Trailer and method for controlling the distance between a trailer and a connecting rod

Abstract

The invention relates to a trailer with at least one driven wheel, comprising an energy source which is designed to supply a wheel drive with energy, a braking unit for decelerating the at least one wheel, a connecting rod which is designed to connect to a towing unit, and which is movably mounted on the trailer, a path sensor which is designed to measure the position of the connecting rod relative to the trailer, a speed measuring unit which is designed to determine the speed of travel based on a measurement of the speed of the trailer and / or of the connecting rod, and an electronic controller, wherein the controller is designed to shift the position of a neutral point relative to the trailer starting from a zero point, as a function of the determined speed of travel, to calculate a control deviation with the distance between the position of the neutral point and the measured position of the connecting rod and to actuate the wheel drive and / or the braking unit with the control deviation.

Description

[0001] Trailer and method for controlling the distance between a trailer and a connecting rod

[0002] The present invention relates to a trailer with a wheel drive and a method for controlling such a trailer.

[0003] State-of-the-art powered trailers use force sensors, particularly strain gauges, to control the trailer drive. These force sensors measure the forces occurring between the trailer and the towing vehicle. These force sensors are known to be susceptible to external influences, particularly environmental influences such as temperature and humidity fluctuations. Furthermore, the connection between the trailer and towing vehicle is always rigid according to the state of the art and thus susceptible to axial and lateral forces between the trailer and towing vehicle. In particular, strong vibrations and even resonant oscillations can occur in the trailer-tow vehicle system. This causes the force sensor to generate a large amount of measurement data, which in turn leads to a high evaluation effort for the control unit.It's also difficult to distinguish the measurement data essential for trailer control from the background noise generated by vibrations and other disturbances. This impairs ride comfort and increases energy consumption, among other things.

[0004] A motor-driven trailer for a bicycle is known from US 2012 / 0037435 A1. The trailer described therein is connected to the bicycle via a drawbar. The drawbar has a force sensor, and the trailer has a motor. Depending on the speed difference between the bicycle and the trailer, the force sensor measures a compressive force if the trailer is faster than the bicycle, or a tensile force if the trailer is lagging behind the bicycle. The motor accelerates the trailer according to the forces measured by the force sensor.

[0005] US Patent No. 8,365,849 B2 describes a system for towing a trailer. The trailer comprises an electric motor, brakes, a drawbar, and a force sensor mounted on the drawbar. Depending on the mechanical forces measured by the force sensor, the trailer is accelerated by the motor or decelerated by the brakes.

[0006] DE 102010 051 838 A1 describes a trailer for a bicycle, wherein the trailer comprises an electric machine that can act both as a brake and as a motor to prevent the trailer from causing a noticeable reaction on the bicycle when pushed or when braking. To achieve this, various sensors are described. A pedal pressure sensor, a braking force sensor provided in the brake lever, and a force measuring sensor provided in the connection between the bicycle and trailer are proposed. The signals from these sensors are transmitted to an electronic logic circuit, which in turn controls the electric machine and / or the brakes. The force measuring sensor can be used to determine whether the bicycle is exerting a pulling force or a pushing force on the trailer, with the motor or brakes being controlled depending on the measured signals in order to steer the trailer along the bicycle.As an alternative to force measurement, preloaded measurement systems are proposed, in which either a pressure sensor records pressure changes in a cylinder or a position sensor measures the position of a spring-loaded disc. While such preloaded measurement systems have a less rigid coupling between the trailer and the bicycle, disruptive, particularly pulsating, feedback effects still remain.

[0007] DE 10 2006 009 862 A1 describes a bicycle push trailer for propelling and braking a bicycle. A battery is mounted as an inertial mass in a trailer frame, so that the battery swings forward during braking and backward during acceleration. The battery is connected in an articulated manner to a position sensor and a Bowden cable via a control lever. During braking, an electric motor is regeneratively operated via the position sensor, while a mechanical brake is simultaneously activated via the Bowden cable. US 2013 / 0311058 A1 discloses a method for controlling a trailer powered by an electric motor.

[0008] EP 3 416 860 A1 relates to a method for controlling a powered trailer and a motor-driven trailer. The method comprises, among other things, a step in which a distance between the trailer and the towing vehicle is defined as the neutral position. The deviation of the distance between the trailer and the towing vehicle from the neutral position is measured and output as a distance value. If the distance between the trailer and the towing vehicle is reduced by at least a first distance value compared to the neutral position, the trailer is braked electrically. If the distance between the trailer and the towing vehicle is reduced by at least a second distance value compared to the neutral position, where the second distance value is greater than the first distance value, the trailer is braked mechanically, independently of the electrically operated braking.If the distance between the trailer and the towing vehicle is increased by a third distance value compared to the neutral position, the trailer is accelerated by an electric motor.

