SE537674C2 - Control system for autonomous vehicles, and a method for the control system - Google Patents

Abstract

A control system (2) adapted to control an autonomous vehicle (4) along a planned carriageway, the control system being adapted to receive a friction signal (6) which includes information about the friction in a lane on which the vehicle is to travel, and a speed signal (8) comprising information about the speed of the vehicle v. The control system (2) comprises a processing unit (10) and a control unit (12), the processing unit being adapted to determine a variable safety SM (p, v) relative to the object in the vicinity of the vehicle based on the ground friction and vehicle speed v; and determining a trajectory (14) gets the planned sausage dough so that said determined safety SM is fulfilled. The control unit is further adapted to control the vehicle with a control signal (16) so that the trajectory is failed by affecting at least the steering and speed of the vehicle using a salting control rules, said control rules including a rule taking into account the lateral acceleration ay of the vehicle.

Description

Control system for autonomous vehicles, and a method for the control system Area of the invention The present invention relates to a method and a control system according to the preambles of the independent claims.

More specifically, the invention relates to a method and a control system that improves the safety of autonomous vehicles when raking in slippery surfaces.

Background of the Invention A vehicle that can be driven without a driver on the ground is called an unmanned ground vehicle (UGV). There are two types of ground-going vehicles, those that are remote controlled and those that are autonomous.

A remote-controlled UGV is a vehicle that is regulated by a human operator via a communication link. All actions are determined by the operator based on either direct visual observation or the use of sensors such as digital video cameras. A simple example of a remote-controlled UGV is a remote-controlled toy car. There is a wide variety of remote controlled vehicles in use today. These vehicles are often used in dangerous situations and environments that are unsuitable for people to live in, for example father to disarm bombs and in case of dangerous chemical emissions.

Remote-controlled driverless vehicles are also used in connection with monitoring assignments and the like.

By an autonomous vehicle is meant a vehicle that is capable of navigating and maneuvering without human control. The vehicle uses sensors to gain an understanding of the surroundings. Sensor data is then used by control algorithms to determine what is the next step for the vehicle to take, with regard to an overriding template for the vehicle, for example to pick up and drop off goods at different positions. More specifically, an autonomous vehicle must be able to read the surroundings well enough to be able to carry out the task assigned to it, for example "move the boulders from place A to place B via the mine passage C". The autonomous vehicle needs to plan and follow a route to the selected destination while detecting and avoiding obstacles. vdgen. In addition, the autonomous vehicle must carry out its task as quickly as possible without committing. mistake. Autonomous vehicles have, among other things, been developed to be used in dangerous environments, for example in the defense and war industry and in the mining industry, both above ground and underground. If people or ordinary, manually controlled vehicles change the working range of the autonomous vehicles, they normally cause a break in work due to safety concerns. NI & the work area is free again, the autonomous vehicles can be ordered to resume work. The autonomous vehicle uses information regarding the road, the surroundings and other aspects that affect the travel to automatically regulate the throttle, braking and steering. An accurate assessment and identification of the planned progress is necessary to assess whether a road is passable and is necessary to be able to salt a person's assessment on a successful salt when it is necessary to drive the vehicle. Road conditions can be complex and when driving a normal driver-controlled vehicle, the driver makes hundreds of observations per minute and adjusts the operation of the vehicle based on the perceived road conditions to find, for example, a passable road past objects that may be on. vdgen. In order to be able to replace the human perception with an autonomous system, this means, among other things, being able to perceive objects in an exact way in order to be able to effectively control the vehicle so that one steers past these objects.

The technical methods used to identify an object adjacent to the vehicle include using one or more cameras and radars to create images of the surroundings. Laser technology is also used, both scanning lasers and fixed lasers, to detect objects and measure distance. These bends are often LIDAR (Light Detection and Ranging) or LADAR (Laser Detection and Ranging). In addition, the vehicle is equipped with various sensors, among other things to detect speed and accelerations in different directions. Positioning systems (eg GPS) and other wireless technology can also be used to determine if the vehicle is approaching, for example, an intersection, a narrowing of the road, and / or other vehicles. 2 The regulation of an autonomous vehicle so that it is driven along a planned carriageway takes place essentially by affecting the vehicle's steering and speed, ie. acceleration and deceleration. This is generally done by the vehicle's control system emitting control parameters to various units in the vehicle, for example the engine, the steering, the transmission and the braking systems.

