METHOD FOR OPTIMIZING THE ACCELERATION BEHAVIOR OF A SELF-PROPELLED SOIL COMPACTION MACHINE AND SOIL COMPACTION MACHINE

Description

[0001] The invention relates to a method for optimizing the acceleration behavior of a self-propelled soil compaction machine and to a soil compaction machine.

[0002] Soil compaction machines are used, among other things, in road construction to compact an asphalt mat laid, for example, by a paver. Such soil compaction machines are known per se and are disclosed by way of example in EP3258014A1 and DE102014018457A. These machines typically comprise one or more ground contact devices that roll over the subsoil, such as roller drums and / or rubber wheels. The compaction effect can be achieved statically by the machine's own weight as it rolls over the subsoil, or dynamically by using so-called vibration exciters. The primary function of such soil compaction machines is to further compact the laid asphalt mat, for example, to smooth the joints of adjacent paving tracks and to compensate for irregularities caused by the paver.Typically, a soil compaction machine passes over the asphalt mat to be compacted multiple times in a reversing motion. During this compaction process, it is crucial to prevent the machine itself from introducing irregularities into the asphalt mat. This can occur due to improper operation of the machine. It is important to consider that the malleability of the asphalt mat decreases as its temperature drops. Therefore, the risk is particularly high in the area immediately behind a preceding asphalt paver, where improper operation of the compaction machine can lead to irregularities being created by the machine itself. In this area, the asphalt mat is still relatively soft and susceptible to surface defects introduced by the compaction machine.Simultaneously, a reversing process of the soil compaction machine frequently occurs in this area, as it first approaches the asphalt paver on the freshly laid asphalt mat and then moves away again in the opposite direction. Improper braking and acceleration of the soil compaction machine can quickly lead to surface irregularities in the asphalt mat caused by the machine. JP 2020 133324 A relates to a compaction machine, in particular a method for improving construction precision in road construction. DE 10 2018 009344 A1 describes a method for performing area-wide, dynamic compaction control of a soil compaction machine using a mobile unit, a soil compaction machine, and a system comprising at least two soil compaction machines.

[0003] Starting from this, the object of the invention is to provide a way to reduce the risk of generating irregularities introduced into a soil substrate, in particular an asphalt mat, by the soil compaction machine.

[0004] The problem is solved by a method and a soil compaction machine according to the independent claims. Preferred embodiments are specified in the dependent claims.

[0005] In a first aspect, the invention relates to a method for optimizing the acceleration behavior of a self-propelled soil compaction machine, particularly in general during travel operation, and especially during compaction operation. Acceleration behavior in this context refers both to an increase in travel speed, for example when the soil compaction machine starts moving from a standstill or when the travel speed increases during travel, and to a decrease in travel speed, for example when the moving soil compaction machine decelerates, for example to a standstill (negative acceleration).

[0006] In its basic design, a soil compaction machine of this type comprises at least one compaction element that rolls on the soil to be compacted. This can be a drum-shaped roller or a set of rubber tires. Typically, viewed in the forward direction, the soil compaction machine includes at least one front and at least one rear compaction element that rolls on the soil. Particularly in the case of a rubber-tired roller, more than two front and more than two rear compaction elements may be included, which, when traveling straight ahead, may be offset from one another and overlapping in their tracks. The soil compaction machine may have a machine frame that forms its supporting structure. The machine frame may be a single piece or may comprise a front and rear frame connected by a steering joint.The soil compaction machine can be steered, axle-steered, or articulated. It can be self-propelled, meaning it moves under its own power and has a primary drive unit that provides the necessary energy for operation. This unit can be, for example, an internal combustion engine or an electric motor. The soil compaction machine can be operated from a control station. Alternatively, it can also be remotely controlled or autonomously operated. The soil compaction machine can include one or more vibration excitation devices, particularly vibratory exciters.With such a vibration excitation device, the soil compaction device can be subjected to vibrations for dynamic compaction of the subsoil.

[0007] A soil compaction machine of this type further comprises a control unit. This can be a computer system including a CPU and other components, such as one or more computer programs. The control unit can be configured to carry out, in particular control and / or regulation, the method according to the invention. It can, for example, be part of a complete machine control unit or be configured as an independent, additional control unit or independent functional module.

[0008] Starting with a soil compaction machine of the generic type, the method according to the invention comprises, in one step a), first determining at least one value of at least one environmental parameter external to the soil compaction machine. For the direct or indirect determination of the at least one value of the external environmental parameter, the soil compaction machine can have one or more suitable sensors as part of a sensor device. In addition to or as an alternative to an actual direct or indirect measurement of the current value of the external environmental parameter, this value can also be calculated or predicted based on, for example, a suitable model. This can be done, for example, on the basis of a temperature model of the subsoil, particularly one that is position-dependent, and, for example, knowledge of a current outside temperature, a time difference, or similar information.Based on this, the cooling behavior of the subsoil can be determined over time, and from this, the (likely) current temperature of the soil, for example, of the core and / or surface of an asphalt mat, can be calculated at a given time. An external environmental parameter is specifically understood to be a state value of an area or point that is not part of the soil compaction machine itself, but lies outside of it. This can be, in particular, an area and / or point located in front of the soil compaction machine in a direction of travel, especially with respect to the current direction of travel of the soil compaction machine.In other words, this is preferably an area and / or point that lies in front of the soil compaction machine in its current travel path and will therefore be traversed by the machine if it continues moving. The current direction of travel can be determined by the current travel settings of the soil compaction machine. To determine the current direction of travel, it is therefore not essential that the soil compaction machine is actually moving in that direction. What is crucial is which direction of travel is specified, for example, by a control element and / or a control program, or whether the soil compaction machine is in a forward or reverse travel mode. This can be determined, for example, by the position of a control element and / or from a control program of a machine control system, which may be part of the control unit.Additionally or alternatively, it is also possible to determine the current direction of travel of the soil compaction machine using one or more sensors, provided the machine is actually moving in that direction. This can be done, for example, using a camera, a motion and / or direction sensor located in the drive train of the soil compaction machine, or similar devices.

[0009] The at least one external environmental parameter can be a soil parameter or a property of the soil to be compacted. Physical properties of the subsoil that influence its compaction behavior when the soil compaction machine passes over it are particularly relevant. These can include, for example, plastic deformability, a modulus of elasticity, a degree of compaction, stiffness, rolling resistance, and / or a value correlating with one or more of these soil properties. The temperature of the subsoil, especially an asphalt mat, located in the direction of travel of the soil compaction machine and in front of the compaction unit, is particularly suitable, as described in more detail below.At least one value of the at least one external environmental parameter to the soil compaction machine, which can be recorded continuously or at intervals, can be supplied to the control unit wirelessly or via a wired signal line.

[0010] For the method according to the invention, it is further provided that in step b) the control unit determines a maximum permissible target acceleration value for the soil compaction machine based on at least one determined value of the external environmental parameter. A suitable control algorithm can be stored in the control unit for this purpose. Additionally or alternatively, one or more characteristic maps, curves, or similar parameters can be used. Furthermore, a learning mode can be provided in which, for example, the operator manually specifies a maximum permissible target acceleration for at least one currently available external environmental parameter, and based on this, a control algorithm varies the maximum permissible target acceleration for different values ​​of the environmental parameter(s), for example, by extrapolating. The learning mode can also be implemented using machine learning.

