Drawbar device and method for open-loop or closed-loop control of a drive and brake device, as well as of a steering device of a following vehicle

Abstract

The invention relates to a drawbar device (1) for coordinating a driverlessly drivable following vehicle (3, 4) with a guide vehicle (5) during forward movement, having a connecting element (20, 21, 22, 23, 24) as well as an open-loop or closed-loop control device (2) for actuating a drive and brake device (16) as well as a steering device (15) exclusively of the following vehicle, taking into account measurement variables detected by measuring devices and / or variables determined therefrom. The invention additionally relates to a corresponding method for open-loop or closed-loop control of a drive and brake device (16) as well as of a steering device (15) of at least one following vehicle (3, 4) connected to a guide vehicle (5).

Description

[0001] Fraunhofer Society...eV

[0002] P149658PC00

[0003] Drawbar device and method for controlling or regulating a drive and brake device and a steering device of a following vehicle

[0004] The invention lies in the fields of mechanical engineering, control technology, and logistics. It can be advantageously used in the logistics of autonomous, mobile work machines. One advantage of the invention is that it allows autonomous, mobile work machines to be guided by a guide vehicle that does not need to be specially prepared or adapted for this purpose.

[0005] In principle, autonomously operating and driving vehicles and work machines are now known. A particular problem with the use of autonomously operating work machines is that they can operate without a human operator, but cannot autonomously reach a work site. This can be due to technical, legal, or logistical reasons.

[0006] Often, such vehicles or machines are transported to the work site using specially equipped towing vehicles or on low-loaders. In some cases, machines can also be temporarily staffed with an operator who can leave the vehicle or machine upon arrival at the actual work site. Both options have fundamental disadvantages. Towing or transporting with a specialized vehicle is very costly and time-consuming. Time constraints can also arise if several vehicles or machines have to be transported sequentially. If the vehicles or machines are driven to the work site by an operator, the operator then needs a means of transport to leave the site.

[0007] Special devices are known for towing autonomous vehicles, facilitating the towing process and utilizing aspects of the vehicle's autonomous driving capabilities. For example, US patent document US 2007 / 0194557A1 discloses a drawbar for connecting two autonomous vehicles, which serves to coordinate the control systems of both vehicles. For this purpose, the relative positions of the two vehicles and the forces acting on the drawbar are measured and used as the basis for control. However, such a drawbar is only practical for controlling convoys of multiple autonomous vehicles.

[0008] In light of the prior art, the present invention aims to ensure the transport of an autonomously driving vehicle or an autonomously driving work machine using the simplest possible means.

[0009] The problem is solved by the features of the invention according to the independent claims. The dependent claims represent possible embodiments of the solution.

[0010] The invention thus relates to a drawbar device for coordinating a driverless following vehicle with a lead vehicle during movement, comprising a connecting element mechanically connectable to the lead vehicle on the one hand and the following vehicle on the other, which has one or more spring elements against whose spring forces the connecting element can be extended and / or shortened, as well as a measuring device for detecting a length or change in length of the connecting element and / or a force acting in the longitudinal direction of the connecting element, and / or an acceleration measuring device for directly measuring the acceleration of at least the lead vehicle, wherein the connecting element is pivotably connectable to the lead vehicle, in particular to a trailer coupling of the lead vehicle.and has a mechanical coupling element that can be pivotally connected to the following vehicle, and each coupling element is equipped with an angle measuring device that detects a pivot angle or a change in the pivot angle between the connecting element on the one hand and the lead vehicle and the following vehicle on the other hand, at least in the horizontal plane.

[0011] Such a drawbar coupling device can be permanently or temporarily attached to an autonomous vehicle or autonomous work machine for the duration of transport, enabling the coupling of such a vehicle or work machine to a lead vehicle as a follower vehicle. Since the drawbar coupling device's control unit exclusively operates the follower vehicle's systems, the lead vehicle does not need to be specially equipped to use the drawbar coupling device. For example, a passenger car or a small truck with a standard trailer hitch can be used as the lead vehicle. Such a vehicle is usually readily available and can guarantee the necessary mobility for the person transporting the autonomous vehicle or work machine to its work site, for example, enabling them to return home.

[0012] In order to ensure competent control or regulation of the drive and brake system as well as the steering system of the following vehicle, the behavior of the drawbar system, in particular changes in length and force as well as the pivot angles between the connecting element and the lead vehicle and between the connecting element and one or more following vehicles, are recorded.

[0013] Direct measurement of acceleration, particularly in the area where the connecting element joins the lead vehicle, enables an extremely fast reaction from the following vehicle. This reaction can be even faster than one derived from force measurements.

[0014] For this purpose, it may be advantageous if the acceleration measuring device has at least one 1-axis acceleration sensor, in particular a 3-axis acceleration sensor, which is arranged in particular on the connecting element.

[0015] The acceleration sensor can advantageously be arranged, for example, on the mechanical coupling element that can be pivotally connected to the lead vehicle. Additionally, an acceleration sensor can also be arranged on the mechanical coupling element that can be pivotally connected to the follow vehicle, or on the end facing the follow vehicle, or at least on the side of the spring element(s) of the connecting element facing the follow vehicle, or on / in the follow vehicle itself, the measured values ​​of which are evaluated in addition to the measured values ​​that represent the acceleration of the lead vehicle.

[0016] Three-axis accelerometers can directly measure acceleration in multiple directions and transmit the measured values ​​to a control unit. In one of the possible implementations, the accelerometers can each be implemented as MEMS sensors.

[0017] More convenient inertial measurement units (IMUs) can also be used for this purpose, which measure both the accelerations in the three translational degrees of freedom and rotation rates in the three rotational degrees of freedom.

