Loader Crane Control System

Abstract

A hydraulically operated loader crane assembly configured to be mounted on a vehicle or on a trailer (figure 10) comprises a stabilizer arm, a loader crane base 102, a loader crane column 1020, a boom

Description

Field of the invention The invention relates to a control system of a hydraulically-operated loader crane assembly. The loader crane assembly may move or operate an attachment, such as a hook or a drill. Background of the invention A hydraulically-operated loader crane assembly may fulfil various functions. The tip of the crane may, for example, move an attachment such as a hook, or operate an attachment such as a drill. The loader crane assembly may be mounted on a working vehicle, a trailer, or a static installation. A grabber attachment may be used to grab bulk building materials such as bricks, blocks or stone. A drill attachment may, for example, drill holes in earth to facilitate the installation of power, communication or advertising poles. Known loader cranes and attachments are controlled by hydraulic actuators. The hydraulic actuators are located in a valve block and are driven by a vehicle’s hydraulic power. The vehicle hydraulic power may be provided either by the vehicle’s ‘power take-off’ (PTO), or by a dedicated slave engine motor pump. When the loader crane is required to lift a load, the primary hydraulic power source provides the lifting capacity through the pump, the hydraulic circuit, and the hydraulic actuators. The hydraulic power that is provided depends on the fluid pressure and flow that are provided. The hydraulic pressure, measured in Bar, influences the lifting force that the loader crane provides. The flow, measured in litres per minute, influences the speed at which the crane can move. The operation of a loader crane may involve lifting a load which may have a mass of several hundred, or even thousands of kilogrammes. With a vehicle-mounted crane, these lifting operations may be carried out in a wide variety of locations, with which the loader crane operator is not familiar. The lifting operation must be done in a way that does not endanger either the operator, the vehicle, the load, or the near surroundings. There is thus a perennial need to achieve ever higher levels of safety with hydraulically-operated loader cranes. Repeated lifting operations may place high loads on the vehicle, trailer or static installation on which the loader crane is mounted. These operations also cause wear on the various elements of the loader crane itself. The considerations above demonstrate clearly that the technical field of hydraulically-operated loader cranes is a distinct field from, for example, tower cranes. Summary of the invention The present invention provides a hydraulically-operated loader crane assembly, including a control system, as described in the accompanying independent claims 1 and 11. Details of specific embodiments of the invention are set forth in the dependent claims. These and other aspects of the invention will be apparent from, and elucidated with reference to, the embodiments described hereinafter. Brief description of the drawings Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. In the drawings, like reference numbers are used to identify like or functionally similar elements. Elements in the drawings are illustrated for simplicity and clarity, and have not necessarily been drawn to scale. FIG. 1 illustrates a perspective view of a hydraulically-operated loader crane assembly in accordance with the invention. FIG. 2 illustrates sensors and the control board of the hydraulically-operated loader crane assembly of figure 1. FIG. 3 illustrates one example of a first ram and sensor, in accordance with the invention. FIG. 4 illustrates a perspective view of one example of a control board, according to an example embodiment of the invention. FIG. 5 is a plan view of the front of the control board of the embodiment of figure 4. FIG. 6 is an illustration of a control unit in accordance with an embodiment of the invention. FIG. 7 illustrates one example of a portion of a loader crane wiring diagram, according to example embodiments of the invention. FIG. 8 illustrates one example of an option flow diagram for operation of the loader crane assembly, according to example embodiments of the invention. FIG. 9 is a Table that illustrates one example of the functions of pins of a Terminal Strip of a control unit, according to example embodiments of the invention. FIG. 10 illustrates a perspective view of an embodiment of the loader crane assembly in a configuration without stabilizer legs that may be used with a trailer. FIG. 11 illustrates two generalised views of a loader crane assembly in operation, according to example embodiments of the invention. Detailed description The invention provides a control processor and algorithm that receive inputs from at least four sensors. The particular sensors employed by the invention allow the implementation of safer operation of the loader crane. Thus, with the invention, there is an even lower risk of damage than with known loader cranes, to either the operator, the vehicle, the load that is being moved, or to any structures in the near surroundings. The operation in accordance with the invention avoids excessive loads on the elements of the loader crane, and on any vehicle, trailer or static installation on which the loader crane is mounted. The results are improved safety, reduced maintenance work, and a longer overall life of the equipment itself. Referring first to figure 1, an example of a hydraulically-operated loader crane assembly is shown. Figure 1 should be read together with figure 2, which separately illustrates the location of five types of sensor and the control board and its enclosure, on the loader crane assembly. Structure shown in figures 1 and 2 In figure 1, a stabilizer arm is configured to be mounted on a vehicle. In the particular configuration illustrated in figure 1, the stabilizer arm is a fabricated section that can be used to increase the width and therefore stability of the vehicle and the loader crane assembly, during operation. The stabilizer arm comprises a central portion 1012. The stabilizer arm also comprises a pair of extendable arms 1013. Each extendable arm 1013 is slidably arranged within one end of the central portion 1012. For the purposes of illustration, in figure 1 the extendable arms 1013 are shown partially extended from central portion 1012. The two extendable arms 1013 can either be manually operated, i.e. ‘pull out’, or can be hydraulically operated. The outer ends of the extendable arms 1013 are illustrated with stabilizer legs 1014. Stabilizer legs 1014 are fabricated sections that may be used to support the loader crane assembly during operation. The lower ends of stabilizer legs 1014 can be lowered to contact the ground, and thus provide support. Stabilizer legs 1014 can either be manually operated, or can be hydraulically operated. The stabilizer arm further comprises leg pressure sensors 208, as shown in figure 2. Leg pressure sensors 208 provide measurements of the support provided by each of the vertical stabilizer legs 1014 when they contact the ground and support the loader crane assembly in operation. Each leg pressure sensor 208 may measure the hydraulic pressure in the feet that support the stabilizer arm. Leg pressure sensors 208 provide a measurement that is used in a calculation of the stability limit value of lifting load stress, and / or the current value of the lifting load stress, as explained later. In contrast to the arrangement in figure 1, the loader crane assembly may be mounted on a trailer. In that configuration, the stabilizer arm itself has an alternative configuration, as shown and explained in relation to figure 10. Returning to figure 1, also extending from the central portion 1012 of the stabilizer arm is overload light 1018. Overload light 1018 is a traffic light totem system, comprising red, amber and green Light Emitting Diodes (LEDs). A loader crane base 102 is mounted on the central portion 1012 of the stabilizer arm. The loader crane base 102 may be a cast or fabricated structure, which forms the main rigid connection to an underlying vehicle, trailer or alternative mount. The loader crane base 102 comprises a rotational actuator 1016. In the particular configuration of figure 1, the rotational actuator 1016 takes the form of a slew tube, which is cast. A slew ram I gear is fitted into the slew tube, and provides rotational force to turn the loader crane column 1020 during operation. Also