SE540430C2

SE540430C2 - System and method for controlling cab suspension and a vehicle including the system

Info

Publication number: SE540430C2
Application number: SE1750034A
Authority: SE
Inventors: Dellrud Jan
Original assignee: Scania Cv Ab
Priority date: 2017-01-17
Filing date: 2017-01-17
Publication date: 2018-09-18
Also published as: DE102018000103B4; DE102018000103A1; SE1750034A1

Abstract

The present disclosure relates to techniques in the context of vehicles, and in particular to a system and method for controlling cab suspension in a vehicle settable to be operated in an autonomous mode. According to one aspect, the disclosure relates to a system (2) for controlling cab suspension in a vehicle (1) settable to be operated in an autonomous mode, wherein the vehicle (1) includes a cab (3) and a vehicle frame (4). The system includes a cab suspension arrangement (5) arranged to flexibly suspend the cab (3) to the vehicle frame (4). The system further includes a locking arrangement (6) configured to obtain control data indicating whether the autonomous mode is activated, and configured to lock the cab (3) in a fixed position with respect to the vehicle frame (4) or to unlock it from the fixed position based on the obtained control data. The present invention also relates to a computer program and a computer program product.

Description

System and method for controlling cab suspension and a vehicle including the system Technical field The present disclosure relates to techniques in the context of vehicles, and in particular to a system and method for controlling cab suspension in a vehicle configurable to be operated in an autonomous mode. The present invention also relates to a computer program and a computer program product.

Background To drive a heavy vehicle often puts high demands on the driver, since there are many complex predictable and unpredictable situations that must be considered. Therefore, driving aids such as adaptive cruise-control systems, emergency braking, carriageway warnings, and similar are currently available to facilitate the work of the driver. These aids require an operator being present in the vehicle who can himself or herself assess the situation and take appropriate action. In addition, the progressive development of vehicle electronics allows the use of automatic driving functions in which both the longitudinal control and the lateral control of the vehicle is carried out automatically (without any manual intervention). This implies that autonomous driving may be performed without any operator or driver being present at the vehicle. In order to operate a vehicle autonomously in a safe manner an accurate assessment of the surroundings of the vehicle is required. This can be achieved using sensors such as cameras, radar devices, and similar with high precision and advanced information processing, and communication between the various control units of the vehicle.

The abovementioned sensors may be arranged to the vehicle at various places. For example, the sensors may be mounted to the cab of the vehicle, such as inside the cab or external to the cab. However, cab mounted sensors may become disturbed by the cab’s movement and consequently provide data having poor quality or being faulty. To mount the sensors to the vehicle frame instead of to the cab is therefore a possible solution. Though vehicle frame mounting may generally result in shorter service life for the sensors, due to rough environment. It might also result in problems in keeping the sensors clean and free from moist etc. To overcome this an additional cab-like environment may be added in order to protect sensors like cameras and radars from rough environment.

Summary It is an object of the disclosure to alleviate at least some of the drawbacks with existing solutions. It is a still further object to provide a system by which a vehicle can be autonomously operated using sensors, while avoiding the abovementioned problems, and wherein no extra hardware for protection of the sensors is required. It is a further object to provide a system that makes it feasible to use cab mounted sensors in an autonomous mode, where the data from the cab mounted sensors can be trusted.

These object and others are at least partly achieved by the system and the method according to the independent claims, and by the embodiments according to the dependent claims.

According to one aspect, the disclosure relates to a system for controlling cab suspension in a vehicle configurable to be operated in an autonomous mode, wherein the vehicle includes a cab and a vehicle frame. The system includes a cab suspension arrangement arranged to flexibly suspend the cab to the vehicle frame. The system further includes a locking arrangement configured to obtain control data indicating whether the autonomous mode is activated, and configured to lock the cab in a fixed position with respect to the vehicle frame or to unlock it from the fixed position based on the obtained control data.

By providing a system including a locking arrangement that can fixate a flexibly or resiliently suspended cab in a fixed position, the above-mentioned problems associated with cab mounted sensors may be avoided.

According to some embodiments, the locking arrangement is configured to lock the cab in the fixed position when the control data indicates that the autonomous mode is activated.