[0011] Step c) involves recording the actual acceleration or a manually set acceleration value of the soil compaction machine. This actual acceleration value can be determined directly or indirectly via one or more suitable sensors within the soil compaction machine itself, for example, using a speed sensor on one or more of the soil compaction units and / or a driving element, and / or by using the external environment, for example, with a camera and suitable image processing software (e.g., image comparison methods). A manually set acceleration is an operator-defined acceleration and can be determined based on a control element position, such as the drive lever position, and / or other control input.The acceleration target thus refers to a value of actual acceleration that is still to be achieved according to the current control setting. The actual acceleration of the soil compaction machine, on the other hand, refers to the current, actual acceleration value of the soil compaction machine. It may also be provided that in step c) (and also in the relevant subsequent steps) both the value of the actual acceleration and the value of the manual acceleration target are recorded and both values ​​are taken into account in the subsequent steps.

[0012] Once the actual acceleration has been determined, the control unit can, in step d), check whether the value of the actual acceleration and / or the manually set acceleration exceeds the value of the maximum target acceleration. This occurs in operating situations where the travel speed of the soil compaction machine is to be changed too quickly, or is being changed, i.e., is being increased or decreased too rapidly, or would be changed.

[0013] In the event that the actual acceleration value and / or the manually set acceleration exceeds the maximum target acceleration value, step e) now provides for the control unit to trigger a countermeasure. This countermeasure can consist of ideally reducing the actual acceleration to such an extent that it does not exceed the determined maximum target acceleration. In the case of an increase in driving speed, this could, for example, be a reduction in the rate of increase in speed per unit of time or maintaining the current driving speed. In the case of a reduction in driving speed, this could be a delay in the braking process. In the case of a countermeasure based on a manually set acceleration value, the triggering of a countermeasure could, for example, be a correction of the actual acceleration process.For example, if the user manually specifies a sudden change in speed that would typically result in a high actual acceleration, the countermeasure can be to reduce the actual acceleration compared to the user's specification to ensure that the maximum target acceleration value from step b), which depends on at least one determined value of the external environmental parameter, is not exceeded when the user's specification is implemented. In In this case, the soil compaction machine accelerates more slowly than it would and could according to the user's instructions.

[0014] Overall, the method according to the invention thus achieves the avoidance of excessive speed changes of the soil compaction device rolling on the subsoil, in accordance with or depending on the external environmental parameter. At the same time, provided the environmental parameter permits, the soil compaction machine can be accelerated relatively quickly, or overly cautious starting and stopping can be avoided, without introducing undesirable irregularities into the subsoil by the soil compaction machine. In this way, the work process of the soil compaction machine can therefore be carried out more efficiently.

[0015] Regarding actual and target acceleration, absolute values ​​can be used. The only relevant factor is the difference in magnitude between the current or specified acceleration and zero, or between a stationary or constantly moving soil compaction machine. Therefore, when a target acceleration is exceeded without further information, this refers to the absolute value of the actual acceleration. This obviously includes situations where a positive acceleration exceeds the maximum positive target acceleration, and a negative acceleration or braking results in the maximum negative target acceleration falling below the target value. A distinction between positive and negative acceleration can be made, for example, by considering the time period.Acceleration within the meaning of the invention therefore relates in particular to the deceleration of the soil compaction machine. Measured values ​​in this context are in particular current values ​​or currently determined values, especially actual values.

[0016] A particularly suitable external environmental parameter for use in the method according to the invention is the temperature of the subsoil, especially the temperature of an asphalt mat to be driven over by the soil compaction machine. It is therefore preferred if, in step a), the temperature of the subsoil to be compacted is determined, in particular by the soil compaction machine itself, for example by means of a suitable temperature sensor. The temperature determination can be position-dependent, for which purpose the soil compaction machine can have a suitable position sensor, for example a GPS receiver.

[0017] The core temperature of a soil layer to be compacted, such as an asphalt mat, can be used as a reference point. The current core temperature, which is particularly dependent on the location, can be modeled or determined using a temperature model. It can be helpful to know when and at what temperature the asphalt mat was laid at a specific location. Based on this information, a cooling curve of the asphalt mat or its core can then be calculated, for example, using a suitable algorithm, particularly by incorporating one or more other external environmental parameters, such as ambient temperature, wind speed, or other weather conditions.In a preferred embodiment of the method according to the invention, it can therefore be provided that the determination in step a) includes determining a, in particular probable, actual temperature of the subsoil to be compacted, taking into account a temperature model of the subsoil to be compacted.

[0018] Alternatively or additionally, for the determination in step a), it is also possible to measure the actual temperature of a soil surface, particularly one located in front of the soil compaction machine in the direction of travel of the machine, using a sensor device. In this case, the soil compaction machine itself determines the current surface temperature in its immediate vicinity. This temperature value alone may be sufficient to determine a maximum permissible target acceleration of the soil compaction machine in step b). It can be advantageous if, at this point, only the current surface temperature is determined by the soil compaction machine and used in the method according to the invention.In this way, the method according to the invention can be carried out independently of any further equipment by the soil compaction machine itself. For measurement, one or more sensors can be arranged on the soil compaction machine as part of a sensor assembly. It is preferred that the measurement of the current temperature of the soil surface is carried out contactlessly, for example by means of an infrared temperature sensor, in particular a thermal imaging camera. Ideally, the measuring point on the soil surface is located practically directly in the current travel path of the soil compaction machine, in the direction of travel, and in particular only a few centimeters, for example a maximum of 50 cm, in front of the soil compaction unit.

[0019] In principle, the control unit for carrying out the method according to the invention is designed such that different maximum permissible target accelerations are specified for positive and negative acceleration. In step b), a value for the maximum permissible target acceleration for positive acceleration and a value for the maximum permissible target acceleration for negative acceleration are then set separately, whereby the values ​​may differ from each other in absolute terms. This can be particularly useful if the current circumstances result in the risks of generating surface irregularities due to a change in speed differing between deceleration and acceleration.However, it is also possible that in step b) the absolute value of the maximum permissible target acceleration is reduced by the control unit if the measured temperature of the subsoil to be compacted exceeds a temperature threshold, and vice versa. This process enhancement therefore does not differentiate between positive and negative acceleration.

[0020] When setting a maximum permissible target acceleration value for the soil compaction machine in step b), one or more additional parameters can be taken into account. These can be manually specified by the operator or transmitted to the control unit from another source, such as another construction machine and / or a central site management server or remote server, particularly wirelessly. Examples of such parameters include the thickness of an asphalt mat, the composition of the subgrade, especially an asphalt mat, the application of aggregate, the time at which a layer beneath the current surface layer was applied, or similar information.These parameters could include the time elapsed since the current time, the temperature of the subsoil on which an asphalt mat has been laid, particularly shortly before or during its placement, the compaction state (e.g., degree of compaction) of the subsoil supporting the asphalt mat, or similar factors. These additional parameters can also be linked to positional data.

[0021] The method according to the invention can also include determining the position of the soil compaction machine, for example, by means of a suitable method for determining position that is known per se in the prior art. This can be done, among other things, using a GPS receiver and / or by using one or more total stations. Determining the position can be useful for documentation purposes. Furthermore, it can also facilitate the integration of other external information, for example, the assignment of parameters linked to position data to the current actual position of the soil compaction machine.

[0022] The specific implementation of step e) can vary. For example, the countermeasure in step e) could involve issuing an acoustic and / or visual signal to the operator of the soil compaction machine. An acoustically perceptible signal could be, for example, a beep or a voice output. A visually perceptible signal could be, in particular, a display, such as on a screen or similar device. The displayed information could simply indicate that the soil compaction machine is currently accelerating too quickly. Alternatively, the currently determined maximum permissible target acceleration could be displayed. These types of countermeasures are therefore more of a suggestion and thus represent rather passive operating recommendations to the operator of the soil compaction machine.

