Control unit and method for regulating the speed of a vehicle in a distance-controlled vehicle convoy during an uphill drive

Abstract

Control unit (2) for regulating the speed of a vehicle in a distance-controlled convoy during uphill travel, wherein the convoy comprises a first vehicle A and a second vehicle B, and the first vehicle A is a vehicle directly in front of the second vehicle B, wherein the control unit (2) is arranged in the second vehicle B, characterized in that the control unit (2) further comprises: - a speed unit (3) configured for determining an acceleration value a1 of the first vehicle A, which describes how strongly the first vehicle A accelerates; - a hill unit (4) configured for determining whether the first vehicle A is on a steep hill;- a computation unit (5) designed to compare the acceleration value a1 with an acceleration constant ka, and if a1 > ka and the first vehicle is on a steep incline, the control unit (2) is designed to generate a control signal sreg, which indicates a limitation of the ability of the second vehicle to increase its speed, thereby limiting the ability of the second vehicle to increase its speed accordingly.

Description

Field of invention The present invention relates to technology for articulated lorries and, in particular, to a control unit and a method for regulating the speed of a vehicle in a distance-controlled group or a distance-controlled convoy when driving uphill. The invention also relates to a computer program and a computer program product. Background of the invention Cooperative driving with vehicles such as trucks is now used in practice. Cooperative driving is also known as platooning. Studies show that fuel consumption can be significantly reduced through cooperative truck driving, meaning the trucks drive close together using a suitable control strategy. Many different control strategies have been proposed for how vehicles should be driven in platoons. However, these proposals have primarily focused on maintaining speed and a predetermined distance to the next vehicle in the platoon in a safe and comfortable manner; only to a limited extent has the role of road topography in the control system been considered. In a cooperative speed control system based on maintaining a predetermined distance to the vehicle ahead, situations can arise where following vehicles cannot maintain the desired distance from each other. To avoid such a situation, the following vehicle can increase its speed relative to the vehicle ahead to close the gap and then gradually reduce the speed difference as the gap decreases, utilizing the vehicle's rolling resistance. This method does not necessarily have a significant impact on fuel consumption. Rolling resistance, as used here, includes air resistance, rolling resistance, engine friction, drivetrain friction, and / or road camber. If, instead, the following vehicle's brakes have to be used to reduce the speed difference relative to the vehicle in front, the following vehicle's fuel consumption will be negatively affected. Such a situation can occur on an uphill section followed by a downhill section so steep that the vehicle accelerates under its own weight. The following can then happen: The first vehicle ascends the hill, increasing engine power to maintain its target speed. As the first vehicle approaches the crest of the hill, it may attempt to make up for the speed lost on the ascent and ultimately accelerates under its own weight on the steeper part of the downhill section.If the cruise control of the following vehicle attempts to maintain a predetermined distance to the vehicle in front, either speed-dependent or time-dependent, the following vehicle will try to match the speed of the vehicle in front and accelerate as the vehicle in front accelerates, and may even increase its speed further to make up for any inaccurate distance that may have developed on the incline. Because this occurs synchronously, it means that the following vehicle will be traveling at a higher speed than the vehicle in front on the steeper part of the hill, causing the following vehicle to catch up with the vehicle in front and potentially have to apply its braking to avoid a collision.When driving in a convoy with adaptive cruise control for heavy vehicles, the road's topography can negatively affect the convoy's operation. Under unfavorable conditions, this interference can have a detrimental impact on fuel consumption. WO 2013 / 095234 A1 describes a cruise control system that uses information about the road's topography to regulate the speed of a single vehicle. As the vehicle approaches a hill, the speed is increased to maintain momentum, and before a hill crest, the speed is reduced to save fuel. US 2005 / 0143895 A1 describes cruise control for a single vehicle. If there are no vehicles ahead, constant speed control is automatically employed. If a vehicle traveling at a lower speed is detected ahead, the cruise control switches to distance control. The road gradient can affect the vehicle's target speed in some way. EP 2 460 706 A1 and US 2012 / 0 123 659 A1 describe how congestion can be avoided at mountains by reducing the distance between vehicles before the mountains and allowing it to return to a normal distance after the crest of the