[0009] Based on this, the invention is based on the object of enabling the most sensitive control possible of a powered trailer.

[0010] The object is achieved by a trailer according to claim 1 and by a method for controlling the distance according to claim 10. Advantageous embodiments are the subject of the dependent claims and the description.

[0011] The trailer according to the invention with at least one driven wheel comprises

[0012] • an energy source designed to supply energy to a wheel drive,

[0013] • a braking device for decelerating at least one wheel,

[0014] • a connecting rod which is designed to be connected to a towing device and which is movably mounted on the trailer, • a displacement sensor which is designed to measure the position of the connecting rod relative to the trailer,

[0015] • a speed measuring device configured to determine the driving speed based on a measurement of the speed of the trailer and / or the connecting rod, and

[0016] • an electronic controller, and is characterized in that

[0017] • the controller is designed to o shift the position of a neutral point relative to the trailer starting from a zero point as a function of the determined driving speed, o calculate a control deviation with the distance between the position of the neutral point and the measured position of the connecting rod and o control the wheel drive and / or the braking device with the control deviation.

[0018] The trailer has one or more wheels. It can therefore stand upright on its own, only in combination with a towing vehicle, or be held upright by an operator. At least one of the wheels is driven by a drive. This is preferably an electric motor. The electric motor can either be a wheel hub motor or be mounted on the trailer and drive the driven wheel via a drive shaft. The trailer also has an energy source that supplies the drive with energy. In the case of an electric motor, this can be a battery. However, a fuel cell or photovoltaics can also be used. If an internal combustion engine is used, a corresponding fuel tank with a fuel supply is used.In addition to the drive, the trailer also has a braking device that acts on at least one wheel to decelerate it and thus the trailer. If the trailer has multiple wheels, the drive and the braking device can be designed so that they can act on different wheels separately. The braking device can have a mechanical brake, such as a disc brake or a shoe brake, with which the at least one wheel or a shaft attached to this wheel is braked. However, the braking device can also comprise a device designed to control the drive so that it generates a braking effect. In the case of an electric motor, this can be a generator operation of the electric motor, which leads to electric braking.In the case of an internal combustion engine, this can involve interrupting the supply of fuel so that it does not deliver any drive power in order to use the internal friction of the internal combustion engine as an engine brake, which leads to braking.

[0019] The trailer has a connecting rod designed to be connected to a towing device. A drawbar is used to connect it to a towing vehicle, which is attached to the vehicle by means of the towing device. A towing vehicle can, in particular, be a bicycle. The trailer can also be pulled by a person or an animal using the towing device.

[0020] The connecting rod is attached to the trailer with a bearing, allowing it to move relative to the rest of the trailer. Suitable bearings, such as linear guides or ball bearings, can be used for this purpose. Depending on the design of the bearing, the connecting rod can have varying degrees of freedom. The bearing absorbs forces only in directions where it does not have any degrees of freedom for the connecting rod.

[0021] The trailer has a displacement sensor. The displacement sensor is designed to measure the position of the connecting rod relative to the trailer. To do this, the displacement sensor determines a point firmly connected to the connecting rod in a coordinate system fixed to the displacement sensor. The orientation of the coordinate system of the displacement sensor relative to the bearing with which the connecting rod is mounted is fixed. If, for example, the bearing is mounted so that it can rotate about a vertical axis of the trailer, the position of the connecting rod relative to the trailer is defined as the position of the connecting rod relative to the part of the trailer that can rotate with the bearing. If the bearing rotates accordingly, the measured position of the connecting rod relative to the corresponding part of the trailer does not change.If the connecting rod is firmly connected to the towing vehicle or the towing device, the position of the towing vehicle or the towing device relative to the trailer can be calculated by adding a corresponding distance vector.

[0022] The trailer has a speed measuring device. The speed measuring device is designed to determine the driving speed. To do so, it uses measurements of the speed of the trailer and / or the connecting rod relative to a world coordinate system. The measurement of the speed of the trailer and / or the connecting rod is therefore absolute, or relative to the fixed world, and not relative to a moving coordinate system, such as the aforementioned coordinate system of the displacement sensor. According to one embodiment, the speed measuring device can be designed to perform these measurements.