US-2010/0114416 relates to systems and methods for navigating an autonomous vehicle using laser detection and distance measurement.

US-2012/0035788 relates to a navigation and control system for autonomous vehicles and which comprises sensors, for example laser sensors, configured to locate objects in front of the vehicle so that it can be driven without colliding with these objects.

A driver of a truck can adapt his cross salt to the prevailing conditions, if it is slippery you can e.g. Increase the safety distance to other road users and obstacles along the road. A machine is not as good as a human being at adapting to different situations. This means that an autonomous vehicle would either be driven with a year too small so that the vehicle collides, which can occur in particular on slippery surfaces, or be driven with an Or large so that the vehicle sometimes fails to get to the stables where it actually had fan place. The following documents refer to different types of systems and methods in connection with the regulation of vehicles, including in connection with slippery surfaces.

US-2012/0083959 relates to a system and method for autonomous control of a vehicle, with the aim of avoiding wear on various vehicle parts. The regulation is based, among other things, on input signals from two sensors, one sensor senses the impact on different vehicle parts and another sensor detects environment-related quantities, e.g. the presence of objects near the vehicle, temperature, humidity, etc. Then the 3 is selected by a first or a second maneuver which is best concerned with avoiding wear on various vehicle parts.

EP-2407357 describes an autonomous braking system for a vehicle. A sensor device adapted to detect obstacles in the environment of the vehicle, and based on the distance to the vehicle, braking parameters are determined so that the vehicle automatically brakes to avoid the obstacle. To determine the braking parameters, information about the friction against the lane is used and braking parameters for the autonomous braking system are adapted accordingly.

DE-19933782 describes a method for preventing collisions between two vehicles as Mfg in succession. Properties of the lane, such as friction, mats and food values are used to calculate a safety distance to the vehicle behind. If the actual distance is too small, the vehicle accelerates automatically.

The present invention is based on the inventors' observations that for a manned vehicle, a vehicle driver adapts his intersection to radiating road conditions and, for example, distances himself from surrounding traffic in the event of slipping. An autonomous vehicle is not as adaptable and therefore sometimes has an unnecessarily large, or alternatively too small, safety, which means that the performance of the autonomous vehicle on slippery surfaces is not satisfactory.

The general object of the present invention is to improve the ability of an autonomous vehicle to travel on slippery ground.

Summary of the Invention The above objects are achieved by the invention defined by the independent claims.

Preferred embodiments are defined by the dependent claims. According to the present invention, the friction of the substrate is detected and, based on the value of the friction, the autonomous vehicle adapts its position, which means that one can always have a good balance between safety and transport efficiency. The corset is adapted i.a. saw that the speed sank and traffic and obstacles Okas said that the probability of a collision becomes law.

In more detail, this is achieved, according to the invention, by calculating a future sausage path for the vehicle, a so-called trajectory, given, inter alia, measured friction values and a predetermined probability model which indicates the probability that the predetermined sausage path can be followed given at least the said friction value. the predetermined carriage. Based on the probability, the autonomous vehicle is regulated so that the predetermined curve path can be followed higher than a predetermined probability threshold. The purpose of using a probability model is to try to mimic the assessments that a driver of a vehicle continuously makes. According to the model, there are a starting number of cohesive values for, among other things, friction, vehicle speed, the future curve shape of the curve and safety. In applying the invention, it is assumed that the probability threshold is constant independent of the other values.

According to the prior art discussed above, it is possible to feed the friction and then adjust the speed to keep a distance from a vehicle in front, but the present invention aims to allow the vehicle itself to adjust parameters around the regulation in both lateral and longitudinal directions. which causes the autonomous vehicle to be able to be driven where there is slippery ground.

Thus, an improved regulation of slippery surfaces is achieved by the present invention by, among other things, taking into account the lateral acceleration to which the vehicle is subjected in connection with the regulation of the vehicle, and thereby improving the regulation in lateral and longitudinal joints.

By applying the present invention to autonomous driverless vehicles, an optimal balance is achieved between efficiency (speed) and safety (avoidance of accidents) which i.a. is dependent on the friction of the surface, which means that you can influence the future position of the vehicle by specifying a safety feature.

Brief Description of the Drawings Figure 1 is a simplified block diagram schematically illustrating the present invention. Figure 2 is a flow chart illustrating the method of the present invention. Figure 3 is a schematic view intended to illustrate the present invention.