mountain. DE 10 2009 014 187 A1 relates to a method for operating a following first vehicle, wherein a distance to a preceding second vehicle is recorded and this distance is regulated and / or controlled between a minimum value and a maximum value. DE 10 2011 083 610 A1 describes a method for controlling the speed of a motor vehicle. The method comprises scanning an area in front of the motor vehicle using a distance sensor to detect a vehicle ahead, as well as detecting the vehicle ahead and controlling the speed of the motor vehicle so that a predetermined distance to the vehicle ahead is maintained. In vehicle convoys, the distance between vehicles is short, and safe solutions are needed to drive uphill in a fuel-efficient manner. One object of the invention is to provide an improved method for controlling vehicles in convoys on hills. Summary of the invention According to a first aspect, the task is at least partially accomplished by a control unit for regulating the speed of a vehicle in a distance-controlled convoy traveling uphill. The convoy comprises a first vehicle A and a second vehicle B, with the first vehicle A being the vehicle directly in front of the second vehicle B. The control unit is located in the second vehicle B and includes a speed unit configured to determine an acceleration value a1 of the first vehicle A, which describes how strongly the first vehicle A accelerates. The control unit further includes a gradient unit configured to determine whether the first vehicle A is on a steep incline, and a calculation unit configured to compare the acceleration value a1 with an acceleration constant k. If a1> kaund the first vehicle is on a steep incline, the control unit is designed to generate a control signal sreg that indicates a limitation of the ability of the second vehicle to increase its speed, thereby limiting the ability of the second vehicle to increase its speed accordingly. The control unit thus interrupts the ongoing distance control on a steep downhill slope and limits the second vehicle's ability to accelerate using its engine. This prevents unnecessary acceleration that would necessitate braking on the downhill section. Any incorrect distance between the vehicles that may exist after the downhill section ends can subsequently be corrected once the slope is level and the second vehicle (B) can no longer get too close to the first vehicle (A). Since braking on the downhill section due to prior unnecessary acceleration is avoided, fuel can be saved. The distance control can be based on maintaining a constant distance between the vehicles or on the vehicle's speed. "Directly ahead" means that no other vehicle is between vehicle A and vehicle B. According to one embodiment, the control signal includes a speed limit, a torque limit, and / or an acceleration limit. The second vehicle B can therefore be limited in various ways. According to one embodiment, the control signal sreg comprises a constant value vk for the speed v2 of the second vehicle. In another embodiment, the constant value vk is the instantaneous value v2 of the second vehicle. Thus, the speed v2 of the second vehicle is frozen at its instantaneous speed. In this way, the second vehicle B can be prevented from increasing its speed. According to another embodiment, the control signal sreg comprises a function of the speed of another vehicle in the convoy that limits the speed v2 of the second vehicle, for example, the speed of the first vehicle (i.e., the speed of the vehicle in front). This function can instead depend on the speed of another vehicle in the convoy.For example, a lead vehicle may be positioned in front of the first vehicle A, belonging to the same convoy as vehicles A and B. The function can then depend on the speed of the lead vehicle. Alternatively, the function can depend on the speed of a vehicle positioned behind the second vehicle B in the convoy. The function can also depend on the combined speeds of multiple vehicles in the convoy. According to one embodiment, the second vehicle is equipped with a sensor unit for determining the relative speed vrel between the second vehicle B and the first vehicle A, wherein the speed unit for determining the acceleration value a1 is based on the relative speed vrel. In this way, the second vehicle B can determine the acceleration of the second vehicle without being dependent on information from the first vehicle A. According to one embodiment, the mountain unit is configured to determine the gradient a of the road on which the first vehicle A is traveling and to determine whether the first vehicle A is on a steep incline, based on the gradient a. According to one embodiment, the second vehicle B is equipped with a map unit containing topographic data, a positioning unit, and a distance sensor unit for measuring the distance between the first vehicle A and the second vehicle B, wherein the mountain unit is configured to determine the position p1 of the first vehicle A and the gradient a based on the position p1 and the topographic data. According to one embodiment, the first vehicle A is equipped with a first wireless communication unit, and the second vehicle B is equipped with a second wireless communication unit. In this way, the vehicles can exchange information wirelessly. According