[0023] Additionally or alternatively, the countermeasure in step e) can include adjusting the operating characteristics of a control element operated by the soil compaction machine operator. This can be achieved, for example, by adjusting the control element's response curve to the maximum permissible target acceleration and / or by having the control unit actively adjust the change in travel speed from the actual speed to the target speed. For example, if the operator sets a control element to full throttle or a specific target speed while the soil compaction machine is stationary, the control unit can adjust the acceleration process required to reach the target speed, taking into account the currently maximum permissible target acceleration. The same procedure can be used for decelerating the soil compaction machine.However, it is advisable that, in the event of a necessary emergency braking, the acceleration process controlled by the control unit can always be manually overridden, or that the triggering of an emergency braking maneuver by the operator is always possible, for example by abruptly actuating a brake element and / or by activating an emergency braking device, and that this braking input by the operator is always prioritized over the control of acceleration by the control unit.

[0024] A further countermeasure in step e) can be, additionally or alternatively, a direct and therefore autonomous intervention by the control unit in the travel speed control of the soil compaction machine. This could, for example, involve intervention in the engine control and / or the braking system. It can thus also be provided that the control unit initiates and controls a change in acceleration on its own, particularly without additional manual input.

[0025] According to a particularly preferred embodiment of the inventive method, during operation of the soil compaction machine, obstacles in the machine's path can be monitored using an obstacle detection device. Possible embodiments of an obstacle detection device are disclosed, for example, in DE102021002728A1. This can be achieved, for example, using one or more distance sensors, one or more cameras and suitable image processing software or computer programs, and / or by detecting geolocated virtual boundaries ("geofencing"), for example, using a position sensor.A key aspect of the present invention is that, upon detection of an obstacle in the path of the soil compaction machine, the required braking distance can be determined, taking into account the actual speed of the soil compaction machine and the value of the maximum permissible target acceleration. The control unit thus predictively calculates the length of the braking distance based on an approaching obstacle, considering the current operating parameters and conditions. Based on this, the control unit can trigger a countermeasure, at least at the latest, when the distance of the soil compaction machine is equal to or greater than the calculated required braking distance.This ensures that the soil compaction machine comes to a stop in time before reaching the obstacle, while adhering to the currently specified maximum permissible target acceleration.

[0026] Ideally, determining the required braking distance should include adding a braking distance reserve and / or braking time reserve, which depends in particular on the actual speed of the soil compaction machine. This braking distance reserve thus represents a distance buffer that is added to the previously determined minimum required braking distance. The braking time reserve represents a buffer in terms of time, which is added to the time interval required to complete the previously determined minimum required braking distance. In this way, the braking process can be carried out reliably under the given operating conditions.The specific braking distance / time reserve can be constant, but it is preferred if the extent of the braking distance / time reserve is variable depending on the actual speed and thus dynamically adjusted to, for example, the current driving speed and / or the current maximum permissible target acceleration. For example, the higher the current actual speed, the greater the braking distance / time reserve. Additionally or alternatively, the extent of the braking distance / time reserve can also be varied depending on the current maximum permissible target acceleration, in which case the braking distance / time reserve increases as the maximum permissible target acceleration decreases.

[0027] A particularly convenient further development of the method according to the invention consists in the control unit controlling a reversing process or in the control unit having a reversing mode. A reversing process comprises, starting from a soil compaction machine moving at a, in particular, defined maximum, travel speed in a current direction of travel, braking the soil compaction machine to a standstill and, in particular, immediately thereafter accelerating the soil compaction machine in the opposite direction of travel until a travel speed is reached, in particular a travel speed to be achieved that is predetermined for the reversing process or the reversing mode itself.This entire process, in which the soil compaction machine is stopped while traveling in one direction and then reverses direction, can ideally be performed autonomously by the control unit. The triggering event could be, for example, the detection of an obstacle approaching the soil compaction machine in its current path by the obstacle detection device, or a manual input from an operator. It goes without saying that the accelerations required for the reversing process are carried out taking into account the currently permissible maximum acceleration. It can also be provided that, additionally or alternatively, the operator is shown on a display the distance required for a reversing maneuver (braking to a standstill and then resuming travel in the opposite direction) under the current operating conditions.This can be achieved, in particular, by overlaying a real-time camera image from a camera that records the path of the compaction machine in front of it, in the direction of travel. In this way, the operator of the compaction machine can see in real time on the camera image how far the machine will travel if they initiate a reversing maneuver. Independently of a reversing maneuver, the braking distance required to bring the compaction machine to a standstill while adhering to the current maximum permissible acceleration can also be overlaid on such a camera image.

[0028] Another aspect of the invention relates to a soil compaction machine, particularly a self-propelled one, comprising a soil compaction device that rolls on the subsoil to be compacted and a control unit. Regarding possible configurations of the soil compaction machine itself, reference is made to the preceding information to avoid repetition. The control unit of the soil compaction machine is designed to carry out the method according to the invention.

[0029] A sensor system with at least one or more sensors is part of the soil compaction machine. The values ​​and / or sensor signals determined by the sensor system can be transmitted to the control unit. The sensor system can be in signal transmission communication with the control unit for this purpose. The signal transmission connection can be wireless or wired.

[0030] Specifically, the sensor device can include a sensor designed to detect an external environmental parameter. This can be, for example, a temperature sensor, in particular a surface temperature sensor. This sensor can most preferably be designed to detect the temperature of the ground surface in the direction of travel, especially directly in front of the soil compaction device. In particular, the soil compaction machine can have at least two such sensors, one of which detects a point or area of ​​ground in the direction of travel in front of the soil compaction device, and the other of which detects a point or area of ​​ground opposite the direction of travel in front of the soil compaction device, or in particular in front of a second soil compaction device.Ideally, the soil compaction machine should have at least two sensors arranged on the machine in such a way that, viewed in the current direction of travel, they together detect a soil point or area in front of and behind the machine. Alternatively or additionally, it is also possible for the sensor to detect a soil point or area located between two soil compaction units arranged one behind the other, specifically between a front and a rear compaction unit, and thus, when projected onto a virtual horizontal plane, below the soil compaction machine.

[0031] Additionally or alternatively, the sensor system can include a position sensor designed to determine the position of the soil compaction machine within a reference coordinate system. This could, for example, be a GPS receiver. This enables the creation and use of position-dependent data and parameters. For instance, when using a temperature model to determine the current temperature of an asphalt mat as an external environmental parameter, determining the current position of the soil compaction machine allows it to be correlated with local, calculated temperature values.

[0032] The sensor system can additionally or alternatively include a sensor for obstacle detection in the area in front of the soil compaction machine in the direction of travel. Such a sensor could be, for example, a lidar sensor, a distance sensor, a scanner, a camera, or similar. Suitable processing software, in particular image processing software or a computer program, can be part of the sensor and / or the control unit. This software uses the available sensor data to identify or detect one or more obstacles in the path of the soil compaction machine. When using a soil compaction machine, this is relatively easy, as the soil surface to be compacted, especially asphalt, is usually already relatively flat, and obstacles are thus clearly visible in the driving path.Furthermore, the sensor(s) are ideally designed for spatial obstacle detection, for example by using a stereo or 3D camera to determine a current distance from the soil compaction machine to the detected obstacle.

