A control system

Abstract

A control system 50 suitable for an electric working machine (10, fig.4), wherein a controller receives data relating to a charging location C and a location of the working machine and calculates a tr

Description

FIELD The present teachings relate to a control system for a working machine such as an 5 electric off-highway working machine, an electric off-highway working machine, and to a method of providing an alert for an electric off-highway working machine. BACKGROUND Off-highway vehicles or working machines are for example those used in construction industries (e.g. backhoe loaders, slew excavators telescopic handlers, 10 forklifts, skid-steer loaders, dump trucks, bulldozers, graders), agricultural industries (tractors, combine harvesters, self-propelled harvesters and sprayers), quarrying (e.g. loading shovels, aggregate crushing equipment), and forestry (timber harvesters, feller bunchers). Such working machines may typically include a number of actuatable devices or components, and a hydraulically driven ground 15 engaging structure such as wheels or a pair of endless tracks. Depending on the particular working machine, a range of different actuatable devices may be provided, such as a working arm, stabiliser legs, a dozer blades, hydraulically powered steering. Working machines are typically diesel powered. However, there is a drive in the 20 industry to move towards electric working machines, in which an electrical source of power is provided to drive the working machine and to operate the devices. During operation of the working machines, they will often need to be recharged at a worksite at various times during the workday. In such electrical working machines, it is desirable that none of these machines are allowed to fully discharge 25 their battery such that productivity on the worksite is maintained and to maintain the health of the battery. The present teachings seek to overcome or at least mitigate one or more problems associated with the prior art. SUMMARY According to the present invention, there is provided a control system for an electric off-highway working machine as defined in claim 1, and a method for providing an alert for an electric off-highway working machine as defined in claim 25. 5 A first aspect of the teachings provides for a control system for an electric off-highway working machine comprising a ground engaging propulsion structure for propelling the working machine, a body supported on the ground engaging propulsion structure, a drive arrangement comprising an energy source, a prime mover, and a transmission operable to transmit drive from the prime mover to the 10 ground engaging propulsion structure, the control system comprising a controller configured to: receive data relating to a charging location; receive data relating to a location of the working machine; calculate a travel energy threshold required to enable the working machine to travel to the charging location; receive data relating to a level of the energy source of the working machine; compare the travel energy 15 threshold to the level of the energy source; and provide an alert when the level of C\l the energy source is equal to the travel energy threshold. In one arrangement, the working may comprise an energy source in the form of a battery, and the prime mover may be an electric motor. The control system may be configured to receive data relating to a state of charge of the battery, and to 20 compare the compare the travel energy threshold to the state of charge of the battery. This configuration of the control system helps to monitor the level of charge of the battery relative to the energy required to travel back to a charge point. This helps to reduce the risk of these electric off-highway working machines being allowed to 25 go fully discharge so as to have insufficient energy to return to a charge point. In one arrangement, the energy source may be a hydrogen fuel cell, and the prime mover may be an electric motor. The control system may be configured to receive data relating to a state of charge of the fuel cell, and to compare the compare the travel energy threshold to the state of charge of the fuel cell. 30 In one arrangement, the energy source may be a diesel or hydrogen, and the prime mover may be an internal combustion engine. The control system may be configured to receive data relating to an amount of diesel or hydrogen remaining in a fuel tank. The control system may be configured to provide an alert when the state of charge of the battery is equal to or less than the travel energy threshold. This configuration alerts an operator of the electric off-highway working machine of the need to stop performing the current working operation and to return the 5 working machine to the charger. In this way, an operator is alerted when the machine is about to be of range of charger. The control system may be configured to determine a distance to the charging location, and to calculate the travel energy threshold required based on the determined distance to the charging location. 10 The control system may be configured to receive data relating to the location of the working machine from a position sensor provided on the working machine. Enables distance to the charging location to be measured to calculate the energy threshold. (XI The control system may be configured to store the XY coordinates of a route 15 travelled by the working machine from the charging location, and to determine the distance to the charging location based on the route travelled. O) More accurate determination of distance to charging point - enables a more 1 accurate determination of energy requirement and so the energy threshold at which the alert is provided. This in turn enables an operator to spend more time 20 performing work functions prior to having to return the working machine to the charging point. The control system may be configured to store data in relation to the altitude of the working machine relative to an altitude of the charging point, and to determine the distance to the charging location based on the based on the altitude of the working 25 machine relative to an altitude of the charging point. More accurate determination of distance to charging point - enables a more accurate determination of energy requirement and so the energy threshold at which the alert is provided. This in turn enables an operator to spend more time performing work functions prior to having to return the working machine to the 30 charging point. 