The invention is directed to a device or a method according to the species of the independent claims. The subject matter of the present invention is also a computer program.
Inclination angle measuring systems for lifting working platforms are known.
Against this background, a method, a control device which uses this method, and a corresponding computer program as claimed in the main claims are provided by the approach provided here. Advantageous refinements and improvements of the device specified in the independent claim are possible by way of the measures set forth in the dependent claims.
A method for controlling a working platform is provided, wherein the working platform comprises at least one distance sensor associated with the wheel of the working platform, wherein the method comprises the following steps:
comparing a time of flight of a measurement beam, which is emitted obliquely by the distance sensor onto a track of the working platform and is reflected from the track, to a reference time of flight in order to ascertain an inclination angle change of the working platform; and
outputting a control signal to control the working platform in dependence on the inclination angle change.
A working platform can be understood as a movable lifting working platform. For example, the working platform can be constructed on a self-propelled chassis. The working platform can also be implemented as a truck superstructure, for example. A distance sensor can be understood, for example, as a laser, lidar, radar, or ultrasonic sensor or a camera. The distance sensor can be installed, for example, on the wheel, a wheel axle, or the chassis and can be aligned in such a way that the measurement beam is incident obliquely on the track. In this case, the measurement beam can comprise a directional component aligned parallel to the vertical axis and a directional component aligned parallel to the longitudinal axis or parallel to a present or future travel direction. A track can be understood as a section of a surface of a terrain traveled presently or foreseeably by the working platform. A time of flight can be understood as a time span between emitting and receiving the reflected measurement beam. In a step of ascertainment, the time of flight of the measurement beam can be ascertained. The reference time of flight can be a time of flight from a prior time of flight measurement by means of the distance sensor or a stored reference value. An inclination angle change can be understood as a difference between a present inclination angle and a foreseeable inclination angle of the working platform. Although reference is predominantly made to a working platform in the embodiments, the described approach can thus also be used in other vehicles or working devices.
If a working platform travels over uneven terrain, for example, over holes or waves or on routes having descents or ascents, depending on the displacement of the mass center of gravity of the working platform, tilting of the working platform can occur. In particular in the case of remote control of the propulsion of the working platform from a platform, the ground profile often cannot be properly seen by the operator.
The approach provided here is based on the finding that an inclination angle change of a working platform when driving on uneven underlying surface can be reliably predetermined by a time of flight measurement carried out individually by wheel. Tipping over of the working platform in arbitrary directions can be avoided, for example, by individually determining a slope change of a track in front of each wheel, for example, by means of laser distance meter, before the respective wheel travels the track section having the slope change. The slope change measured in the travel direction in front of each wheel or the change of the mass center of gravity of the working platform resulting therefrom can then be visualized for the operator, for example, or a corresponding warning message can be output to the operator. Alternatively or additionally, the working platform can be automatically braked or stopped. Damage to persons and property due to an inclining or tilting working platform can thus be prevented.
According to one embodiment, the method can comprise an additional step, in which the measurement beam is emitted having a directional component in a travel direction of the working platform. The measurement beam can thus be incident in a section of the track located in front of the wheel in the travel direction. The inclination angle change can thus be ascertained before the working platform travels the section on which the measurement beam is incident. Additionally or alternatively, the measurement beam can be emitted having a directional component opposite to the travel direction of the working platform. The travel direction can be a present or future travel direction or trajectory of the vehicle. In the step of emitting, the measurement beam can thus be emitted having a directional component along a trajectory of the working platform. It can thus be a directional component oriented on the trajectory. For this purpose, the trajectory and/or wheel track of the respective wheel which is known or predicted in accordance with the steering wheel position and/or wheel position can be brought into congruence with the point of incidence and/or the alignment of the associated measurement beam, for example, a laser beam. The known kinematics of the vehicle can be used for determining the trajectory. Alternatively, the kinematics can be computed using the vehicle parameters. If the distance sensor is fastened to the wheel, an emission direction of the distance sensor is automatically changed in the event of a steering movement of the wheel, so that the measurement beam is always aligned on a section of the track located in front of the wheel in the travel direction. Alternatively, the measurement beam can be emitted in the step of emitting having a directional component set using a steering angle setting of the wheel. For this purpose, the distance sensor can comprise a settable emission direction. This is advantageous if the distance sensor is arranged on a chassis of the working platform.
