TECHNICAL FIELD

The present disclosure generally relates to an articulated vehicle, and specifically to a steering system for such an articulated vehicle, wherein the steering system is adapted to adjust a steering angle for the articulated vehicle with the purpose of reducing whole body vibrations (WBV) affecting e.g. the driver of the articulated vehicle. The present disclosure also relates to a corresponding method and computer program for operation such a steering system.

BACKGROUND

Articulated vehicles or working machines, in the form of e.g. excavators, dozers, loaders, and the like, may be used to perform various tasks in construction, mining and/or landscaping operations. Such articulated vehicles or working machines are often operated in off the-road conditions, such as at a work site presenting sand, gravel, etc., resulting in a rugged and highly uneven terrain for the working machine.

During operation in such an environment, a driver of the articulated vehicle or working machine will typically be exposed to a great deal of vibrations stemming from the uneven terrain. Such vibrations include whole body vibrations, being one of the major environmental problems for the driver. There is of course a general desire to ensure that the working environment for the driver is as good as possible, and preferably within set regulations that limit the maximum allowed dose of whole body vibrations for the driver. One generally used methodology for reducing such whole body vibrations relates to the implementation of a suitable suspension system for compensate for the vibrations. Many of these systems involve sensing of vibrations produced in the machine and reducing the vibrations transferred from a vibration source to the frame of the articulated vehicle or working machine. However, with the ongoing development of inexpensive sensors and computing systems, it has also been proposed to adapt the suspension system to function proactively, taking into account a possible upcoming condition of the surface ahead of the articulated vehicle or working machine. An example of such a proactive suspension system is disclosed in US6000703. Specifically, US6000703 combine a present vibration within a cab of the working machine with information collected using forward-looking sensors and/or based on geo-referenced maps. Even though US6000703 shows an interesting approach to handling vibrations issues for the driver, there seems to be room for further improvements for allowing an even further reduction of e.g. whole body vibrations affecting the driver of the articulated vehicle or working machine.

SUMMARY

According to an aspect of the present disclosure, the above is at least partly alleviated by a steering system for an articulated vehicle, comprising an electronic control unit (ECU), wherein the ECU is adapted to determine an initial steering angle based on information indicative of a current steering angle for the articulated vehicle, receive information being indicative of a disturbance in a terrain ahead of the articulated vehicle in a direction of travel of the articulated vehicle, determine a first compensation steering angle based on the disturbance, form a first adjusted steering angle based on the initial steering angle and the first compensation steering angle, and apply the first adjusted steering angle for steering the articulated vehicle.

In accordance to the present disclosure, the idea is to allow the articulated vehicle to perform an in comparison fast steering deflection when hitting irregularities in the terrain where the articulated vehicle is operated. Preferably, the steering deflection should be just enough for compensation for the arisen disturbance but at the same time not make a steering deflection so distinct that it will affect the overall steering of the articulated vehicle. Accordingly, in line with the present disclosure information being indicative of an upcoming disturbance in the terrain will be used for slightly adjusting a steering angle (i.e. with the first adjusted steering angle) for the articulated vehicle, whereby a“would have been” vibration of the articulated vehicle is reduced in a proactive manner. The overall appearance for the driver of the articulated vehicle may advantageously be interpreted as a steadier and with an in comparison reduced amount of vibrations when operating of the articulated vehicle.

In accordance to the present disclosure, the expression“articulated vehicle” should be interpreted in the broadest sense, including any type of being a frame-steered articulated construction equipment, machine, etc. Accordingly, the articulated vehicle may for example be at least one of a wheel loader, a dozer, a grader and a backhoe loader, or any similar form/type of construction vehicle, equipment or machine. The articulated vehicle may, in some embodiments, comprise an internal combustion engine, or be at least one of a pure electrical vehicle (PEV) and a hybrid electric vehicle (HEV). The articulated vehicle may be manually or semi-automatically operated by a driver. Alternatively, the articulated vehicle may be an autonomous articulated vehicle.