19 06 24 The control system may be configured activate a restricted operation mode of the working machine when the state of charge of the battery is below the travel energy threshold by a first predetermined amount. The control system may be configured activate a restricted operation mode of the 5 working machine when the state of charge of the battery is substantially equal to a second energy threshold, which is less than the travel energy threshold. Restricting operation of the working machine reduces the machine's energy usage and enables the working machine to travel to the charge location even when the state of charge of the battery is below the energy requirement. 10 The control system may be configured to activate a limp home operation mode when the state of charge of the battery is below the travel energy threshold by a second predetermined amount, greater than the first predetermined amount. The control system may be configured activate a limp home operation mode when the state of charge of the battery is substantially equal to a third energy threshold, 15 which is less than the travel energy threshold and the second energy threshold. In the limp home operation mode, the RPM of the electric motor is fixed at a relatively low RPM. In this way, only basis operation of the working machine is possible, thus reducing energy usage while enabling the operator to return the working machine to the charge point. 20 The control system may be configured to determine a travel energy requirement based on the distance to the charging location and an estimated energy consumed per unit distance, and wherein the travel energy threshold is based on, and is greater than, the travel energy requirement. This additional energy provides an additional safety factor in the state of charge of 25 the battery at which the alert is provided, to take account for different route that may need to be taken, and / or differing conditions such as ambient temperature, ground conditions, altitude etc. The travel energy threshold may be in the region of 110-130% of the travel energy requirement, for example approximately 120% of the travel energy requirement. This has been found to provide the optimal balance between maximising time on site performing working operations and ensuring that the working vehicle is able to safely return to the charging location. The control system may be configured to retrieve data relating to the estimated 5 energy consumed per unit distance from a memory for a configuration of the working machine selected by an operator. The working machine may comprise an operator input to select a particular configuration of the working machine, and the control system is configured to receive a signal based on the operator selection. 10 This tailors the travel energy threshold to the particular configuration of the working machine, helping to maximise time on site performing working operations. The control system may be configured to monitor an electrical energy usage of the working machine in a travelling mode over a predetermined period of time, and to calculate the estimated energy consumed per unit distance the electrical energy CM 15 usage. This tailors the travel energy threshold to the particular configuration of the working machine and the conditions (e.g. ambient temperature, terrain etc.) in which the machine is operation, helping to maximise time on site performing working operations. 20 The control system may be configured to monitor the electrical energy usage in the travelling mode since the battery was last charged. The control system may be configured to detect a signal whether the working machine is in a travelling mode based on one or more of: detecting when the working machine is travelling above a predetermined travel speed; movement of 25 the working machine beyond a predetermined distance in one direction; an orientation or position of an operator seat (e.g. movement between a rearward facing position to a forward facing position); and / or detecting a ground engaging component (e.g. stabiliser legs or a dozer blade) of the working machine has moved from a ground engaging position to a raised position. 30 The control system is configured to monitor energy usage of the working machine in a working mode, and to provide an estimated time remaining before the alert is provided. The control system is configured to detect a signal whether the working machine is in a working mode based on one or more of: detecting when the working machine is travelling below a predetermined travel speed; an orientation or position of an operator seat (e.g. movement between a rearward facing position to a forward 5 facing position); and / or detecting a ground engaging component (e.g. stabiliser legs or a dozer blade) of the working machine has moved to a ground engaging position from a raised position. The alert may comprise an audio and / or visual alert. The control system may be configured to receive data relating to the charging 10 location via a global navigation satellite system (GNSS) such as the global positioning system (GPS). The control system may be configured to receive data relating to the charging location by retrieving charging location data stored on a memory when the battery of the working machine was last charged. ’’T <N 15 The control system may be configured to calculate the travel energy threshold CO based on data relating to an ambient temperature received from an ambient temperature sensor on the working machine. According to a second aspect of the teachings, an off-highway working machine comprising: a ground engaging propulsion structure for propelling the working 20 machine; a body supported on the ground engaging propulsion structure; a drive arrangement comprising an energy source, a prime mover, and a transmission operable to transmit drive from the prime mover to the ground engaging propulsion structure; and a control system configured to retrieve information relating to a comparison between a travel energy threshold and an energy remaining in the 25 energy source from a memory provided on the working machine or a remote server, and wherein the control system is configured to provide an alert based on the comparison between the energy remaining in the energy source and the travel energy threshold. The working machine may be an electric off-highway working machine. 