For example, in a vehicle that needs to be driven by a human driver in some situations and driverless in other situations, the cab is locked to the chassis when the vehicle is operating in autonomous modes and the cab is resiliently suspended to the chassis when a driver is present in the cab. Thereby, the problem of faulty or low quality sensor data in the autonomous mode because of movements of the cab with respect to the chassis is avoided, while still providing a comfortable environment for the driver when he or she is present in the cab.

According to some embodiments, the locking arrangement is arranged to receive the control data being a control signal provided by an input device in the vehicle. Thereby, a simple solution is achieved, whereby the locking arrangement may be controlled with a sole signal provided by the input device.

According to some embodiments, the system further includes a control unit configured to receive driving mode data indicative of a driving mode of the vehicle, to determine the control data based on the driving mode data, and to send the control data to the locking arrangement in order to control the locking arrangement in accordance with the control data. By introducing a control unit, it is possible to implement more advanced rules for when the cab should be fixated and not. According to some further embodiments, the control unit is arranged to determine the control data based on at least one predetermined rule for the driving mode data and/or the sensor data.

According to some embodiments, the control unit is further configured to obtain sensor data indicative of cab movement and to determine the control data based on the driving mode data and the sensor data. Thereby it is possible to fixate the cab only when it is required due to e.g. extensive cab movements. According to some embodiments, the control unit is configured to control the locking arrangement to lock the cab in the fixed position in response to the sensor data indicating cab movements above a predefined threshold. Thereby, the cab is only fixated when the movement is above a certain threshold.

According to some embodiments, the cab suspension arrangement includes at least one of a hydraulic suspension mechanism, an air suspension mechanism and a mechanic suspension mechanism. According to some embodiments, the autonomous mode is a semi-autonomous mode or a driverless mode.

According to some embodiments, the locking arrangement includes at least one of a mechanical device actuated by an electric solenoid, a mechanical device actuated by an electric motor, a pressurized air cylinder and a hydraulic cylinder.

According to a second aspect, the disclosure relates to a vehicle including the system described above and below. According to some embodiments, the vehicle includes at least one sensor arranged to the cab and arranged to be used in the autonomous mode. According to some embodiments, the vehicle includes at least one input device configured to receive user input and to provide the control data to the system, based on the user input.

According to a third aspect, the disclosure relates to a method for controlling cab suspension in a vehicle settable to be operated in an autonomous mode, wherein the vehicle includes a cab flexibly suspended to a vehicle frame of the vehicle. The method includes obtaining control data indicating whether the autonomous mode is activated and locking the cab in a fixed position with respect to the vehicle frame based on the obtained control data.

According to some embodiments, the method includes locking the cab in a fixed position with respect to the vehicle frame when the driving mode data indicates that the autonomous mode is activated.

According to some embodiments, the method includes receiving driving mode data indicative of a driving mode of the vehicle, and then the obtaining includes determining the control data based on the driving mode data.

According to some embodiments, the method includes obtaining sensor data indicative of cab movement and wherein the locking is based on the driving mode data and the sensor data.

According to some embodiments, the method includes the locking includes using at least one predetermined rule for the driving mode data.

According to a fourth aspect, the disclosure relates to computer program P, wherein the computer program P includes a computer program code to cause a control unit, or a computer connected to the control unit, to perform the method described above and below.

According to a fifth aspect, the disclosure relates to computer program product including a computer program code stored on a non-transitory computer-readable medium to perform the method steps according to the method described above, when the computer program code is executed by a control unit or by a computer connected to the control unit.

Brief description of the drawings Fig. 1 illustrates a vehicle in which the proposed system and methods can be used.

Fig. 2A illustrates a cab including an example cab suspension arrangement. Fig. 2B illustrates the cab of Fig. 2A seen from above.

Fig. 3A illustrates a cab including another example cab suspension arrangement. Fig. 3B illustrates the cab of Fig. 3A seen from above.

Fig. 4A illustrates a system for controlling cab suspension in a vehicle according to a first example embodiment.

Fig. 4B illustrates an alternative implementation of the system in Fig. 4A.

Fig. 5 illustrates a system for controlling cab suspension in a vehicle according to a second example embodiment.

Fig. 6 illustrates a flow chart of a method according to some embodiments.