In a preferred embodiment of the present disclosure, the ECU is further adapted to receive, following applying the first adjusted steering angle, information indicative of a whole body vibration of the articulated vehicle, determine a second compensation steering angle based on the whole body vibration, form a second adjusted steering angle based on the initial steering angle, the first compensation steering angle and the second

compensation steering angle, and apply the second adjusted steering angle for steering the articulated vehicle. That is, it may in accordance to the present disclosure be possible to allow not only the steering to be proactively controlled, but rather to preferably consider and take into account an actual measurement by e.g. a vibration sensor arrangement comprised with the articulated vehicle of any (possible) not handled vibration

compensations. Such a vibration sensor arrangement may for example comprise at least one inertial measurement unit (IMU).

Thus, in line with the present disclosure information indicative of the whole body vibration of the articulated vehicle may directly or indirectly be used as a feedback for further adjusting the steering angle when operating the articulated vehicle. Advantageously, such information indicative of the whole body vibration of the articulated vehicle may further be recorded and stored tagged with a location for later use if/when the articulated vehicle is returned back to the same location. Such information may also be distributed for use by other vehicles or machines when operation at the same location.

It is preferred to apply the adjusted steering angle (the first adjusted steering angle)“just” when hitting the disturbance in the terrain, thereby ensuring that the influence of the overall steering is minimized. In addition, it is also desirable to further arrange the ECU to also form a third adjusted steering angle based on the initial steering angle, and to apply the third adjusted steering angle when the articulated vehicle has passed the disturbance. Put differently, once the articulated vehicle has passed the disturbance in the terrain, the steering angle is the then preferably again returned to the steering angle that was applied before the disturbance in the terrain where the articulated vehicle is operated. The“return back” to the original steering angle is also preferably taking place as soon as possible after the vehicle has passed the disturbance in the terrain.

It may in some embodiments of the present disclosure be advantageous to provide the articulated vehicle with a sensor arrangement comprising at least one of a camera, a laser arrangement, a radar arrangement and a LIDAR arrangement, for forming the information being indicative of the disturbance. Accordingly, the articulated vehicle will in an autonomous manner make use of the sensor arrangement for determining is any upcoming disturbances in the terrain may be expected. For example, the camera possibly in combination with the laser arrangement may be used for continuously“scan” the terrain in a forward direction in front of the articulated vehicle for locate and preferably determine a size of the disturbance in the terrain.

Alternatively or also, the information being indicative of the disturbance in the terrain could be received from a work site system arranged in wireless communication with the steering system. The work site system may for example be adapted to hold and distribute information relating to known disturbances at throughout a worksite where the present articulated vehicle as well as further working machines and vehicles are operating. The information collected for a specific geographical location by the sensor system comprised with the articulated vehicle may also be provided to the work site system for use by the other vehicle and/or machines when potentially arriving at the specific geographical location.

Accordingly, in a preferred embodiment of the present disclosure the ECU may be further adapted to receive data from e.g. a radionavigation received, such as a GPS or

GLONASS receiver, work site related radionavigation system (such as in a mine), etc.

The geolocation may be used to“tag” collected data relating to the whole body vibration (e.g. using the vibration sensor arrangement) or the own collected information relating to terrain disturbances. The geolocation may of course also be used in acquiring and using the data received form the work site system in relation to specific geographical locations.

In a preferred embodiment of the present disclosure, the steering system further comprises at least one actuator for steering the articulated vehicle, wherein the at least one actuator is operated for applying the first adjusted steering angle. Accordingly, the ECU will thus preferably directly or indirectly connected to the at least one actuator for controlling the actuator in relation to the determined first adjusted steering angle, as well as for“turning back” to the second adjusted steering angle once the vehicle has passed the disturbance in the terrain.

In a possible embodiment of the present disclosure the at least one actuator is a hydraulic steering actuator. Accordingly, the ECU may be adapted to be connected to means adapted for controlling a hydraulic arrangement in turn controlling the hydraulic steering actuator. The at least one actuator may also be implemented as a steer by wire actuator, where the ECU may be adapted to electrically control the at least one actuator.

Preferably, the articulated vehicle further comprises an operator controlled steering input device, such as e.g. a steering wheel, wherein the information indicative of a current steering angle is determined based on an operation of the steering input device. As such, it may for example be possible to arrange an angle sensor in relation to the steering input device, where the angle sensor is adapted to generate an indication of the current steering angle of the steering input device.