30 The drive arrangement may comprise an energy source in the form of a battery, and prime mover in the form of an electric motor. The control system may be configured to retrieve information relating to a state of charge of the battery. In one arrangement, the energy source may be diesel or hydrogen, and the prime mover may be an internal combustion engine. The control system may be configured to receive data relating to an amount of diesel or hydrogen remaining in a fuel tank. 5 The control system may be configured to: receive data relating to the charging location; determine a distance to the charging location; determine an energy requirement of the working machine to travel to the charging location; and to compare the energy requirement to a state of charge of the battery. The electric off-highway working machine may comprise one or more actuatable 10 device selected from one or more of: a working arm mounted to the body; and / or at least one stabiliser leg mounted to the body; and / or a dozer blade mounted to the body; and / or a container pivotally mounted to the body; and / or a working implement such as a bucket, a shovel, or forks. 15 The body may comprise an undercarriage supported on the ground engaging structure and a superstructure mounted to the undercarriage, optionally wherein the superstructure is rotatably mounted to the undercarriage. The ground engaging propulsion structure may comprise front and rear pairs of wheels or a pair of endless tracks. The electric off-highway working machine may comprise a sensor configured to 20 provide data in relation to the ambient temperature, and wherein the travel energy threshold is based on the ambient temperature. It will be appreciated that the second aspect may comprise one or more of the features of the first aspect. According to a third aspect, there is provided a method for providing an alert for an 25 electric off-highway working machine comprising a ground engaging propulsion structure for propelling the working machine, a body supported on the ground engaging propulsion structure, a drive arrangement comprising an energy source, a prime mover configured to be powered by the energy source, and a transmission operable to transmit drive from the prime mover to the ground engaging propulsion 30 structure, the method comprising: receiving data relating to a charging location; receiving data relating to a location of the working machine; calculating a travel energy threshold required to enable the working machine to travel to the charging location; receiving data relating to an energy remaining in the energy source of the working machine; comparing the travel energy threshold to the energy remaining in the energy source; providing an alert when the energy remaining in the energy source is equal to the travel energy threshold; and monitoring energy usage of the working machine in a working mode, and providing an estimated time remaining 5 before the alert is provided; and detecting a signal whether the working machine is in a working mode based on one or more of: detecting when the working machine is travelling below a predetermined travel speed; an orientation or position of an operator seat; and / or detecting a ground engaging component of the working machine has moved to a ground engaging position from a raised position. 10 The method may comprise determining a distance to the charging location. The drive arrangement may comprise an energy source in the form of a battery, and prime mover in the form of an electric motor. The method may comprise receiving information relating to a state of charge of the battery. It will be appreciated that the third aspect may comprise one or more of the features 15 of the first aspect and / or the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 is a side view of a working machine according to an embodiment of 20 the present teachings; Figure 2 is a block diagram of a control system of the working machine of Figure 1; Figure 3 is a schematic representation of a drive arrangement of the working machine of Figure 1; 25 Figure 4 is a schematic view of a the working machine of Figure 1 on a worksite; and Figure 5 is a control logic diagram for providing an alert to an operator of the working machine of Figure 1. DETAILED DESCRIPTION OF EMBODIMENT(S) 30 Referring firstly to Figures 1 and 2, an embodiment of the teachings includes a working machine 10. The working machine may be a load handling machine. The working machine 10 includes a machine body 12. The machine body 12 may include, for example, an operator's cab 14 from which an operator can operate the machine 10. The operator cab 14 may be mounted on the body 12 so as to be offset from a centre of the body. Although in alternative arrangements, the cab 14 may be substantially central. 5 The working machine 10 has a ground engaging propulsion arrangement. The ground engaging propulsion arrangement or structure supports the body 12. A working arm 20 is pivotally connected to the body 12 so as to be inclinable relative to the body 12. The working arm 20 is connected to the body 12 by a mount 22 proximate a first end, or proximal end, of the working arm 20. 10 In some arrangements, the body 12 may include an undercarriage or chassis including the ground engaging propulsion arrangement, and a superstructure including the cab and arm. The superstructure may be rotatable (e.g. about a substantially vertical axis) relative to the undercarriage / chassis. Put another way, the superstructure may be rotatable relative to the ground engaging propulsion 15 structure. It will be appreciated that the mount 22 may be provided on the undercarriage / chassis or the superstructure. 20 The ground engaging propulsion structure includes a first, or front, axle Al and a second, or rear, axle A2, each axle being coupled to a pair of wheels 16, 18. In other embodiments, the ground engaging propulsion structure may include a pair of endless tracks. One or both of the axles Al, A2 may be coupled to a drive arrangement (not shown) configured to provide motive power to the ground engaging propulsion structure (i.e. the axles Al, A2). The drive arrangement causes movement of the working machine 10 over a ground surface. In this embodiment, the working machine 10 is a telescopic handler. In other 25 embodiments the working machine 10 may be any working machine including a working arm 20, such as a rotating telescopic handler, an excavator, a skid-steer loader, or a telescopic wheel loader, for example. Such working machines may be denoted as off-highway vehicles or as non-road mobile machinery. In further embodiments, the working machine 10 may be a dumper vehicle or a tractor. 