[0018] The connecting element can include a coupling element that can be pivotally connected to the lead vehicle, in particular to a trailer coupling of the lead vehicle. This coupling element, for example, carries all angle sensors used to measure the horizontal and, in particular, the vertical angles between the connecting element, especially its longitudinal axis, and the longitudinal axis of the lead vehicle. In this way, the lead vehicle can be free of sensors for the drawbar assembly and does not need to be adapted for use with the drawbar assembly. The sensors used to determine forces acting in the longitudinal direction of the connecting element, such as braking or acceleration forces, can also be arranged entirely on and supported by the connecting element. This allows the sensors of the drawbar assembly to be arranged predominantly or entirely within the drawbar assembly itself.A spring device, whose spring travel is used to determine the forces acting in the longitudinal direction of the connecting element by means of a change in length, should have a well-characterized force / displacement characteristic that can also be measured and calibrated in order to reliably assign a force to a given extension. For this purpose, the spring element can only consist of rigid, elastically deformable bodies with a stable spring characteristic.

[0019] Such a drawbar coupling can then be used for several different vehicle combinations without major modifications. It can be detached and removed from both the lead and follower vehicles, along with all necessary sensors, and used for a different combination. Only the follower vehicle needs to be equipped with a control unit for its steering and drive.

[0020] The connecting element can also include a coupling element that can be pivotally connected to the following vehicle. This coupling element, for example, carries all angle sensors used to measure the horizontal and, in particular, the vertical angles between the connecting element, especially its longitudinal axis, and the longitudinal axis of the following vehicle. In this way, the following vehicle can also be free of sensors on the drawbar assembly. The measured values ​​of all sensors located on the connecting element can be transmitted wirelessly or via cable to a control unit of the following vehicle using a communication device.

[0021] Typically, the lead vehicle can start moving at the beginning of the transport movement and exert a tractive force on the following vehicle via the drawbar. To prevent a sudden increase in tractive force and the associated high forces on the drawbar, the drawbar, or more precisely, the connecting element of the drawbar, is elastically extendable and compressible in the longitudinal direction. This elasticity is achieved via spring elements that tension or connect two mutually movable parts of the connecting element. The spring characteristic of one or more springs can be adjusted as required, for example, with a linear spring characteristic or with a spring characteristic that causes the force to increase more or less than linearly with the extension.This can be achieved using special spring designs such as pneumatic springs, elastomer springs, strip springs, disc springs, helical springs, or spiral springs, or by a combination of different spring designs. Furthermore, various springs can be connected in parallel and / or in series. In many cases, it is also advantageous to use spring assemblies that are pre-tensioned in a spring guide. The connecting element can also be designed so that, at maximum spring deflection in both the extension and compression directions, the moving parts of the connecting element reach end stops.

[0022] The control system is designed to operate the drive and braking systems as well as the steering system of the following vehicle in such a way as to relieve the drive and braking systems of the lead vehicle and / or to achieve optimized overall braking acceleration or acceleration for the vehicle combination. Furthermore, the steering system should be controlled to ensure that the following vehicle maintains the most accurate possible tracking.

[0023] The control system for the drive and braking system determines an optimized acceleration or deceleration of the following vehicle at any given time. However, in some cases, it is also advantageous to proactively control the following vehicle during an acceleration or braking maneuver to, for example, avoid peak loads that are foreseeable during the maneuver. A simple example of such control behavior is an accelerated start by the lead vehicle, where it is foreseeable that the following vehicle cannot accelerate quickly enough and the moving parts of the connecting element will collide. In this case, the control system can attempt to control the drive and braking system of the following vehicle in such a way that it accelerates the following vehicle to the maximum possible speed.In most cases, the acceleration of the following vehicle can be configured so that the total driving force acting on the following vehicle is only partially supplied by the spring forces acting in the connecting element and is supplemented and replaced as quickly as possible by the following vehicle's own driving forces. The control algorithms of the control or regulating device can be designed, in particular, to prevent the drawbar assembly from oscillating in the sense of a mechanical longitudinal oscillation of a mass / spring system, in which the masses are formed by the vehicles and the spring is formed by the springs of the drawbar assembly.As will be explained in more detail below, input variables for the control device can include, among others, the measured forces and length changes acting on the connecting element, as well as the measured swivel angles on both coupling elements and also the rates of change / mathematical derivatives with respect to time of these quantities and, if necessary, second mathematical derivatives.

[0024] The coupling elements can, for example, be designed as a coupling that can be mounted on a standard ball-shaped trailer hitch. This coupling is essentially in the shape of a hollow sphere, or part thereof, and is pivotable on the trailer hitch ball. Various devices can be provided to detect the swivel angle between the coupling element and the lead vehicle or the following vehicle in one or more planes. For example, an element equipped with various magnets can be attached to the trailer hitch of the lead or following vehicle, and magnetic sensors connected to the respective coupling element can detect the angular position of the coupling element relative to the trailer hitch in multiple planes. Optical detection devices for detecting the angular position are also conceivable.

[0025] In addition to horizontal swivel angles, angles around a horizontal axis perpendicular to the connecting axis between the vehicles (transverse axis) can also be measured at the coupling elements, as well as a rotation angle (roll angle) of the vehicles around their connecting axis. These latter angles may need to be considered on uneven terrain and also when controlling or regulating longitudinal movement.

[0026] In general, both the absolute values ​​of the measured angles / swivel angles and the ratio of the angles between the connecting element and the leading vehicle on the one hand and between the connecting element and the following vehicle on the other hand must be taken into account when controlling or regulating the steering device and also the drive and braking device of the following vehicle in order to avoid accidents or harmful situations.

[0027] The measured parameters of movement in the longitudinal direction (acceleration, velocity) and in the lateral direction (swivel angle) can enable optimized control of the following vehicle if they are processed and linked together. Thus, the drive or braking system of the following vehicle can also be controlled depending on measured swivel angles, and / or the steering system of the following vehicle can be controlled depending on detected changes in length or force values ​​of the connecting element.

[0028] The control or regulating device of the drawbar assembly can be connected to the drive and brake system and the steering system of the following vehicle, for example, by means of a cable and a plug connection, but also wirelessly via a radio connection.

[0029] For example, the drawbar assembly may include a control or regulating device for controlling a drive and brake assembly as well as a steering assembly exclusively of the following vehicle, taking into account measured quantities and / or quantities determined from the measuring device and / or the acceleration measuring device and the angle measuring devices, wherein the control or regulating device is arranged on the connecting element or on / in the following vehicle, and wherein the control or regulating device is in particular designed to limit the force acting in the longitudinal direction of the connecting element during the movement of the leading vehicle and the following vehicle by controlling the drive and brake assembly exclusively of the following vehicle, in particular to a specified maximum value.