to one embodiment, the hill unit for determining whether the first vehicle A is on a steep incline is designed based on vehicle-specific data of the first vehicle A, wherein the vehicle-specific data includes a status marker, the instantaneous gear ratio, the instantaneous vehicle weight, the maximum engine torque curve, the instantaneous engine power, the mechanical friction and / or the vehicle's driving resistance at the instantaneous speed. According to a second aspect, the problem is at least partially solved by a procedure for controlling the speed of a vehicle in a distance-controlled convoy traveling uphill. The convoy comprises a first vehicle A and a second vehicle B, and the first vehicle A is the vehicle directly in front of the second vehicle B. The procedure includes the following: - Determining an acceleration value a1 of the first vehicle A, which describes how strongly the first vehicle A accelerates; - Determining whether the first vehicle A is traveling on a steep downhill slope; - Comparing the acceleration value a1 with an acceleration constant kA, and if a1 > kA and the first vehicle is on a steep downhill slope, the procedure includes - Limiting the ability of the second vehicle to increase its speed. According to one embodiment, the method includes limiting the second vehicle's ability to increase its speed by providing a speed limit, a torque limit, and / or an acceleration limit. Acceleration limiting here means limiting the engine's acceleration capability. According to one embodiment, the method comprises limiting the speed v2 of the second vehicle to a constant value vk. According to one embodiment, the constant value vk is the instantaneous value v2 of the second vehicle. According to another embodiment, the method comprises limiting the speed v2 of the second vehicle according to a function of the speed of another vehicle in the convoy, for example, the speed of the first vehicle (that is, the speed of the vehicle in front). According to one embodiment, the second vehicle is equipped with a sensor unit for determining a relative speed vrel between the second vehicle B and the first vehicle A, whereby the acceleration value a1 is determined on the basis of the relative speed vrel. According to one embodiment, determining whether the first vehicle A is on a steep slope includes determining the gradient a of the road on which the first vehicle A is located. According to one embodiment, the second vehicle B is equipped with a map unit containing topographic data and a position determination unit as well as a distance sensor unit for measuring the distance between the first vehicle A and the second vehicle B, wherein determining the inclination α includes determining the position p1 of the first vehicle A as well as the inclination value a based on the position p1 and the topographic data. According to one embodiment, the first vehicle A is equipped with a first wireless communication unit and the second vehicle is equipped with a second wireless communication unit. According to one embodiment, determining whether the first vehicle A is on a steep incline includes, based on vehicle-specific data of the first vehicle A, wherein the vehicle-specific data includes a status marker, the instantaneous gear ratio, the instantaneous vehicle weight, the peak torque curve, the instantaneous engine power, the mechanical friction and / or the vehicle's rolling resistance at the instantaneous speed. According to a third aspect, the task is at least partially fulfilled by a computer program P, wherein the computer program P comprises program code to cause a control unit or another computer connected to the control unit to execute the procedure according to one of the procedure steps described herein. According to a fourth aspect, the task is at least partially fulfilled by a computer program product comprising program code stored on a computer-readable non-volatile medium for executing the procedure according to one of the procedure steps described herein, wherein the program code is executed on a control unit or on another computer connected to the control unit. The preferred embodiments are described in the dependent claims and in the detailed description. Brief description of the enclosed figures The invention is described below with reference to the accompanying figures. Fig. 1 shows vehicles in a convoy subject to distance control. Figs. 2A and 2B show two different known situations in which distance control can lead to unnecessary fuel consumption. Fig. 3 shows a control unit according to one embodiment of the invention. Fig. 4 shows a method according to one embodiment of the invention. Detailed description of preferred embodiments of the invention A vehicle convoy, as used here, refers to a number of vehicles traveling in close succession and moving as a single unit. Figure 1 shows an example of a vehicle convoy with three vehicles, labeled A, B, and C. Vehicle A is the lead vehicle, i.e., the first vehicle in the convoy, and thus the vehicle to which the following vehicles B and C must follow. The following vehicles B and C in the convoy are equipped with at least one automatic speed control system, which also regulates the distance between the vehicles. The direction of vehicles B and C can also