30 The working arm 20 is a telescopic arm. The telescopic arm 20 includes a plurality of sections, which are configured to be telescopically extendable. The sections are extendable by an actuator (not shown). The length of the telescopic arm 20 is adjustable between a retracted position and an extended position. In the illustrated embodiment, the working arm 20 includes a first section 26 connected to the body 12 (i.e. the mount 22) and a second section 28 which is telescopically fitted to the first section 26. In this embodiment, the second section 28 of the working arm 20 is telescopically moveable with respect to the first section 26 such that the working arm 20 can be extended and retracted along an elongate axis A of the arm 20. In 5 alternative embodiments (not shown), the working arm 20 may include more than two sections, for example three, four or more sections. Each arm section may be telescopically fitted to at least one other section, and an actuator may be provided therebetween. The working arm 20 is inclinable or pivotable relative to the machine body 12. The working arm 20 is inclinable about a substantially transverse axis 10 located at the mount 22. Rotational movement of the working arm 20 about said transverse axis with respect to the machine body 12 is achieved by use of an actuator (not shown) that is coupled between the arm 20 and the body 12. Movement of the working arm 20, e.g. pivoting and extension / retraction, is operable via an actuator (not shown), and so the working arm 20 is an actuatable 15 device or component. It will be appreciated that the actuator may be a hydraulic actuator or an electric actuator. The working arm 20 has a working implement 30 mounted at the distal end thereof. In the illustrated embodiment, the working implement 30 is a bucket, but in alternative arrangements any suitable working implement may be used such as 20 forks, a shovel, a sweeper, a grapple etc. The bucket 30 is pivotable relative to the working arm 20. The bucket 30 is pivotable about an axis orthogonal to the elongate axis A of the working arm 20. The bucket 30 is pivoted by a second actuator (not shown) that is coupled between the bucket 30 and the arm 20. Movement or operation of the working implement 30, e.g. bucket curl / dump, pivoting etc., is 25 operable via an actuator (not shown), and so the working implement 30 is an actuatable device or component. It will be appreciated that the actuator may be a hydraulic actuator or an electric actuator The working machine 10 is provided with a pair of stabilising legs 32. The stabilising legs 32 are provided on the body 12 of the working machine 10. Raising and 30 lowering of the stabiliser legs 32 is operable via an actuator (not shown), and so the stabiliser legs 32 are an actuatable device or component. It will be appreciated that the actuator may be a hydraulic actuator or an electric actuator Further examples of actuatable devices or components of a working machine that are not illustrated are: a pivotable container or skip; and a dozer blade pivotally 35 mounted to the body. Referring to Figure 2, a drive arrangement of the working machine 10 is illustrated. The drive arrangement includes an energy source, a prime mover, and a transmission 38. In the illustrated arrangement, the working machine 10 include an energy source 5 in form of an electrical source of power 34. In the present arrangement, the electrical source of power 34 is a battery. The battery 34 provides power to an electric motor arrangement. The electric motor arrangement is configured to provide power the actuatable devices or components of the working machine 10 and to drive the ground engaging propulsion system. 10 The working machine 10 includes a prime mover in the form an electric motor arrangement. The electric motor arrangement includes a first electric motor 36 and a second electric motor 37. The first electric motor 36 is configured to drive the ground engaging structure 32 to propel the working machine 10. The second electric motor 37 is configured to drive a hydraulic pump 40 to power the actuatable 15 devices (i.e. in the present arrangement, the actuatable devices are hydraulically actuatable devices). In order to transmit drive to the hydraulic pump 40, the transmission 38 includes a first output member 42 connected to the hydraulic pump 40, and a second output member 44 connected to the ground engaging structure. In alternative arrangements, however, it will be appreciated that the hydraulic 20 pump 40 and the ground engaging propulsion system may be driven by the same electric motor. The illustrated embodiment, power is provided to the working machine 10 by the battery via one or more electric motors. In some alternative arrangements, the one or more electric motors may be powered by a hydrogen fuel cell, or any other 25 alternative source of power. In further alternative arrangements, it will be appreciated that the working machine 10 may be provided with an energy source in the form of diesel or hydrogen fuel and a primer mover in the form of a diesel or hydrogen internal combustion engine. In some arrangements, the working machine may be a hybrid working machine comprising both an internal combustion engine 30 and an electric motor. Referring to Figures 3 to 5, the working machine is provided with a control system 50. The control system 50 is configured to provide an alert based on a comparison between a state of charge of the battery 40 and a determined travel energy threshold required to enable the working machine 10 to travel to a charging location 35 C. It will be appreciated that the alert may be provided in the form of an audio and / or visual alert or alarm. In such arrangements, the working machine 10 may be provided with an audio indicator 52 such as a speaker, a bell and / or a horn. Alternatively or additionally, the working machine 10 may be provided with a visual indicator 54 such as a light or a display. 5 The working machine 10 is provided with a battery management system to monitor the performance of the battery 40. The control system 50 is configured to retrieve data relating to a state of charge of the battery 40 from the battery management system 56 on the working machine 10. The working machine 10 is provided with a position sensor 58 configured to provide 10 location data in relation to the location of the working machine 10. The control system 50 is configured to retrieve data relating to a location of the working machine 10 from a position sensor 58 on the working machine 10. In some arrangements, the position sensor 58 may include and / or comprise a component of global navigation satellite system (GNSS) such as the global positioning system 15 (GPS), GLONASS or Galileo. The control system 50 is configured to retrieve data relating to a location of the charging location C. In some arrangements, a further position sensor (not shown) may be provided at the charging location C. In such arrangements, the control system 50 may be 20 configured to retrieve data relating to the charging location C from the further position sensor. Alternatively, the data relating to the charging location C may be stored on a memory 60, and the control system 50 may be configured to retrieve data relating to the charging location C from the memory 60. In alternative arrangements, data relating to the charging location may stored on the memory 60 25 by storing the location at which the battery 40 was last charged, and the control system 50 may be configured to retrieve data relating to the charging location from the memory 60. It will be appreciated that the memory 60 may be provided on the working machine 10, i.e. it may be a working machine memory, or may be provided at a remote server, i.e. it may be a remote server memory. 