[0030] If the control or regulating device is located on the connecting element, it can encompass all essential functions and be used for various following vehicles. However, the control or regulating device can also be located in the following vehicle and specifically adapted to it.

[0031] The described force limitation principle ensures in many cases that the moving parts of the connecting element do not collide with each other. This guarantees that the relative movement of the following vehicle and the lead vehicle is dampened at all times.

[0032] Another control principle can, for example, be designed such that the control or regulating device is configured to minimize the force acting in the longitudinal direction of the connecting element during the movement of the lead vehicle and the following vehicle by controlling the drive and braking device of only the following vehicle, in particular to zero or a specified value.

[0033] In this way, the lead vehicle can be optimally relieved of its workload, so that even smaller passenger vehicles can be used as lead vehicles.

[0034] It may also be provided that the connecting element has shock absorbers that dampen a shortening and / or an extension movement of the connecting element.

[0035] In addition to the spring action of the springs or spring combinations, the shock absorbers guarantee the avoidance of acceleration or force peaks, so that a jerk-free or low-jerk transport can be achieved and neither the leading vehicle nor the drawbar device or the following vehicle or their connecting elements are overloaded.

[0036] In another implementation, the control or regulating device can be configured to receive braking or acceleration signals and / or steering angles directly from the lead vehicle and, taking these signals into account, to control the drive and braking system and / or the steering system of the following vehicle. For this purpose, the control or regulating device can be connected to the lead vehicle via a wired connection using a plug connection or via a wireless connection, and the lead vehicle can transmit corresponding signals indicating these maneuvers to the control or regulating device immediately upon initiating its own braking process, acceleration, or steering movement.In many cases, this system can process the signals faster than the measurement results from the detection device, which records the changes in length or force in the drawbar assembly and the swivel angles. This allows the control system to react more quickly and initiate a rapid response by sending control signals to the drive and braking system and / or the steering system of the following vehicle at an early stage. The signals transmitted by the lead vehicle can often be limited to simply indicating that braking, acceleration, or a steering movement is imminent. This puts the control system into a state of readiness, enabling it to process the drawbar assembly's measurement data more quickly.

[0037] In one embodiment of the drawbar device, it may also be provided that the control or regulating device is configured to link the detected pivot angles or changes in pivot angles between the connecting element on the one hand and the leading vehicle and the following vehicle on the other hand, and to determine control commands for the steering device and / or the drive and braking device of the following vehicle from the relationship of the said pivot angles or changes in pivot angles to each other.

[0038] This can occur, for example, if the swivel angle determined between the connecting element and the following vehicle has a different sign than the swivel angle determined between the connecting element and the lead vehicle. Such a situation can mean that, when driving straight ahead, there is a transverse offset between the vehicles. This offset should then be minimized or eliminated by influencing the steering system of the following vehicle.

[0039] With the described angle configuration, a problem can also arise during a starting maneuver due to the longitudinal control system functioning imperfectly. In this case, the lead vehicle can start moving, and the connecting element will increasingly pivot into the straight-ahead direction, without the following vehicle being able to accelerate at this point. However, longitudinal forces may already be acting on the connecting element, which can unintentionally lead to accelerated propulsion of the following vehicle. For this reason, with the aforementioned angle configuration, the algorithm for controlling the drive and braking system of the following vehicle can be deactivated or a modified algorithm can be activated. It can also be advantageous to deactivate certain control algorithms or replace them with specific alternative algorithms when reversing.

[0040] Ultimately, if certain swivel angles are exceeded, the control or regulating device can also cause braking or blocking of the longitudinal movement of the vehicle combination by influencing the drive and braking system of the following vehicle.

[0041] In the aforementioned critical cases, an additional alarm signal or control request can be issued to a display or signaling device in the form of an operating unit in the lead vehicle in order to make the behavior of the control or regulating device transparent to the driver and, if necessary, to request intervention or cooperation.

[0042] The invention relates not only to a drawbar device of the type mentioned above, but also to a driverless following vehicle capable of being guided by a lead vehicle, with a drawbar device of the type described above connected to a lead vehicle, wherein at least one drive and brake device as well as a steering device of the following vehicle can be controlled by means of the control or regulating device.

[0043] Furthermore, the invention also relates to a method for controlling or regulating a drive and braking device as well as a steering device of at least one follower vehicle connected to a lead vehicle by means of a mechanical connecting element, in which a measuring device detects the length or change in length of a connecting element that is variable in length against the force of one or more springs between the lead vehicle and the at least one follower vehicle and / or a force acting on the connecting element in its longitudinal direction and / or directly by means of an acceleration sensor an acceleration of the lead vehicle, wherein a swivel angle or a change in swivel angle between the connecting element on the one hand and the lead vehicle and the follower vehicle on the other hand is also detected.and wherein, based on the recorded measured values ​​and / or on the basis of values ​​determined from these, a drive and braking device as well as a steering device of exclusively one or more following vehicles is controlled or regulated.

[0044] This method makes it possible to use conventional motor vehicles as lead vehicles when transporting an autonomously driving vehicle or an autonomously driving work machine. These vehicles do not need to be specially equipped for the transport process and only need to have a device for coupling the drawbar. During transport, the aforementioned measured variables are recorded and processed at the connecting element of the drawbar. To optimize the driving behavior of the vehicle combination consisting of the following vehicle and the lead vehicle, only the following vehicle—more precisely, its drive and braking system and steering system—is controlled, without affecting the drive and braking system or the steering system of the lead vehicle.The steering system of the following vehicle can be controlled based on the detected angular positions of the drawbar relative to the following and leading vehicles, taking into account the longitudinal movement of the vehicle combination and the measured values ​​of the force acting on the drawbar. Conversely, in many cases, the measured values ​​of the swivel angles are considered when controlling the drive and braking system of the following vehicle, together with the measured values ​​of the change in length of the coupling element or the force acting on the coupling element. In this way, problems can be avoided, especially with large steering angles of the leading vehicle or during maneuvering, particularly when reversing or when the vehicles are offset from each other laterally.