Detailed description In the following a system and a method for controlling cab suspension in a vehicle configurable to be operated in an autonomous mode will be described. As mentioned above, sensors arranged to the cab of a truck may become disturbed by the cab’s movement or vibration and consequently provide data that is faulty or that has poor quality. The reason is that the cab of a vehicle is often flexibly or resiliently suspended to the vehicle frame in order to provide a comfortable environment to the driver.

The proposed technique is based on the insight that the resilient suspension might cause problems in an autonomous mode, e.g. if sensors that are used for operating the vehicle in an autonomous mode are arranged to the cab. The reason is that the cab may be moved or displaced with regard to the chassis in an unpredictable way. Sensors are typically used for tracking objects. The position of an object may be estimated based on sensor data. However, because of the above mentioned cab movements, an estimated position of an object tracked by sensors mounted on the frame may deviate from an estimated position of the same object, when tracked by sensors placed on the cab. For example, if a vehicle operating in an autonomous mode is driving on a straight road and if the cab is resiliently suspended to the vehicle frame, then a bump on one side of the road might cause the cab to swing such that the cab is moved and displaced with regards to the vehicle frame. Consequently, if a camera used for e.g. lane keeping is mounted on the cab, the camera will also move. An autonomous driving system may interpret the movement as that the vehicle is turning. Thus, the movement might trigger an incorrect reaction in the autonomous driving system. The autonomous driving system might e.g. try to compensate the perceived turn with a turn in the opposite direction. Note that, e.g. cab mounted cameras are generally tracking objects (e.g. lanes) a few meters in front of the vehicle. Hence, even a small movement of the cab, might cause a considerable reaction in the autonomous driving system. Furthermore, as these movements are unpredictable, it is difficult to adapt the autonomous driving system to take such movements into account when controlling a vehicle in an autonomous mode.

The system and method that will now be described, enables a vehicle cab to be alternately locked and unlocked with regards to the vehicle frame, depending on data associated with an autonomous driving mode. Thereby, problems caused by faulty or low quality sensor data caused by cab movements may be avoided. This effect will in the following be exemplified with reference to a cab suspension system in a truck, but it should be understood that the system and method could also be used in other vehicles.

Fig. 1 schematically illustrates an example vehicle 1, here a truck, which may include the proposed solutions. The vehicle 1 includes a cab 3 and a vehicle frame 4, sometimes referred to as a chassis or truck body. The cab 3 is flexibly suspended to the vehicle frame 4 through a cab suspension arrangement 5. The flexibility of the suspension arrangement entails that the cab 3 and the vehicle frame 4 are movable with regards to each other in at least one direction. The suspension arrangement 5 is typically arranged to resiliently suspend the cab 3 to the vehicle frame 4 such that driving becomes comfortable for the driver. In other words, the cab 3 is resiliently attached to the vehicle frame 4.

In Fig. 1, the suspension arrangement 5 is mechanically driven. A mechanical suspension arrangement 5 may e.g. include coil springs 51 (e.g. steel springs). However, the suspension arrangement 5 might alternatively be air based or hydraulically driven.

An air based suspension arrangement typically includes one or more air bellows, an air valve for injecting or withdrawing air from the air bellows and a pressure sensor configured to measure the pressure within the air bellows. By injecting and withdrawing air from the air bellows, the stiffness of the air bellows may be adjusted as well as the location of the cab in relation to the frame.

In a hydraulically driven suspension arrangement the cab is typically suspended to the vehicle frame by one or more hydraulic cylinders being in interactive relationship with a container including hydraulic fluid and gas. The compressibility of the gas, e.g. air, will allow a variable amount of the hydraulic fluid to enter the container, depending on the pressure in the hydraulic cylinder. Thereby a resilient suspension is achieved. The suspension arrangements briefly described above, are all commonly known and will therefore not be described in detail herein.

Furthermore, the cab 3 may be flexibly suspended relative to the vehicle's frame 4 in different ways. In a typical implementation, the cab 3 is suspended to the vehicle frame 4 in three or four different points. Generally, three points are required for stability. However, the cab 3 may of course be suspended in more points depending on the implementation.

One possibility is to suspend the cab 3 to the vehicle frame 4 using a plurality of springs 51, which will now be explained referring to an example suspension arrangement 5 illustrated in Fig. 2A-2B, wherein Fig. 2A illustrates the cab 3 seen from the long side of the vehicle 1 and Fig. 2B illustrates the cab 3 seen from above. In Fig. 2A-2B four mechanical coil springs 51 are used, one in each corner of the cab 3 (when seen from above). In order to provide stability, the springs 51 are typically placed near the corners of the cab 3 (when seen from above) as can be seen in Fig. 2B.