[0033] The soil compaction machine can have one or more accelerometers as part of its sensor system. The accelerometer is designed to directly or indirectly determine the actual acceleration of the soil compaction machine in or against a direction of travel. Additionally or alternatively, the actual acceleration of the soil compaction machine can also be derived from other movement parameters of the machine, such as changes in speed and / or position, each as a function of time. Acceleration can also be determined using a camera and image processing software, for example, via an image comparison method of sequentially acquired images.

[0034] The sensor system can also include a travel speed sensor. This can be used to directly or indirectly determine the actual travel speed of the soil compaction machine. For example, this could be a speed sensor that determines the rotational speed of one of the soil compaction units. Determining the travel speed using a camera and image processing software is also possible, for example, via an image comparison method of images taken sequentially.

[0035] The proposed setting of a maximum permissible target acceleration can be used to assist the operator, particularly during reversing operations, and to counteract excessively abrupt changes in speed, especially braking of the soil compaction machine. For this purpose, it can be particularly advantageous if the soil compaction machine includes a signaling device designed to output a signal when the actual acceleration exceeds or falls below the maximum permissible target acceleration, or, if absolute values ​​are used for the maximum permissible target acceleration, always exceeds it. The signal could, for example, be an audible signal perceptible to the operator of the soil compaction machine, such as a horn, loudspeaker, or similar device.Alternatively or additionally, a signal perceptible to the operator of the soil compaction machine can be used, such as one or more warning lights, a display screen (especially one located within the operator's cab), or similar. A display screen, in particular, can also be used to show a travel path prediction and / or the minimum braking distance required under the current operating conditions, especially considering the current maximum permissible target acceleration, to decelerate the soil compaction machine from its current speed to a standstill.In this case, the control unit includes a prediction function designed to determine a minimum braking distance from the available operating parameters and taking into account the current maximum permissible target acceleration, and to display this, for example, as a distance indication and / or superimpose it onto a real-time camera image.

[0036] According to the invention, the soil compaction machine comprises a triggering device that can be actuated by an operator. This device is designed such that, after actuation of the triggering device by the operator, a reversing process of the soil compaction machine is controlled by the control unit. This process involves braking the soil compaction machine from one direction of travel to a standstill and then accelerating it in the other direction of travel, without exceeding or falling below a maximum target acceleration and / or target acceleration range. Actuation of the triggering device thus initiates an automated reversing process controlled by the control unit, which ensures that the currently permissible maximum target acceleration is neither exceeded nor fallen below.It may be necessary for the operator to keep the release device, such as a push button or similar, pressed for safety reasons throughout the entire reversing process, which is automatically controlled by the control unit. If the operator releases the release device, the control unit may initiate an emergency stop.

[0037] According to a further preferred embodiment, the soil compaction machine includes a control element, operable by an operator of the soil compaction machine, for changing the speed of the soil compaction machine. This can be, for example, a manually operated control lever, a joystick, or a pedal. The control unit is designed such that it adapts the control inputs entered by the operator via the control element to the maximum permissible target acceleration of the soil compaction machine. For example, if the operator adjusts the control element to a maximum acceleration or deflects it to its maximum, the control unit adjusts the acceleration performed by the soil compaction machine to the currently maximum permissible target acceleration. This can thus lead to the situation that, with one and the same deflection or deflection,Changing the position of the control element allows different accelerations to be performed, depending on the currently maximum permissible target acceleration. This can be achieved, for example, by intervening in the motor and / or drive control of the soil compaction machine, such as by limiting the speed / acceleration setting within the drive control.

[0038] In principle, the control unit can define separate maximum permissible acceleration values ​​for positive and negative acceleration. These values ​​can differ in absolute terms. Preferably, the maximum permissible negative acceleration is lower in absolute terms than the maximum permissible positive acceleration.

[0039] The invention is explained in more detail below with reference to the exemplary embodiments shown in the figures. The figures schematically depict: Fig. 1: A side view of a tandem roller soil compaction machine; Fig. 2: A side view of a rubber-tired roller soil compaction machine; Fig. 3: A side view of an irregularity introduced into a soil surface by improper braking acceleration; Fig. 4: An overview of the operation of a control unit; Fig. 5: A braking process from a driving speed at a comparatively high surface temperature of the subsoil; Fig. 6: A braking process from a driving speed at a comparatively medium surface temperature of the subsoil; Fig. 7: A braking process from a driving speed at a comparatively low surface temperature of the subsoil; Fig. 8: A comparison of the braking curves from the Figures 5 to 7Fig. 9: A characteristic curve for determining a maximum permissible target acceleration depending on a determined current external environmental parameter; Fig. 10: A side view of a braking distance prediction function; Fig. 11: A screen view of a camera image in the direction of a current travel direction of a soil compaction machine; Fig. 12: The view from Fig. 11 with the braking distance shown, calculated from a driving speed at a comparatively low surface temperature of the ground; Fig. 13 the view from Fig. 11 with the braking distance shown, calculated from a driving speed at a comparatively average surface temperature of the ground; Fig. 14 the view from Fig. 11with the braking distance shown from a driving speed at a comparatively high surface temperature of the subsoil; and Fig. 15 a flowchart of a method for optimizing the acceleration behavior of a self-propelled soil compaction machine.

[0040] Identical or similarly functioning components are identified in the figures by the same reference symbol. Repeating components are not numbered separately in each figure.

[0041] Figure 1 Figure 1 shows a soil compaction machine 1 in a side view. Specifically, it is a tandem roller that is articulated or, as shown in Figure 2, can be articulated. Fig. 1The soil compaction machine 1, which can be steered, comprises a front soil compaction unit 2 (viewed in a forward direction F) and a rear soil compaction unit 2 (viewed in a forward direction F). In the present embodiment, the soil compaction units 2 are designed as roller drums, specifically smooth-shell roller drums. In combination rollers, one of the two soil compaction units can be designed as a set of rubber tires. One or more vibration exciters 3, in particular unbalance exciters, can be arranged inside the soil compaction units 2. The soil compaction machine can have a machine frame 4 as its main supporting structure. The drive energy required for travel and operation is generated by a primary drive unit 5, for example, by an internal combustion and / or electric motor.The soil compaction machine moves under its own power in forward direction F or in the opposite reverse direction R during operation and is therefore self-propelled.

[0042] Part of the soil compaction machine 1 can be a driver's cab 6, which, viewed in the direction of travel (F / R), can be located approximately in the center of the soil compaction machine 1. The driver's cab 6 can contain a driver's seat 7, a display device 8, and / or one or more control elements 9 to enable an operator to control the driving and working operation of the soil compaction machine 1. The soil compaction machine 1 can also be designed to be remotely controlled or autonomously operated, either additionally or alternatively.

[0043] Fig. 2Figure 1 shows a further embodiment of a soil compaction machine 1 in a side view, specifically a rubber-tired roller, whereby only existing essential differences are pointed out below and otherwise reference is made to the description of the soil compaction machine 1 from the [reference to be added]. Fig. 1 Reference is made to the soil compaction machine 1 from the Fig. 2 can therefore be used for soil compaction machine 1 from Fig. 1 They have a similar structure. One difference lies in the specific design of the soil compaction devices 2, where a rubber-tired roller consists of rubber wheels. More than three rubber wheels can be provided as front and rear soil compaction devices 2.