According to one embodiment, in the step of comparing, an inclination angle change representing a descent can be ascertained if the time of flight is greater than the reference time of flight. Additionally or alternatively, an inclination angle representing an ascent can be ascertained if the time of flight is less than the reference time of flight. The inclination angle change can thus be reliably ascertained with low processing effort.
It is advantageous if, in the step of comparing, the inclination angle change is ascertained using a present inclination angle of the working platform or, additionally or alternatively, a permissible inclination angle of the working platform. A permissible inclination angle can be understood as a maximum inclination angle, at which the working platform is still just tilt stable. Tipping over of the working platform can thus be reliably prevented.
Furthermore, in the step of comparing, the inclination angle change can be ascertained using at least one wheel dimension value representing a dimension of the wheel or, additionally or alternatively, an inclination profile of the track provided by means of a digital map. A wheel dimension value can be understood, for example, as a radius, a diameter, a circumference, a width, or also a pressure of the wheel. A digital map can be understood, for example, as a map based on GPS data. The accuracy of the method can be enhanced by this embodiment.
Furthermore, in the step of outputting, the control signal can be output to brake or stop the working platform or to output a warning message to an operator of the working platform. The working platform can thus be automatically controlled in dependence on the inclination angle change. Tipping over of the working platform can thus be prevented particularly reliably or at least the risk of tipping over can be pointed out in a timely manner.
According to a further embodiment, the working platform can comprise at least one further distance sensor associated with a further wheel of the working platform. In this case, in the step of comparing, a further time of flight of a further measurement beam emitted obliquely by the further distance sensor onto the track and reflected from the track can be compared to the reference time of flight to ascertain the inclination angle change. The accuracy in the ascertainment of the inclination angle change can be further enhanced by this embodiment. In this case, the wheels, with each of which a distance sensor is associated, can be associated with the same or different axles of the working platform. According to one embodiment, a distance sensor is associated with each of the wheels.
The working platform can comprise at least one second distance sensor associated with the wheel, wherein in the step of comparing, a second time of flight of a second measurement beam emitted obliquely by the second distance sensor onto the track opposite to the measurement beam and reflected from the track, is compared to a second reference time of flight to ascertain a second inclination angle change. For example, the inclination angle change ascertained using the measurement signal can represent a change upcoming in the case of a forward travel and the inclination angle change ascertained using the second measurement signal can represent a change of the inclination of the working platform upcoming in the case of a reverse travel. The section of the track located in front of the wheel in the travel direction can thus be monitored independently of the travel direction.
This method can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example, in a control device.
The approach provided here furthermore provides a control device, which is designed to carry out, control, and/or implement the steps of a variant of a method provided here in corresponding units. The object on which the invention is based can also be achieved rapidly and efficiently by this embodiment variant of the invention in the form of a control device.
For this purpose, the control device can comprise at least one processing unit for processing signals or data, at least one storage unit for storing signals or data, at least one interface to a sensor or an actuator for inputting sensor signals from the sensor or for outputting control signals to the actuator, and/or at least one communication interface for inputting or outputting data which are embedded in a communication protocol. The processing unit can be, for example, a signal processor, a microcontroller, or the like, wherein the storage unit can be a flash memory, an EPROM, or a magnetic storage unit. The communication interface can be designed to input or output data in a wireless and/or wired manner, wherein a communication interface which can input or output data in a wired manner can input these data from a corresponding data transmission line or can output these data into a corresponding data transmission line, for example, electrically or optically.
A control device can be understood in the present case as an electrical device which processes sensor signals and outputs control and/or data signals in dependence thereon. The control device can comprise an interface which can be designed in hardware and/or software. In the case of a hardware design, the interfaces can be, for example, part of a so-called system ASIC, which contains greatly varying functions of the control device. However, it is also possible that the interfaces are separate integrated circuits or at least partially consist of discrete components. In the case of a software design, the interfaces can be software modules which are provided, for example, on a microcontroller in addition to other software modules.