shown in figure 1 is a pendulum mount 104. Pendulum mount 104 is a fabricated mount, and may provide a rotational connection between the loader crane base 102 and an underlying vehicle. Manual operating levers 106 are shown. Manual operating levers 106 mechanically operate the valve sections that control the flow of hydraulic fluid. This flow, in turn, controls the movement of each part of the loader crane assembly. Manual operating levers 106 are shown in a location where they can be easily reached by an operator standing beside a vehicle, for example. Remote control unit 108 works by operating a solenoid in the valve block, and sends electronic signals to the valve block actuators within the loader crane assembly. These electronic signals each generate a movement which operates the valve section and controls the hydraulic flow to generate a particular movement function. The relationship between manual operating levers 106 and remote control unit 108 varies in different applications. On a crane assembly such as that in figure 1 where both manual operating levers 106 and remote control unit 108 are fitted, the manual operating levers 106 override inputs to the remote control unit 108. However, if manual operating levers 106 are not touched, then inputs to the remote control unit 108 will control the crane assembly, and it is then possible to see the manual levers 106 move correspondingly. However, in many situations, the loader crane assembly can be supplied with the manual operating levers 106 not either no fitted at all, or are removed and supplied separately in a bag for emergency use only. Stabilizer leg mechanical lock 1010 is also shown. Each extension arm 1013 of the stabilizer arm is fitted with two forms of storage lock. Stabilizer leg mechanical lock 1010 is mechanical, and must be released manually by the operator. The other lock is by directional valve on the hydraulic circuit. These locks are a regulatory requirement, to prevent the extension arms 1013 from extending during vehicle travel. Details of the requirement that these locks meet is set out in the overriding loader crane standard BSEN12999. Moving upwards in figure 1, a loader crane column 1020 is mounted on the loader crane base 102 on a rotating joint. Loader crane column 1020 is a fabricated component, which is generally arranged vertically. Loader crane column 1020 is rotated by the operation of rotational actuator 1016. The loader crane column 1020 comprises a first hydraulically operated ram 1022. First ram 1022 is the main lifting ram of the loader crane assembly. First ram 1022 is configured as an actuating ram, which provides the hydraulic lifting force. The direction of movement is controlled by the main valve block operation. As shown in greater detail in figure 3, a lower hydraulic inlet to first ram 1022 is fitted with a non-return valve 302, to prevent the load dropping in the event of any component failure. This non-return valve has a sensor comprising an electronic transducer 304, which is also shown as 202 in figure 2, which monitors the pressure in the lower section of the first ram 1022, representing the lifting force, and provides a corresponding signal. The loader crane column 1020 in figure 1 shows a rectangular housing at its lower left portion. That housing is the control board housing, and is shown again in figure 2. An exploded view of the housing is shown with reference 2012 to the left of figure 2. Reference 2012 indicates the ‘Atlas Crane Manager’ (ACM) and its enclosure. These components are discussed in more detail with reference to figures 4-6. The ACM is a bespoke design of control board. The ACM can be configured through Atlas’ bespoke software to provide control, monitoring and feedback of the crane system. A boom 1024 is mounted on the loader crane column 1020, on a first hinged joint. Boom 1024 is the main boom, and is a fabricated generally horizontal component, which is subject to the lifting force produced by the first ram 1022. The boom 1024 comprises a second hydraulically operated ram 1028. A sensor may send a signal to the ACM to confirm that boom 1024 is horizontal when stored for transport. Further details of this requirement are provided in overriding loader crane standard BSEN12999. A jib 1026 is mounted on the boom 1024 on a second hinged joint. Jib 1026 is a fabricated component, which may take on a variety of orientations in operation. Second ram 1028 controls the orientation of jib 1026, which is also dependent on the angle of boom 1024. Second ram 1028 is an actuating ram that provides hydraulic lifting force. The jib 1026 comprises a third hydraulically operated ram 1032. An extension arm 1030 is mounted on jib 1026. The extension arm 1030 may comprise multiple fabrications of reducing size, which fit inside each other. These sections of the extension arm 1030 are operable to slide, relative to a long axis of the jib 1026. This provides the facility to extend and retract the end of the extension arm 1030 furthest from the second hinged joint. The extension arm 1030 is connected to third ram 1032. Third ram 1032 provides the hydraulic extension force, with the direction controlled by the main valve block operation. In an alternative arrangement, extension arm 1030 may comprise multiple rams in series. The end of the extension arm 1030 furthest from the second hinged joint is configured either to support a load hook 1034 or an attached tool. Only load hook 1034 is shown in figure 1. However, a tool can be attached in place of the hook shown. For example, a grabber attachment may be used to grab bulk building materials. Alternatively, a drill attachment may be used to drill holes in earth. The rams shown in figure 1 enable movement of the crane assembly. The rotational actuator 1016 is connected to the loader crane column 1020, and is operable to rotate the loader crane column 1020 relative to the loader crane base 102. The first ram 1022 is connected to the boom 1024, and is operable to raise or lower the boom 1024. The second ram 1028 is connected to the jib 1026, and is operable to increase or decrease an angle between the boom 1024 and the jib 1026. The third ram 1032 is connected to the extension arm 1030. Third ram 1032 is operable to selectively extend or retract the sections of the extension arm 1030 relative to the jib 1026, along the long axis of the jib 1026. Figure 2 also illustrates two leg-extension sensors 2010. The location of the extendable arms 1013 of the stabilizer arm can be measured by the leg-extension sensors 2010. Each legextension sensor 2010 is configured to provide a measurement of how far the extendable arm and hence the corresponding leg 1014 has been extended outwards, away from the fixed central portion 1012 of the stabilizer arm. Thus the term ‘leg-extension’ refers to how far the leg 1014 has moved horizontally, rather than how far it has moved downwards to reach the ground. The measurements provided by the leg-extension sensors 2010 may further enhance the calculation of the stability limit value of lifting load stress, and / or the current value of the lifting load stress. They also serve to indicate when the extendable arms have been stowed for transport. Operation and control in figures 1 and 2 The hydraulically-operated loader crane assembly of figure 1 further comprises a remote control unit 108 with a user interface. The user interface is configured to receive input signals from user operated levers that are mounted on it, to command movements of the loader crane assembly. The remote control unit 108 may be portable, so may be located in other positions than shown in figure 1. A transducer 202, as shown in figure 2, is configured to monitor a pressure in the first ram 1022. A tilt sensor 204, also in figure 2, is configured to monitor a tilt of the jib 1026. A slew sensor 206, also shown in figure 2, is configured to measure a rotational movement of the loader crane column 1020. A measurement of the rotational movement of the loader crane column 1020 can be used to calculate positional stability. In one exemplary operational configuration, the stabilizer arm may be attached across the back of a vehicle. In this configuration, an orientation of the loader crane column 1020 such that the main boom 1024 extends along the length of the trailer or vehicle may be more stable than an alternative orientation, in which the main boom 1024 extends parallel to stabilizer arm 1012 and hence across the trailer or vehicle, i.e. along the long axis of the stabilizer arm. The hydraulically-operated loader crane assembly of figure 1 further comprises a