30 Using the data relating to the location of the working machine 10 and the location of the charging location C, a distance (e.g. a straight-line or direct distance) to the charging location C is able to be calculated / determined by the control system 50. The determined travel energy threshold is based on a distance between the location of the working machine 10 and the charging location C. In some arrangements, the control system 50 may be configured store location data from the position sensor 58 in a memory 60 so as to store the XY coordinates of a route or path P travelled by the working machine 10 from the charging location C for determining the location of the working machine (often referred to as a 5 breadcrumb trail). It will be appreciated that the memory 60 may be provided on the working machine 10, i.e. it may be a working machine memory, or may be provided at a remote server, i.e. it may be a remote server memory. The control system 50 may be configured so as to retrieve the data relating to route P travelled by the working machine 10 from the charging location C from the memory 60. In 10 this way, the return route (i.e. the distance to be travelled) to the charging location C is able to be calculated / determined by the control system 50. The determined travel energy threshold is based on the distance between the location of the working machine 10 and the charging location C. In some arrangements, the working machine 10 may be provided with a sensor 15 configured to provide data in relation to the altitude of the working machine 10 relative to the charging point. The data relating to the altitude of the working machine 10 may be stored in the memory 60. It will be appreciated that the altitude of the charging point may be stored in the memory 60 when the battery 40 was last charged, or that a further sensor may provide data to the control system 50 of 20 the altitude of the charging location C. It will be appreciated that the memory 60 may be provided on the working machine 10, i.e. it may be a working machine memory, or may be provided at a remote server, i.e. it may be a remote server memory. The control system 50 may be configured so as to retrieve the data relating to the altitude of the working machine 10 relative to the charging location 25 C from the memory 60. In this way, the distance to the charging location C is able to be calculated / determined by the control system 50 incorporating the change in altitude. The determined travel energy threshold is based on the change in altitude of the working machine 10 and the charging location C. Using the determined distance of the working machine 10 to the charging location 30 C, the control system 50 caIculates / determined an energy threshold required to enable the working machine 10 to travel to the charging location C. As discussed above, the control system 50 is configured to provide an alert when the travel energy threshold is substantially equal to the state of charge of the battery 40. This alerts an operator of the electric off-highway working machine of the need to stop 35 performing the current working operation and to return the working machine to the charger. In this way, an operator is alerted when the machine is about to be out of range of the charger at the charge location. The control system 50 calculates a travel energy requirement based the distance from the working machine 10 to the charging location C and an estimated energy 5 consumed per unit distance. It will be appreciated that the estimated energy consumed per unit distance may be based on as worst case scenario situation. The estimated energy consumed per unit distance may vary depending on the type of working machine and also depending on the configuration of the working being used for a particular application. The estimated energy consumed per unit distance 10 for a range of working machines, and for different configurations of each working machine, may be stored on the memory 60. The working machine 10 may comprise an operator input to select a particular configuration of the working machine, and the control system is configured to receive a signal based on the operator selection. It will be appreciated that the memory 60 may be provided on the working machine 15 10, i.e. it may be a working machine memory, or may be provided at a remote server, i.e. it may be a remote server memory. The control system 50 may be configured so as to retrieve the data relating the estimated energy consumed per unit distance from the memory 60, e.g. based on a selection made by an operator. In some arrangements, the control system 50 may be configured to monitor the 20 electrical energy usage over a predetermined period of time whilst the machine is in a travelling mode (i.e. when the machine 10 is travelling) (e.g. since the battery was last charged) to calculate the estimated energy consumed per unit distance. This helps to tailor the travel energy threshold to the particular configuration of the working machine and the conditions (e.g. ambient temperature, terrain etc.) in 25 which the machine is operation, helping to maximise time on site performing working operations. In such arrangements, the control system 50 may be configured to detect a signal whether the working machine 10 is in a working mode or a travelling mode, and to monitor the electrical energy usage over a predetermined period of time whilst the working machine 10 is in the travelling 30 mode. In some arrangements, the working machine 10 may include a travel speed sensor (not shown), and the control system 50 may detect that the working machine 10 is in a travelling mode when the working machine 10 is travelling above a predetermined travel speed and / or movement of the working machine beyond a predetermined distance in one direction. In this way, the control system 50 may be 35 configured to distinguish between movement of the working machine 10 during a material handling operation and movement of the working machine 10 from a charging location C to a worksite. Additionally or alternatively, the working machine 10 may be configured to detect that the working machine 10 is in the travelling mode by detecting: an orientation or position of an operator seat (e.g. movement between a rearward facing position