[0045] For example, in certain combinations of measured swivel angles, the drive of the following vehicle can be blocked or braked. Additionally, a warning signal can be sent to a display and control unit in the lead vehicle. For instance, when reversing begins, the following vehicle can first be braked or blocked, and a signal sent to the display and control unit in the lead vehicle. The following vehicle can then be manually enabled for reversing at the display and control unit by either entering or acknowledging the command. Simultaneously, a different control algorithm for steering and drive can be activated for reversing, compared to the one used for forward travel.

[0046] Similarly, if there is a significant lateral offset between the lead and follow vehicles, the follow vehicle can be braked and a specific steering maneuver initiated, or a signal can be sent to the display and control unit in the lead vehicle requesting or recommending a specific steering or braking maneuver by the lead vehicle.

[0047] For example, in a method of the type mentioned above, it may also be provided that, taking into account a measured time course of the force acting on the connecting element in its longitudinal direction or the change in length, an acceleration or braking acceleration of the drive and braking device of the following vehicle is determined which is suitable to prevent a change in length of the connecting element until a fixed stop is reached.

[0048] In addition to the measured temporal profile of the force or change in length acting on the connecting element in its longitudinal direction, or the measured swivel angles, the first and second derivatives of these quantities can also be used as a basis for control. On the one hand, it is conceivable to provide a precise control mechanism in the form of an algorithm that calculates correction values ​​for the drive, braking, and steering systems of the following vehicle from these quantities and transmits them to the following vehicle. However, it is also conceivable to generate a prediction of the temporal profile of the forces, changes in length, and swivel angles at the drawbar assembly based on current measurements and the aforementioned temporal derivatives of these values, and to optimize the future profile of the forces, changes in length, and steering angles by appropriately selecting the control variables.For this task, it can be useful to employ a learning system, such as a neural network or an expert system, which can be trained with many acceleration or braking maneuvers and can then generate optimized control variables that protect all elements of the vehicle combination, i.e., the lead vehicle as well as the drawbar assembly and the following vehicle.

[0049] In a slightly modified procedure, it may also be provided that, taking into account a measured temporal profile of the force or the change in length, a minimum acceleration or braking acceleration of the drive and braking device of the following vehicle is determined, wherein the minimum acceleration or braking acceleration is designed to limit or minimize the maximum force acting on the connecting element in its longitudinal direction during the course of the movement.

[0050] In this specific case, it is often possible to ensure that even during further acceleration or hard braking of the lead vehicle, the moving parts of the drawbar assembly do not reach a mechanical stop. This means that the entire relative movement of the lead and follow vehicles can be dampened by the control system in conjunction with the mechanical suspension. Additionally, if present, the shock absorbers of the drawbar assembly also dampen the relative movement.

[0051] In a further modification of the method, it may be provided, for example, that taking into account a measured temporal profile of the force and / or the change in length, an acceleration or braking acceleration of the drive and braking device of the following vehicle is determined, wherein the determined acceleration or braking acceleration is designed to minimize the force currently acting on the connecting element in its longitudinal direction.

[0052] In this case, the power or force required by the lead vehicle during towing is minimized. This is particularly useful when transporting large and heavy vehicles or construction equipment.

[0053] Ultimately, as part of a modification of the procedure, it may also be provided that, based on a measured temporal profile of the force or the change in length, an acceleration or braking acceleration of the drive and braking device of the following vehicle is determined, which dampens the change in length of the connecting element in its longitudinal direction, in particular aperiodically.

[0054] By controlling or regulating the acceleration or deceleration of the following vehicle, vibrations of the system—comprising the lead vehicle, the following vehicle, and the drawbar assembly—are minimized or avoided. Such damping can also be implemented as active damping and achieved with a fast control method. Purely mechanical shock absorbers can also provide or enhance the damping effect. The damping effect of the shock absorbers can also be adjustable.

[0055] A method of the above-mentioned type may also provide that the control or regulating device receives signals directly from the leading vehicle about executed braking or acceleration signals and / or steering angles and, taking these signals into account, controls the drive and braking device and / or the steering device of the following vehicle.

[0056] Furthermore, a method of the above-mentioned type may provide that the control or regulating device links the detected swivel angles or swivel angle changes between the connecting element on the one hand and the leading vehicle and the following vehicle on the other hand and determines control commands for the steering device and / or the drive and braking device of the following vehicle from the relationship of the said swivel angles or swivel angle changes to each other.

[0057] For example, it may be provided that the control or regulating device blocks or slows down further travel if a specified swivel angle between the connecting element and the following vehicle and / or between the connecting element and the lead vehicle is exceeded.

[0058] Such a situation can occur, for example, when maneuvering the vehicle combination or if the lead vehicle makes an excessively sharp and sustained steering input. In such cases, it is advisable to first bring the vehicle combination back into a controlled, straightened position, that is, to reduce the angle between the longitudinal axes of the lead and following vehicles and, if possible, also to reduce or at least prevent any lateral offset between the two vehicles.If the vehicle combination is to be started or accelerated in such a situation, when assessing the change in length of the connecting element or the force acting on the length element, it must be taken into account that the forces between the connecting element and the leading vehicle and the following vehicle do not act in the longitudinal direction of the connecting element or in the direction of travel of one of the vehicles, and therefore only a part of the acting forces actually needs to be considered for the control or regulating device when acting on the drive and braking device of the following vehicle.

[0059] In one embodiment of the method, it may further be provided that, in the event that the pivot angle between the connecting element and the lead vehicle has the same sign as the pivot angle between the connecting element and the following vehicle, the control or regulating device causes the steering device of the following vehicle to reduce the pivot angle between the following vehicle and the connecting element, and that the control or regulating device in particular brakes the following vehicle.

[0060] This method can be used, for example, to determine a lateral offset of the lead vehicle relative to the following vehicle and to initiate countermeasures.

[0061] The determination of correction values ​​can be carried out, for example, by taking into account the current speed and the currently measured changes in length of the connecting element or forces acting on the connecting element.

[0062] The invention is shown below with reference to exemplary embodiments in figures of a drawing and then described.

[0063] Figure 1 shows, in an overview view, a vehicle combination consisting of a lead vehicle, a drawbar assembly and a following vehicle in a side view.