preferably be controlled, for example, by an automated steering wheel control system. The lead vehicle can be driven manually or with the aid of automatic control functions, such as an adaptive cruise control system.The vehicles are controlled to maintain specific distances from each other, which can be the same or adapted to the situation and / or the individual vehicles. The distance between vehicle A and the following vehicle B is denoted by dB,Abe, and the distance between vehicle B and the following vehicle C is denoted by dC,Bbe. These distances can range from, for example, 1 to 50 m, depending on the chosen control strategy, current conditions, etc. The vehicles in a convoy typically maintain a constant speed adapted to the applicable traffic restrictions. The desired speed that the vehicles are supposed to maintain is called the target speed and is the speed at which the vehicle's cruise control regulates its speed. However, on inclines, for example, the speeds of the vehicles can change because the vehicles cannot maintain the desired target speed. Figures 2A and 2B show examples of two vehicles, A and B, in a convoy traveling uphill. Vehicle A is directly in front of the following vehicle, B. Vehicle A can be the lead vehicle or any other vehicle in the convoy. Vehicle A is traveling at speed v1, and vehicle B is traveling at speed v2.Figure 2A initially shows a first level stretch of road, followed by a slope 1 with an incline α, and then a second level stretch of road. Vehicles traveling on the first level stretch maintain a constant speed. Shortly after the first vehicle A reaches slope 1, it accelerates on its own, i.e., without any fuel supply, due to its weight and the incline α. This increases the distance between the first and second vehicles. The higher-level control strategy of the distance control aims to maintain a specific distance between the vehicles and now increases the speed of the second vehicle B to maintain this distance. Vehicle B thus accelerates using its engine until it reaches the slope.This causes the second vehicle B to reach the downhill slope at too high a speed, as it too accelerates due to its own weight and the incline. The second vehicle B must now be braked to avoid getting too close to the first vehicle A. Fig. 2B shows first a level road followed by a steep incline, then a steep descent 1, and finally another level road. A steep incline is defined as a hill with such a steep gradient that, despite the engine's maximum torque, the vehicle cannot maintain its speed. The descent 1 has a gradient of α. As the first vehicle A travels up the incline, its speed decreases, as it cannot maintain the desired target speed due to its weight and the gradient. The second vehicle B then adjusts its speed to match the reduced speed of the first vehicle A in order to maintain the specified distance between the vehicles. As the first vehicle approaches the crest of the hill, it accelerates to reach the desired target speed.The acceleration is further increased when vehicle A reaches the steeper part of the slope and is accelerated by its weight. The behavior of vehicle A on the incline leads to an incorrect distance between vehicles A and B, assuming vehicle B also cannot maintain its speed on the incline. This incorrect distance is essentially due to two factors: First, vehicle B travels at a lower speed than vehicle A on the steepest part of the incline because it begins to decrease in speed, until it adjusts to vehicle A's speed. Second, when vehicle A begins to accelerate as the gradient decreases, vehicle B cannot follow this acceleration because it is still on the steep section. This leads to vehicle B attempting to match its speed to vehicle A before reaching the steep section of the slope 1, while simultaneously trying to increase its speed to close the gap created on the incline. This can result in vehicle B reaching the slope 1 at too high a speed and having to brake, as shown in the example in Fig. 2A, to avoid getting too close to vehicle A. A steep slope here means a gradient that has at least one steep section. In both of the examples mentioned, situations arise with energy-wasting driving behavior by the vehicle convoy. Fig. 3 shows a control unit 2, which is arranged to provide an improved method for controlling vehicles in a convoy when driving uphill, with the vehicles typically being controlled based on the distances between them. The control unit 1 can, for example, be an ECU (Electronic Control Unit). The control unit 2 includes a speed unit 3, which is configured to determine an acceleration value a1 of the first vehicle A, describing how strongly the first vehicle A accelerates. The acceleration value a1 can be determined in various ways, which are described below. The control unit 2 also includes a hill unit 4, which is configured to determine whether the first vehicle A is on a steep hill. This can be based on vehicle-specific data of the first vehicle A and / or on road topography data. The vehicle-specific data or the road topography data can, for example, include a status marker and / or an element of the vehicle-specific data described below. Whether the vehicle A is on a steep downhill slope can be assessed directly by examining instantaneous and / or historical engine