According to another aspect of the present disclosure there is provided a computer implemented method for operating a steering system of an articulated vehicle, the method comprising the steps of determining an initial steering angle based on information indicative a current steering angle for the articulated vehicle, receiving information being indicative of a disturbance in a terrain ahead of the articulated vehicle in a direction of travel of the articulated vehicle, determining a first compensation steering angle based on the disturbance, forming a first adjusted steering angle based on the initial steering angle and the first compensation steering angle, and applying the first adjusted steering angle for steering the articulated vehicle. This aspect of the present disclosure provides similar advantages as discussed above in relation to the previous aspect of the present disclosure.

It should be understood that the concept according to the present disclosure may be implemented as a computer program, adapted to e.g. be executed using a control unit comprised with the above discussed working machine. In addition, such an implementation of the present disclosure provides similar advantages as discussed above in relation to the previous aspects of the present disclosure. The computer program may for example be stored onto a computer readable medium, where the computer readable medium may be any type of memory device, including one of a removable nonvolatile random access memory, a hard disk drive, a floppy disk, a CD-ROM, a DVD-ROM, a USB memory, an SD memory card, or a similar computer readable medium known in the art.

Further advantages and advantageous features of the present disclosure are disclosed in the following description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a more detailed description of embodiments of the present disclosure cited as examples.

In the drawings:

Fig. 1A presents an exemplary articulated vehicle provided with a steering system according to the present disclosure, and Fig. 1 B is a detailed view of a steering mechanism for steering of the exemplary articulated vehicle of Fig. 1 A;

Fig. 2 conceptually shows a steering system according to the present disclosure comprised with an articulated vehicle as shown in in Fig. 1 A;

Fig. 3 presents a work site where the articulated vehicle of Fig. 1 A is operating, and

Fig. 4 illustrates the processing steps for performing the method according to the present disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the present disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the disclosure to the skilled addressee. Like reference characters refer to like elements throughout. Fig. 1 is a side view of an exemplary articulated vehicle 100 in the form of an articulated hauler having a tractor unit 102, also denoted as a forward vehicle section, provided with a cab 104 for an operator (driver) and a trailer unit 106, also denoted as a rear vehicle section, provided with a platform having a dump body 108, here in the form of a container, arranged thereon, for receiving load. The dump body 108 is preferably pivotally connected to the trailer unit 106 and tiltable by means of a material discharge mechanism comprising e.g. a pair of tilting cylinders (not shown), for example hydraulic cylinders. The tractor unit 102 has a frame 1 10 and a pair of wheels 1 12 supported from the frame 1 10. The trailer unit 106 has a frame 1 14 and two pair of wheels 1 16, 1 18 supported from the frame 1 14.

The articulated vehicle 100 is frame-steered, using a joint arrangement 120 comprising e.g. an articulation joint 124, connecting the tractor unit 102 and the trailer unit 106 of the articulated vehicle 100 for allowing mutual rotation of the tractor unit and the trailer unit around a geometrical axis 122. The articulation joint 124 may possibly comprise an inter axle differential.

The tractor unit 102 typically comprises a drive unit, where the drive unit comprises e.g. an internal combustion engine and a gearbox/transmission. The drive unit may, also or alternatively, comprise an electric motor and a battery for powering the electric motor. In addition, the articulated vehicle 100 comprises steering means, such as a hydraulic system having two hydraulic actuators 126, 128 (as further detailed in Fig. 1 B), steering cylinders, arranged on opposite sides of the articulated vehicle 100 for turning the articulated vehicle 100 by means of relative movement of the tractor unit 102 and the trailer unit 106. The hydraulic cylinders 126, 128 can, however, be replaced by any other linear actuator for steering the working machine 1 , such as an electromechanical linear actuator. One end of each of the hydraulic actuators 126, 128 is mechanically connected to the tractor unit 102 and the other end is mechanically connected to the trailer unit 106.

The articulated vehicle 100 further comprises an electronic control unit (ECU) 130, adapted to be directly or indirectly connected to the hydraulic actuators 126, 128. The ECU 130 may for example be manifested as a general-purpose processor, an application specific processor, a circuit containing processing components, a group of distributed processing components, a group of distributed computers configured for processing, a field programmable gate array (FPGA), etc. The ECU 130 may be or include any number of hardware components for conducting data or signal processing or for executing computer code stored in memory. The memory may be one or more devices for storing data and/or computer code for completing or facilitating the various methods described in the present description. The memory may include volatile memory or non-volatile memory. The memory may include database components, object code components, script components, or any other type of information structure for supporting the various activities of the present description. According to an exemplary embodiment, any distributed or local memory device may be utilized with the systems and methods of this description. According to an exemplary embodiment the memory is communicably connected to the processor (e.g., via a circuit or any other wired, wireless, or network connection) and includes computer code for executing one or more processes described herein.