[0064] Figure 2: a team consisting of a lead vehicle and two following vehicles,

[0065] Figure 3: a vehicle combination with a lead vehicle and a following vehicle in detail in side view,

[0066] Figure 4: a team of horses similar to the one shown in Figure 3 in a

[0067] Top view

[0068] Figure 5: a possible embodiment of the suspension between two movable parts of the connecting element of a drawbar device,

[0069] Figure 6: in one possible embodiment, a detailed representation of the suspension and shock absorption,

[0070] Figure 7: schematically, in a top view, a team of horses under ideal conditions

[0071] Straight ahead

[0072] Figure 8: in a top view a team of horses driving through a regular curve nf a hrt,

[0073] Figure 9: a top view of a vehicle combination with a lateral offset when traveling straight ahead, as well as

[0074] Figure 10: in a top view two vehicles of a team in a position twisted and offset relative to each other.

[0075] Figure 1 shows a side view of a lead vehicle 5 to which a follower vehicle 3 is coupled by means of a drawbar 1. The combination of the lead vehicle and the follower vehicle moves forward in the direction indicated by arrow 19. In this embodiment, a control or regulating device 2, which belongs to the drawbar 1, is located in the follower vehicle. However, it can also be located on the connecting element of the drawbar 1, which is positioned between the two vehicles. For this reason, it is also symbolically shown as an optional element on the connecting element in Figure 1 and is labelled 2'.

[0076] Figure 2 shows an example of a vehicle combination or convoy with a lead vehicle 5 and two follower vehicles 3 and 4, wherein the first follower vehicle 3 is coupled to the lead vehicle 5, while the second follower vehicle 4 is coupled to the first follower vehicle 3. The two drawbar assemblies are labeled 1a and 1lb, and the two control or regulating devices are labeled 2a and 2b.

[0077] Figure 3 shows a side view of a lead vehicle 5 to which a follower vehicle 3 is coupled by means of a drawbar 1. The combination of the lead vehicle and the follower vehicle moves forward in the direction indicated by arrow 19 and, if necessary, backward in the opposite direction. The lead vehicle 5 can be a conventional passenger car that requires no special equipment for its role as a lead vehicle other than a trailer hitch and is, for example, manually steerable. This means that the drawbar does not affect the steering of the lead vehicle. However, the drawbar can be configured to transmit signals to a driver of the lead vehicle.This could include warning signals, an assessment of the vehicle combination's situation, or the driving status, such as steering angle, braking or acceleration values, or the following vehicle's control options, categorized as "OK," "Caution advised," "Drive slowly," or "Dangerous situation - stop immediately." These categories can also be displayed using a color-coded traffic light system with red, yellow, and green signals. For example, the display can also indicate on a scale what percentage of the following vehicle's maximum drive power or maximum steering angle is currently being used.

[0078] The display 44 and the display and control unit 45 can be combined in a single device.

[0079] The drawbar assembly is suitable for attaching or coupling a following vehicle to a lead vehicle not specifically designed for this purpose. For this purpose, the lead vehicle 5 has, as shown in Figure 3, a trailer coupling 8 to which a coupling element 23 of the drawbar assembly is attached. The coupling element 23 is rigidly connected to a guide-side part 21 of a connecting element 20, 21, 22, 23, 24. The guide-side part 21 is connected to a length-variable part 20 of the connecting element, which is connected on the following side, i.e., on the side of the following vehicle 3, to a following-side part 22 of the connecting element.The leading-side part 21, the length-adjustable part 20, and the following-side part 22, together with the coupling element 23 and the further coupling element 24, form parts of the connecting element that connects the leading vehicle 5 to the following vehicle 3, or more precisely, the trailer coupling 8 of the leading vehicle to the trailer hitch 11 of the following vehicle. The coupling element 24 is coupled to the trailer hitch 11 of the following vehicle. The leading-side part 21 and, if applicable, also the following-side part 22 can be designed as telescopic rods or hollow profiles and, in this case, can be adjusted to different, fixed lengths. The length-adjustable element 20 can be compressed or extended against spring forces in the longitudinal direction of the vehicle combination.

[0080] The length of the variable element 20, or its changes in length indicated by arrow 30, can be detected by means of the measuring device 40. The detected lengths and / or changes in length can be converted into forces acting in the longitudinal direction of the connecting element, taking into account the spring forces and, if applicable, the effects of shock absorbers. However, the measuring device 40 can also be designed to directly detect a force acting in the longitudinal direction of the connecting element in the compression or extension direction, for example, by means of a strain gauge. The respective measured value is transmitted via a transmitter 10 and a radio link or a connecting cable to a measuring or control device 2 of the drawbar assembly, which can be directly mechanically connected to the connecting element or can also be located in the following vehicle 3.The control device 2, taking into account the measured values ​​of the measuring device 40, the swivel angles detected at the coupling elements, and, if applicable, mathematical quantities calculated therefrom (e.g., rates of change, mathematical derivatives with respect to time, or second derivatives with respect to time), can determine control variables that are transmitted to a drive and brake unit 16 of the following vehicle. The drive and brake unit 16 of the following vehicle generates corresponding acceleration forces or braking accelerations in response to these control variables. Figure 3 also shows a swivel angle 33, 36 in the area of ​​the coupling elements 23, 24, which is measured by the angle measuring devices 41, 42 and describes the relative position of the connecting element to the lead vehicle and / or the following vehicle in the vertical direction.If these vertical swivel angles exceed certain thresholds, this should be interpreted as a signal that the vehicle combination is moving on uneven ground, and in this case, the combination can be braked as a safety precaution. For this purpose, a brake signal can be sent to the drive and braking system of the following vehicle.

[0081] The angle measuring devices also detect horizontal swivel angles 34, 37 on the coupling elements 23, 24, which are visible in Figure 4 and which are characteristic of a curve travel of the combination in many cases.

[0082] Furthermore, acceleration sensors 200 and 201 can each be provided on the coupling elements 23 and 24 for direct acceleration measurement. An acceleration sensor 200 on the coupling element 23 is particularly advantageous, as this is closest to and most strongly coupled to the lead vehicle, whose accelerations have the greatest influence on the movements of the vehicle combination.