to a forward facing position); and / or that a 5 ground engaging component (e.g. stabiliser legs or a dozer blade) of the working machine 10 has moved from a ground engaging position to a raised position. The travel energy threshold at which the control system 50 provides an alert is greater than the calculated travel energy requirement. This additional energy provides an additional safety factor to take account for different route that may 10 need to be taken, and / or differing conditions such as ambient temperature, ground conditions, altitude etc. The travel energy threshold may be in the region of 110-130% of the travel energy requirement, for example approximately 120% of the travel energy requirement. In some arrangements, the working machine may be provided with a temperature 15 sensor configured to provide data in relation to the ambient temperature. In such arrangements, the travel energy threshold may be based on the ambient temperature. Once the travel energy threshold has been determined / calculated, the control system 50 compares the state of charge of the battery 40 and the travel energy 20 threshold, and provides an alert. The state of charge of the battery 40 and the travel energy threshold may change from position-to-position as the working machine 10 is operated. For example, the state of charge of the battery 40 decreases during operation of the working machine 10, and the travel energy threshold changes based on the distance of the path to 25 the charging location C destination. The di stance / route to the charging location C destination, the travel energy threshold, and the state of charge of the battery 40 may be calculated multiple times during operation of the working machine 10, for example these may be updated periodically or continuously in real-time to enable the comparison to be made. 30 As has been described above, the working machine 10 may be provided with one or more actuatable devices or components. In some arrangements, the control system 50 may be configured to monitor energy usage while performing a working operation and to provide an estimated time remaining before the alert is provided. The control system 50 has been described above as one comprising a controller that is configured to: receive or retrieve data relating to the charging location C; receive or retrieve data relating to the location of the working machine; determine a distance to the charging location C; determine an energy requirement of the 5 working machine 10 to travel to the charging location C; and to compare the energy requirement to a state of charge of the battery. It will be appreciated that in some arrangements that this processing may be performed on the working machine 10 and in others it may be performed remotely (e.g. at a remote server), and the control system on the working machine 10 may retrieve the data relating to the 10 comparison between the state of charge of the battery and a determined travel energy threshold required to enable the working machine to travel to a charging location C. In arrangements, where the working machine is configured to communicate with a memory at a remote server location, the working machine 10 may be provided with 15 a telemetry module (not shown). The telemetry module may include a transmitter capable of communicating via a cellular radio network using a suitable protocol, CM such as GPRS, UMTS or LTE, and / or the internet with a server at a remote location, CO such that operating parameters of the machine may be presented to authorised Users. To enable this, the telemetry module may be capable of collecting data from 20 the battery management system regarding the state of the battery, the position sensor, the control system, and the memory on the working machine. The alert the based on the comparison between a state of charge of the battery 40 and a determined travel energy threshold required to enable the working machine 10 to travel to a charging location C, provides a warning or signal to an operator of 25 the need to return the working machine 10 to a charging location C. If the working machine 10 continues to be operated once the alert has been provided, the control system 50 may be configured to degrade operation or control of the working machine. This degradation of the operation or control of the working machine 10 provides a further indication or warning to an operatorthat the working 30 machine 10 needs to be returned to a charging location C. In one arrangement, the control system may be configured to activate a restricted operation mode of the working machine when the state of charge is below the energy requirement by a first predetermined amount. Put another way, the control system may be configured to activate a restricted operation mode of the working machine when 35 the state of charge is below a second energy threshold, which is lower than the 19 06 24 travel energy threshold. Restricting operation of the working machine reduces the machine's energy usage and enables the working machine to travel to the charge location even when the state of charge of the battery is below the energy requirement. 5 Further use of the working machine once operation or control of the working machine 10 has been degraded may result in the control system 50 activating a limp home operation mode. The limp home operation mode may be activated when the state of charge is below the energy requirement by a second predetermined amount greater than the first predetermined amount and / or when the state of 10 charge is at a predetermined level. Put another way, the control system may be configured to activate a limp home operation mode of the working machine when the state of charge is below a third energy threshold, which is lower than the travel and second energy thresholds. In the limp home operation mode, the RPM of the electric motor may be fixed at a relatively low RPM and / or one or more functions of 15 the working machine (e.g. heating, air conditioning etc.) may be switched off. Put another way, in the limp home operation mode, only basic operation of the working machine is possible, thus reducing energy usage. In this way, the working machine reduces the machine's energy usage and enables the working machine to travel to the charge location even when the state of charge of the battery is below the energy 20 requirement. Moreover, activation of the limp home operation mode provides a further warning to an operator of the working machine 10 of the need to return the working machine 10 to the charging location C. Although the teachings have been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications 25 may be made without departing from the scope as defined in the appended claims.

