Mobile elevating work platform

Abstract

A mobile elevating work platform 1 has a mobile base unit 3 and an extending structure comprising a boom assembly 15, which may be telescopic, pivotally attached to the mobile base unit at a pivot axi

Description

The invention relates to a mobile elevating work platform. For example, a mobile elevating work platform having a virtual boom rest. BACKGROUND Mobile Elevating Work Platforms (MEWPs) are typically equipped with a base unit, an extending structure, which can include a telescopic boom assembly, pivotally attached at a first end to the base unit or to another part of the extending structure, a jib pivotally attached to a second end of the boom assembly, and a work platform pivotally attached to the jib. The work platform is typically protected by a cage. MEWPs can include a mechanical boom rest which stops the boom at a defined angle when lowering the boom and prevents the work platform and associated parts from contacting the floor when the platform is close to the ground. The mechanical boom rest is mounted to a fixed position on the MEWP and typically includes a sensor or safety switch which detects the presence of the boom and changes the operating mode of the MEWP based on the machine configuration, between a lower travel position mode (where it is possible to operate at the maximum speed) and an elevated travel position mode (where operating speed is limited).A problem with a fixed mechanical boom rest is that the ideal boom angle to get the platform close to the ground will depend on several factors, such as how far the telescopic boom is extended, the inclination of the chassis, the configuration of the extending structure, the slew angle, and the mass in the cage. The inventors have determined that these factors ideally require a boom rest to be able to change position thereby changing the angle of the boom relative to the configuration of the MEWP, which a fixed mechanical boom rest cannot do. Another problem is that the boom cannot move past the fixed mechanical boom rest into a lower position, even when there is no risk of the work platform colliding with the ground, for example if the jib is raised thereby increasing the clearance between the underside of the platform and the ground. The inventors have determined that having the boom positioned lower than a traditional mechanical boom rest, may be more desirable for transporting the MEWP to prevent the boom structure bouncing during transportation. Accordingly, the invention seeks to provide an MEWP that mitigates at least one of the above-mentioned problems, or that at least provides an alternative MEWP from known MEWPs. SUMMARY OF INVENTION According to one aspect, there is provided a mobile elevating work platform according to claim 1. The invention provides a virtual boom rest for the boom assembly by controlling operation of the MEWP. The invention helps to reduce the likelihood of the working platform from crashing into the ground. Furthermore, since the mobile elevating work platform does not include a physical boom rest, the boom assembly can be pivoted about the axis below the resting angular orientation, for example to make it easier for an operator to climb on to the working platform. According to another aspect of the invention there is provided a mobile elevating work platform. The mobile elevating work platform can include a mobile base unit. The mobile elevating work platform can include an extending structure. The extending structure can be adjustable, for example to move from a fully retracted position to a fully extended position, and to any position between the fully retracted position and the fully extended position. The extending structure can be pivotally attached to the mobile base unit. The extending structure can comprise a boom assembly. In some embodiments, the boom assembly is pivotally attached to the mobile base unit at a pivot axis. In some embodiments, the boom assembly is pivotally attached to an extending structure member at a pivot axis. In some embodiments, the extending structure includes a plurality of extending structure members. In some embodiments, at least one of the extending structure members is pivotally attached to the mobile base unit. In some embodiments the extending structure members comprise at least one links boom and / or at least one links knuckle. The boom assembly can be pivotally attached to at least one links boom and / or at least one links knuckle. In some embodiments, the boom assembly is moveable independently of at least one links boom and / or at least one links knuckle. The mobile elevating work platform can include a drive system. The drive system can be arranged to adjust the angular orientation of the boom assembly about the pivot axis. The drive system can be arranged to adjust a length of the boom assembly by telescopically extending and retracting the boom assembly. The mobile elevating work platform can include a control system. The control system can include at least one controller. The controller can be arranged to control operation of the drive system. The control system can include a first sensor. The first sensor can be arranged to determine the angular orientation of the boom assembly about the pivot axis. The control system can include at least one further sensor. The at least one further sensor can be arranged to determine at least one operating condition of the mobile elevating work platform. The drive system can be arranged to adjust the position and / or orientation of the links booms. The controller can be arranged to receive signals from the first sensor and the at least one further sensor. The controller can be arranged to determine a resting angular