Alternatively, the driver's cab 3 is suspended on, and tiltable relative to the vehicle frame 4, which will now be explained referring to another example suspension arrangement 5 illustrated in Fig. 3A-3B, wherein Fig. 3A illustrates the cab 3 seen from the long side of the vehicle 1 and Fig. 3B illustrates the cab 3 seen from above. In the example of Fig. 3A-3B the cab 3 is tiltably attached to the vehicle frame 4 at one end by a pivotable coupling 53, such as a hinge or a joint. The pivotable coupling 53 is typically placed at the front end of the cab 3 with regards to the driving direction of the vehicle 1, but other solutions are of course also possible. The cab 3 may be tiltable to allow access to the engine for servicing and, where applicable, repairs. Note that the pivotable coupling 53 is not necessarily resilient. Furthermore, the cab 3 is resiliently suspended at another end of the cab 3 with regards to the pivotable coupling 53, e.g. at the rear edge of the cab 3 in the driving direction if the pivotable coupling 53 is positioned at the front end of the cab 3. The resilient suspension may be provided by a hydraulic or air spring arrangement or by mechanical coil springs.

As mentioned above, one or more sensors 8 may be arranged to the cab 3 of the vehicle 1. For simplicity only one sensor 8 is shown in Fig. 4. The sensor 8 is e.g. a camera used for object tracking in an autonomous mode. As explained above, the resilience of the cab 3 with regards to the vehicle frame 4 gives comfort for a driver. However, sensors 8 attached to the cab 3 may be disturbed by displacement of the cab 3 with regards to the vehicle frame 4, caused by the resilience of the suspension arrangement 5 and consequently provide data being incorrect having with poor quality.

To overcome this, this disclosure proposes a system 2 for controlling cab suspension in a vehicle 1 configurable to be operated in an autonomous mode. That the vehicle is settable or configurable to be operated in an autonomous mode implies that an autonomous mode can be activated and deactivated. The setting or configuring can be performed e.g. by a driver during driving or by a remote operator. In other words, the vehicle 1 is arranged to be set in an autonomous mode.

In this disclosure, an autonomous mode refers to a driving mode where the vehicle is self-governed, i.e. driven without any driver being present in the cab 3. In other words, in the autonomous mode the vehicle 1 is autonomously operated without any action from a driver being required. Though, in some embodiments the autonomous mode is a semi-autonomous driving mode, where some driver interaction is required. However, common for these modes is generally that the operation is dependent on advanced sensor data provided by sensors 8 arranged to the vehicle 1.

The system 2 will now be described with reference to Fig. 4A illustrating the vehicle 1 of Fig. 1 including the system 2. Note that while the vehicle 1 of course includes lots of other parts, Fig. 4A only illustrates parts of the vehicle 1 that are related to or somehow associated with the system 2.

The system 2 includes a cab suspension arrangement 5 arranged to flexibly suspend the cab 3 to the vehicle frame 4, as described in relation to Fig 2A-2B and 3A-3B. The system further includes a locking arrangement 6. The locking arrangement 6 is configured to lock the cab 3 in a fixed position with respect to the vehicle frame 4 or to unlock it from the fixed position. In other words, the locking arrangement 6 is a mechanism that can be used to fixate the resiliently suspended cab 3 to the vehicle frame 4 in a low-resilient, non-resilient or nonflexible way. Low-resilience implies that there is some flexibility in the fixed position, e.g. in order to avoid tension in the cab caused by rotary movements of the vehicle frame 4. In any case, even when there is some resilience in the fixed position, it is a less resilient position than the un-locked position. The locking arrangement 6 is further arranged to obtain control data indicating whether the autonomous mode is activated, and configured to lock the cab 3 in a fixed position with respect to the vehicle frame 4 or to unlock it from the fixed position based on the obtained control data. The locking arrangement 6 may obtain the control data actively or passively. For example, the locking arrangement 6 may obtain the control data by receiving it from another unit inside or outside the vehicle 1, or it might read it from a data storage. The control data may be an analogue signal or control parameters, as will be further described below.