[0023] The trailer has an electronic controller designed to control the drive and the braking device. The drive and / or the braking device then change the output drive and / or braking force so that the trailer is accelerated or decelerated. The controller can determine the control using a control rule. The control rule can be, for example, an electronic circuit integrated into the controller or a computer program stored on the controller. The controller can be a microcontroller. The controller takes the control deviation into account as an input signal. The control rule can have a component that calculates the control signal proportional to the control deviation, proportional to the change in the control deviation, and proportional to the integral of the control deviation.By designing the control specification so that it is tailored to the characteristics of the trailer, as well as the drive and braking systems, optimal control of the drive and braking systems can be achieved. Optimal can mean achieving one or more control objectives. It is preferable for the control deviation to be as constant and small as possible. It is also preferable for a control deviation to be eliminated quickly after it occurs. The challenge here is that disturbances can affect the system. In particular, this includes changes in the speed of the towing vehicle or the towing equipment. Uneven ground or other environmental conditions, such as changing wind speeds, also represent disturbances. As soon as such a disturbance affects the control deviation, the controller attempts to quickly minimize the control deviation by controlling the wheel drive and braking system accordingly.Collision of the connecting rod with other components of the trailer must be avoided at all costs.

[0024] The controller calculates the control deviation by calculating the difference between a neutral point and the position of the connecting rod. Just like the position of the connecting rod, the neutral point is defined relative to the trailer, specifically in the coordinate system of the travel sensor. If there is no control deviation, the trailer is neither accelerated nor decelerated. To determine the neutral point, the computing device uses the driving speed. The relationship between the neutral point and these measured variables can be stored on the controller, e.g. in the form of a saved computer program, an algorithm, or a look-up table. The controller is designed in such a way that the neutral point is defined relative to the trailer, i.e. in the coordinate system of the travel sensor, as a function of the driving speed. To do this, the controller shifts the neutral point starting from a point relative to the trailer, orzero point fixed to the displacement sensor coordinate system.

[0025] The advantage of shifting the neutral point depending on a measured speed is that it is easier to achieve sensitive control, in which the operator or the towing vehicle are not influenced by the trailer.

[0026] According to the above description, the control of the wheel drive and the braking system, which causes acceleration or deceleration of the trailer, depends on the controller and the control deviation. It is usually advantageous for the controller not to provide a control signal that leads to strong acceleration or deceleration even with very small control deviations. Measurement uncertainties and inaccuracies in the mechanical or electrical system mean that optimal control is not achieved. Therefore, the controller is usually designed such that a sufficiently large control deviation must exist to generate a control signal that leads to correspondingly strong acceleration or deceleration. The control strategy should therefore not respond too sensitively to the control deviation.The disadvantage of such a control strategy is that, even during normal operation, large distances must exist between the connecting rod and the trailer to cause a sufficiently large control deviation. If an additional disturbance occurs unexpectedly, a further displacement occurs between the connecting rod and the trailer. This displacement can be so large that it causes the connecting rod to collide with other components of the trailer.

[0027] One solution to this problem would be to increase the freedom of movement of the connecting rod between the respective end stops. However, the installation space required for this is disadvantageous for the trailer design. The invention solves this dilemma. According to the invention, the controller is designed to change the neutral point used to calculate the control deviation depending on the driving speed. At higher speeds, the thus changed neutral point can be moved closer to or further away from the center of gravity of the trailer, depending on the controller's design. By changing the neutral point in this way, a virtual extension of the freedom of movement available to the connecting rod is achieved. In this way, a larger control deviation, which enables sensitive control, can be tolerated without having to risk the connecting rod colliding with the rest of the trailer.This also avoids having to provide more installation space.

[0028] According to one embodiment of the invention, the trailer is characterized in that the displacement sensor is designed as an inductive displacement sensor, a capacitive displacement sensor, or a resistance change displacement sensor. These sensors typically consist of a stationary component and a movable component. A change in their relative position causes a change in an electromagnetic property of the stationary component, which is measured and output as a distance measurement signal by calculation with a proportionality factor or a corresponding function. Preferably, a sensor target is attached to the connecting rod, and a signal pickup is attached to the trailer, which measures a change in the distance between the sensor target and the signal pickup by changing an inductance.

[0029] These sensors are characterized by their low cost, robustness, and accuracy. Furthermore, they are electronic components that are particularly easy to connect to the rest of the electronics.

[0030] According to another embodiment, optical sensors or radar-based sensors are used.