With further reference to Figs. 2 and 3, there is presented a steering system 200, typically comprised with the articulated vehicle 100. The steering system 200 includes the ECU 130, where the ECU 130 is adapted to control the hydraulic actuators 126, 128 in line with the concept according to the present disclosure, with the purpose of reducing e.g. whole body vibrations, such as in case the articulated vehicle 100 is operating in an environment/terrain, such as at a work site 300, where one or a plurality of disturbances 304 may be present. In operating the hydraulic actuators 126, 128, the ECU 130 may for example be arranged to control means (such as e.g. a valve) for selectively provide e.g. a hydraulic fluid to the hydraulic actuators 126, 128.

Alternatively and as mentioned above, it may be possible to use electrically controlled actuators instead of the hydraulic actuators 126, 128. In such an implementation the ECU 130 may be arranged to control e.g. driver means (such as a driver circuitry) in turn controlling the operation of such electrically controllable actuators in line with the concept according to the present disclosure.

Thus, in line with the concept according to the present disclosure, the ECU 130 is adapted to receive the above mentioned information being indicative of the disturbance 304 in a terrain 302 ahead of the articulated vehicle 100 in a direction of travel of the articulated vehicle 100. The information being indicative of the disturbance 304 may for example be received from a sensor arrangement 204 comprised with the articulated vehicle 100 or a work site system 206 arranged in wireless communication with the steering system 200. The sensor arrangement 204 may for example comprise at least one of a camera 208, a laser arrangement 210, a radar arrangement 212 and a LIDAR arrangement 214, etc., capturing information that may be processed by the ECU 130 for identifying the disturbance 304 ahead of the vehicle. In case of the sensor arrangement 204 comprising a camera 208, the camera may be arranged to capture one or a plurality of images and/or a video sequence of the terrain ahead of the articulated vehicle 100. The ECU 130 may in turn be adapted to execute an image analysis process based on the captured image(s)/video for identifying said disturbance 304. The disturbance may for example be a pot-hole, a“bump”, etc. The e.g. laser arrangement 210, radar arrangement 212 and LIDAR arrangement 214 may be arranged to function in a similar manner in conjunction with the ECU 130 for determining the presence of the disturbance 304.

The information collected by the sensor arrangement 204 may in some embodiments of the present disclosure be transmitted to the work site system 206. The work site system 204 may accordingly be adapted to allow the collected information to be distributed to (the same) or other articulated vehicles operating at the work site 300. Thus, for efficient use of the collected information it is desirable that the information collected by the sensor system 204 is “tagged” with e.g. a geographical location relating to “where” the information relating to a specific disturbance 304 was collected. Accordingly, the articulated vehicle 100 may continuously or over time receive information relating to disturbances 304 at the work site 300, collected by the“own” articulated vehicle 100 or by other articulated vehicles. The articulated vehicle 100 is thus preferably equipped with e.g. a wireless transceiver (not shown) for wireless communication with the work site system 206.

In a preferred embodiment of the present disclosure the articulated vehicle 100 is thus further equipped with geolocation arrangement (not shown). The geolocation arrangement may for example comprise a GPS receiver or a local positioning arrangement at a construction site, such as for example a Wi-Fi positioning system. It may, as understood by the skilled addressee, be necessary to use an alternative to satellite navigation in case the working machine is operating underground, such as for example in a mine or similar.

The ECU 130 is preferably also connected to an operator controlled steering input device 222 comprised with the articulated vehicle 100, where the operator controlled steering input device 222 for example may comprise a steering wheel. As mentioned above, the operator controlled steering input device 222 may be equipped with e.g. an angular sensor adapted to collect information relating to a current steering angle for the articulated vehicle 100. Such an angular sensor may of course be arranged elsewhere with the articulated vehicle 100, such as in relation to the hydraulic actuators 126, 128.