In some embodiments, the locking arrangement 6 is configured to lock the cab 3 in the fixed position when the control data indicates that the autonomous mode is activated. That an autonomous mode is activated may imply that the mode is currently active or that the driver or controller has “switched- on” the driving mode, such that it will soon become active. In other words, in some embodiments, when the autonomous mode is active (or soon to be active) the locking arrangement 6 locks the cab 3 in a fixed position with regards to the vehicle frame 4, whereby sensors 8 arranged to the cab 3 are not disturbed by movements, displacement or vibrations caused by a resilient cab suspension arrangement 5. The locking arrangement 6 is typically configured to be unlocked in the “opposite way”, when the autonomous mode is de-activated.

The locking arrangement 6 may be implemented in a plurality of ways. As discussed above, the system 2 may be a hydraulic system including a hydraulic suspension arrangement, an air based suspension arrangement or it may be a mechanical system including a mechanical suspension arrangement.

In a mechanical system, the locking arrangement 6 for example includes a mechanical lock such as a cotter or peg 62, arranged to in a locked position protrude from the vehicle frame 4 into a hole 63 in the cab 3 in order to fixate the cab 3 against the vehicle frame 4, as illustrated in Fig. 4A. The mechanical lock may be actuated by an electric solenoid 61 arranged in the vehicle frame 4, by an electric motor or by another actuator. The mechanical lock may e.g. be arranged such that in a default position, when no control data is received, the peg is indented in the vehicle frame 4 and the mechanical lock is open. The mechanical lock is then arranged such that when control data indicating that the cab 3 should be locked is received, then the mechanical lock is activated to lock the cab 3 to the vehicle frame 4. For example, the control data is a current that flows through the solenoid thereby forcing the peg to exit the solenoid and protrude from the vehicle frame 4 into the hole 63 in the cab 3. Reverse operation, wherein the default position is a locked position, is of course also possible. The solenoid and the peg may alternatively be arranged in the cab 3 instead and then the peg would in the locked position protrude into a hole in the vehicle frame 4. Note that a mechanical lock may also be used with any of the suspension systems.

An alternative implementation of the locking arrangement 6 is illustrated in Fig. 4B. In Fig. 4B the suspension arrangement 5 includes an air bellow 52. In air based systems, the locking arrangement 6 may be arranged to obtain a predetermined pressure, or similar, in order to fixate the cab 3 to the vehicle frame 4. This might be done by pumping air into the bellow through an air inlet 64.

According to some embodiments the locking arrangement 6 includes one or more valves 65 arranged in order to start or stop the transfer of air to the air bellow or bellows 52 via an air inlet 64. For example, the locking arrangement 6 may be arranged to close the valve 65 when the air bellow 52 is at a predetermined pressure, or similar, in order to fixate the cab 3 to the vehicle frame 4. The predetermined pressure may typically correspond to that the air bellow 52 is relatively stiff, whereby the cab’s 3 movement relative the vehicle frame 4 is insignificant. However, complete stiffness is impossible, or at least very difficult, to achieve with air filled bellows 52.

In a hydraulically driven system, higher stiffness might be achieved at least if there is a significant amount of fluid in the system, as fluid is less compressible than air. In a hydraulically driven cab suspension system the resilience is typically provided by one or more hydraulic cylinders (not shown) being in interactive relationship with a container including air and fluid, as described above. The locking arrangement 6 may in such a system, similar to in the air based system, include one or several valves arranged in the fluid line, in order to start or stop the transfer of fluid to the hydraulic cylinder. When the fluid transfer to and from the container is stopped, the hydraulic cylinder will be relatively stiff, due to the low compressibility of the fluid.

In an air or hydraulically driven system, the locking arrangement 6 may according to some embodiments be arranged to press the cab 3 against a mechanical stop with a positive force, whereby the cab 3 is securely fastened against the vehicle frame 4. The required pressure is e.g. the pressure needed to fasten the cab 3 against the vehicle frame 4 plus some newton, which would be a pressure required to create a force in order to fixate the cab 3 to the frame 4. This at least is possible to accomplish with the hydraulically driven system as the hydraulic fluid is not compressible to any larger extent.