[0083] Figure 4 shows the vehicle combination in a top view, with swivel angles 34 and 37 indicated in the area of ​​the coupling elements 23 and 24, describing a horizontal swivel movement or a horizontal swivel angle. The angles measured there are transmitted by the transmitter 10 via cable or wirelessly to the control unit 2, which, among other things, uses these measured values ​​to control the active steering device 15 and a drive and brake device 16 of the following vehicle 3. In this way, the following vehicle 3 can be controlled so that, when traveling straight, it follows the lead vehicle 5 with the smallest possible lateral offset / lateral displacement, or reduces a lateral offset / lateral displacement, and when cornering, follows the curved track of the lead vehicle as precisely as possible.This is particularly important if the vehicle combination includes not just a single following vehicle 3, but also further following vehicles 4 attached to the following vehicle 3. For attaching further following vehicles, the following vehicle 3 has a trailer coupling 11a and an electrical connector 9a at its end. Drawbar devices according to the invention can also be provided between each of the following vehicles. However, it is also possible to control several following vehicles using a single drawbar device. To provide the driver of the lead vehicle with information about what is happening behind the following vehicles, a rear-facing camera 43 is provided on the following vehicle 3 or on the rearmost following vehicle in the rear area.Images from this camera, for example, are transmitted to a display 44 on the dashboard of the lead vehicle, together with information from the control or regulation unit and / or driving recommendations for the driver of the lead vehicle, as part of an assistance system. In addition to the display 44, the lead vehicle may also be equipped with a control unit 45, which allows the adjustment of certain parameters of the drawbar assembly. The display 44 and the display and control unit / control panel 45 can be combined in a single device. These parameters include, for example, the damping strength of the length-adjustable element 20 in the longitudinal connecting element, acceleration limits for the drive and braking system 16 of the following vehicle, or the maximum degree of extension or compression of the spring-loaded length-adjustable element 20, which can be limited by mechanical stops.The display and control unit can be integrated into a portable unit that can be mounted in a suitable location on a lead vehicle as needed. If the lead vehicle has a flexible multimedia unit, this can also be used as an input / output unit. A separately selectable reverse driving mode can also be provided. If this mode is not selected, the drive and braking system of the following vehicle can be configured to block reverse travel. Selecting the reverse driving mode can also include explicitly switching to specific control algorithms, such as a speed limit or restricting the steering angle of the following vehicle.

[0084] In Figures 3 and 4, reference 35 denotes an additional measuring device for a roll angle, i.e. a measuring device that indicates a rotation of the lead vehicle relative to the following vehicle about the longitudinal axis of the vehicle combination.

[0085] Such a rotation of the lead vehicle relative to the following vehicle around its longitudinal axis typically occurs when the vehicle combination is traveling on uneven terrain, for example, with potholes and bumps. In such a case, it is advisable to limit the speed of the vehicle combination and / or the steering angles of the lead and following vehicles. This can be signaled to a control unit in the lead vehicle and also taken into account in the control of the drive and braking unit and the steering system of the following vehicle.

[0086] The lead vehicle 5 has a connector 6 into which a cable 7 from the drawbar assembly can be plugged. This cable leads directly, or via another cable 12 and a connector 9 on the following vehicle, to the control unit 2. The lead vehicle can, for example, directly output signals via the electrical contacts of the connector and the cables. These signals may represent the current acceleration or deceleration values ​​of the lead vehicle, or generally indicate the start of a braking or acceleration process. Signals representing the steering angle of the lead vehicle can also be transmitted. The transmission of these signals and data via a connector and a cable is mentioned only as one possible embodiment.In many cases, it can also be advantageous to implement wireless communication between the lead vehicle, the drawbar assembly, and the components (drive and brake system and steering system) of the following vehicle in all directions via a radio link. The wired or wirelessly transmitted signals can reach the control unit 2 faster than they are reflected in the measurement results of the measuring device 40 and the swivel angle measurement. This allows the control unit 2 to react particularly early and forward corresponding signals to the drive and brake system 16 of the following vehicle before the measured values ​​are processed by the measuring device 40. This then often enables more precise control of the drive and brake system after a short time.

[0087] Reference numeral 38 in Figure 4 denotes the deviation of the lead vehicle's direction of travel from its previously straight-ahead position. During such a change of direction, the measured swivel angles or changes in swivel angles in the area of ​​the coupling elements 23, 24 are processed by the control unit 2 in such a way that the active steering device 15 of the following vehicle receives signals that trigger steering actions. These actions either keep the following vehicle as precisely as possible on the path of the lead vehicle or create a swept path that deviates from the lead vehicle's path only to a limited and controllable extent. Similar signals are to be transmitted to further following vehicles in the case of a longer convoy, since the swept path of a longer convoy consisting of more than two vehicles and / or long vehicles often deviates even further from the leading path.

[0088] Figure 5 schematically shows parts of the connecting element, namely the guide-side part 21, which can be designed as a telescopic rod, and the follow-side part 22, which can also be designed as a telescopic rod, wherein parts 21 and 22 can each be fixed at a selectable, fixed length. Coupling elements 23 and 24 are arranged at the opposite ends of the two parts 21 and 22, respectively, which serve for coupling to a coupling device of the guide vehicle on the one hand and the follow-side vehicle on the other. The two parts 21 and 22 of the connecting element are also connected to the length-variable part 20 arranged between them in the longitudinal direction 19. This part has a spring guide cylinder 20a and a piston 20b that is movable longitudinally in the spring guide cylinder, and a spring 20c and 20d on each side of the piston.The piston 20b is thus displaceable in the longitudinal direction of the drawbar assembly and therefore in the direction of travel 19 of the vehicle combination within the spring guide cylinder against the force of two spring elements 20c, 20d. The piston 20b is rigidly connected to a piston rod 20e, which in turn is connected to the subsequent part 22.

[0089] The two spring elements 20c, 20d are shown symbolically in Figure 5 and can represent a combination of several springs and shock absorbers. An example of such a possible construction is shown in Figure 6.