control system, generally shown as reference 2012 in figure 2. In general terms, in accordance with the invention, the control system 2012 uses the various measurements generated by the sensors to ensure that the loader crane assembly only performs movements that will neither endanger safety, nor overly stress the components of the loader crane assembly, when the loader crane assembly is close to an overload situation. The control system 2012 may be located at various points locally to the loader crane assembly. As an alternative to the location shown for the control system 2012, and its enclosure, in figure 2, the control system 2012 may be housed in remote control unit 108, co-located in a housing with the operating levers 106, or located remotely from these units. The remote control unit 108 or the operating levers 106 provide the control interface which provides a signal to the control system 2012, that then allows movement of the loader crane assembly. The control system 2012 is configured to: (i) Receive input signals from the user interface of the remote control unit 108, or of the operating levers 106. (ii) Control a lifting movement of the loader crane assembly, by sending control signals to a hydraulic power source and a valve block to control a pressure and flow rate of hydraulic fluid sent to the rotational actuator 1016, and to the first 1022, second 1028 and third 1032 rams. (iii) Send signals to operate the green LED, the amber LED and the red LED of the overload light 1018. The control system 2012 is further configured to: a) (i) Receive measured values of the pressure in the lower section of the first ram 1022 from the transducer 202. (ii) Receive measured values of the tilt of the jib 1026 from the tilt sensor 204. (iii) Receive measured values of the rotational movement of the loader crane column 1020 from the slew sensor 206. (iv) receive measurements of the support provided by each of the vertical legs 1014. b) Calculate a current value of lifting load stress on the loader crane assembly, from the received measured values of the pressure, tilt, rotational movement and support. The control system is further configured to: c) Send a signal to illuminate the green LED, when the loader crane assembly is ready for operation; d) For each lifting movement of the loader crane assembly, compare the current value of the lifting load stress with a stability limit value of lifting load stress, the stability limit value of lifting load stress corresponding to a maximum value of lifting load stress for stability of the vehicle. e) When the current value of the lifting load stress is less than 80% of the stability limit value of lifting load stress, control the lifting movement of the loader crane assembly in direct response to the input signals from the user interface of the remote control unit 108 or of the operating levers 106, with a rate of movement of the end of the extension arm 1030 that is proportional to an amount by which a corresponding lever on the user interface has been displaced from a previous displacement value, and also send a signal to illuminate the green LED. f) When the current value of the lifting load stress is more than 80% but less than 100% of the stability limit value of lifting load stress, control the lifting movement of the loader crane assembly in response to the input signals from the user interface, at a rate that is lower than the rate of movement specified in step e), and send a signal to illuminate intermittently the amber LED; g) When the current value of the lifting load stress reaches 100% of the stability limit value of lifting load stress, prevent any further lifting movement of the loader crane assembly in response to input signals from the user interface that would cause the current value of the lifting load stress to exceed 100% of the stability limit value of lifting load stress, and send a signal to illuminate constantly the red LED. The sensors of figure 2 provide feedback position or pressure measurements constantly to the ACM, when the crane is in operation. To operate the crane, the operator manipulates a lever on remote control unit 108. However, the same effects can be achieved if the operator manipulates a manual lever 106. The movement of each lever on remote control unit 108 is measured by a sensor. The movement of each lever is fed back to the control unit 2012, i.e. the ACM. In addition, each lever on the valve block that controls the actual hydraulic flow has a position sensor, to tell the control unit 2012 what functions were currently being demanded by the operator. The ACM takes the information fed to it, and calculates if the requested change from the current position of the loader crane assembly to the new position request can be safely started. The change to the new position of the loader crane assembly can be started if the resulting lifting load stress on the crane assembly does not exceed a preset stability limit value of lifting load stress. To allow a movement which may increase the loading on the crane installation, the lift ram pressure and the leg pressure are checked. If the desired movement of the loader crane assembly is determined to result in lifting load stresses that are within safe limits, i.e. within the stability limit value, then the movement is allowed. These safe limits are set during installation of the crane assembly. The safe limits are individual to the particular vehicle / body / crane combination. When a movement is allowed, the crane system moves and the pressure in the lift ram increases. This increase in pressure is monitored by the ACM. As explained above, if the lifting load stress on the crane assembly reaches approximately 80% of a pre-set limit, then the ACM will highlight this condition with an intermittent amber warning. Movements thereafter, in response to signals from the user interface, will be at a slower rate than movements when the crane is less than the 80% limit If the crane reaches approximately 100% of the pre-set limit, then the ACM will highlight this situation with a red light, and will stop further movement of the loader crane assembly that would increase further the lifting load stress on the crane assembly. The operator will then only be allowed to perform load reducing movements. The stability limit value of lifting load stress, providing a factor of safety for the loader crane assembly, is set during installation of the crane assembly. An exemplary approach to setting the stability limit value is to set it at a value such that exceeding that value by 10% would lead either to an actual instability in the loader crane assembly, or to instability of the vehicle. One theoretical calculation forjudging crane lifting performance is to multiply load x distance, to provide a measure of total force. Alternatively, this ‘force’ may be termed the ‘torque’ or ‘moment of the force’, which in physics are defined as the product of force and distance. To use a numerical example, at installation a crane may be determined to be capable of a maximum lift performance of 10 tonne / metre, and this is the stability limit value. This means that, for example, the loader crane assembly would be safely able to lift a mass of 7 tonnes at a horizontal separation distance of one metre from the loader crane column 1020. This corresponds to a total force of 7 tonnes x 1 metre = 7 tonne / metres. In this example, the 10 tonne / metre stability limit value relates only to the performance of the loader crane assembly, and does not take account of any separate limitations due to the vehicle (or a trailer) on which the loader crane assembly is mounted. With this 10 tonne / metre stability limit value, the loader crane assembly can, for example, also safely lift a mass of 3 tonnes at a distance of 2 metres. This corresponds to a total force of 3 tonnes x 2 metres = 6 tonne / metres. Alternatively, we can consider an example of a different desired movement with a 4 tonne mass. The force (torque / moment) would be much greater if the desired movement were to be to extend the crane arm to a horizontal distance of 3 metres. If such a movement were completed, it would result in a total force that would be of 4 tonnes x 3 metres = 12 tonne I metres. This force exceeds the loader crane assembly’s 10 tonne / metre limit. The control system of the invention would prevent such a movement of the loader crane assembly. With the invention, the loader crane assembly would first warn that the limit was being approached, when 80% of the 10 tonne / metre stability limit value had been reached. With the 4 tonne mass, the