As described above, the suspension arrangement 5 may include a plurality of individually controllable springs 51, 52. If the suspension arrangement 5 includes two or three springs, then typically all need to be locked, in order to provide full fixation of the cab 3. If the suspension arrangement 5 includes four springs 51, 52, then only three would need to be locked in order to get an effect, but an even better effect is achieved if all four are locked.

In some embodiments, the locking arrangement 6 is arranged to receive control data being a control signal provided by an input device 9 in the vehicle 1. For example, the autonomous mode may be activated through an input device 9, e.g. a switch, a knob, a rocker or a button, that is e.g. placed on the dashboard of the vehicle 1. When a driver operates the input device 9, a signal is sent to the locking arrangement 6, which then locks the cab 3 in a fixed position with respect to the vehicle frame 4 or unlocks it from the fixed position based on the received signal. The signal may for example be a current, which is used to activate one or more solenoids in the locking arrangement 6. Hence, in this embodiment only a current is needed to lock or unlock the locking arrangement 6.

As described above, the locking arrangement 6 may be activated by a signal activated in response to an input, provided by the driver, putting the vehicle 1 in autonomous mode. However, the locking arrangement 6 may also be controlled by driving mode data received e.g. from a control system in the vehicle 1 or from remote unit, as will now be described with reference to a second example embodiment of the system 2, which is illustrated in Fig. 5.

Fig. 5 illustrates the cab 3 of the vehicle 1 seen from above and a cab suspension arrangement 5 including four springs (in this example embodied as hydraulically cylinders 54) arranged for suspending the cab 3 to the vehicle frame 4 (not visible in Fig. 5). The system 2 also includes a locking arrangement 6 including one valve 66 arranged in connection with each hydraulically cylinder 54. Thereby, the resilience of the hydraulic cylinder 54 may be controlled by opening and closing the respective valves 66 as described above. The system 2 of Fig. 5 further includes a control unit 7. The control unit 7 for example includes a processing unit 71 and a memory unit 72. The processing unit 71 may be made up of one or more Central Processing Units, CPU. The memory unit 72 may be made up of one or more memory units. A memory unit 72 may include a volatile and/or a non-volatile memory, such as a flash memory or Random Access Memory, RAM. The control unit 7 may further include a computer program P including a computer program code to cause the control unit 7, or a computer connected to the control unit 7, to perform any of the method steps that will be described in the following. The control unit 7 may be an Electronic Control Unit, ECU.

The control unit 7 is arranged to receive driving mode data indicative of a driving mode of the vehicle 1. Example of driving mode data is data indicating if the driving mode is active or not. Driving mode data may also be other data related to the driving mode, such as sensor data or data from the suspension arrangement 5 as will be further described below. The driving mode data may be received from an autonomous operation system 10 in the vehicle 1. The autonomous operation system 10 is e.g. a unit that controls the operation of the vehicle when the autonomous mode is active. The driving mode data may also be received from a remote system such as an off-board system 11 . An off-board system 11 is a remote control system of the vehicle 1 that is e.g. connected to the control unit 7 by wireless communication means, included in the control unit 7 or in the autonomous operation system 10.

The control unit 7 is further configured to determine the control data based on the driving mode data, and to send the control data to the locking arrangement 6 in order to control the locking arrangement 6 in accordance with the driving mode data. In other words, the control unit 7 is arranged to control the locking arrangement 6 based on the received driving mode data. For example, the control unit 7 is arranged to determine the control data based on at least one predetermined rule for the driving mode data and/or the sensor data. The predetermined rule is for example a table or a formula. The predetermined rule takes driving mode data as input. The predetermined rule results in control data that can be used or interpreted by the locking arrangement 6. The locking arrangement 6 may then be controlled in the same way as described above e.g. such that the cab 3 is fixated to the chassis when the driving mode data indicates that an autonomous mode is activated i.e. presently active or soon to be active.

The vehicle 1 is arranged to communicates internally i.e. between its units, devices, sensors, detectors etc. via a communication bus, for example a CAN-bus (Controller Area Network) which uses a message based protocol. Examples of other communication protocols that may be used are TTP (Time-Triggered Protocol), Flexray, etc. In that way signals and data described herein may be exchanged between different units, devices, sensors and/or detectors in the vehicle 1. Signals and data may instead be transferred wirelessly between the different units, devices, sensors and/or detectors. In some embodiments, the control unit 7 is arranged to use the CAN to receive driving mode data from a system or unit in the vehicle 1 and/or to send the control data to the locking arrangement 6.