[0090] Figure 6 shows a spring guide cylinder 20a to which the guide-side part 21 is attached. Within the spring guide cylinder 20a, the piston 20b is movable longitudinally against the force of various springs or spring assemblies 20i, 20k and shock absorbers 20g, 20h. The piston 20b is connected to the downstream part 22 in the form of a rod by means of a linkage 20f.

[0091] If the piston 20b is moved relative to the spring guide cylinder 20a under the force exerted by the lead vehicle and a following vehicle, such that the variable-length part 20 is compressed, the shock absorber 20g generates a counterforce from a certain deflection onwards. Conversely, if the variable-length part 20 is extended, the other shock absorber 20h can generate a counterforce. The shock absorbers can be designed, for example, as hydraulic or pneumatic shock absorbers, each with a piston / cylinder system. Furthermore, the piston 20b is held between the pre-tensioned spring assemblies 20i and 20k. Each of these assemblies contains longitudinally pre-compressed springs, and compression of these spring assemblies 20i and 20k is only possible when a certain pressure force threshold is exceeded, which corresponds to the pre-tension force of the respective springs in the spring assemblies.

[0092] As an example, another spring 201 is shown on the guide side of the piston 20b, which only becomes effective above a certain compression of the spring assembly 20i and additionally brakes the piston 20b. This configuration is only intended to illustrate how a complex spring characteristic can be created by combining different springs.

[0093] Figure 6 also clearly shows that after traveling a certain distance, the movement of the piston 20b, and thus the compression of the variable-length part 20, is abruptly limited by a stop either in the area of ​​the spring 201 or at one of the shock absorbers 20g, 20h. A similar stop is provided for an expansion / lengthening movement of the variable-length part 20. The damping strength of the shock absorbers can also be adjustable, for example.

[0094] The control algorithms of the control or regulating device 2 are at least partially adapted to the damping and spring characteristics of the variable-length part 20 in order to, for example, avoid the piston 20b hitting a hard stop in the spring guide cylinder 20a and to be able to take into account the dynamics of the springing and shock absorption in the control.

[0095] Some characteristics of the variable-length section 20, including the spring forces and damping of the shock absorbers, can be adjusted. The control algorithms can or should be adapted to these settings, as well as to the performance of the drive, braking, and steering systems of the following vehicle. Finally, the control algorithms can also be adapted to characteristics of the lead vehicle. Such adaptation through a suitable selection of control algorithms can be achieved, for example, by inputting parameters such as those of the lead vehicle and / or a route, or even weather conditions, at the display and control unit in the lead vehicle.

[0096] For example, the weight ratio of the lead vehicle and the following vehicle can be important in this context, or with regard to weather conditions, the probability of poor road grip, for example due to rain, unpaved road surface or black ice.

[0097] The display and control unit, which can also include all displays of values ​​and statuses of the following vehicle and the drawbar assembly, can be connected to the drawbar assembly, for example, via a radio link. This is particularly useful when several lead vehicles, which do not need to be specifically adapted for the lead vehicle function, are used alternately. In this case, the driver only needs to take the control unit, in the form of a self-contained box with, for example, its own battery power supply, to the lead vehicle.

[0098] Figures 7 to 10 show various relative positions of a lead vehicle, a drawbar assembly, and a follower vehicle in top-down views. These positions can occur depending on a previously traveled distance or a specific maneuver, and some require or are advantageous for the control or regulation of the drawbar assembly. The figures show the forward direction 19 of the lead vehicle 5, the longitudinal axis 101 of the follower vehicle 3, the longitudinal axis 102 of the lead vehicle 5, and a line 100 indicating the longitudinal axis of the drawbar assembly's connecting piece. The figures also show the pivot angle 103 between the longitudinal axis 100 of the connecting piece and the longitudinal axis 101 of the follower vehicle 3, and the pivot angle 104 between the longitudinal axis 100 of the connecting piece and the longitudinal axis 102 of the lead vehicle.Figure 7 shows the vehicle combination in its extended position without any lateral offset. The swivel angles are zero degrees.

[0099] Figure 8 shows a curve maneuver. The swivel angle 103 has a different sign than the swivel angle 104, since the longitudinal direction 100 deviates to the right from the longitudinal axis of the following vehicle (as viewed in the direction of travel), but to the left from the longitudinal axis of the leading vehicle (as viewed in the direction of travel). This indicates a normal curve maneuver. As long as the size of the swivel angles does not exceed a certain threshold, no special conditions need to be considered in the control algorithm. However, the following vehicle can receive a command to decelerate as soon as one of the swivel angles exceeds a certain value.

[0100] Figure 9 shows a significant lateral offset between the vehicles, resulting in large pivot angles 103, 104 in the same direction. In this situation, a steering maneuver should be initiated by the steering system of the following vehicle to reduce the lateral offset. The control unit can also brake the following vehicle or limit its speed by controlling its braking and drive systems. Furthermore, when starting in such a configuration, it should be taken into account that only small tractive forces act on the vehicles in the longitudinal direction of the connecting element 100, and the control unit should be adjusted accordingly.

[0101] Figure 10 shows a scenario that can occur, for example, during a sharp turn or when reversing. It is important to note that, on the one hand, the swivel angle 104 is very large, and on the other hand, the difference and ratio between the two swivel angles 103 and 104 are significant. These two properties / parameters can each result in specific conditions, modifications, or settings of the control algorithm. Such scenarios are detected by measuring the swivel angles and transmitting this information to the control device.

Claims

TI Patent claims 1. Drawbar device (1) for coordinating a driverless following vehicle (3, 4) with a lead vehicle (5) during movement, characterized by a connecting element (20, 21, 22, 23, 24) that can be mechanically connected to the lead vehicle on the one hand and the following vehicle on the other, the connecting element having one or more spring elements (20) against whose spring forces the connecting element can be extended and / or shortened, and by a measuring device (40) for detecting a length or change in length of the connecting element and / or a force acting in the longitudinal direction of the connecting element and / or an acceleration measuring device for directly measuring the acceleration of at least the lead vehicle, wherein the connecting element (20, 21, 22, 23, 24) can be pivotably connected to the lead vehicle (5), in particular to a trailer coupling (8) of the lead vehicle, and a connecting element (3, 4) can be pivotally connected to the following vehicle (5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 1 ...4) has a pivotably connectable mechanical coupling element (23) and each of the coupling elements has an angle measuring device (41, 42) which detects a pivot angle or a change in the pivot angle between the connecting element on the one hand and the lead vehicle and the follow vehicle on the other hand, at least in the horizontal plane.