Figure 4 is a schematic block diagram illustrating an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION The invention will now be described in more detail with reference to the accompanying figures.

Referring first to Figure 1, the present invention relates to a control system 2 adapted to control an autonomous vehicle 4 along a planned ridge path.

A planned sausage day is to be regarded as an overarching concept and may, for example, refer to the vagus which the vehicle must follow to get from a point A to a point B. The control system is adapted to receive a friction signal 6 which includes information about the friction on the roadway the vehicle is to be driven on, and a speed signal 8 which includes information about the speed of the vehicle v.

The friction of the path is determined, for example, by optical means by emitting a light beam towards the path and analyzing the reflected light. EP2402737 gives an example of such a feed.

According to another example, to determine the friction of the roadway, a known measuring device is used to analyze the speeds of the wheels for the vehicle 4. By determining the wheel speeds 6 wheels on the same axle and analyzing the difference between them, a mat can be obtained for the friction on the roadway. The detection can also be done by measuring how much driving or braking force is required to drive on the ground.

According to a further example, the vehicle comprises a known feeding device for analyzing a steering torque on the front wheels of the vehicle 4 and comparing this with the threshold value, where a lower torque meant lower friction, ie. en halare vagbana.

The vehicle's speed v is available, for example, on a suitable data bus, where the information is obtained, for example, from the vehicle's speed feeder.

According to the invention, the control system 2 comprises a processing unit 10 and a control unit 12, the processing unit being adapted to determine a variable safety SM (p., V) relative object in the vicinity of the vehicle based on the measured friction and the vehicle speed v. The processing unit 10 is further adapted to determine a trajectory 14 for the planned carriageway so that the said specified safety SM is met.

By trajectory is meant hdr the curve that the vehicle follows on the carriageway, ie. the position on the carriageway that the vehicle will have.

The control unit is adapted to control the vehicle with a control signal 16 so that the trajectory is folded. This is done by influencing at least the control, e.g. the yaw angle of the vehicle, and the speed of the vehicle using a set of control rules, said control rules including a rule that takes into account the lateral acceleration ay of the vehicle.

Of course, the regulation takes into account the extent of the vehicle, ie. its length and width, in relation to the carvage available, e.g. regarding available space on the carriageway (eg the width and curvature of the carriageway). According to one embodiment, said set of control rules comprises a rule which means that the sum of the lateral forces of the front wheels and the rear wheels (F12 and F34) respectively of the vehicle must be equal regardless of the friction value, and that the relationship F12 ± F34 = m * aygaller where m is vehicle mass. This will be explained further below.

The said set of control rules preferably includes a number of equations for station & curry grain (see below).

Thus, according to the invention, a safety SM is calculated based on the speed of the vehicle and the friction of the roadway. Sakerhetsá that the probability, ie. the risk, getting to drive on an obstacle becomes law. Then the trajectory is determined, ie. the calculated future carriageway with a navigable length of the order of up to 100 meters, so that the obstacle is avoided.

Thereafter, control parameters for the vehicle are calculated so that the calculated trajectory falls. Then one takes into account, among other things, a number of generally known equations for station & curry grain, which will be explained below.

These equations show, among other things, how friction affects regulation.

It holds that F12 ± F34 = M * ay,, where F12 is the lateral force on the front wheels, F34 is the lateral force on the rear wheels, ay is the lateral acceleration and m is the mass of the vehicle.

For linear clack, the following also applies: F12 = C '* 12, and F34 = C' * 34 C denotes the coefficient of lateral force and a denotes the drift angle of the respective wheels. 8 This meant that a prerequisite for the vehicle to follow a predetermined trajectory, with the same mass and the same lateral acceleration ay - if the lateral acceleration is directly linked to the curvature of the trajectory and the speed 5 of the vehicle - is that the sum of F12 and F34 must be equal if the friction is law.

In order for F12 and F34 to be equal in case of low friction when the lateral force coefficients go down as much as possible the drift angles Oka, which is achieved by turning the steering wheel more. Thus, the coefficient of friction also enters the step when adjusting the vehicle, including the steering wheel angle, to follow a trajectory.