warning would come when the product of force and distance was 80% of the 10 tonne / metre limit, i.e. at a distance of 2 metres, at which point the force is 2 metres x 4 tonnes = 8 tonne / metres. The loader crane assembly would stop extending at a distance of 2.5 metres, when the force is 2.5 metres x 4 tonnes = 10 tonne / metre. Further calculations may be used in relation to the crane load and leg pressure. For example, a calculation of leg pressure can be made, in order to ensure a desired safety margin. At the start of each customer build, a stability calculation is performed. The ‘build’ is a particular specification of crane assembly at a specific mounting location on a particular vehicle or trailer. The stability calculation provides the maximum theoretical load that would be seen on each leg, for that particular customer build. Each leg may be different, particularly in cases where the loader crane assembly is offset on the truck, for example by 100mm. In such a case, the loader crane assembly can be mounted either way around, so it is not predetermined which is the right or the left leg in the configuration. In order to address this, the acceptable loads are set by the test engineer looking at the stability calculation, calculating 80 % and then testing. The interface with the truck axles I wheel base and the truck body weight will all have an effect that is taken into account. The final figure is revised, relying on the engineer’s opinion, which must also be based on an interpretation of the regulatory requirement that ‘one braked wheel must remain on the ground’. In some configurations, a wheel of the vehicle or trailer may lift a couple of centimetres, but in other configurations the engineer may permit a wheel to lift by tens of centimetres. The lower the amount of wheel lift, the safer the installation, generally. The engineer is responsible for signing the installation off as safe. The legs themselves are always provided with plenty of structural capacity. For example If the stability calculation predicts a maximum load of 48kN, a standard leg from a range with for example 75kN rating might be used. An actual maximum design load for that leg may in fact be 110kN for example, providing yet further safety margin above the stated 75kN rating for the leg. For a trailer installation or a ‘special’ installation, the leg pressure feedback is replaced by a measurement from a sensor of trailer inclination. At crane installation, the system would be tested with a load close to the ground, to establish the safe angles of the trailer. In a numerical example, it maybe established that on a flat surface the warning should begin at a trailer angle of 9 degrees, and that movement should stop at a trailer angle of 16 degrees. This arrangement is shown later in connection with figure 10. Specific details of the mounting structure A standard installation of the loader crane assembly involves mounting the loader crane assembly to a subframe, which runs the full length of a vehicle such as a flat-bed lorry. The subframe is omitted from figures 1 and 2. The loader crane assembly, in this configuration, includes loader crane base 102, pendulum mount 104, the stabilizer arm’s central portion 1012, the extending arms 1013 and the stabilizer legs 1014. Each of the stabilizer legs 1014 is mounted to the outer end of one of the stabilizer arms 1013 by four bolts. The pendulum mount 104 is mounted on loader crane base 102 by a large retaining circlip. This assembly is then mounted to the subframe of the vehicle by four more bolts through leg pockets and usually four bolts through the pendulum mount 104. When the loader crane assembly is mounted on a trailer, as explained in connection with figure 10, the same approach may be taken as outlined above for mounting on a vehicle such as a flat-bed lorry. However, in the alternative case of figure 10, the stabilizer arm comprises only a central portion 10012 generally corresponding to 1012 of figure 1, but the extendable arms 1013 and the stabilizer legs 1014 of figure 1 may not be fitted. Figure 3 Figure 3 illustrates one example of the first ram 1022 in accordance with the invention. Figure 3 shows a load-holding valve 302 and sensor 304 in exploded view, i.e. slightly separated from their mounting point on first ram 1022. Load holding valve 302 comprises a non-return valve. In the event of a failure, such as of the hydraulic pump of the loader crane assembly, the non-return valve closes to prevent the load from accidentally dropping. Sensor 304 monitors the pressure in the first ram 1022, which is an indicator of the lifting force exerted by the first ram 1022. Sensor 304 sends a signal back to the control system 1012, with the current value of the measured pressure. Figure 4 Figure 4 illustrates a perspective view of one example of a control board, according to an example embodiment of the invention. The perspective view is from below the control board. Figure 4 shows the ‘Atlas Crane Manager1, ACM, which is a bespoke design of control board. The ACM has 9 strips of 24 input pins. By monitoring the voltage / amps through the pins, the pins can be configured through Atlas’ bespoke software to provide the monitoring and feedback to the loader crane assembly explained above. Figure 5 Figure 5 is a plan view of the front of the control board of the embodiment of figure 4. This view is the opposite face of the control board than that shown in the perspective view of figure 4. The control board has fourteen slots, as illustrated in the plan view of figure 5. Figure 6 Figure 6 is an illustration of the control unit in accordance with an embodiment of the invention. Figure 6 shows only part of the control unit, to allow magnification of that part, and the image is broken to the right of the seventh slot of Figure 6. The control unit of figure 6 is configured to perform the control operations of the invention, as detailed above in connection with the embodiments of figures 1 and 2, and as claimed in the appended claims. Thus the control unit of figure 6 receives the measurement values and generates the control signals, as specified above. The ‘ACM2001’ control unit may be installed in an aluminium housing, with protection class IP65. The control unit itself may, in an embodiment, consist of a power board and a signal board. The whole control unit may be enclosed in an additional steel housing, that itself has protection class IP52. The further specific elements of the ACM2001 control unit shown in Figure 6 are as follows, using the boxed references 1-5 adjacent to the drawing: 1: A connecting plug for adjusting the device (X10). 2: A button for overload bridging (S1). 3: A status display for the supply voltage (a green LED on the control unit itself), emergency escape interrupted (a red LED on the control unit itself) and computer malfunction (another red LED on the control unit itself). 4: Safety devices, with monitoring (F1-F4). 5. Connecting plugs X1-X9 (24 pole) The safety devices F1-F4 are allocated as follows: F1 (15A): Fuse for the outputs of the ACM control unit. F2 (30A): Fuse for the ACM control unit when incorrect polarity in the earth pin. F3 (5A): Radio installation fuse. F4 (1A): Winch fuse. The invention may be implemented with the ACM2001 control unit being fully equipped, as shown in figure 6. However, in a partially equipped version, the illustrated connecting plugs X4-X7 and the safety device F4 are not supplied. In both the fully equipped and the partially equipped versions, the connecting plugs X1-X7 are protected against incorrect polarity. Hence connecting plug X1 cannot be inserted into connecting plug X3 of the control unit, for example. Figure 7 Figure 7 illustrates one example of a portion of a loader crane wiring diagram, according to example embodiments of the invention. Figure 7 shows a section of the loader crane wiring diagram of the ACM, and in particular shows the terminal pin connections for the X1 and X2 terminal strips. The wiring is made up of several separate harnesses, selected for an individual loader crane system and model type. Harness 1 is the main harness which provides the connection between the power supply to the ACM, the main control input panel, the secondary input panel, and the crane’s stored system. Figure 8 Figure 8 illustrates one example of an option flow diagram for operation of the loader crane assembly, according to example embodiments of the invention. Figure 8 provides a non-limiting specific example of parameters that the invention may use in one practical implementation. The Atlas ACM software has several