torques and the vehicle's acceleration.If the acceleration exceeds a threshold, for example 0, as soon as the engine torque is equal to or less than 0, vehicle A is on a steep incline. The hill unit 4 can also be configured to determine the gradient a of road 1 on which the first vehicle A is traveling. Furthermore, the hill unit 4 can be configured to determine a threshold kbrant backe for the gradient on a steep incline. If the gradient a of road 1 is greater than or equal to the threshold kbrant backe, the road on which the first vehicle A is traveling has a steep gradient. The gradient a of road 1 can be calculated using a vehicle model of vehicle A and, for example, engine torque, acceleration, and / or speed of vehicle A, which can be retrieved as pre-measured data from the vehicle's internal network.Alternatively, the inclination can be measured directly with an inclination sensor or determined from information on the topography data of the respective road in combination with the position of the vehicle. Mountain Unit 4 can receive more or less processed data. If it receives a status marker indicating that vehicle A is on a steep slope, the data from vehicle A has been processed in a control unit within vehicle A to report that vehicle A is on a steep slope. Alternatively, data can be sent to Mountain Unit 4 as described previously, which then determines whether or not vehicle A is on a steep slope. A steep gradient is defined here as one where the incline is so steep that the vehicle traveling on it accelerates due to its own weight. This means the vehicle's speed increases even though no fuel is being supplied. According to one embodiment, the limit value for the incline is calculated based on vehicle-specific data for the vehicle traveling on the slope, here the first vehicle A, such as the instantaneous gear ratio, instantaneous vehicle weight, maximum engine torque curve, instantaneous engine power, mechanical friction, and / or vehicle resistance at the current speed. A vehicle model that estimates the resistance at the current speed can be used. Gear ratio and maximum torque are known values ​​in the vehicle's control system, and the vehicle weight can be estimated, for example, while driving. According to another embodiment, the limit value for the incline is calculated based on vehicle-specific data for the second vehicle B. The control unit 2 further includes a calculation unit 5, which is configured to compare the acceleration value a1 with an acceleration constant ka. The acceleration constant ka can, for example, be equal to 0 (zero) or close to 0, which means no acceleration. If a1 > ka and the first vehicle is on a steep incline, the control unit 2 is configured to generate a control signal sreg, which specifies a limit to the second vehicle's ability to increase its speed. The control signal sreg includes, for example, a speed limit, a torque limit, and / or an acceleration limit. The control signal sreg can, for example, include a constant value vk for the speed v2 of the second vehicle. The constant value vk can, for example, be the instantaneous speed v2 of the second vehicle.According to one embodiment, the control signal sreg is sent to a further control unit 14, for example, a control unit 14 with a speed controller, a torque limiter, and / or an acceleration limiter, thereby limiting the ability of the second vehicle to increase its speed according to the control signal sreg. According to another embodiment, the speed controller, the torque limiter, and / or the acceleration limiter are included in the control unit 2. According to one embodiment, the second vehicle is equipped with a sensor unit 6 for determining a relative speed vrel between the second vehicle B and the first vehicle A. The sensor unit 6 can then send the relative speed vrel to the control unit 2. According to one embodiment, the speed unit 3 is configured to determine the acceleration value a1 based on the relative speed vrel. According to one embodiment, the second vehicle B is equipped with a map unit 7 containing topographic data and a positioning unit 8. The second vehicle B can also be equipped with a distance sensor unit 9 for measuring the distance between the first vehicle A and the second vehicle B. The distance sensor unit 9 can, for example, comprise a radar, a laser, and / or a camera. The distance sensor unit 9 is configured to detect a relative distance and to generate a sensor signal containing the relative distance. The distance sensor unit 9 is further configured to transmit the sensor signal to the control unit 2. The mountain unit 4 can be configured to determine the gradient value a by determining the position p1 of the first vehicle A, as well as the gradient value α based on the position p1 and topographic data. The position determination unit 8 provides the position of the second vehicle B, and if the distance to the first vehicle A is known, the position of the second vehicle B can also be determined by the mountain unit 4. Optionally, directional data of the second vehicle B can also be used. If the position of the first vehicle is known, the mountain unit 4 can determine the gradient α of the road on which the first vehicle A is traveling by using the topographic data from the map unit 7. The positioning