[0031] According to one embodiment, the trailer is characterized in that the connecting rod is mounted on the trailer so as to be displaceable along its longitudinal axis in the direction of a side facing the trailer and a side facing away from the trailer.

[0032] The bearing according to this design grants the connecting rod only one degree of freedom for movement relative to the trailer. It therefore ensures that the connecting rod can only move along its longitudinal axis in the direction of one side facing the trailer and one side facing away from the trailer. The side facing away from the trailer is closer to the trailer's center of gravity than the side facing away from the trailer. Due to the degree of freedom defined by the bearing, the position of the connecting rod relative to the trailer can be expressed as a scalar distance of the connecting rod from a fixed point on the trailer or in the position sensor coordinate system. The bearing can, in particular, be a linear guide.

[0033] The advantage of using a bearing that allows the connecting rod only one degree of freedom along its longitudinal axis is that it allows for improved control. This type of bearing restricts the degrees of freedom, making it easier to model the physical processes that occur when the distance changes and to incorporate them into the controller.

[0034] According to one embodiment, the trailer has an additional mounting that allows rotation of the travel sensor and trailer components firmly connected to it relative to the rest of the trailer. This additional mounting can, in particular, be a mounting that allows rotation around the vertical axis. In such a case, all relative information relating to the trailer refers to the trailer components that are firmly connected to the travel sensor and its coordinate system.

[0035] According to one embodiment, the trailer is characterized in that the calculation rule is designed to shift the neutral point, starting from the zero point located on the longitudinal axis, along the longitudinal axis in the direction of the side facing away from the trailer by a correction distance which is positively proportional to the determined driving speed minus a zero speed.

[0036] According to this design, the controller uses a linear relationship to calculate the position of the neutral point. According to this relationship, the neutral point is defined by the correction distance and the zero point located on the longitudinal axis. The neutral point corresponds to the zero point after the controller has virtually shifted it by the correction distance along the longitudinal axis away from the trailer's center of gravity, i.e., toward the side facing away from the trailer. The correction distance is calculated using the driving speed. For this purpose, the zero speed is subtracted from the driving speed, and this difference is multiplied by a proportionality factor.

[0037] The position of the neutral point p is determined from the zero position p0, the correction distance Ap, the proportionality constant c, the driving speed v and the zero speed v0 according to the following relationship, p = Ap + p0 = c (v - v0) + p0. This relationship means that as long as the driving speed corresponds to zero speed, the neutral point corresponds to the zero point, i.e. there is no shift of the neutral point. Only when the driving speed increases beyond zero speed is the neutral point shifted relative to the zero point towards the side facing away from the trailer. At lower speeds, in turn, the neutral point is shifted relative to the zero point towards the side facing the trailer. The neutral point therefore moves towards the towing device at higher speeds and away from it at lower speeds.

[0038] The advantage of the controller design described above is that it facilitates sensitive control. At high speeds, there may be a large distance between the connecting rod and the side facing the trailer, but only a small control deviation is calculated. The connecting rod is therefore located relatively far from the side facing the trailer. In the event of braking by the towing vehicle, the connecting rod can move a considerable distance before reaching the end of the bearing or before colliding with other components of the trailer. A correspondingly large control deviation can therefore occur without a collision occurring.

[0039] Conversely, at low speeds, a small control deviation is calculated when the distance between the trailer-facing side and the connecting rod is short. As soon as the towing vehicle or the drawbar accelerates, with acceleration typically being greater at low speeds than at high speeds, a large control deviation can occur before the connecting rod collides.

[0040] The speed-variable shift of the neutral point allows a virtual extension of the clearance available to the connecting rod without collision. This takes advantage of the fact that the connecting rod must be positioned at a large distance from the side closest to the trailer at high speeds and at low speeds farther away from the trailer to avoid collisions. Consequently, the virtual extension allows for larger control deviations to be tolerated.

[0041] It is advantageous to design the controller to operate with larger control deviations. Due to the electronic and mechanical components used, the controller exhibits inaccuracies; for example, the position measurement signal may be subject to noise, or a corresponding analog-to-digital converter may cause a time delay. These inaccuracies mean that, for small control deviations, a relatively large proportion of the control deviation can be attributed to these inaccuracies. Using such an erroneous control deviation to control the drive and braking device could lead to excessively strong or weak acceleration or deceleration. If, as envisaged by the invention, a large control deviation is used, the corresponding inaccuracies are less significant in relation to the remaining control deviations. They therefore do not lead to a corruption of the control signal.