function page ‘modes’. Each of these modes allows the multiple custom options and crane functions to be turned on / off, and values adjusted to control the safe working capacity of the loader crane assembly to suit each customer configuration. Figure 8 is a small extract from the ‘mode A’ program (as designated by notes to the left of the flow chart), which controls the movement of the loader crane assembly. Figure 8 illustrates the software checking the loader crane column’s 1020 rotational position, then the pressure in the first ram 1022, followed by the angle of the boom 1024. At each of these stages, if the customisable parameters (CR note to the right in fig 8) are not met by the individual sensor’s response, then movement of the loader crane assembly will be prevented. If the parameter is met, then the program moves to the next check, until the requested movement of the loader crane assembly is approved or prevented. In the specific example of Figure 8, the multiple boxes marked “L” and “M” are for buttons on a proprietary tool. The tool allows users of the invention to both see and change settings, but not to either edit or permanently change the software. Figure 9 Figure 9 is a table that illustrates one example of the functions of pins of a terminal strip of a control unit 2012, according to example embodiments of the invention. Figure 9 shows the ACM terminal pin allocations for the single input strip X1 of Figure 6, see the title of figure 9. The table shows the power input to the ACM controller unit 2012. The table also shows the output power to the various electronic sensors and components fitted to an exemplary loader crane assembly, to monitor and provide feedback on the loader crane assembly’s actions. Figure 10 Figure 10 illustrates a perspective view of a loader crane assembly as installed without stabiliser legs, according to an example embodiment of the invention. Such an installation is typically on a trailer. However, the configuration in figure 10 may be used when the loader crane assembly is mounted on a fixed object such as a plinth. Elements in figure 10 that correspond to elements in figure 1 are shown with reference numerals that differ only by an additional zero from the references in figure 1. The positions of the various sensors used in the configuration of figure 10, generally correspond to the positions shown in figure 2. In the embodiment of figure 10, a transducer corresponding to transducer 202, a slew sensor corresponding to slew sensor 206, and a tilt sensor corresponding to tilt sensor 204 as shown in figure 2, are also fitted. However, in place of the leg sensors 208 for position and pressure that were shown in figure 2, the loader crane assembly includes a second tilt sensor 10040, which acts as an inclination sensor. The second tilt sensor 10040 is activated by the ACM software. The Atlas ACM software has several function page ‘modes’, as discussed in relation to figure 8. For the configuration of figure 10, within the crane specific settings, the leg sensors for position and pressure can be disabled. This approach allows for the safe working capacity of the loader crane assembly in the configuration of figure 10 to be calculated, based on each customer configuration. The stability limit value of lifting load stress for the loader crane assembly is, again, pre-set at a value providing a factor of safety. As in the configuration of figure 1, this pre-set value is such that exceeding that value by 10% would lead either to an actual instability in the loader crane assembly, or an instability of the trailer to which the loader crane assembly is attached. Thus, in the configuration of figure 10, the leg pressure sensor 208 of figure 2 has been replaced with a second tilt sensor to monitor the inclination of the trailer. When the loader crane assembly is mounted directly on the trailer as shown in figure 10, and does not include the stabilizer legs 1014 of the extendable arms 1013 that were shown in figures 1 and 2, the second tilt sensor 10040 provides measurements of the lateral angle of the trailer. These measurements indicate the deviation from horizontal, from left to right in figure 10 along stabilizer arm 10012, and hence along a long axis of the stabilizer arm 10012 and across the narrow width of the trailer. The second tilt sensor 100040 is mounted where it can provide a reliable measurement. This might be on the pendulum mount 1004 as shown in figure 10, or alternatively on the stabilizer arm 10012. These measurements of the lateral angle of the trailer replace the measurements from the leg pressure sensors 208 and the leg-extension sensors 2010. The embodiment of figure 10 is claimed in appended independent claim 11. The features of independent claim 11 differ from those of independent claim 1 in several aspects. These differences include: (a) The stabilizer arm 10012 is configured to be mounted on the trailer, with a long axis of the stabilizer arm 10012 aligned across the trailer, or alternatively mounted on a plinth. The stabilizer arm 10012 comprises just the central portion 1012 that was shown in figure 1, on which the loader crane base 102 is mounted. (b) The second tilt sensor 10040 is configured to provide a measurement of a lateral angle of the trailer, thus measuring a deviation from horizontal along the long axis of the stabilizer arm 10012, across the trailer. The second tilt sensor 10040 is mounted where it can provide a reliable measurement. In figure 10, this might be on the stabilizer arm 10012 or alternatively on the pendulum mount 1004. (c) The control system is configured to receive measured values of the lateral angle of the stabilizer arm / trailer from the second tilt sensor 10040. (d) Calculating a current value of lifting load stress on the loader crane assembly, from the received measured values of the pressure, tilt, rotational movement and lateral angle. In other applications, a solid mount may be available, such as a concrete base or plinth. Mounting of the loader crane assembly to a solid mount can be done as explained above in figure 10 for mounting on a trailer. The loader crane base 102 and pendulum mount 104 are then attached to the plinth. In this configuration, second tilt sensor 10040 of figure 10, and transducer 202 and tilt sensor 204 as shown in figure 2, are also fitted. This embodiment on the plinth does not include the stabilizer’s extendable arms 1013, or the stabilizer legs 1014, of the embodiment of figures 1 and 2. In a further arrangement, an alternative base for the crane employs a large circular flange under the loader crane assembly with approximately 30 bolt holes. Figure 11 Figure 11 provides two side elevation views. The upper view in figure 11 shows a loader crane assembly 1102 in accordance with the present invention mounted immediately behind the cab of a lorry. In the upper view, a stabilizer leg 1104 is shown immediately below the position of the loader crane assembly, just behind the cab of the lorry. The lower view in figure 11 shows an alternative arrangement to that in the upper view. The lower view in figure 11 shows a loader crane assembly 1106 in accordance with the present invention mounted at the rear of a lorry. In the lower view, a stabilizer leg 1108 is shown immediately below the position of the loader crane assembly at the rear of the lorry. Concluding comments In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein, without departing from the scope of the invention as set forth in the appended claims. The claims are not limited to the specific examples described above. The connections as discussed herein may be any type of connection suitable to transfer signals from or to the respective nodes, units or devices, for example via intermediate devices. Accordingly, unless implied or stated otherwise, the connections may for example be direct connections or indirect connections. The connections may be illustrated or described in reference to being a single connection, a plurality of connections, unidirectional connections, or bidirectional connections. However, different embodiments may vary the implementation of the connections. For example, separate unidirectional connections may be used rather than bidirectional connections and vice versa. Also, a plurality of connections may be replaced with a single connection that transfers multiple signals serially or in a time multiplexed manner. Likewise, single connections carrying multiple signals may be separated out into various different connections carrying subsets of these signals. Therefore, many options exist for transferring