unit 8 can, for example, be configured to receive signals from a global positioning system such as GNSS (Global Navigation Satellite System), GPS (Global Positioning System), GLONASS, Galileo, or Compass. Alternatively, the positioning unit 8 can be configured to receive signals from, for example, one or more distance sensor units 9 in the second vehicle B, which measure the relative distances to a road junction, vehicles in the vicinity, or similar objects with a known position. Based on these relative distances, the positioning unit 8 can then determine the position of vehicle B itself. A sensor can also be configured to detect a signature at, for example, a road junction, where the signature represents a specific position. The positioning unit 8 can then be configured to determine its own position by detecting this signature.The positioning unit 8 can alternatively be configured to determine the signal strength of one or more signals from a base station or a road junction with a known position, and thus determine the position of vehicle B by triangulation. In this way, the vehicle B's own position can be determined. Naturally, the aforementioned techniques for determining the position of vehicle B can also be combined. The positioning unit 8 is configured to generate a position signal containing the position of vehicle B and to transmit this signal to the control unit 2. Vehicles in convoys are typically equipped for wireless communication with each other. The first vehicle, A, can therefore be equipped with a first wireless communication unit 10. The second vehicle, B, can be equipped with a second wireless communication unit 11. Wireless communication can be V2V (vehicle-to-vehicle) communication or, via other means such as mobile communication units, an application on a communication unit, or a server and infrastructure, in the form of V2I (vehicle-to-industry) communication. Communication can, for example, take place from one vehicle to another via a road junction. Each vehicle in a convoy has, for example, a unique vehicle identification number and a vehicle identification number that is uniform throughout the convoy to allow for verification of which vehicles belong to the convoy.Data transmitted wirelessly between vehicles in the convoy can be tagged with these identities so that received data can be assigned to the correct vehicle. The first wireless communication unit 10 can, for example, be configured to wirelessly transmit the speed v1 or the acceleration a1 of the first vehicle to the second vehicle B. Vehicle-specific data can also be wirelessly transmitted from the first vehicle A to the second vehicle B. Vehicle-specific data can be provided by various units within the first vehicle A. This data can then be used by the units in the control unit 2 to determine whether the first vehicle A is on a steep incline. Alternatively, the first vehicle A, for example, a control unit within the first vehicle A, can calculate whether the first vehicle A is on a steep incline and send a status marker to the second vehicle B indicating this. The vehicles in the convoy communicate internally between their various units via a bus, such as a CAN (Controller Area Network) bus, which uses a message-based protocol. Examples of other communication protocols that can be used include TTP (Time-Triggered Protocol), FlexRay, etc. In this way, signals and data can be exchanged between different units in a vehicle, as described previously. Alternatively, signals and data can be transmitted wirelessly between the different units. The speed unit 3, the mountain unit 4, and the calculation unit 5 can be parts of a computer program P in a memory unit 12 within the control unit 2. The control unit 2 also includes a processor unit 13. The computer program P comprises program code to cause the control unit 2 to execute one of the process steps described below with reference to the flowchart in Fig. 4 and the control unit 2 in Fig. 3. The remaining units 6, 7, 8, 9, 10, and 11 can comprise one or more processor units and one or more memory units. A processor unit can consist of a CPU (Central Processing Unit). A memory unit can comprise volatile and / or non-volatile memory, for example, flash memory or RAM (Random Access Memory). The units 7, 8, and 11 can be stand-alone units or integrated into the control unit 2, as indicated by the dashed line in Fig. 3.Figure 4 shows a flowchart for the procedure described below. The procedure can be used to control the speed of a vehicle in a distance-controlled convoy when driving uphill. Examples of distance-controlled convoys are shown in Figures 2A and 2B. As previously described, the convoy comprises a first vehicle A and a second vehicle B. The first vehicle A is a vehicle directly in front of the second vehicle B. The procedure involves determining an acceleration value a1 of the first vehicle A, which describes how strongly the first vehicle A accelerates (A1). This can be done by having the second vehicle B measure the relative speed between the vehicles at various times and then determining the acceleration of the first vehicle based on this measurement.The first vehicle can also transmit information about its acceleration a1 or speed v1 to the second vehicle 2 via wireless communication in order