2. Drawbar device according to claim 1, characterized in that the acceleration measuring device has at least one 1-axis acceleration sensor, in particular a 3-axis acceleration sensor, which is in particular arranged on the connecting element.

3. Drawbar device according to claim 1 or 2, characterized in that it comprises a control or regulating device (2, 2') for controlling a drive and brake device (16) and a steering device (15) exclusively of the following vehicle, taking into account measured quantities and / or quantities determined from the measuring device (40) and / or the acceleration measuring device and the angle measuring devices (41, 42), wherein the control or regulating device is arranged on the connecting element (20, 21, 22, 23, 24) or on / in the following vehicle (3, 4), and wherein the control or regulating device is in particular configured to limit the force acting in the longitudinal direction of the connecting element (20, 21, 22, 23, 24) during the movement of the leading vehicle (5) and the following vehicle (3, 4) by controlling the drive and brake device (16) exclusively of the following vehicle.especially to a specified maximum value.

4. Drawbar device according to claim 1, 2 or 3, characterized in that the control or regulating device (2, 2') is configured to minimize the force acting in the longitudinal direction of the connecting element (20, 21, 22, 23, 24) during the movement of the lead vehicle (5) and the following vehicle (3, 4) by controlling the drive and brake device exclusively of the following vehicle, in particular to zero or a specified value.

5. Drawbar device according to one of claims 1 to 4, characterized in that the connecting element (20, 21, 22, 23, 24) has shock absorbers (17, 18) which dampen a shortening and / or an extension movement of the connecting element.

6. Drawbar device according to one of claims 1 to 5, characterized in that the control or regulating device (2, 2') is configured to receive brake or acceleration signals and / or steering angles directly from the lead vehicle (5) and to control the drive and brake device (16) and / or the steering device (15) of the following vehicle taking these signals into account.

7. Drawbar device according to one of claims 1 to 6, characterized in that the control device (2, 2') is configured to link the detected pivot angles or changes in pivot angles between the connecting element (20, 21, 22, 23, 24) on the one hand and the leading vehicle (5) and the following vehicle (3, 4) on the other hand and to determine control commands for the steering device (15) and / or the drive and braking device (16) of the following vehicle from the relationship of the said pivot angles or changes in pivot angles to each other.

8. Driverless following vehicle (3, 4) which is equipped to be guided by means of a guide vehicle (5) with a drawbar device connected to a guide vehicle according to one of the preceding claims, wherein at least one drive and brake device (16) of the following vehicle and a steering device (15) can be controlled by means of the control device (2).

9. Method for controlling or regulating a drive and braking device (16) and a steering device (15) of at least one follower vehicle (3, 4) connected to a lead vehicle (5) by means of a mechanical connecting element (20, 21, 22, 23, 24), wherein a length or change in length of a connecting element (20, 21, 22, 23, 24) that is variable in length against the force of one or more springs (20) between the lead vehicle and the at least one follower vehicle and / or a force acting on the connecting element in its longitudinal direction and / or an acceleration of the lead vehicle is detected by means of a measuring device (40), wherein a swivel angle or a change in swivel angle between the connecting element on the one hand and the lead vehicle and the follower vehicle on the other hand is detected,and wherein, on the basis of the recorded measured values ​​and / or on the basis of values ​​determined from these, a drive and braking device (16) and a steering device (15) of exclusively one or more following vehicles is controlled or regulated.

10. Method according to claim 9, characterized in that, taking into account a measured time course of the force acting on the connecting element in its longitudinal direction or the change in length, an acceleration or braking acceleration of the drive and braking device (16) of the following vehicle is determined which is suitable to prevent a change in length of the connecting element (20, 21, 22, 23, 24) until a fixed stop is reached.

11. Method according to claim 9 or 10, characterized in that, taking into account a measured time course of the force or the change in length, a minimum acceleration or braking acceleration of the drive and braking device (16) of the following vehicle (3, 4) is determined, wherein the determined minimum acceleration or braking acceleration is designed to limit or minimize the maximum force acting on the connecting element (20, 21, 22, 23, 24) in its longitudinal direction during the movement.

12. Method according to one of claims 8 to 11, characterized in that, taking into account a measured temporal profile of the force and / or the change in length, an acceleration or braking acceleration of the drive and braking device (16) of the following vehicle (3, 4) is determined, wherein the determined acceleration or braking acceleration is designed to minimize the force momentarily acting on the connecting element (20, 21, 22, 23, 24) in its longitudinal direction and / or to minimize or, in particular, aperiodically dampen the change in length of the connecting element (20, 21, 22, 23, 24) in its longitudinal direction.

13. Method according to one of claims 8 to 12, characterized in that the control or regulating device (2, 2') receives signals directly from the lead vehicle (5) about executed braking or acceleration signals and / or steering angles and, taking these signals into account, controls the drive and braking device (16) and / or the steering device (15) of the following vehicle.

14. Method according to one of claims 8 to 13, characterized in that the control or regulating device (2, 2') links the detected pivot angles or changes in pivot angle between the connecting element (20, 21, 22, 23, 24) on the one hand and the lead vehicle (5) and the follower vehicle (3, 4) on the other hand and determines control commands for the steering device and / or the drive and brake device (16) of the follower vehicle from the relationship of said pivot angles or changes in pivot angle to each other, wherein the control or regulating device blocks or slows down further travel, in particular when a defined pivot angle between the connecting element and the follower vehicle and / or between the connecting element and the lead vehicle is exceeded.

15. Method according to claim 14, characterized in that the control or regulating device (2, 2') causes the steering device of the following vehicle to reduce the pivot angle between the following vehicle and the connecting element in the case that the pivot angle between the connecting element and the following vehicle has the same sign as the pivot angle between the connecting element and the following vehicle, and that the control or regulating device in particular brakes the following vehicle.

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