[0044] The task of a soil compaction machine 1 is to compact a subsoil as it passes over it and / or to shape a soil surface U, particularly for smoothing. During compaction or operation, the soil compaction machine 1 travels over the soil surface U, compacting the subsoil statically and / or dynamically. For this purpose, the respective soil compaction unit 2 rolls along the soil surface U and rotates about its respective axis of rotation A. The subsoil to be compacted can be, in particular, an asphalt mat with a layer thickness D, laid relatively recently, for example, by a preceding asphalt paver, and thus still malleable. As a rule, several passes by one or more soil compaction machines 1 are required to achieve sufficient compaction of the subsoil.The soil compaction machines 1 therefore frequently travel back and forth several times on the soil surface U, reversing their current direction of travel in the process. To do this, the soil compaction machine 1, which is traveling at a certain speed in one direction, must be decelerated or decelerated until it comes to a standstill. The soil compaction machine 1 is then decelerated in the opposite direction, for example, until a desired target speed is reached. During such a reversing process, a driver's seat 7, a display device 8, and / or one or more control elements 9 can also be rotated from a position facing one direction of travel to a position facing the other direction, in particular by 180°.

[0045] Particularly during such a reversing process, there is a risk that, in the event of an unfavorable movement sequence, irregularities will be introduced into the soil surface U by the soil compaction machine 1, which is undesirable. Fig. 3 This phenomenon is illustrated by an example of a soil compaction device in a side view. Coming from the direction of travel F, the soil compaction device 2, or the soil compaction machine with this soil compaction device 2, is decelerated. In this case, this negative acceleration is so great that the soil compaction device 2 pushes a wave of material W in the direction of travel F, creating soil irregularities. These are due to the deviation from the ideally flat surface V in the Figure 3This phenomenon is also observable. It occurs similarly when the soil compaction machine 1, especially from a standstill, is accelerated too strongly in one direction. The susceptibility of the subsoil or soil surface U to the development of irregularities in the soil surface U due to excessive negative and positive acceleration processes of the soil compaction machine 1 can depend on many factors, such as the material and composition of the subsoil, the temperature of the subsoil, the moisture content of the subsoil, the degree or state of compaction of the subsoil, the condition of the soil surface (water and / or bulk material cover), etc.The method described in more detail below provides a way to optimize the acceleration behavior of the soil compaction machine 1 during compaction operation and, in particular, to reduce the formation of the in . Fig. 3 to counteract the irregularities shown in the soil surface U.

[0046] The soil compaction machine 1 can have a control unit 10. This unit can include a computer system for carrying out the procedure described in more detail below, using a suitable computer program.

[0047] Furthermore, a sensor device 11 may be included with the soil compaction machine, which has at least one or more sensors 12 for detecting a value of at least one external environmental parameter. The sensor data / signals determined by the sensor device 11 can be transmitted via the Figures 1 and 2Signal transmission lines not shown are transmitted to control unit 10 either wired or wirelessly. Fig. 1The sensor device 11 for detecting at least one external environmental parameter comprises, for example, a temperature sensor 12 that detects the actual temperature of the soil surface lying in the direction of travel of the soil compaction machine 1. This can be, for example, a thermal imaging or infrared camera or an infrared sensor with one or more measuring points. The soil compaction machine 1 comprises such a sensor 12 on each side (front and rear) as viewed in the direction of travel. The respective measuring beam is indicated by a dashed arrow. The measuring beam preferably strikes the soil surface U practically immediately in front of the soil compaction unit 2 following in the direction of travel of the soil compaction machine 1. The sensor 12 can also be configured such that the measuring beam(s) scan an area, for example, a line or surface.When the direction of travel is reversed, the temperature sensor can also be switched from the one previously located at the front in the direction of travel to the temperature sensor 12 that will be located at the front in the direction of travel in the future. Additionally or alternatively, it is also possible to arrange such a temperature sensor in the area between the two soil compaction devices 2 when viewed in the direction of travel.

[0048] The acquisition of an external environmental parameter can also be carried out using one or more image acquisition devices 13, for example, a 3D camera, infrared camera, PMD camera, and / or stereo camera. For this purpose, one or more such image cameras 13 can be arranged on the soil compaction machine 1, in particular such that the recording area captured by the image acquisition device 13 extends in the direction of travel in front of the soil compaction machine 1, and in particular such that at least part of the soil surface located in the direction of travel in front of the soil compaction machine 1 is also captured. The recording area of ​​the image acquisition devices 13 is defined in the Figures 1 and 2denoted by B, it extends horizontally and transversely to the direction of travel, preferably at least over the entire width of the soil compaction machine 1. Using a suitable evaluation computer program and depending on the type of image acquisition device 13 used, properties of the soil surface, such as the presence of bulk material distributed on the soil surface, surface roughness, etc., can be determined as external environmental parameters.

[0049] Additionally or alternatively, the soil compaction machine 1 can also include a temperature sensor 14, which is designed to determine the air temperature as an external environmental parameter. The current outside temperature, as an external environmental parameter, can, for example, affect the cooling behavior of a freshly laid asphalt mat.

[0050] Another possibility for acquiring an external environmental parameter, which can be additionally or alternatively included by the soil compaction machine 1, is a precipitation and / or wind sensor 15. This sensor can be configured to detect whether precipitation is currently occurring and, if so, ideally the amount of precipitation per unit of time and / or the temperature of the precipitation. A wind sensor 15 is configured to determine the wind speed present in the immediate vicinity of the soil compaction machine 1, preferably when the soil compaction machine 1 is at least briefly stationary during a reversing operation. Existing precipitation and / or wind, as external environmental parameters, can also affect, for example, the cooling behavior of a freshly laid asphalt mat.

[0051] In addition to the sensor device 11 being configured to detect at least one external environmental parameter, the sensor device 11 can also include one or more sensors for detecting one or more operating parameters of the soil compaction machine 1 itself. These can be, for example, a travel speed and / or direction sensor 16, an acceleration sensor 17, a position sensor 18, a vibration sensor 19, an operating status sensor 20, or similar. These sensors 16 to 20 are located in the Figures 1 and 2 For the sake of clarity, only a cursory description is given.

[0052] The travel speed sensor 16 is designed to directly or indirectly determine the current travel speed of the soil compaction machine and can, for example, be a speed sensor. The travel direction sensor is designed to directly or indirectly detect movement of the soil compaction machine 1 in forward and / or reverse directions F and R.

[0053] The acceleration sensor 17 is designed for the direct or indirect detection of the acceleration of the soil compaction machine in and / or against the current direction of travel F / R. Sensors 16 and 17 can also be combined in a single sensor.

[0054] The position sensor 18 is designed to determine the current position of the soil compaction machine 1 with respect to a reference coordinate system. This can be, for example, a locally installed reference coordinate system, such as one or more local total stations and at least one suitable signal receiver on the soil compaction machine. Alternatively or additionally, a satellite-based reference coordinate system can also be used, such as with a GPS receiver on the soil compaction machine.

[0055] The vibration detection sensor 19, for example an acceleration sensor, can be used to determine, for example, the progress of compaction and / or to ascertain whether one or more vibration exciters, if any, are activated and / or deactivated and / or in which vibration excitation mode they are currently operating.

[0056] Finally, the operating condition sensor 20 can be used to record one or more operating parameters, in particular of the drive system of the soil compaction machine 1, for example to determine the operation and / or operating intensity of one or more components of the soil compaction machine 1, such as the primary drive unit, a sprinkler system, a travel drive, a vibratory drive, etc.