signals. Those skilled in the art will recognize that the architectures depicted herein are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. Any arrangement of components to achieve the same functionality is effectively ‘associated’ such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as ‘associated with’ each other such that the desired functionality is achieved, irrespective of architectures or intermediary components. Likewise, any two components so associated can also be viewed as being ‘operably connected,’ or ‘operably coupled,’ to each other to achieve the desired functionality. Furthermore, those skilled in the art will recognize that boundaries between the above described operations are merely illustrative. The multiple operations may be combined into a single operation, a single operation may be distributed in additional operations and operations may be executed at least partially overlapping in time. Also for example, in one embodiment, the illustrated examples may be implemented as circuitry located on a single integrated circuit or within a same device. In some examples, the various components within the control system can be realized in discrete or integrated component form, with an ultimate structure therefore being an application-specific or design selection. As the illustrated embodiments of the present invention may, for the most part, be implemented using electronic components and circuits known to those skilled in the art, details have not been explained in any greater extent than that considered necessary as illustrated below, for the understanding and appreciation of the underlying concepts of the present invention. A skilled artisan will appreciate that the level of integration of circuits or components may be, in some instances, implementation-dependent. Also for example, the examples, or portions thereof, may be implemented as soft or code representations of physical circuitry or of logical representations convertible into physical circuitry, such as in a hardware description language of any appropriate type. Also, the invention is not limited to physical devices or units implemented in non-programmable hardware but can also be applied in programmable devices or units able to perform the desired operation in accordance with suitable program code, such as minicomputers, personal computers, notepads, personal digital assistants, electronic games, automotive and other embedded systems, and various other wireless devices, commonly denoted in this application as ‘computer systems’. However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense. In the claims, the reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms ‘a’ or ‘an,’ as used herein, are defined as one or more than one. Unless stated otherwise, terms such as ‘first’ and ‘second’ are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A hydraulically-operated loader crane assembly comprising:a stabilizer arm, the stabilizer arm configured to be mounted on a vehicle, the stabilizer arm comprising:(i) a central portion (1012), on which a loader crane base (102) is mounted;(ii) a pair of extendable arms (1013), each extendable arm (1013) slidably arranged within one end of the central portion (1012);(iii) a pair of vertical legs (1014) configured to provide support when resting on the ground, each leg mounted on an end of one of the extendable arms (1013) furthest from the central portion (1012);(iv) leg pressure sensors (208) providing measurements of the support provided by each of the vertical legs (1014);wherein the loader crane base (102) comprises a rotational actuator (1016);a loader crane column (1020), the loader crane column (1020) mounted on the loader crane base (102) on a rotating joint, the loader crane column (1020) comprising a first ram (1022);a boom (1024), the boom (1024) mounted on the loader crane column (1020) on a first hinged joint, the boom (1024) comprising a second ram (1028);a jib (1026), the jib (1026) mounted on the boom (1024) on a second hinged joint, the jib (1026) comprising a third ram (1032);an extension arm (1030), the extension arm (1030) mounted on the jib (1026) and operable to slide relative to a long axis of the jib (1026);an end of the extension arm (1030) furthest from the second hinged joint being configured either to support a load hook (1034) or an attached tool;wherein:(i) the rotational actuator (1016) is connected to the loader crane column (1020), and is operable to rotate the loader crane column (1020) relative to the loader crane base (102);(ii) the first ram (1022) is connected to the boom (1024), and is operable to raise or lower the boom (1024); and(iii) the second ram (1028) is connected to the jib (1026), and is operable to increase or decrease an angle between the boom (1024) and the jib (1026); and(iv) the third ram (1032) is connected to the extension arm (1030), and is operable to selectively extend or retract the extension arm (1030) relative to the jib (1026), along the long axis of the jib (1026);a user interface (106, 108), the user interface (106, 108) receiving input signals from user operated levers to command movements of the loader crane assembly;a transducer (202), the transducer (202) configured to monitor a pressure in the lower section of the first ram (1022);a tilt sensor (204), the tilt sensor (204) configured to monitor a tilt of the jib (1026);a slew sensor (206), the slew sensor (206) configured to measure a rotational movement of the loader crane column (1020);an overload light (1018), the overload light (1018) comprising a green light-emitting diode (LED), an amber LED and a red LED;a control system (2012), the control system (2012) configured to:(i) receive input signals from the user interface (106, 108);(ii) control a lifting movement of the loader crane assembly, by sending control signals to a hydraulic power source and a valve block to control a pressure and flow rate of hydraulic fluid sent to the rotational actuator (1016) and to the first ram (1022), the second ram (1028) and the third (1032) ram; and(iii) send signals to the overload light (1018) to operate the green LED, the amber LED and the red LED;the control system (2012) further configured to:a) (i) receive measured values of the pressure in a lower section of the first ram (1022) from the transducer (202);(ii) receive measured values of the tilt of the jib (1026) from the tilt sensor (204);(iii) receive measured values of the rotational movement of the loader crane column (1020) from the slew sensor (206);(iv) receive measurements of the support provided by each of the vertical legs (1014) from the leg pressure sensors (208); andb) calculate a current value of lifting load stress on the loader crane assembly, from the received measured values of the pressure, tilt, rotational movement and support;the control system (2012) further configured to:c) send a signal to illuminate the green LED, when the loader crane assembly is ready for operation;d) for each lifting movement of the loader crane assembly, compare the current value of the lifting load stress with a stability limit value of lifting load stress, the stability limit value of lifting load stress corresponding to a maximum value of lifting load stress for stability of the vehicle;e) when the current value of the lifting load stress is less than 80% of the stability limit value of lifting load stress, control the lifting movement of the loader crane assembly in direct response to the input signals from the user interface (106, 108), with a rate of movement of the end of the extension arm (1030) that is proportional to an amount by which a corresponding lever on the remote control unit has been displaced from a previous displacement value, and send a signal to illuminate the green LED;f) when the current value of the lifting load stress is more than 80% but less than 100% of the stability limit value of lifting load stress, control the lifting movement of the loader crane assembly in response to the input signals from the user interface (106, 108), at a rate that is lower than the rate of movement specified in step e), and send a signal to illuminate intermittently the amber LED;g) when the current value of the lifting load stress reaches 100% of the stability limit value of lifting load stress, prevent any further lifting movement of the loader crane assembly in response to input signals from the user interface (106, 108) that would cause the current value of the lifting load stress to exceed 100% of the stability limit value of lifting load stress, and send a signal to illuminate constantly the red LED.