[0042] According to one embodiment, the trailer is characterized in that the controller is designed to calculate the correction distance negatively proportional to the determined driving speed minus the zero speed if the determined speed is less than a starting speed which is less than the zero speed.

[0043] According to this embodiment, there is a starting speed which is lower than the zero speed. If the driving speed falls below the limit speed, the previously described linear mathematical function with a positive proportionality factor is no longer used to calculate the correction distance. Instead, a continuously decreasing function is used. The corresponding function is designed so that it continuously follows the function at higher speeds. According to this embodiment, at speeds below the starting speed, i.e. at very low speeds, correction distances are calculated which are greater than the correction distance calculated at the starting speed. This results in the neutral point being shifted slightly further towards the side facing away from the trailer.In a condition without control deviation, there is therefore an increased distance between the neutral point and the side facing the trailer. Shaking or other irregularities during acceleration do not directly lead to a collision between the connecting rod and the other components of the trailer.

[0044] According to one embodiment, the trailer is characterized in that the controller is designed to control the wheel drive and / or the braking device only if the amount of the control deviation is greater than a tolerance deviation.

[0045] The advantage of a tolerance deviation is that small control deviations do not immediately trigger the activation of the wheel drive and / or braking system. Small control deviations can arise in particular from non-uniform tractive force loading on the connecting rod. A non-uniform tractive force load is typical when the towing vehicle is a bicycle that is propelled by the operator's pedaling. Especially at high speeds, strong accelerations or decelerations would be necessary to avoid even small control deviations at all times. This would place strain on the wheel drive and braking system. Providing a tolerance deviation therefore leads to a reduced load on the wheel drive and braking system, as well as on the entire trailer.

[0046] According to one embodiment, the trailer is characterized in that the controller is designed to calculate the tolerance deviation positively proportional to the determined driving speed.

[0047] It is advantageous to select a larger tolerance deviation at high speeds. Especially at such speeds, permanent control of the wheel drive and braking system would lead to accelerated wear of these components. According to one embodiment, the trailer is characterized by a mechanical brake actuation device designed to mechanically actuate the braking system when the distance between the trailer and the connecting rod falls below a certain limit.

[0048] According to this embodiment, the trailer has a mechanical brake actuation device for the braking system. This mechanical brake actuation device serves as a backup to the electrical control of the braking system by means of the controller. The brake actuation device is designed to be mechanically triggered as soon as the connecting rod falls below a certain distance from the trailer. This can, in particular, be a very small distance between a part of the connecting rod and, for example, an end stop. However, another device, such as a protruding driver on the connecting rod and a corresponding stop on the trailer, can also be provided to represent the brake actuation device.

[0049] The advantage of a mechanical brake actuation system is that it effectively brakes the trailer even in the event of a power failure or if the control system is too slow. This prevents a collision between the trailer and the towing device, thus preventing damage. The mechanical brake actuation system thus increases the safety of the trailer during operation.

[0050] According to one embodiment, the trailer is characterized in that the mechanical brake actuation device a) comprises a lever designed to be moved by the connecting rod as soon as the limit distance is exceeded, and b) comprises a cable connected to the braking device and to the lever and designed to be tensioned by moving the lever.

[0051] In this design, the mechanical brake actuation device is designed as a cable pull. The cable pull is actuated by a lever, which is moved by the connecting rod when the limit distance is exceeded. This design uses proven components, making it particularly reliable.

[0052] The object is also achieved by a method according to claim 10 for regulating the distance between a trailer having at least one wheel, a wheel drive and a braking device and a connecting rod which is designed to be connected to a towing device and which is movably mounted and attached to the trailer, which comprises the steps

[0053] • Measuring a position of the connecting rod relative to the trailer,

[0054] • Measuring a speed of the trailer and / or a speed of the connecting rod,

[0055] • Determining a driving speed using the speed of the trailer and / or the speed of the connecting rod,

[0056] • Control of the control of the wheel drive and / or the braking device using a control deviation, and is characterized in that

[0057] • with the driving speed, the position of a neutral point relative to the trailer is shifted from a zero point,

[0058] • the control deviation is calculated using the distance between the position of the neutral point and the position of the connecting rod.

[0059] The method is particularly suitable for implementation with the trailer according to the invention. The previously described advantages of the trailer according to the invention and its embodiments also apply mutatis mutandis to the method and its embodiments.