According to the invention, the calculations are carried out preferably for the speed the vehicle is expected to have at the respective position and if the friction is not sufficiently high to meet the requirement that F12 + F34 must be constant, an estimate must be made of the speed at which the vehicle is able to reach in the current environment and slow down to this value.

The expected speed of the vehicle in a future position is calculated, for example, by always trying to increase the speed as much as the vehicle can handle up to its maximum speed, or to follow speed limits. According to further alternatives, a speed profile can be followed which, for example, is received from a separate module designed to obtain as low fuel consumption as possible.

Another situation that may occur is that there is no possibility of sd. a lot of safety SM requires for the current speed and friction so it results in the speed decreasing.

The vehicle dynamic term drift angle α (also called grinding angle) is the angle between the forward direction of a rolling wheel and the direction in which the wheel points (ie the angle of the vector sum for the wheel speed forward vx and the wheel lateral speed view). 9 The driving angle results in a force that is parallel to the wheel axle and the force component that is perpendicular to the direction of travel of the wheel is called the lateral force of the cornering. This lateral force is largely linear for the first degrees of the drift angle. At larger grinding angles, the lateral force increases non-linearly to a maximum, after which it decreases.

The drift angle a is defined according to: CC = - arctan (—I vx I) According to a further embodiment, said set of control rules comprises a speed rule which meant that the speed should be as high as possible, of course provided that other control rules are met.

According to the invention, the trajectory is preferably determined so that the distance between the vehicle and an object is not less than SM when the trajectory is followed.

An object can for example be a fixed object along the sausage route, e.g. a mining rock, but can also be a moving object, e.g. another vehicle.

Figure 3 shows a schematic view of a sausage wagon where two different trajectories have been drawn, T1 (solid) and T2 (dashed).

For each trajectory, the calculated safety SM1 and SM2, respectively, have been marked, while SM1 is safety word Ti and SM2 for 20 T2.

As can be seen from the figure, SM1 is larger than SM2, which is to be interpreted as meaning that the measured friction for T1 is lower than for T2, ie. vdgbanan ãr halare i fallet da. Ti berdknats and therefore must safetyT2 as you can drive the vehicle with less safety.

The present invention also includes a method in a control system adapted to control an autonomous vehicle along a planned carriageway.

The method will now be described with reference to the flow chart in Figure 2. It is also referred to the above description of the control system.

The method comprises: Al - feeding the friction on a lane on which the vehicle is to travel; A2 - feed vehicle speed v.

The friction is fed, for example, using the measuring methods described above.

Information about the vehicle's speed is available via a suitable data bus in the vehicle where the information is obtained, for example, from the vehicle's speed feeder.

The method according to the invention further comprises: B - determining a variable safety SM (p, v) relative object in the vicinity of the vehicle based on the measured friction p and the speed of the vehicle v; C - determine a trajectory if the planned carriageway so that said determined safety SM is met, and D - regulate the vehicle so that the trajectory is followed by affecting at least the steering and speed of the vehicle using a set of control rules, said control rules including a rule that takes hansyn till sidoaccelerationen ay for fordonet.

Said set of control rules preferably comprises a rule which meant that the sum of the lateral forces causes the front wheels and rear wheels (F12 and F34 respectively) to be equal regardless of the friction value, and that the relationship F12 25 + F34 = m * ay grille where m is the mass of the vehicle.

Furthermore, the set of control rules dangerously includes a number of equations for station & curve carving. These have been described above.

According to one embodiment, said set of control rules comprises a speed rule which meant that the speed should be as high as possible. Step B of the method preferably comprises that the trajectory is determined so that the distance between the vehicle and an object is not less than SM when the trajectory is followed.

The present invention further comprises a computer program (P) for vehicles, wherein said computer program (P) comprises program code for causing a processing unit 10; 500 or another computer 500 connected to the processing unit 10; 500 to perform the steps according to the method described above.

Furthermore, the invention also comprises a computer program product comprising a program code stored on a computer readable medium for performing the method steps described above, when said program code. Referring to the block diagram in Figure 4, the computer 500 will now be described.

The program P may be stored in an executable manner or in a compressed manner in a memory 560 and / or in an Ids / write memory 550. NI & it is described that the data processing unit 510 performs a certain function, it should be understood that the data processing unit 510 performs a certain part of the program which dr is stored in the memory 560, or a certain part of the program which is stored in the read / write memory 550.

The data processing device 510 may communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit 510 via a data bus 511.