[0057] The soil compaction machine may also have a transmitting and / or receiving unit 21. This unit allows the reception of signals / information from outside the soil compaction machine 1, for example, from a remote server, from one or more other construction machines, in particular from a preceding road paver, and additionally or alternatively, the transmission of information, values, and / or signals that were produced and / or generated at the soil compaction machine 1, for example, for reception by a remote server and / or one or more other construction machines. The transmitting and / or receiving unit 21 thus enables the integration of the soil compaction machine 1 and its control system into a higher-level construction site management system, so that information, in particular regarding an external environmental parameter, can also be used and accessed from elsewhere for the execution of the procedure described in more detail below.In this context, information about the paving process of an asphalt mat by a paver traveling in front of the soil compaction machine 1 (viewed from the paving direction) can be particularly relevant. This can include, in particular, position-specific data on the time and / or temperature and / or paving thickness and / or the composition of the material laid by the paver, especially asphalt. If this information, and for example the position of the soil compaction machine 1 on the asphalt mat laid by the paver, is known, the cooling behavior of the asphalt mat can be calculated or predicted, for example, using a temperature model or a cooling model.Direct temperature measurement of the ground surface at soil compaction machine 1 is not necessary as long as the position of soil compaction machine 1 and the time difference between laying the asphalt mat at the current position of soil compaction machine 1 are known. Further environmental factors, such as the outside temperature, wind speed, the occurrence and extent of precipitation, etc., can then be included in this model calculation or simulation. These are all external environmental parameters that influence the cooling behavior of the asphalt mat and can therefore be taken into account.

[0058] Fig. 4Figure 11 schematically summarizes the exemplary setup of the sensor device 11 and its connection to the control unit 10. The temperature sensors 12 and the image acquisition device 13 are divided into "sensors measuring in the forward direction F in front of the soil compaction machine" 12f and 13f, and "sensors measuring in the reverse direction R in front of the soil compaction machine 1" 12r and 13r. This ensures that, regardless of the current direction of travel F, R of the soil compaction machine 1, one of the sensors 12 and / or 13 can always detect the soil surface U in the direction of the current travel direction in front of the soil compaction mesh 1. The sensor device 11 can additionally or alternatively include one of the sensors 14 and 15. The sensor device 11 can thus be used to determine the current values ​​of one or more external environmental parameters.The current values ​​of the external environmental parameter(s) determined by the sensor device 11 are transmitted to the control unit 10 via a signal line 22.

[0059] Furthermore, the control unit 10 can be connected via a signal line 23 to other sensors, for example, the travel speed and / or direction sensor 16, the acceleration sensor 17, the position sensor 18, the vibration sensor 19, the operating status sensor 20, a control element position sensor, and / or similar sensors, and receive current values ​​of the operating and status parameters of the soil compaction machine 1 itself, as detected by one or more of these sensors. These sensors can also be combined in a sensor unit 24 for detecting operating and status parameters of the soil compaction machine 1 itself and configured as an independent functional unit separate from the sensor unit 11.

[0060] Furthermore, the operating element 9 can be connected to the control unit 10 via a signal transmission link 25. Additionally or alternatively, an autonomy mode module 26 can be provided, which transmits control commands to and / or receives them from the control unit 11 via a signal transmission link 27. Such a bidirectional communication link can also exist between the control unit 10 and the transmit and receive unit 21 via a signal transmission link 28, for example, to obtain data and / or values ​​relating to external environmental parameters of the subsoil from another location, such as a remote server and / or another construction machine, such as a paver.Such information can include, for example, layer thickness, material composition, installation temperature, a measured temperature (core and / or surface), compaction state, installation time, or similar data. This information is preferably linked to a position and / or time value. The control unit can also include a timer for this purpose. In this way, the control unit 11 can assign one or more of the values ​​and / or data received via the transmitting and receiving unit 21 to a position where the soil compaction machine 1 is currently located and / or will shortly reach, and use this information to control the acceleration behavior of the soil compaction machine 1. Additionally or alternatively, the soil compaction machine 1 can transmit data and / or values ​​it has determined to a receiver, such as a remote server and / or another construction machine.

[0061] Via a further signal transmission connection 29, the control unit 11 can control a display of the display device 8 and / or, for example for documentation purposes, transmit data and / or values ​​to a storage device 30.

[0062] The control unit 11 can generate one or more control commands and transmit them to one or more elements for influencing the operation of the soil compaction machine 1. This can be done via a signal transmission link 31 and may, for example, control a braking device 32, such as a friction and / or motor brake, and / or the primary drive unit 5, and / or another element in the drive train of the soil compaction machine 1, such as a clutch, a hydraulic motor, a resistance-generating element such as a hydraulic retarder, a vibration exciter, or the like. All these measures have in common that they can influence the acceleration, positively or negatively, of the soil compaction machine. By controlling one or more of these elements, the control unit 11 can thus actively influence the acceleration behavior of the soil compaction machine 1.The criteria according to which the control unit 10 influences the acceleration behavior of the soil compaction machine 1 are described in more detail below.

[0063] The signal transmission links 22, 23, 25, 27, 28, 29 and 31 can also be partially or completely combined in a common signal transmission system, for example a CAN bus.

[0064] The Figures 5, 6 and 7The figures exemplify the operation of the process controlled by the control unit 10. Each figure shows a soil compaction machine 1 in a top view, which, traveling over the ground surface U on a road section to be compacted, approaches a planned turning point O in the direction of travel from F to R at a speed P1. The transverse bars on the ground surface in the figures indicate the distance traveled by the soil compaction machine 1 per unit of time. In all three figures, the soil compaction machine 1 initially has the same speed P1 in the direction of travel F. The initial conditions differ between the three figures. Figures 5, 6 and 7 in that the temperature T of the asphalt mat, determined by the respective temperature sensor 12 of the soil compaction machine 1 (or calculated by simulation), is different. In the Figure 5 The temperature T1 is comparatively high, in the Figure 6in contrast lower and in the Figure 7 the lowest. Therefore, T1>T2>T3. The current temperature T of the asphalt mat or the ground surface U thus decreases in the following order: Figures 5, 6 and 7 Depending on this current external environmental parameter, the control unit sets different maximum target acceleration values. In the Figure 5 In the present case, for example, the negative acceleration or deceleration is smaller compared to the currently maximum permissible target accelerations in the Figures 6 and 7 This means that the braking distance S of the soil compaction machine 1 required from the current driving speed until the machine comes to a standstill is in Fig. 5 considerably longer and therefore gentler on the ground than at the lower temperatures from the Figures 6 and 7 The overall picture of Figures 5, 6 and 7This illustrates that the control unit's maximum permissible target acceleration, which it controls, increases in absolute terms with decreasing soil surface temperature U, the current external environmental parameter in this example, and vice versa. A triggering event for the braking process shown in the figures could be, for example, the operator of the soil compaction machine 1 actuating a control element and / or a control command from the autonomous drive control system of the soil compaction machine.

[0065] Figure 8 is a graphical comparison of the process in the Figures 5, 6 and 7in the form of a time-dependent velocity diagram (time t [s] versus driving speed P [m / s]) and illustrates the various maximum permissible target accelerations specified by the control unit 10 depending on the temperatures T1, T2 and T3. The higher the current temperature T of the ground surface U, the lower the maximum permissible acceleration determined by the control unit 10 (corresponding to the absolute slope of the curves in the Figure 8 The control unit can determine the maximum permissible target acceleration, which depends on the current external environmental factor(s) to be considered, for example, using stored curves, as in the Fig. 8 depicted, characteristic curves and / or a suitable algorithm.