orientation for the boom assembly based, at least in part, on the signals received from the at least one further sensor. The controller can be arranged to control operation of drive system to automatically arrest pivoting movement of the boom assembly at the resting angular orientation based, at least in part, on signals received from the first sensor. The boom assembly can be telescopically adjustable. The at least one further sensor includes a sensor arranged to determine the telescopic operating condition of the boom assembly. Since the resting angular orientation is determined by the controller for the boom assembly, the controller can take into account the telescopic operating condition of the boom assembly. Thus an appropriate resting angular orientation for the boom assembly can be determined for each telescopic operational condition of the boom assembly. The boom assembly can comprise of a plurality of boom sections. For example, the boom assembly can include an outer section boom (hereinafter “outer boom”). The outer boom can be pivotally attached to the base unit or extending structure. The boom assembly can include a tele section boom (hereinafter “tele boom”). The tele boom can be mounted within the outer boom. The tele boom can extend axially relative to the outer section boom in a telescopic manner. The tele boom can extend beyond a distal end of the outer boom in a telescopic manner. Optionally, the boom assembly can include at least one inner section boom (hereinafter “inner boom”) located between the outer boom and the tele boom. The inner boom can be mounted within the outer boom. The inner boom can extend axially relative to the outer boom in a telescopic manner. The inner boom can extend beyond a distal end of the outer boom in a telescopic manner. The tele boom can be located within the inner boom. The tele boom can extend axially relative to the inner boom in a telescopic manner. The tele boom can extend beyond a distal end of the inner boom in a telescopic manner. In a first condition, wherein the boom assembly is fully telescopically retracted, the controller can be arranged to determine a first resting angular orientation for the boom assembly. In a second condition, wherein the boom assembly is in a fully telescopically extended condition, the controller can be arranged to determine a second resting angular orientation for the boom assembly. The second resting angular orientation can be different from the first resting angular orientation. A distal end of the boom assembly can be positioned vertically higher from the ground in the second resting angular orientation than in the first resting angular orientation. The distal end of the boom assembly is the end of the boom assembly that is opposite to the end of the boom assembly that is pivotally attached to the base unit or extending structure member. In a third condition, wherein the boom assembly is partially telescopically extended, the controller can be arranged to determine a third resting angular orientation for the boom assembly. The third resting angular can be located between the first resting angular orientation and the second resting angular orientation. In a third condition, wherein the boom assembly can be partially telescopically extended, the controller can be arranged to select one of the first resting angular orientation and the second resting angular orientation for the boom assembly. In the first resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, can be oriented within ±5° of a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground. In the first resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, can be inclined downwards, for example through an angle P below a horizontal plane passing through the pivot axis. This is the case at least in a condition wherein the base unit is located on flat horizontal ground. The angle P can be around -3°. In the second resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, can be oriented within ±5° of a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground. In the second resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, can be inclined upwards, for example through an angle p above a horizontal plane passing through the pivot axis. This is the case at least in a condition wherein the base unit is located on flat horizontal ground. The angle P can be around +1°. The controller can be arranged to calculate a braking distance for the boom assembly based on the pivoting speed of the boom assembly. The controller can be arranged to calculate a braking distance for the boom assembly, to automatically arrest pivoting movement of the boom assembly at the first resting angular orientation. The controller can be arranged to calculate a braking distance for the boom assembly, to automatically arrest pivoting movement of the boom assembly at the second resting angular orientation. The controller can be arranged to calculate a braking distance for the boom assembly, to automatically arrest pivoting movement of the boom assembly at the third resting angular orientation. The braking distance can be calculated by the following formula: m = wherein m is the braking slope, w2 is the angular speed of the boom assembly when moving towards the resting orientation RO, tol is the final speed (zero) at the resting orientation RO, 02 is the angle read by the angle sensor when the boom assembly is at the resting orientation, and 01 is the braking angle, that is, the angle of the boom assembly at which the PLC should start the braking operation for the boom assembly to reach the resting orientation RO smoothly. The controller can be arranged to calculate the pivoting angle of the boom assembly at which braking of