The read / write memory 550 is arranged to communicate with the data processing unit 5 via a data bus 514. The units connected to the processing unit 10 (see figure 1) can be connected to the data port 599.

NM data received on the data port 599 is temporarily stored in the second memory part 540. Once the input data has been temporarily stored, the data processing unit 5 is ready to perform code execution in a manner described above.

Parts of the methods described herein may be performed by the device 500 (corresponding to the processing unit 10 in Figure 1) using the data processing unit 510 which runs the program 12 stored in the memory 560 or the read / write memory 550. When the device 500 is programmed, the methods described herein are executed.

The present invention is not limited to the above-described preferred embodiments. Various alternatives, modifications and equivalents can be used.

The above embodiments are, therefore, not to be construed as limiting the scope of the invention as defined by the appended claims. 13

Claims (16)

Pate ntkrav A method in a control system adapted to all regulate an autonomous vehicle along a planned basket carriage, the method comprising: Al - m5ta the friction p for a carriageway on which the vehicle is to be driven; A2 - feed vehicle speed v; characterized in that the method comprises: B - determining a variable safety SM (p, v) relative object in the vicinity of the vehicle based on the measured friction p and the vehicle speed v; C - determine a trajectory for the planned carriageway so that the said certain safety SM is met, and D - regulate the vehicle so that the trajectory is followed by all influences at least the steering and speed the vehicle uses using a set of control rules, said control rules include a rule that takes into account to the lateral acceleration ay of the vehicle and there the said control rules include a rule which takes into account the coefficient of friction of the vehicle. The method according to claim 1, wherein said set of control rules comprises a rule which meant that the sum of the lateral forces of the front wheels and the rear wheels, respectively (F12 and F34, respectively) must be equal regardless of the friction value. The method according to claim 2, wherein the relationship F12 + F34 = m * ay grid where m is the mass of the vehicle. The method according to any of the preceding claims, wherein said set of control rules comprises a speed rule which meant all the speed shall be as high as possible. The method according to any of the preceding claims, wherein said set of control rules comprises a number of equations for station & curve carving. The method according to any one of the preceding claims, wherein the trajectory is determined 14 so that all the distance between the vehicle and an object is not less than SM when the trajectory is joined. The method according to any of the preceding claims, wherein said object is a fixed object. A control system (2) adapted to control an autonomous vehicle (4) along a planned basket carriage, the control system being adapted to receive a friction signal (6) which includes information on the friction p of a lane on which the vehicle is to be ridden, and a speed signal (8) comprising vehicle speed information v; The control system (2) may comprise a machining unit (10) and a control unit (12), the machining unit being adapted to determine a variable safety SM (p, v) relative to objects in the vicinity of the vehicle based on the friction achieved on and vehicle speed v; and determining a trajectory (14) for the planned carriageway so that said determined safety SM is met, and wherein the control unit is adapted to control all the vehicle with a control signal (16) so that the trajectory is followed by affecting at least the steering and speed of the vehicle using a set of control rules, wherein said control rules comprise a rule which takes into account the lateral acceleration ay of the vehicle and wherein said control rules comprise a rule which takes into account the coefficient of friction of the vehicle. The control system according to claim 8, wherein said set of control rules comprises a rule which meant that the sum of the lateral forces of the front wheels and the rear wheels, respectively (F12 and F34, respectively) shall be equal regardless of the friction value. The control system according to claim 9, wherein the relationship F12 4 "F34 = m * ay grid where m is the mass of the vehicle. The control system according to any one of claims 8-10, wherein said set of control rules comprises a speed rule which meant that the speed should be as high as possible. The control system according to any one of claims 8-11, wherein said set of control rules comprises a number of equations for station & curve grain. The control system according to any one of claims 8-12, wherein the trajectory 10 is determined so that the distance between the vehicle and an object is not less than the SM cla trajectory fogs. The control system according to any one of claims 8-13, wherein said object is a fixed object. Computer program (P) for vehicles, wherein said computer program (P) comprises program code for causing a processing unit (10; 500) or another computer (500) connected to the processing unit (10; 500) to perform the steps according to the method according to any of claims 1-7. A computer program product comprising a program code stored on a computer readable medium may perform the method steps according to any one of claims 1-7, when said program code is executed on a processing unit (10; 500) or another computer (500) connected to the processing unit. (10; 500). 16 1/2