[0066] Fig. 9This illustrates an alternative representation of the relationship between a current external environmental parameter (abscissa), for example, a ground surface temperature T U, and the currently maximum permissible target acceleration Z (ordinate) determined by the control unit 10 as a function of this environmental parameter. T1 is again > T3. Using this diagram, the control unit can define a maximum permissible target acceleration Z3 for temperature T3. Conversely, a significantly lower maximum permissible target acceleration Z1 can be specified for temperature T1.

[0067] It is also possible that the control unit does not define absolute values ​​for maximum permissible target accelerations, so that the same limits are defined for braking and speed increases, but rather differentiates between a braking process and an acceleration and / or speed increase process. This is in the Fig. 9 with the acceleration Z1* in addition to the acceleration Z1, which is based on the characteristic curve shown as a dashed line in the graph. In This further development thus provides a characteristic curve (in this case, for example, the dashed curve) for processes in which the soil compaction machine is positively accelerated, and a characteristic curve (in this case, for example, the solid curve) for processes in which the soil compaction machine is negatively accelerated or decelerated. Preferably, the curves are positioned such that the maximum permissible target acceleration set by the control unit 10 at a given temperature is smaller in magnitude for a deceleration process than for an acceleration and / or speed increase process.

[0068] Based on at least one value of at least one current external environmental parameter, the control unit 10 determines an optimized maximum permissible target acceleration. Adherence to this target acceleration reduces or practically eliminates the probability of irregularities being introduced into the soil surface by the acceleration processes of the soil compaction machine 1. For example, in the case of manual operation of the soil compaction machine 1, the control unit 10 may control a display device 8 and signal to the operator, via the display device 8, whether the operator is currently controlling the soil compaction machine in such a way that its acceleration is above or below the maximum permissible target acceleration currently set by the control unit 10.Based on this information, an operator can then optimize and adjust their own control settings accordingly. However, the control unit 10 can also control the movement behavior itself, adhering to the relationships described above.

[0069] In theIn the practical application of the method described here, a challenge can lie in accurately estimating the braking distance required for the soil compaction machine 1 at a given travel speed and a current maximum permissible target acceleration set by the control unit 10. This is because the soil compaction machine 1 often needs to approach its planned turning point as closely as possible, for example, an obstacle in its path, without overshooting the planned turning point or colliding with the obstacle. At the same time, it is desirable, for example, for time reasons, to initiate the braking process as late as possible. However, excessively abrupt braking can introduce unevenness into the soil surface.

[0070] The present invention proposes, for example, a brake assist system, the operation of which is described in more detail below. The starting point is a soil compaction machine with a control unit, as described above. Knowing the current driving speed P and the maximum permissible target acceleration currently set by the control unit 10, it is possible to determine the minimum braking distance required until the soil compaction machine 10 comes to a standstill. Fig. 10 This illustrates a possible operating principle of such a brake assist system. The soil compaction machine 1 moves in the Fig. 10The soil compaction machine 1 is currently traveling in direction F over the ground surface U and is approaching an obstacle 33 located in its path. The current distance of the soil compaction machine 1 to the obstacle 33 is given as AB. The soil compaction machine 1 includes a distance measuring device, in this case, for example, the image acquisition device 13, in particular in the form of a 3D camera, which is designed such that the distance to the obstacle 33 lying in the path of the soil compaction machine 1 can be determined with it. In this case, the image acquisition device 13 thus also serves as an obstacle detection device in conjunction with a suitable image evaluation computer program. Examples are given in the Fig. 10 The scenarios for a temperature T1 and a temperature T3, where T1 > T3, and the control unit 10 determines the currently maximum permissible target acceleration, for example, based on the values ​​in the Fig. 9 determines the characteristic curve shown.

[0071] For the comparatively lower temperature T3, a braking distance of L3min results from this, assuming a given travel speed. A safety reserve Lres can be added to this braking distance L3min, resulting in a total braking distance L3. This ends in the direction of travel F before obstacle 33, so the braking process does not yet need to be initiated, but only when the soil compaction machine 1 has reached position 34 (then L3 ends shortly before obstacle 33, thus avoiding a collision). The reaching of position 34 could, for example, be displayed to the operator and / or registered by the control unit 11, and the braking process could then be initiated and controlled by the control unit 10.

[0072] At temperature T1, the braking distance L1 (L1min plus Lres) is greater than the braking distance L3 at T3. Assuming the same travel speed P of the soil compaction machine 1 in Fig. 10 The soil compaction machine would therefore potentially collide with the obstacle in the situation shown, with obstacle 33 being located within the safety reserve Lres. The braking process should actually have been triggered at position 35.

[0073] In addition, in this context, for example, one or more vibration exciters can be deactivated and / or activated, and / or the operating parameters of one or more vibration exciters, such as the vibration amplitude and / or vibration frequency, can be adjusted, in particular, for example, by automatically deactivating the vibration excitation operation with sufficient distance before the planned turning point and then activating it when a minimum driving speed in the opposite direction is reached.

[0074] The Figures 11, 12, 13 and 14The figures illustrate a practical example of how such a brake assist system can support the operator of a soil compaction machine. Each figure shows the image captured by the image acquisition device 13 of the area in front of the soil compaction machine 1 in the direction of travel F. The captured image section also includes, in particular, the soil surface U located in front of the soil compaction machine in the direction of travel.

[0075] The Figure 11 The image initially shows the actual camera image. Obstacle 33, for example, can be identified using suitable image processing software. Figures 12, 13 and 14 They show the same camera image, but with a brake assist function superimposed onto the existing camera image. In all four of the Figures 11 to 14 In the depicted operating situations, the soil compaction machine 1 currently maintains the same travel speed P. During the Fig. 12The measured temperature of the ground surface is UT3. Fig. 13 T2 and in the Fig. 14 T1, where T1>T2>T3 also applies here.

[0076] Taking into account the previously described embodiments, the control unit 10 is designed for the Fig. 12 The currently maximum permissible target acceleration is therefore the largest in terms of amount and in the Fig. 14The shortest. This means that the braking distance required from the position of the soil compaction machine 1 shown in the figures varies in length. L3, L2, and L1 represent the potential end of the braking distance of the soil compaction machine 1 in the camera image. The dashed line, which symbolizes the end of the braking distance in each case, thus represents a prediction under the current operating conditions of the soil compaction machine 1, if it were to be braked to a standstill from its current position and speed, while adhering to the maximum permissible target acceleration currently set by the control unit 10. Figures 12 and 13Initiating a braking process is not yet necessary, as the ends of L1 and L2 are still well before obstacle 33. The operator can, for example, continue the driving movement until the indicator bar of the prediction function reaches obstacle 33 on the display. They can then initiate the braking process themselves or, for example, activate an automatic braking function by which the control unit 10 controls the braking process until the soil compaction machine 10 comes to a standstill, ideally also with simultaneous and timely deactivation and / or activation of one or more vibration excitation devices.

[0077] The Fig. 14In contrast, this shows a situation in which braking the soil compaction machine 1 is no longer possible, at least while maintaining the maximum permissible target acceleration currently set by the control unit 10, before the obstacle 33, or the soil compaction machine is at a distance from the obstacle 33 that is not yet less than the minimum distance, but is already within the safety margin. The operator can then be alerted to such a situation, for example, by the display of a warning symbol 36 and / or the output of an acoustic signal or similar.

[0078] Fig. 15 Finally, an exemplary flowchart illustrates a method for optimizing the acceleration behavior of a self-propelled soil compaction machine 1 during compaction operation. Reference is also made to the description of the preceding embodiments.