the boom assembly commences in order to arrest pivoting movement of the boom assembly at the resting angular orientation. The first sensor can comprise a rotary angle sensor. The rotary angle sensor can be arranged to monitor the angle of the boom assembly. The at least one further sensor can comprise at least one boom switch sensor. The base unit can include a chassis. The base unit can include a turntable. The turntable can be arranged to pivot relative to the chassis about a turntable pivot axis. For example, the drive system can include a slew ring, and the slew ring can be arranged to pivot the turntable with respect to the chassis. The at least one further sensor can include a chassis level sensor. The controller can be arranged to receive signals from the chassis level sensor. The controller can be arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the chassis level sensor. The chassis level sensor can determine if the chassis is on flat horizontal ground and, where this is not the case, the extent to which the chassis is inclined to the horizontal. The at least one further sensor can include a turntable angle sensor. The turntable angle sensor can be arranged to determine the angular orientation of the turntable with respect to the chassis about the turntable pivot axis. The controller can be arranged to receive signals from the turntable angle sensor. The controller can be arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the turntable angle sensor. The turntable angle sensor can be arranged to monitor operation of the slew ring. The mobile elevating work platform can include a jib. The mobile elevating work platform can include a working platform assembly. A first end of the jib can be pivotally attached to a distal end of the boom assembly. A second end of the jib can be connected to the working platform assembly, and is preferably pivotally connected to the working platform. The jib can be pivotally attached to the tele boom. The jib can comprise a first arm. The jib can comprise a second arm. The first arm can be pivotally attached to the tele boom at a pivot axis Zi. The second arm can be pivotally attached to the tele boom at a pivot axis Z2. The first arm can be arranged parallel to the second arm. The first arm can be pivotally attached to the working platform at a pivot axis Z3. The second arm can be pivotally attached to the working platform at a pivot axis Z4. In some embodiments a rotator can be located between the first arm and the working platform. In some embodiments the rotator can be located between the second arm and the working platform. In some embodiments the first arm can be pivotally attached to the rotator at the pivot axis Z3. In some embodiments the second arm can be pivotally attached to the rotator at the pivot axis Z4. In some embodiments the working platform can be pivotally attached to the rotator. The at least one further sensor can include a jib angle sensor. The jib angle sensor can be arranged to determine the angular orientation of the jib with respect to the boom assembly. For example, the jib angle sensor can be arranged to determine the angle of the jib with respect to the tele boom. The controller can be arranged to receive signals from the jib angle sensor. The controller can be arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the jib angle sensor. The at least one further sensor can include a weight sensor. The weight sensor can be arranged to determine a weight value for a mass loaded on to the working platform assembly. The controller can be arranged to receive signals from the mass sensor. The controller can be arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the weight sensor. On MEWPs with an extending structure comprising a plurality of articulating booms or links, the at least one further sensor can include a links position sensor. The controller can be arranged to receive signals from the links position sensor. The controller can be arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the links position sensor. The control system can include a manually operable control arranged to control pivoting movement of the boom assembly about the pivot axis. The control system can include a manually operable control arranged to control telescopic extension and retraction of the boom assembly The control system can include a manually operable control arranged to control pivoting movement of the jib relative to the boom assembly. The control system can include a manually operable control arranged to control movement of the links booms. The drive system can be arranged to pivot the boom assembly downwards beyond the resting orientation of the boom assembly. For example, the drive system can be arranged to pivot the boom assembly downwards beyond the resting orientation of the boom assembly in response to signals received from the manually operable control arranged to control pivoting movement of the boom assembly about the pivot axis. In some embodiments the controller can be arranged to operate the drive system to pivot the boom assembly downwards beyond the resting orientation only in a condition wherein the manually operable control for controlling pivoting movement of the boom assembly is moved to a neutral position subsequent to the boom assembly stopping at the resting orientation, and the control for controlling pivoting movement of the boom assembly can be subsequently actuated to recommence downward movement of the boom assembly. The boom assembly can be arranged to pivot downwardly about the pivot axis through an arc from the resting orientation to a lower limit. The controller can be arranged to drive the boom assembly in a reduced speed mode through at least part of