Claims

1. A control system for an electric off-highway working machine comprising a ground engaging propulsion structure for propelling the working machine, a body supported on the ground engaging propulsion structure, a drive 5 arrangement comprising a battery, an electric motor configured to be powered by the battery, and a transmission operable to transmit drive from the electric motor to the ground engaging propulsion structure, the control system comprising a controller configured to:receive data relating to a charging location;10 receive data relating to a location of the working machine;calculate a travel energy threshold required to enable the working machine to travel to the charging location;receive data relating to a state of charge of the battery of the working machine;15 compare the travel energy threshold to the state of the charge of thebattery;provide an alert when the state of charge of the battery is equal to the travel energy threshold;detect a signal indicating whether the working machine is in a working mode 20 based on one or more of detecting when the working machine is travelling below a predetermined travel speed, an orientation or position of an operator seat, and / or detecting a ground engaging component of the working machine has moved to a ground engaging position from a raised position; andmonitor energy usage of the working machine in the working mode, and to 25 provide an estimated time remaining before the alert is provided.

2. The control system according to claim 1, configured to provide an alert when the state of charge of the battery is less than the travel energy threshold.

3. The control system according to claim 1 or claim 2, configured to determine a distance to the charging location, and to calculate the travel energy threshold30 required based on the determined distance to the charging location.

4. The control system according to any preceding claim, configured to receive data relating to the location of the working machine from a position sensor provided on the working machine.

5. The control system according to claim 4, configured to store XY coordinates of a route travelled by the working machine from the charging location, and to determine the distance to the charging location based on the route travelled.

6. The control system according to claim 4 or claim 5, configured to store data 5 in relation to an altitude of the working machine relative to an altitude of the charging point, and to determine the distance to the charging location based on the altitude of the working machine relative to the altitude of the charging point.