The ECU 130 may also be arranged in communication with e.g. a vibration sensor arrangement 216 comprised with the articulated vehicle 100. The vibration sensor arrangement 216 may in turn comprise at least one inertial measurement unit (IMU) 218, where the IMU 218 for example may be arranged at a structure of the articulated vehicle 100. The IMU 218 may be adapted to continuously monitor any vibrations within the articulated vehicle 100. The information relating to the vibrations may in some embodiment be used as a feedback to the vibration compensation achieved in accordance to the concept according to the present disclosure.

Turning now also to Fig. 4, that should be interpreted in light of Figs. 1 - 3 and which together illustrates an example of the overall operation of the steering system 200 according to the present disclosure when the articulated vehicle 100 is operating at e.g. the work site 300, where the terrain 302 of the work site 300 comprises at least a disturbance 304.

The process start by that the ECU 130 determines, S1 , an initial steering angle for the articulated vehicle 100. The determination is advantageously performed based on information indicative a current steering angle for the articulated vehicle 100, such as by analyzing information received from the angle sensor arranged in conjunction with the operator controlled steering input device 222.

In conjunction with the reception of the information indicative a current steering angle for the articulated vehicle 100, the ECU also receives, S2, information being indicative of the disturbance 304 in the terrain 302 ahead of the articulated vehicle 100 in a direction of travel of the articulated vehicle 100, such as in front of the articulated vehicle 100. The information being indicative of the disturbance 304 is for example based on information collected using the sensor arrangement 204 or from corresponding information received from the work site system 206. When the information being indicative of the disturbance 304 is received from the sensor arrangement 204, for example based on image data collected using the camera 208 (arranged to acquire image data in a forward moving direction of the articulated vehicle 100), the ECU 130 will process the image data for identifying the disturbance 304, e.g. the illustrated pot-hole.

The ECU 204 will further determine, S3, a first compensation steering angle based on the disturbance 304. This determination may for example be performed by identifying a size and area of the disturbance 304 and compare such information with previously collected or simulated disturbance data. That is, the ECU 130 may for example perform a matching between the identified disturbance 304 and the previously collected or simulated disturbance data, where the previously collected or simulated disturbance data possibly also may comprise information relating to“how” such a disturbance 304 will influence the articulated vehicle 100, e.g. as seen from a vibration perspective.

Based on the performed matching, the ECU 130 may further form, S4, a first adjusted steering angle based on the initial steering angle and the first compensation steering angle. That is, if for example the articulated vehicle 100 is operated at an initial steering angle of X degrees (e.g. defined as a relative angle between the tractor unit 102 and the trailer unit 106), and the first compensation steering angle for a specific type of disturbance 304 is determined to be Y degrees, then the first compensation steering angle, denoted as Z, may be determined to be X + Y degrees.

Accordingly, based on the determination of the first compensation steering angle, the ECU 130 may then control (directly or indirectly) e.g. the two hydraulic actuators 126, 128 by applying, S5, the first adjusted steering angle Z for steering the articulated vehicle 100. The application of the first adjusted steering angle Z is preferably applied just before (such as 0 - 1 seconds before, e.g. dependent on a speed of the articulated vehicle 100) or at the time of arriving at the disturbance 304.

Once the articulated vehicle 100 has passed (such as 0 - 1 seconds after, e.g. dependent on a speed of the articulated vehicle 100) the disturbance 304, the ECU 130 may again operate the two hydraulic actuators 126, 128, for example“returning back” to the initial steering angle for the articulated vehicle 100. If a further disturbance 304 is identified, the ECU 130 may again determine a compensation steering angle and operate the two hydraulic actuators 126, 128 with the purpose of compensating for any vibrations induced by the disturbance 304.

Thus, in line with the present disclosure information being indicative of an upcoming disturbance in the terrain may be used for slightly adjusting a steering angle (i.e. with the first adjusted steering angle) for the articulated vehicle 100, whereby a“would have been” vibration of the articulated vehicle 100 is reduced in a proactive manner. The overall appearance for the driver of the articulated vehicle 100 may advantageously be interpreted as a steadier with an in comparison reduced amount of vibrations when operating of the articulated vehicle 100.

The present disclosure contemplates methods, devices and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine- readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor.

By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine- readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data that cause a general-purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions. Although the figures may show a specific order of method steps, the order of the steps may differ from what is depicted. In addition, two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps. Additionally, even though the disclosure has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art.

Variations to the disclosed embodiments can be understood and effected by the skilled addressee in practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims. Furthermore, in the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.