2. The hydraulically operated loader crane assembly of claim 1, further comprising the control system (2012) being configured to calculate at least one corrective signal to control the lifting movement of the loader crane assembly, the corrective signal initiating a further movement of the loader crane assembly in a direction to reduce a required lifting torque.

3. The hydraulically operated loader crane assembly of claim 2, wherein the further movement of the loader crane assembly to reduce a required lifting torque comprises:a controlled movement of the end of the extension arm (1030) towards the loader crane base (102).

4. The hydraulically operated loader crane assembly of claim 3, wherein the further movement of the loader crane assembly to reduce a required lifting torque comprises:an actuation of the third ram (1032) to retract the extension arm (1030).

5. The hydraulically operated loader crane assembly of claim 2 or claim 3, wherein the further movement of the loader crane assembly to reduce a required lifting torque comprises:an actuation of the second ram (1028) to reduce an extension provided by the boom (1024), thereby bringing the load hook or the attached tool of the loader crane assembly closer to the loader crane base (102).

6. The hydraulically operated loader crane assembly of any of claims 3-5, wherein the further movement of the loader crane assembly to reduce a required lifting torque comprises: preventing the end of the extension arm (1030) from moving upwards, during the controlled movement of the end of the extension arm (1030) towards the loader crane base (102).

7. The hydraulically operated loader crane assembly of any previous claim, wherein:the stability limit value of lifting load stress is further derived from a maximum value of a stress on the loader crane assembly that allows the loader crane assembly to remain stable and safe.

8. The hydraulically operated loader crane assembly of claim 7, wherein:the stability limit value of lifting load stress for the loader crane assembly is pre-set at a value providing a factor of safety, such that exceeding that value by 10% leads either to an actual instability in the loader crane assembly, or instability of the vehicle.

9. The hydraulically operated loader crane assembly of claim 8, wherein:the stabilizer arm is mounted on a heavy goods vehicle, and the actual instability of the vehicle is determined empirically in accordance with standard BSEN12999-2020.

10. The hydraulically operated loader crane assembly of any previous claim, whereinthe stabilizer arm also comprises:leg-extension sensors (2010), the leg-extension sensors (2010) providing a measurement of the extension of each vertical leg (1014).