7. The control system according to any preceding claim, configured activate a restricted operation mode of the working machine when the state of charge of 10 the battery is below the travel energy threshold by a first predetermined amount.

8. The control system according to any preceding claim, configured to activate a limp home operation mode when the state of charge of the battery is below the travel energy threshold by a second predetermined amount, greater than 15 the first predetermined amount.

9. The control system according to any preceding claim, configured to determine a travel energy requirement based on the distance to the charging location and an estimated energy consumed per unit distance, and wherein the travel energy threshold is based on, and is greater than, the travel energy 20 requirement.

10. The control system according to claim 9, wherein the travel energy threshold is in the region of 110-130% of the travel energy requirement, for example approximately 120% of the travel energy requirement.11.The control system according to claim 9 or claim 10, configured to retrieve 25 data relating to the estimated energy consumed per unit distance from a memory for a configuration of the working machine selected by an operator.12.The control system according to any one of claims 9 to 11, configured to monitor an electrical energy usage of the working machine in a travelling mode over a predetermined period of time, and to calculate the estimated energy 30 consumed per unit distance from the electrical energy usage.13.The control system according to claim 12, configured to monitor the electrical energy usage in the travelling mode since the battery was last charged.14.The control system according to claim 12 or claim 13, configured to detect 5 a signal indicating whether the working machine is in a travelling mode based on one or more of: detecting when the working machine is travelling above a predetermined travel speed; movement of the working machine beyond a predetermined distance in one direction; an orientation or position of an operator seat; and / or detecting a ground engaging component of the working 10 machine has moved from a ground engaging position to a raised position.15.The control system of claim 14, wherein the signal indicating whether the working machine is in a travelling mode is based on movement between a rearward facing position to a forward facing position of the operator seat.16.The control system according to any preceding claim, wherein the signal 15 indicating whether the working machine is in a working mode is based on movement between a rearward facing position to a forward facing position of the operator seat.17.The control system according to any preceding claim, wherein the ground engaging component comprises stabiliser legs or a dozer blade.20 18.The control system according to any preceding claim, wherein the alertcomprises an audio and / or visual alert.19.The control system according to any preceding claim, configured to receive data relating to the charging location via a global navigation satellite system (GNSS) such as the global positioning system (GPS).25 20.The control system according to any preceding claim, configured to receivedata relating to the charging location by retrieving charging location data stored on a memory when the battery of the working machine was last charged.3021. The control system according to any preceding claim, configured to calculate the travel energy threshold based on data relating to an ambient temperature received from an ambient temperature sensor on the working machine.

22. An electric off-highway working machine comprising:a ground engaging propulsion structure for propelling the working machine; a body supported on the ground engaging propulsion structure;a drive arrangement comprising a battery, an electric motor configured to5 be powered by the battery, and a transmission operable to transmit drive from the electric motor to the ground engaging propulsion structure; andthe control system of any preceding claim.23.The electric off-highway working machine according to claim 22, comprising one or more actuatable device selected from one or more of: a working arm 10 mounted to the body; and / or at least one stabiliser leg mounted to the body;and / or a dozer blade mounted to the body; and / or a container pivotally mounted to the body; and / or a working implement such as a bucket, a shovel, or forks.24.The electric off-highway working machine according to claims 22 or 23, 15 wherein the body comprises an undercarriage supported on the ground engaging structure and a superstructure mounted to the undercarriage, optionally wherein the superstructure is rotatably mounted to the undercarriage.

25. A method for providing an alert for an electric off-highway working machine 20 comprising a ground engaging propulsion structure for propelling the working machine, a body supported on the ground engaging propulsion structure, a drive arrangement comprising a battery, an electric motor configured to be powered by the battery, and a transmission operable to transmit drive from the electric motor to the ground engaging propulsion structure, the method comprising:25 receiving data relating to a charging location;receiving data relating to a location of the working machine;determining a distance to the charging location;calculating a travel energy threshold required to enable the working machine to travel to the charging location;30 receiving data relating to a state of charge of the battery of the workingmachine;comparing the travel energy threshold to the state of the charge of the battery;providing an alert when the state of charge of the battery is equal to the 35 travel energy threshold;CMdetecting a signal indicating whether the working machine is in a working mode based on one or more of detecting when the working machine is travelling below a predetermined travel speed, an orientation or position of an operator seat, and / or detecting a ground engaging component of the working machine5 has moved to a ground engaging position from a raised position; andmonitoring energy usage of the working machine in a working mode, and providing an estimated time remaining before the alert is provided.

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