[0060] According to one embodiment, the method is characterized in that • the connecting rod is displaced along its longitudinal axis in the direction of a side facing the trailer or a side facing away from the trailer,

[0061] • the neutral point is shifted from the zero point located on the longitudinal axis along the longitudinal axis in the direction of the side facing away from the trailer by a correction distance that is positively proportional to the driving speed minus a zero speed.

[0062] According to one embodiment, the method is characterized in that the correction distance is calculated negatively proportional to the driving speed if the determined driving speed is less than a starting speed which is less than the zero speed.

[0063] According to one embodiment, the method is characterized in that the wheel drive and / or the braking device are only controlled if the amount of the control deviation is greater than a tolerance deviation.

[0064] According to one embodiment, the method is characterized in that the tolerance deviation is calculated positively proportional to the driving speed.

[0065] According to one embodiment, the trailer is characterized in that the braking device is mechanically actuated when a limit distance between the trailer and the connecting rod is exceeded.

[0066] The invention is further explained below using an exemplary embodiment. The accompanying drawings show:

[0067] Fig. 1 : a trailer according to the invention and a bicycle;

[0068] Fig. 2: a functional diagram of the trailer;

[0069] Fig. 3 : a schematic representation of a distance measuring device;

[0070] Fig. 4: a schematic representation of an oscillating distance between

[0071] trailer and towing vehicle;

[0072] Fig. 5: a schematic representation of the correction distance as a function of the driving speed.

[0073] Fig. 1 shows a trailer 1 according to the invention and a bicycle 2. The trailer 1 and the bicycle 2 are connected by a coupling rod 3. The trailer has a wheel drive, not shown separately in this view. The wheel drive drives the trailer 1 so that it follows the bicycle 2 without the cyclist having to exert any muscle power.

[0074] Fig. 2 shows a functional diagram of trailer 1. The functional diagram shows the acceleration and deceleration device 4, which comprises a wheel drive and a braking device. This is supplied with the energy required for propulsion by an energy source 5. The drive and braking devices are controlled by the controller 6. The control is implemented in such a way that the cyclist or other towing vehicle is as unaware as possible that the trailer 1 is following behind the bicycle. To ensure appropriate control, the distance measuring device 7 measures the distance between the bicycle 2 and the trailer 1. The distance is transmitted to the controller 6.

[0075] Fig. 3 shows a schematic representation of the distance measuring device 7. The distance measuring device 7 has a housing 8 which is firmly connected to the rest of the trailer 1. A connecting rod 9 projects into the housing. The connecting rod 9 is connected to the carriage 10 which is movably mounted on the linear guide 11. The linear guide 11 defines the degree of freedom that the connecting rod 9 can travel during a relative movement to the housing 8. The freedom of movement of the connecting rod 9 is limited by the wall of the housing on the right-hand side, which the connecting rod touches with the rubber end stop 12 as soon as the connecting rod 9 has moved as far as possible to the right. On the left-hand side, the freedom of movement is limited by the rubber end stop 13. The right-hand side corresponds to a side facing away from the trailer, facing the bicycle. The left-hand side therefore corresponds to a side facing the trailer.The corresponding stops in the form of the rubber end stops 12, 13 define an end of the path facing away from the trailer and an end of the path facing towards the trailer that the connecting rod 9 can travel.

[0076] A sensor target 14 is attached to the connecting rod 9. The displacement sensor 15 is capable of determining the position of the sensor target 14 relative to it. The displacement sensor 15 and its coordinate system are firmly connected to the housing 8 and thus to the trailer 1. Measuring the position of the sensor target 14 relative to the displacement sensor 15 thus corresponds to a measurement of the connecting rod 8 relative to the trailer 1. The displacement sensor 15 is an inductive displacement sensor. The sensor target 14 and the displacement sensor 15 form a displacement sensor.

[0077] The controller 6 is designed to subtract a neutral point position from the measured position of the connecting rod and thus calculate the control deviation. The controller 6 controls the wheel drive and the braking device based on the control deviation, so that the trailer 1 is accelerated or braked. The linear guide 11 ensures that the connecting rod 9 can only move relative to the housing 8 and the trailer 1 along a defined path, namely along the longitudinal axis of the connecting rod 9. The neutral point is also located on the longitudinal axis. The control deviation can therefore also be expressed as a distance along the longitudinal axis. The control deviation is positive or negative depending on whether the connecting rod is closer to the side facing away from the trailer or closer to the side facing the trailer relative to the neutral point.