to determine the acceleration of the first vehicle. The procedure further includes determining whether the first vehicle A is traveling on a steep gradient (A2). This can be done based on vehicle-specific data and / or information about the gradient a of the road on which the first vehicle is traveling. Vehicle-specific data can include, in particular, a status marker, the weight of the first vehicle, the instantaneous driving resistance, and / or the instantaneous engine power. Determining the gradient value α can include determining the position p1 of the first vehicle A, as well as the gradient value a based on the position ρ1 and topographic data.The position of the first vehicle can be determined in the second vehicle B by measuring the relative distance to the first vehicle A and by data on the vehicle B's own position from a positioning unit 8 (Fig. 3). Alternatively, the position of the first vehicle can be determined in the first vehicle A and transmitted wirelessly to the second vehicle B. According to a further embodiment, the inclination value a is determined in the first vehicle A and transmitted wirelessly to the second vehicle B. The acceleration value a1 is then compared with an acceleration constant ka (A3). ka can, for example, be equal to 0 or nearly equal to zero. If a1 > ka and the first vehicle is on a steep incline (A4), the method includes limiting the ability of the second vehicle to increase its speed (A5). Limiting the ability of the second vehicle to increase its speed can be achieved, for example, by providing a speed limit, a torque limit, and / or an acceleration limit. According to one embodiment, the speed v2 of the second vehicle is limited to a constant value vk. For example, the constant value vk can be the instantaneous speed v2 of the second vehicle. If a1 is not greater than ka and / or the first vehicle is not on a steep incline (A4), the procedure involves using the normal spacing control of the vehicles in the convoy (A6). However, the procedure ensures that the distance between the first vehicle A and the second vehicle B does not fall below a predetermined distance. The procedure then returns to step A1 and determines the acceleration value a1 of the first vehicle A. According to one embodiment, the weight of one or both vehicles is estimated. This can be done, for example, on a preceding hill, observing the behavior of the vehicle(s). This information can then be used to adjust the speed of one or both vehicles. If a high weight is estimated for one or both vehicles, the speed of the second vehicle, or the speed of both vehicles, can be further reduced as soon as the first vehicle (A) is on a steep downhill slope, in order to avoid unnecessary braking later. According to one embodiment, the speed v1 of the first vehicle is also used to compensate for any decrease in the speed of the second vehicle B. The speed v1 of the first vehicle can thus be reduced to prevent the distance between the vehicles from becoming too large, to prevent the second vehicle B from accelerating, etc. The control unit 2 in the second vehicle B can be configured to continuously receive, determine, and / or calculate the acceleration value a1 or velocity value v1 from / at the first vehicle A. These values ​​can then be used to determine the behavior of the first vehicle A. For example, if there is a gradual, non-linearly increasing acceleration, this could indicate that the first vehicle A is on a steep incline. The present invention is not limited to the embodiments described above. Various alternatives, modifications, and equivalents may be used. Therefore, the embodiments mentioned above do not limit the scope of the invention as defined in the appended claims.

Claims

Control unit (2) for regulating the speed of a vehicle in a distance-controlled convoy during uphill travel, wherein the convoy comprises a first vehicle A and a second vehicle B, and the first vehicle A is a vehicle directly in front of the second vehicle B, wherein the control unit (2) is arranged in the second vehicle B, characterized in that the control unit (2) further comprises: - a speed unit (3) configured for determining an acceleration value a1 of the first vehicle A, which describes how strongly the first vehicle A accelerates; - a hill unit (4) configured for determining whether the first vehicle A is on a steep hill;- a computation unit (5) designed to compare the acceleration value a1 with an acceleration constant ka, and if a1 > ka and the first vehicle is on a steep incline, the control unit (2) is designed to generate a control signal sreg, which indicates a limitation of the ability of the second vehicle to increase its speed, thereby limiting the ability of the second vehicle to increase its speed accordingly. Control unit (2) according to claim 1, wherein the control signal comprises a speed limit, a torque limit and / or an acceleration limit. Control unit (2) according to claim 1 or 2, wherein the control signal sregein constant value vk for the speed v2 of the second vehicle. Control unit (2) according to claim 3, wherein the constant value vk is the instantaneous speed v2 of the second vehicle. Control unit (2) according to one of the preceding claims, wherein the control signal sregeine function of the speed of another