In some embodiments, the locking arrangement 6 is arranged to be controlled based on other parameters related to the autonomous mode. This implies that the cab 3 may stay flexibly attached to the vehicle frame 4 even when the autonomous mode is active. However, when the additional data indicates that the cab 3 is moving or vibrating such that there is a risk for faulty data, then the locking arrangement 6 may be controlled to lock the cab 3 to the vehicle frame 4.

One possibility is that the locking arrangement 6 is arranged to be controlled by signals or data from one or more sensors. The sensors may be the sensors 8 used in the autonomous mode or it may be other sensors 12. In other words, in some embodiments the control unit 7 is further configured to obtain sensor data indicative of cab movement and to determine the control data based on the driving mode data and the sensor data. For example the control unit 7 may be arranged to receive driving mode data from one or more other sensors 12. For example, the at least one sensor 12 is a position or motion sensor e.g. a capacitive transducer or a gyro, indicating cab displacement or movement. Displacement indicated by the sensor 12 is for example displacement of the cab 3 with regards to the vehicle frame 4. Movements are e.g. vibrations caused by an uneven road.

The control unit 7 may be configured to analyze data received from the sensors 8, 12 and to determine if the cab 3 is moving to such an extent that the data from the sensors 8, 12 is likely to become corrupt. If this is the case, then the locking arrangement 6 is controlled to fixate the cab 3 to the vehicle frame 4. This is typically done when the vehicle 1 is already in autonomous mode. Hence, in some embodiments, the control unit 7 is configured to control the locking arrangement 6 to lock the cab 3 in the fixed position in response to the sensor data indicating cab movement above a predefined threshold. In other words, when cab movements are small, the locking arrangement 6 may not need to be activated, when the level of the movements is above a predetermined level, the locking arrangement 6 is activated to fixate the cab 3 to the vehicle frame 4.

In one example the control unit is arranged to obtain sensor data from a plurality of sensors. For example, sensor data is obtained from two image sensors, one sensor 8 arranged to the cab 3 and one sensor (not shown) arranged to the vehicle frame 4, see figure 4. In this example, the sensor 8 arranged to the cab is the same sensor 8 that is used in the autonomous mode. However, it may alternatively be another sensor. By comparing the images from the image sensors, an indication of cab 3 movement or displacement is acquired.

Another possibility is that the control unit 7 is arranged to receive driving mode data from the suspension arrangement 5 itself. Such data signals e.g. that the suspension arrangement is being used actively or the level of cab movement.

The disclosure also relates to a corresponding method for controlling cab suspension in a vehicle 1 configurable to be operated in an autonomous mode, wherein the vehicle 1 includes a cab 3 flexibly suspended to a vehicle frame 4 of the vehicle 1. The method will now be explained with reference to the flow chart illustrated in Fig. 6, and to the illustrations in the other figures. The method is for use in a vehicle such as the vehicle 1 described above, for example in an electrical control system. The method may be implemented as program code and saved in the memory unit 72 in the control unit 7 (Fig. 5). The method may be performed at any time when the vehicle 1 is operated. In a typical scenario, the method steps are performed when an autonomous mode is switched on by the driver driving the vehicle 1.

The method includes obtaining A1 control data indicating whether the autonomous mode is activated. For example, the system 7 receives control data from an input device 9 in the vehicle 1 as explained above.

Alternatively, the control data is internally obtained (e.g. by the control unit 7) based on driving mode data. Then the method includes receiving A0 driving mode data indicative of a driving mode of the vehicle 1, and then the obtaining A1 includes determining the control data based on the driving mode data.

The method further includes locking A3 the cab 3 in a fixed position with respect to the vehicle frame based on the obtained control data. In some embodiments, the method includes, including locking the cab 3 in a fixed position with respect to the vehicle frame 4 when the driving mode data indicates that the autonomous mode is activated. As described above, the locking A3 may also be based on other parameters related to the autonomous mode such as sensor data.

In further embodiments, the method includes obtaining A2 sensor data indicative of cab movement and wherein the locking A3 is based on the driving mode data and the sensor data, as described above. In some embodiments, the locking A3 includes using at least one predetermined rule for the driving mode data, as also explained above.