[0079] Method 37 includes, in step a), the determination of a value of an external environmental parameter. This determination can be achieved either by the soil compaction machine itself acquiring this external environmental parameter or by receiving information about its value from a location remote from the soil compaction machine, such as another construction machine and / or a remote server. The external environmental parameter is, in particular, an environmental parameter located directly in front of the soil compaction machine in the direction of travel and can be a condition parameter of the subsoil and / or the soil surface to be compacted, such as temperature, roughness, or similar. Actual measured values ​​of the environmental parameter can be used at this point, as well as simulated and / or predicted values.

[0080] According to step b), the control unit 10 determines a value for a maximum permissible target acceleration of the soil compaction machine as a function of the determined value of the external environmental parameter. For this purpose, characteristic curves, maps, algorithms or similar can be used, as illustrated in the preceding figures.

[0081] In step c), the actual acceleration value of the soil compaction machine is recorded, for example, directly and / or indirectly using a suitable recording device. This device can be part of a sensor system. Additionally or alternatively, this step can also record a manual acceleration input, i.e., an acceleration request specified by an operator, for example, due to a desired increase or decrease in travel speed.

[0082] If the actual acceleration and / or the manual acceleration setting is known, the control unit checks in step d) whether the actual acceleration value and / or the manual acceleration setting exceeds the maximum target acceleration value. If this is not the case, there is no risk that the soil compaction machine will introduce unwanted irregularities into the soil surface during the current acceleration process. However, if the actual acceleration and / or the manual acceleration setting exceeds the target acceleration (especially in relation to the existing absolute values), the control unit triggers a countermeasure in step e).The specific design of the countermeasure can range from rather passive countermeasures, such as the output of an acoustic and / or visual warning signal perceptible to an operator of the soil compaction machine 1, to active countermeasures by the control unit 10, such as intervention in the control system of the soil compaction machine 1 to change its movement behavior. For further details, reference is made in particular to the description of the preceding figures.

[0083] Steps a) to d), and in particular a) to e), can run cyclically, thereby enabling situation-dependent adjustments throughout the entire compaction operation, especially of step e), depending on at least one current external environmental parameter. In this way, for example, changes in environmental conditions over time and / or depending on position can be taken into account.

[0084] In step a), in particular the recording of a current temperature, especially a temperature of the surface of the subsoil to be compacted and / or a core temperature of a material layer, such as an asphalt mat, can be carried out.

[0085] The method according to the invention is particularly suitable for use on a soil compaction machine of the tandem roller or pneumatic tire roller type. The method is especially suitable for use in the compaction of an asphalt mat.

Claims

1. A method (37) for optimizing the acceleration behavior of a self-propelled ground compaction machine (1), wherein the ground compaction machine (1) comprises a ground compaction device (2) that rolls over the ground to be compacted and a control unit (10), comprising the steps of: a) determining a value of an environmental parameter external to the ground compaction machine (1); b) determining, by the control unit (10), a value for a maximum permissible target acceleration of the ground compaction machine (1) as a function of the determined value of the external environmental parameter; c) detecting a value of the actual acceleration of the ground compaction machine (1) or a manually set acceleration target; d) checking by the control unit (10) whether the value of the actual acceleration or the manually set acceleration target exceeds the value of the maximum target acceleration; e) initiating a countermeasure by the control unit (10) if a value of the actual acceleration or the manual acceleration setpoint exceeds the value of the maximum target acceleration.

2. Method (37) according to claim 1, characterized in that step a) comprises determining a temperature of the ground to be compacted.

3. Method (37) according to claim 2, characterized in that the determination in step a) comprises detecting an actual temperature of a ground surface (U), in particular one located in front of the ground compaction device (3) in the direction of travel of the ground compaction machine (1), using a sensor device (11).

4. Method (37) according to one of claims 2 or 3, characterized in that the determination in step a) comprises determining an actual temperature of the ground to be compacted, taking into account a temperature model of the ground to be compacted.

5. A method (37) according to one of the preceding claims, characterized in that in step b) - the control unit (10) reduces the absolute value of the maximum permissible target acceleration if the determined temperature of the ground to be compacted exceeds a temperature threshold, and vice versa and / or a value of the maximum permissible setpoint acceleration for positive acceleration and a value of the maximum permissible setpoint acceleration for negative acceleration are set, wherein the values differ from one another in terms of their absolute values.

6. A method (37) according to one of the preceding claims, characterized in that the countermeasure in step e) comprises outputting an acoustic and / or visual signal to an operator of the ground compaction machine (1) and / or adjusting the operating characteristics of a control element to be actuated by an operator of the ground compaction machine (1) and / or an intervention in a travel speed control system.

7. A method (37) according to one of the preceding claims, characterized in - that during operation of the ground compaction machine (1), monitoring for obstacles (33) located in the path of travel of the ground compaction machine (1) is performed in the direction of travel of the ground compaction machine (1) using an obstacle detection device, - that, upon detection of an obstacle (33) located in the path of travel of the ground compaction machine (1), a required braking distance (L1, L2, L3) is determined, taking into account the actual speed of the ground compaction machine (1) and the value of the maximum permissible target acceleration, - and that the control unit (10) initiates a countermeasure when the distance of the ground compaction machine (1) is at most equal to the determined required braking distance (L1, L2, L3).

8. Method (37) according to claim 7, characterized in that the determination of the required braking distance (L1, L2, L3) comprises adding a braking distance reserve (Lres) that depends, in particular, on the actual speed of the ground compaction machine (1).

9. Method (37) according to one of the preceding claims, characterized in that the control unit (10) controls a reversing operation.

10. A ground compaction machine (1) comprising a ground compaction device rolling over the ground to be compacted and a control unit (10), characterized in that it is configured to carry out the method according to any of the preceding claims, that it comprises a sensor device (11) having at least one of the following features: - a sensor configured to detect an external environmental parameter; - a position-determining sensor (18) configured to detect the position of the ground compaction machine (1) in a reference system; - a sensor for monitoring an area located in front of the ground compaction machine (1) in the direction of travel; - an acceleration sensor (17); - a travel speed sensor (16); wherein the values determined by the sensor device (11) are transmitted to the control unit (10), and that it comprises a trigger device operable by an operator of the ground compaction machine (1), which is configured such that, following actuation of the trigger device by the operator, a reversing operation of the ground compaction machine (1) involving deceleration of the ground compaction machine (1) from a direction of travel to a standstill and an acceleration of the ground compaction machine (1) in a direction of travel is controlled by the control unit (10), without exceeding or falling below a maximum target acceleration.

11. Ground compaction machine (1) according to claim 10, and, characterized in that the sensor configured to detect the external environmental parameter is a temperature sensor (12) configured to detect a temperature of the ground surface (U) in the direction of travel in front of the ground compaction device (3).

12. A ground compaction machine (1) according to any one of claims 10 or 11, characterized in that it comprises a signaling device configured to output a signal when a value of the actual acceleration exceeds and / or falls below the value of the maximum setpoint acceleration.

13. A ground compaction machine (1) according to any one of claims 10 to 12, characterized in that it comprises a control element operable by an operator of the ground compaction machine (1) for changing the speed of the ground compaction machine (1), wherein the control unit (10) is configured such that it adapts control inputs entered via the control element to the maximum permissible target acceleration of the ground compaction machine (1).

14. Ground compaction machine (1) according to any one of claims 10 through 13, characterized in that it is an asphalt roller, in particular a tandem roller or a rubber-tired roller.