vehicle in the vehicle convoy limits the speed v2 of the second vehicle. Control unit (2) according to one of the preceding claims, wherein the second vehicle is equipped with a sensor unit (6) for determining a relative speed vrel between the second vehicle B and the first vehicle A, wherein the speed unit (3) is designed to determine the acceleration value a1 on the basis of the relative speed vre. Control unit (2) according to one of the preceding claims, wherein the mountain unit (4) is designed to determine the gradient a of the road on which the first vehicle A is traveling and to determine whether the first vehicle A is on a steep slope, based on the gradient α. Control unit (2) according to claim 7, wherein the second vehicle B is equipped with a map unit (7) with topographic data and a position determination unit (8) as well as a distance sensor unit (9) for measuring the distance between the first vehicle A and the second vehicle B, wherein the mountain unit (4) is configured to determine the position p1 of the first vehicle A and the inclination α based on the position p1 and the topographic data. Control unit (2) according to one of the preceding claims, wherein the first vehicle A is equipped with a first unit (10) for wireless communication and the second vehicle B is equipped with a second unit (11) for wireless communication. Control unit (2) according to one of the preceding claims, wherein the hill unit (4) for determining whether the first vehicle A is on a steep incline is designed on the basis of vehicle-specific data of the first vehicle A, wherein the vehicle-specific data includes a status marker, the instantaneous gear ratio, the instantaneous vehicle weight, the curve of the maximum engine torque, the instantaneous engine power, the mechanical friction and / or the driving resistance of the vehicle at the instantaneous speed. A method for controlling the speed of a vehicle in a distance-controlled convoy traveling uphill, wherein the convoy comprises a first vehicle A and a second vehicle B, and the first vehicle A is a vehicle traveling directly in front of the second vehicle B, wherein the method comprises: - determining an acceleration value a1 of the first vehicle A, which describes how much the first vehicle A accelerates; - determining whether the first vehicle A is traveling on a steep gradient; - comparing the acceleration value a1 with an acceleration constant ka, and if a1 > ka and the first vehicle is on a steep gradient, the method comprises - limiting the ability of the second vehicle to increase its speed. The method according to claim 11, which comprises limiting the ability of the second vehicle to increase its speed by providing a speed limit, a torque limit and / or an acceleration limit. Method according to claim 11 or 12, which comprises limiting the speed v2 of the second vehicle to a constant value v. Method according to claim 13, wherein the constant value vk is the instantaneous speed v2 of the second vehicle. Method according to one of claims 11 to 14, which comprises limiting the speed v2 of the second vehicle according to a function of the speed of another vehicle in the convoy. Method according to any one of claims 11 to 15, wherein the second vehicle is equipped with a sensor unit (6) for determining a relative speed vrel between the second vehicle B and the first vehicle A, wherein the acceleration value a1 is determined on the basis of the relative speed vrel. Method according to any one of claims 11 to 16, wherein determining whether the first vehicle A is on a steep slope comprises determining the gradient a of the road on which the first vehicle A is located. Method according to claim 17, wherein the second vehicle B is equipped with a map unit (7) with topographic data and a position determination unit (8) as well as a distance sensor unit (9) for measuring the distance between the first vehicle A and the second vehicle B, wherein determining the inclination a comprises determining the position p1 of the first vehicle A as well as the inclination value a based on the position p1 and the topographic data. Method according to any one of claims 11 to 18, wherein the first vehicle A is equipped with a first unit (10) for wireless communication and the second vehicle B is equipped with a second unit (11) for wireless communication. Method according to claims 11 to 19, wherein determining whether the first vehicle A is on a steep incline is based on vehicle-specific data of the first vehicle A, wherein the vehicle-specific data includes a status marker, the instantaneous gear ratio, the instantaneous vehicle weight, the maximum engine torque curve, the instantaneous engine power, the mechanical friction and / or the vehicle's driving resistance at the instantaneous speed. Computer program P, wherein the computer program P comprises program code to cause a control unit (2) or another computer connected to the control unit (2) to perform steps according to any one of claims 11 to 20. Computer program product comprising a program code stored on a computer-readable non-volatile medium for executing the process steps according to one of claims 11 to 20, wherein the program code is executed on a control unit (2) or on another computer connected to the control unit (2).

Images