11. A hydraulically-operated loader crane assembly comprising:a stabilizer arm (10012), the stabilizer arm (10012) configured to be mounted on a trailer, with a long axis of the stabilizer arm (10012) aligned across the trailer;a loader crane base (1002), the loader crane base (1002) mounted on the stabilizer arm (10012), the loader crane base (1002) comprising a rotational actuator (10016);a loader crane column (10020), the loader crane column (10020) mounted on the loader crane base (1002) on a rotating joint, the loader crane column (10020) comprising a first ram (10022);a boom (10024), the boom (10024) mounted on the loader crane column (10020) on a first hinged joint, the boom (10024) comprising a second ram (10028);a jib (10026), the jib (10026) mounted on the boom (10024) on a second hinged joint, the jib (10026) comprising a third ram (10032);an extension arm (10030), the extension arm (10030) mounted on the jib (10026) and operable to slide relative to a long axis of the jib (10026);an end of the extension arm (10030) furthest from the second hinged joint being configured either to support a load hook (10034) or an attached tool;wherein:(i) the rotational actuator (10016) is connected to the loader crane column (10020), and is operable to rotate the loader crane column (10020) relative to the loader crane base (1002);(ii) the first ram (10022) is connected to the boom (10024), and is operable to raise or lower the boom (10024); and(iii) the second ram (10028) is connected to the jib (10026), and is operable to increase or decrease an angle between the boom (10024) and the jib (10026); and(iv) the third ram (10032) is connected to the extension arm (10030), and is operable to selectively extend or retract the extension arm (10030) relative to the jib (10026), along the long axis of the jib (10026);a user interface (1006, 1008), the user interface (1006, 1008) receiving input signals from user operated levers to command movements of the loader crane assembly;a transducer (202), the transducer (202) configured to monitor a pressure in the lower section of first ram (10022);a first tilt sensor (204), the tilt sensor (204) configured to monitor a tilt of the jib (10026);a second tilt sensor (10040), the second tilt sensor (10040) configured to provide a measurement of a lateral angle of the stabilizer arm (10012), thus measuring a deviation from horizontal along the long axis of the stabilizer arm (10012) across the trailer;a slew sensor (206), the slew sensor (206) configured to measure a rotational movement of the loader crane column (10020);an overload light (10018), the overload light (10018) comprising a green light-emitting diode (LED), an amber LED and a red LED;a control system (2012), the control system (2012) configured to:(i) receive input signals from the user interface (1006, 1008);(ii) control a lifting movement of the loader crane assembly, by sending control signals to a hydraulic power source and a valve block to control a pressure and flow rate of hydraulic fluid sent to the rotational actuator (10016) and to the first ram (10022), the second ram (10028) and the third (10032) ram; and(iii) send signals to the overload light (10018) to operate the green LED, the amber LED and the red LED;the control system (2012) further configured to:a) (i) receive measured values of the pressure in a lower section of the first ram (10022) from the transducer (202);(ii) receive measured values of the tilt of the jib (10026) from the tilt sensor (204);(iii) receive measured values of the rotational movement of the loader crane column (10020) from the slew sensor (206);(iv) receive measured values of the lateral angle of the stabilizer arm (10012) from the second tilt sensor (10040);b) calculate a current value of lifting load stress on the loader crane assembly, from the received measured values of the pressure, tilt, rotational movement and lateral angle;the control system (2012) further configured to:c) send a signal to illuminate the green LED, when the loader crane assembly is ready for operation;d) for each lifting movement of the loader crane assembly, compare the current value of the lifting load stress with a stability limit value of lifting load stress, the stability limit value of lifting load stress corresponding to a maximum value of lifting load stress for stability of the trailer;e) when the current value of the lifting load stress is less than 80% of the stability limit value of lifting load stress, control the lifting movement of the loader crane assembly in direct response to the input signals from the user interface (1006, 1008), with a rate of movement of the end of the extension arm (10030) that is proportional to an amount by which a corresponding lever on theuser interface (1006, 1008) has been displaced from a previous displacement value, and send a signal to illuminate the green LED;f) when the current value of the lifting load stress is more than 80% but less than 100% of the stability limit value of lifting load stress, control the lifting movement of the loader crane assembly in response to the input signals from the user interface (1006, 1008), at a rate that is lower than the rate of movement specified in step e), and send a signal to illuminate intermittently the amber LED;g) when the current value of the lifting load stress reaches 100% of the stability limit value of lifting load stress, prevent any further lifting movement of the loader crane assembly in response to input signals from the user interface (1006, 1008) that would cause the current value of the lifting load stress to exceed 100% of the stability limit value of lifting load stress, and send a signal to illuminate constantly the red LED.

12. The hydraulically operated loader crane assembly of claim 11, wherein:the second tilt sensor (10040) is attached to either the stabilizer arm (10012), or to a pendulum mount (1004) co-located with the stabilizer arm (10012).

13. The hydraulically operated loader crane assembly of claim 11 or claim 12, wherein:the second tilt sensor (10040) is mounted on a bracket comprising 4mm plate, the bracket being attached to the stabilizer arm (10012) or to the pendulum mount (1004).

14. The hydraulically operated loader crane assembly of any of claims 11-13, wherein: the stabilizer arm (10012) is further configured to, alternatively, be mounted on a trailer.

15. The hydraulically operated loader crane assembly of any of claims 11-14, further comprising the control system (2012) being configured to calculate at least one corrective signal to control the lifting movement of the loader crane assembly, the corrective signal initiating a further movement of the loader crane assembly in a direction to reduce a required lifting torque.

16. The hydraulically operated loader crane assembly of claim 15, wherein the further movement of the loader crane assembly to reduce a required lifting torque comprises:a controlled movement of the end of the extension arm (10030) towards the loader crane base (1002).

17. The hydraulically operated loader crane assembly of claim 16, wherein the further movement of the loader crane assembly to reduce a required lifting torque comprises: an actuation of the third ram (10032) to retract the extension arm (10030).

18. The hydraulically operated loader crane assembly of any of claims 11-17, wherein the further movement of the loader crane assembly to reduce a required lifting torque comprises:an actuation of the second ram (10028) to reduce an extension provided by the boom (10024), thereby bringing the load hook or the attached tool of the loader crane assembly closer to the 5 loader crane base (1002).

19. The hydraulically operated loader crane assembly of any of claims 16-18, wherein the further movement of the loader crane assembly to reduce a required lifting torque comprises: preventing the end of the extension arm (10030) from moving upwards, during the controlled 10 movement of the end of the extension arm (10030) towards the loader crane base (1002).

20. The hydraulically operated loader crane assembly of any of claims 14-19, wherein:the stability limit value of lifting load stress is further derived from a maximum value of a stress on the loader crane assembly that allows the loader crane assembly to remain stable and safe.1521. The hydraulically operated loader crane assembly of claim 20, wherein:the stability limit value of lifting load stress for the loader crane assembly is pre-set at a value providing a factor of safety, such that exceeding that value by 10% leads either to an actual instability in the loader crane assembly, or instability of the vehicle.

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