[0078] As soon as the connecting rod 9 touches the rubber end stop 13 facing the trailer and continues to move toward the wall of the housing 8 facing the trailer, the lever 16 is flipped. In doing so, it rotates around the bearing point 17. Flipping the lever 16 tensions the cable 18. The cable 18 is connected to the braking system of the trailer 1. The lever 16 and the cable 18 are a mechanical brake actuation device that actuates the braking system as soon as a limit distance between the trailer 1 and the bicycle 2 and the connecting rod 8 connected to the bicycle 2 is exceeded.

[0079] Fig. 4 shows a schematic representation of an oscillating distance 19 between trailer 1 and towing vehicle 2, which is caused by the cyclist's pedaling. Regulating this distance 19 by corresponding acceleration and deceleration of trailer 1 would result in significant stress on the drivetrain.

[0080] Fig. 5 shows a schematic representation of the correction distance as a function of the driving speed, with the correction distance shown on the horizontal axis and labeled "position," and the driving speed shown on the vertical axis and labeled "speed." In this embodiment, the driving speed corresponds to the trailer speed, but it can also correspond to the bicycle speed or a combination of these two speeds.

[0081] The correction distance serves to shift the neutral point along the longitudinal axis. Consequently, at different driving speeds, with a different position of the connecting rod 9 relative to the displacement sensor 15 or the housing 8 or the trailer 1, no control deviation occurs. The illustration shows four different driving speed positions of the connecting rod 9 for which no control deviation exists. A zero speed 20 is assigned to position 21. A higher driving speed is assigned to position 22. A starting speed 23 is assigned to position 24. A driving speed below the starting speed is assigned to position 25.

[0082] From the illustrations of positions 21, 22 and 24 it is clear that as the driving speed increases the connecting rod 9 must move further towards the right side facing away from the trailer so that no control deviation occurs. This is due to the curve of the correction distance shown, which increases with increasing driving speed and is added to the zero position in order to calculate the neutral point. At zero speed 20 there is no correction distance. The zero point corresponds to the neutral point. In the state shown without control deviation the connecting rod 9 is located in the middle of the side facing towards the trailer and the side facing away from the trailer. Above zero speed 20 the correction distance is positive so that the neutral point is shifted towards the side facing away from the trailer. Below zero speed 20 the neutral point is shifted towards the side facing towards the trailer.Accordingly, connecting rod 9 must be shifted toward the side facing the trailer or the side facing away from the trailer to avoid any control deviation. Below starting speed 23, the correction distance increases again. Accordingly, the connecting rod must again be moved slightly further toward the side facing away from the trailer to avoid any control deviation.

[0083] The speed dependence of the correction distance means that the neutral point, and thus also the connecting rod 9, is closer to the side facing away from the trailer at high speeds. This can result in a large control deviation when braking the bicycle 2 before the connecting rod 9 touches the end facing the trailer in the form of the rubber end stop 13. On the other hand, the speed dependence of the correction distance means that the neutral point, and thus also the connecting rod 9, is closer to the end facing the trailer at low speeds. This can result in a large control deviation when accelerating the bicycle 2 before the connecting rod 9 reaches the end facing away from the trailer in the form of the rubber end stop 12.

[0084] Large control deviations are less affected by noise caused by mechanical and electronic inaccuracies in the components used. A large control deviation thus enables sensitive control. At very low speeds, the correction distance is selected so that the neutral point is slightly farther from the side closest to the trailer to compensate for jerking or shaking when starting off.

[0085] Furthermore, Fig. 5 shows that a tolerance deviation 26 exists. The control deviation must be large enough that the position of connecting rod 9 lies outside the respective tolerance deviation for controller 6 to control the acceleration and deceleration device 4. The tolerance deviation 26 increases with increasing travel speed. The tolerance deviation prevents the acceleration and deceleration device from being controlled at relatively small control deviations. This protects the acceleration and deceleration device and prevents wear.