The present disclosure is not limited to the above-described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the disclosure, which is defined by the appending claims.

Claims

1. A system (2) for controlling cab suspension in a vehicle (1) configurable to be operated in an autonomous mode; wherein the vehicle (1) includes a cab (3) and a vehicle frame (4), characterized in that the system (2) includes: - a cab suspension arrangement (5) arranged to flexibly suspend the cab (3) to the vehicle frame (4); and - a locking arrangement (6) configured to obtain control data indicating whether the autonomous mode is activated, and configured to lock the cab (3) in a fixed position with respect to the vehicle frame (4) or to unlock it from the fixed position based on the obtained control data.

2. The system (2) according to claim 1, wherein the locking arrangement (6) is configured to lock the cab (3) in the fixed position in response to control data indicating that the autonomous mode is activated.

3. The system (2) according to claim 1 or 2, wherein the locking arrangement (6) is arranged to receive the control data being a control signal provided by an input device (9) in the vehicle (1).

4. The system (2) according to any of the preceding claims, further including: - a control unit (7) configured to: • receive driving mode data indicative of a driving mode of the vehicle (1), • determine the control data based on the driving mode data, and to • send the control data to the locking arrangement (6) in order to control the locking arrangement (6) in accordance with the control data.

5. The system (2) according to claim 4, wherein the control unit (7) is further configured to obtain sensor data indicative of cab movement and to determine the control data based on the driving mode data and the sensor data.

6. The system (2) according to claim 5, wherein the control unit (7) is configured to control the locking arrangement (6) to lock the cab (3) in the fixed position in response to the sensor data indicating cab movement above a predefined threshold.

7. The system (2) according to any of claims 4 to 6, wherein the control unit (7) is arranged to determine the control data based on at least one predetermined rule for the driving mode data and/or the sensor data.

8. The system (2) according to any of the preceding claims, wherein the system (2) includes at least one of a hydraulic suspension system, an air suspension system and a system suspension mechanism.

9. The system (2) according to any of the preceding claims, wherein the autonomous mode is a semi-autonomous mode or a driverless mode.

10. The system (2) according to any of the preceding claims, wherein the locking arrangement (6) includes at least one of a mechanical device actuated by an electric solenoid, a mechanical device actuated by an electric motor, a pressurized air cylinder and a hydraulic cylinder.

11. A vehicle (1) configurable to be operated in an autonomous mode including: - a vehicle frame (4), - a cab (3), and - a system according to any of claims 1 -10.

12. The vehicle (1) according to claim 11, further including: - at least one sensor (8) arranged to the cab, wherein the sensor (8) is arranged to be used in the autonomous mode.

13. The vehicle (1) according to claim 11 or 12, further including: - at least one input device (9) configured to receive user input and to provide the control data to the system (2) based on the user input.

14. A method for controlling cab suspension in a vehicle (1) configurable to be operated in an autonomous mode, wherein the vehicle (1) includes a cab (3) flexibly suspended to a vehicle frame (4) of the vehicle (1), the method including: - obtaining (A1) control data indicating whether the autonomous mode is activated and - locking (A3) the cab in a fixed position with respect to the vehicle frame based on the obtained control data.

15. The method according to claim 14, including locking the cab (3) in a fixed position with respect to the vehicle frame (4) when the driving mode data indicates that the autonomous mode is activated.

16. The method according to claim 14 or 15, including: - receiving (A0) driving mode data indicative of a driving mode of the vehicle (1), and wherein the obtaining (A1) includes determining the control data based on the driving mode data.

17. The method according to any of claims claim 14 to 16, including: - obtaining (A2) sensor data indicative of cab movement and wherein the locking (A3) is based on the driving mode data and the sensor data.

18. The method according to any of claims 14 to 17, wherein the locking (A3) includes using at least one predetermined rule for the driving mode data.

19. A computer program P, wherein the computer program P includes a computer program code to cause a control unit (7), or a computer connected to the control unit (7), to perform the method steps according to any of claims 14 to 18.

20. A computer program product including a computer program code stored on a non-transitory computer-readable medium to perform the method steps according to any of the claims 14 to 18, when the computer program code is executed by a control unit (7) or by a computer connected to the control unit (7).