In one advantageous design, a control of the vehicle is performed by the control device. For this purpose, the control device can access, for example, sensor signals such as acceleration, pressure, steering angle, or surroundings sensor signals. The activation takes place via actuators such as braking or steering actuators or a motor control device of the vehicle.
The approach provided here moreover provides an inclination angle measuring system for a working platform, wherein the inclination angle measuring system comprises the following features:
at least one distance sensor associated with a wheel of the working platform for emitting a measurement beam obliquely to a track of the working platform; and
a control device according to the preceding embodiment.
According to one embodiment, the distance sensor can be designed to emit the measurement beam in a direction facing in the travel direction of the working platform. For example, the distance sensor can comprise a first sensor element facing in a first travel direction and a second sensor element facing in a second travel direction opposite to the first travel direction. A foreseeable inclination angle can thus be ascertained reliably and accurately during the movement of the working platform.
According to a further embodiment, the inclination angle measuring system can comprise at least one further distance sensor associated with a further wheel of the working platform for emitting a further measurement beam obliquely to the track. For example, the wheel and the further wheel can be associated with a common axle or different axles. The robustness of the inclination angle measuring system against measurement errors can be significantly increased by this embodiment.
A computer program product or computer program having program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard drive memory, or an optical memory and is used to carry out, implement, and/or control the steps of the method according to one of the above-described embodiments, in particular if the program product or program is executed on a computer or a device, is also advantageous.
Exemplary embodiments of the invention are illustrated in the drawings and explained in greater detail in the following description. In the figures:
In the following description of advantageous exemplary embodiments of the present invention, identical or similar reference signs are used for the similarly-acting elements illustrated in the various figures, wherein a repeated description of these elements is omitted.
According to the exemplary embodiment shown in
According to the exemplary embodiment shown, the distance sensors 104, 120 are associated with wheels 103, 121 of different axles of the working platform 100. In this case, the measurement beams 106, 122 can face in opposing directions or in the same direction. If the measurement beams 106, 122 face in the same direction, the respective rear wheel can monitor a section of the track 108 located in the travel direction in front of the rear wheel and the respective front wheel can monitor a section of the track 108 located in the travel direction in front of the front wheel. In this case, according to one exemplary embodiment, the emission direction of the measurement beams 106, 122 reverses when the travel direction reverses. The distance sensors 104, 120 can thus be designed to emit the measurement beams 106, 122 having a directional component dependent on the travel direction. In this way, the respective section of the track 108 located in the travel direction in front of the wheels 103, 121 can be monitored. According to an alternative exemplary embodiment, the distance sensors 104, 120 are associated with wheels of the same axle of the working platform 100. According to an alternative exemplary embodiment, a separate distance sensor 104, 120 is associated with each wheel 103, 121 of the working platform 100, so that the track 108 may be monitored very accurately.
As is apparent from
Depending on the exemplary embodiment, the working platform 100 can also comprise more than two distance sensors 104, 120 for emitting measurement beams 106, 122.
Depending on the exemplary embodiment, the distance sensors 104, 120 are designed for optical distance measurement on the basis of a time of flight measurement, also called laser distance measurement, for phasing measurement, or for laser triangulation of light. Laser triangulation and laser interferometers are suitable in particular for short distances between several micrometers up to 100 m. Time of flight methods, in contrast, are more suitable for large distances between 1 and approximately 1000 m.
The working platform 100 stands stably on the horizontal track shown in
The determination of the present inclination of the working platform 100 on the track 108 is performed, for example, by means of inclination sensors or three-axis acceleration sensors. The distance sensors 104, 120, such as laser distance meters, face with the respective measurement beam thereof in the direction of a future possible travel direction of the respective wheels. To detect irregularities of the track 108, for example, a corresponding distance sensor is installed on each wheel of the working platform 100.
The measurement beams 106, 122 are each directed onto the track 108 at such an angle that a future descent still permissible with respect to the tilt stability of the working platform 100 is detectable without the measurement beams 106, 122 going into empty space (however, the change is also detected here). An ascent is detected, for example, if the respective time of flight 112, 124 of the measurement beams 106, 122 decreases. Vice versa, a descent is detected if the respective time of flight 112, 124 of the measurement beams 106, 122 increases.