[0086] Reference symbol

[0087] 1 trailer

[0088] 2 bicycles

[0089] 3 coupling rod

[0090] Acceleration and deceleration device

[0091] 4 tung

[0092] 5 Energy source

[0093] 6 controls

[0094] 7 Distance measuring device

[0095] 8 housings

[0096] 9 Connecting rod

[0097] 10 sleds

[0098] 11 Linear guide

[0099] 12 Trailer-facing rubber end stop

[0100] 13 Trailer-facing end stop

[0101] 14 Sensor target

[0102] 15 displacement sensors

[0103] 16 levers

[0104] 17 storage location

[0105] 18 cable pull

[0106] 19 Oscillating distance

[0107] 20 Zero speed

[0108] 21 Zero speed position

[0109] 22 Higher speed position

[0110] 23 Starting speed

[0111] 24 Starting speed position

[0112] 25 Under starting speed position

[0113] 26 T ol erance deviation

Claims

Claims 1) Trailer (1) with at least one driven wheel, comprising o an energy source (5) designed to supply a wheel drive with energy, o a braking device for decelerating the at least one wheel, o a connecting rod (9) designed to be connected to a towing device and which is movably mounted on the trailer, o a travel sensor designed to measure the position of the connecting rod (9) relative to the trailer (1), o a speed measuring device designed to determine the driving speed based on a measurement of the speed of the trailer and / or the connecting rod, and o an electronic controller (6), characterized in that o the controller (6) is designed to ■ to shift the position of a neutral point relative to the trailer (1) starting from a zero point depending on the determined driving speed, ■ to calculate a control deviation with the distance between the position of the neutral point and the measured position of the connecting rod (9) and ■ to control the wheel drive and / or the braking device with the control deviation. 2) Trailer (1) according to the preceding claim, characterized in that the displacement sensor is designed as an inductive displacement sensor, a capacitive displacement sensor or a resistance change displacement sensor. 3) Trailer (1) according to one of the preceding claims, characterized in that the connecting rod (9) is mounted on the trailer (1) so as to be displaceable along its longitudinal axis in the direction of a side facing the trailer and a side facing away from the trailer. 4) Trailer (1) according to the preceding claim, characterized in that the controller (6) is designed to shift the neutral point, starting from the zero point located on the longitudinal axis, along the longitudinal axis in the direction of the side facing away from the trailer by a correction distance which is positively proportional to the determined driving speed minus a zero speed. 5) Trailer (1) according to the preceding claim, characterized in that the controller (6) is designed to calculate the correction distance negatively proportional to the determined driving speed minus the zero speed if the determined speed is less than a starting speed which is less than the zero speed. 6) Trailer (1) according to one of the preceding claims, characterized in that the controller (6) is designed to control the wheel drive and / or the braking device only when the amount of the control deviation is greater than a tolerance deviation. 7) Trailer (1) according to the preceding claim, characterized in that the controller (6) is designed to calculate the tolerance deviation positively proportional to the determined driving speed. 8) Trailer (1) according to one of the preceding claims, characterized in that a mechanical brake actuating device is provided which is designed to actuate the brake device mechanically when a limit distance is undershot between the trailer (1) and the connecting rod (9). 9) Trailer (1) according to the previous claim, characterized in that the mechanical brake actuation device o comprises a lever (16) which is designed such that it is moved by the connecting rod (9) as soon as the limit distance is exceeded, and o comprises a cable (18) which is connected to the braking device and the lever (16) and is designed to be tensioned by moving the lever (16). 10) Method for regulating the distance between a trailer (1) having at least one wheel, a wheel drive and a braking device and a connecting rod (9) which is designed to be connected to a towing device and which is movably mounted on the trailer (1), comprising the steps of o measuring a position of the connecting rod (9) relative to the trailer (1), o measuring a speed of the trailer (1) and / or a speed of the connecting rod (9), o Determining a driving speed by means of the speed of the trailer (1) and / or the speed of the connecting rod (9), o Controlling the activation of the wheel drive and / or the braking device using a control deviation, o characterized in that o with the driving speed the position of a neutral point relative to the trailer (1) is shifted starting from a zero point, o the control deviation is calculated with the distance between the position of the neutral point and the position of the connecting rod. 11) Method according to claim 10, characterized in that o the connecting rod (9) is displaced along its longitudinal axis in the direction of a side facing the trailer or a side facing away from the trailer, o the neutral point, starting from the zero point located on the longitudinal axis, is displaced along the longitudinal axis in the direction of the side facing away from the trailer by a correction distance which is positively proportional to the driving speed minus a zero speed. 12) Method according to claim 11, characterized in that the correction distance is calculated negatively proportional to the driving speed if the determined driving speed is less than a starting speed which is less than the zero speed. 13) Method according to one of claims 10 to 12, characterized in that the wheel drive and / or the braking device are only controlled if the amount of the control deviation is greater than a tolerance deviation. 14) Method according to the preceding claim, characterized in that the tolerance deviation is calculated positively proportional to the driving speed. 15) Method according to one of claims 10 to 14, characterized in that the braking device is actuated mechanically when a limit distance between the trailer and the connecting rod is undercut.

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