, the inertia data and the laser data, and - detecting, in real-time, abnormalities in the inertia data by comparing a geographical position of the vehicle obtained by only the provided positioning data with a geographical position of the vehicle obtained by only the provided inertia data. A method for imaging the surrounding environment according to claim 8, wherein the route has been traveled at least three times, and wherein the method further comprises the steps of: - determining height levels of the vehicle during each route traveled based on the provided route inertia data, and wherein the step of imaging the surrounding environment comprises: - imaging the surrounding environment based on an average of the determined elevation levels. A method of imaging the surrounding environment according to any of claims 8 to 9, wherein the method further comprises the steps of: - detecting, by the inertia navigation system, at least one bump in the route and providing the inertia data comprises data related to the detected at least one bump; - detecting, by the computer system, abnormalities in the provided inertia data related to the detected at least one hump by laser scanning, by at least one of the at least three laser scanner devices, of a position of the detected at least one hump.