According to one exemplary embodiment, the control unit 110 ascertains a future inclination of the working platform 100 during the further travel from the distance measurement or time of flight measurement and the present inclination. The future inclination is graphically or numerically displayed, for example, on a display screen.
If the mass center of gravity of the working platform 100 is determined, for example, a permissible tilt-free inclination angle for the working platform 100 is determined and compared to the future inclination during further travel. If the future inclination exceeds the tilt-free inclination, a corresponding warning message is generated for the operator or the further travel of the working platform 100 is also stopped. The stopping procedure takes place sufficiently slowly in this case that the working platform 100 does not tilt as a result of the mass inertia, and sufficiently rapidly that the critical inclination is not reached. This also applies accordingly to the startup. The tilt inclination as a result of the required braking distance is also taken into consideration in the computation of the permissible future inclination. This also applies accordingly to the startup.
According to a further exemplary embodiment, the control device 110 determines a position-accurate inclination profile of the track 108 on the basis of GPS data with respect to already traveled paths and saves it in a dynamic map. The inclination profile can be read out via a suitable interface and thus made available to other vehicles or operators when traveling on the track 108. The corresponding inclination data are thus already provided to the operators before the inclination angle change is detected by the inclination angle measuring system 100. The operators can thus select a different travel path in a timely manner, for example.
Alternatively to laser distance meters, lidar, camera, radar, or ultrasonic systems or other distance measuring systems or combinations of different measuring systems are conceivable as distance sensors.
To reduce to a minimum the risk of tilting when traveling over irregularities or in the event of direction changes, for example, two distance sensors 104, 120 are attached to each wheel or wheel pair. In this case, the two distance sensors 104, 120 of a wheel or wheel pair each face in one of two possible travel directions of the working platform 100. Optionally, the distance sensors also move during steering. Therefore, it is ensured under all possible conditions that an area directly in front of the wheels is continuously monitored independently of the travel direction and thus tilting is precluded.
According to one exemplary embodiment, a second distance sensor 504 is associated with at least one of the wheels 103, 121, the wheel 103 here, which emits a second measurement beam 506, which is aligned opposite to the measurement beam 106. Therefore, independently of the travel direction, one of the measurement beams 106, 506 is aligned obliquely downward in the travel direction and the other of the measurement beams 106, 506 is aligned obliquely downward opposite to the travel direction. According to this exemplary embodiment, a second time of flight 512 of the second measurement beam 506 is compared to a second reference time of flight to ascertain a second inclination angle change which is then relevant if the working platform 100 moves in the direction of the second measurement beam 506.
According to one exemplary embodiment, directional components of the measurement beams 106 are set in this case using the steering angle settings of the wheels 103. The respective steering angle setting of a wheel 103 can be provided in this case, for example, by steering angle sensor coupled to the wheel 103 or a steering unit of the working platform 100.
The alignment of a measurement beam 106 can be different from the wheel alignment of the associated wheel 103. As a result, the alignment of, for example, laser and wheel 103 are not congruent during cornering, similarly to the intelligent cornering light. This results from the fact that according to one exemplary embodiment, the predicted trajectory of the working platform 100 or the predicted trajectory of a wheel 103 is brought into correspondence with the point of incidence and/or the alignment of the measurement beam 106. The measurement beam 106 can thus be aligned to the trajectory of the working platform 100. The predicted trajectory can be predetermined, provided by a control unit of the working platform 100, or determined, for example, using the kinematics of the working platform 100 and the steering angle.
The reference time of flight is stored, for example, in the comparison unit 1920. The comparison unit 1920 transmits a change value 1922 representing the inclination angle change to an output unit 1930, which processes it to generate and output the control signal 114. According to one exemplary embodiment, the comparison unit 1920 is designed to store the present time of flight 112 as a reference time of flight for a subsequent comparison of a subsequently ascertained time of flight and to use it for the subsequent comparison.
If an exemplary embodiment comprises an “and/or” linkage between a first feature and a second feature, this is to be read to mean that the exemplary embodiment comprises both the first feature and also the second feature according to one embodiment and comprises either only the first feature or only the second feature according to a further embodiment.
Number | Date | Country | Kind |
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10 2017 209 695.0 | Jun 2017 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/063834 | 5/25/2018 | WO | 00 |