the arc. This helps to prevent the working platform from crashing into the ground since it provides the operator with more time to recognise that a risk of crashing could occur, and a provides the operator with a greater period of time to stop the crash from occurring by operating the manual control, which controls pivoting movement of the boom assembly. The arc can be split into a plurality of arcuate zones. For example, the plurality of arcuate zones can include a first arcuate zone located adjacent the resting orientation. The plurality of arcuate zones can include a second arcuated zone located adjacent to the lower limit. The second zone can have an arc length that can be approximately half the length of a first zone arc length. The controller can be arranged to select a reduced speed mode to drive downward pivoting movement of the boom assembly in the second arcuate zone. The controller can be arranged to select a normal speed mode for driving downward pivoting movement of the boom assembly in the first arcuate zone. The advantage of this arrangement can be that the boom assembly can be driven at normal speed for a period of time below the resting orientation, thereby enabling the boom assembly to approach the lower limit more quickly, then as the lower limit can be approached the controller automatically selects the reduced speed mode, thereby providing the operator with more time to determine if a crash can be likely at the part of the movement when the risk of a crash occurring can be highest. In some embodiments the reduced speed mode can be selected for the first arcuate zone and the second arcuate zone. In some embodiments a first reduced speed mode can be selected for downward pivoting movement of the boom assembly in the first arcuate zone and a second reduced speed can be selected for downward pivoting movement of the boom assembly in the second arcuate zone, wherein second reduced speed mode drives at a lower speed than the first reduced speed mode. For at least some operating conditions, wherein the boom assembly is oriented below the resting orientation and an operator actuates the manually operable control arranged to control telescopic extension and retraction of the boom assembly, the controller can be arranged to drive telescopic adjustment of the boom assembly in a reduced speed mode. For example, the reduced speed mode can be selected by the controller when the boom assembly reaches the second arcuate zone. For at least some operating conditions, wherein the boom assembly is oriented below the resting orientation and an operator actuates a drive control, the controller can be arranged to drive the base unit across the ground in a reduced speed mode. For example, the reduced speed mode can be selected by the controller in a condition wherein the boom assembly reaches the second arcuate zone. In a condition wherein the boom assembly, jib and working platform assembly are in a lowered travel position configuration, the controller can select the reduced driving speed mode for driving the base unit. The control system can be arranged to issue an alert to an operator, for example via a display and / or a speaker, which notifies the operator that the boom assembly has reached the resting orientation. In some embodiments, the alert has to be cleared / acknowledged by the operator prior to the control system allowing further movement of the boom assembly. According to another aspect there is provided a mobile elevating work platform according to claim 30. The invention provides a virtual boom rest for the boom assembly by controlling operation of the MEWP. The invention helps to reduce the likelihood of the working platform from crashing into the ground. Since the resting angular orientation is determined by the controller for the boom assembly, the controller can take into account the telescopic operating condition of the boom assembly. Thus an appropriate resting angular orientation for the boom assembly can be determined for each telescopic operational condition of the boom assembly. Furthermore, since the mobile elevating work platform does not include a physical boom rest, the boom assembly can be pivoted about the axis below the resting angular orientation, for example to make it easier for an operator to climb on to the working platform. BRIEF DESCRIPTION OF DRAWINGS Embodiments of the invention will now be described by way of example only with reference to the drawings, wherein: Figure lisa side view of a MEWP according to a first embodiment of the invention; Figure 2 is a side view of the MEWP of Figure 1, with a boom assembly oriented in a resting orientation wherein the boom assembly is in a retracted condition and a jib is oriented downwards; Figure 3 is a side view of the MEWP of Figure 1, with the boom assembly oriented in a resting orientation wherein the boom assembly is in a fully extended condition and the jib is oriented downwards; Figure 4 is a side view of the MEWP of Figure 1, with the boom assembly oriented in a resting orientation wherein the boom assembly is in a retracted condition, the jib is oriented downwards, and illustrating a lower limit of the boom assembly’s pivotal movement and different pivotal speed zones for the boom assembly; Figure 5 is a side view of the MEWP of Figure 1, with the boom assembly oriented downwardly at an angle a from the restring orientation, wherein the boom assembly is in a retracted condition and the jib has a horizontal orientation; Figure 6 is a graph of Angular Speed vs Angular Orientation, to illustrate how to calculate braking distance for the boom assembly; Figure 7 illustrates diagrammatically part of a MEWP control system, which is arranged to determine the resting orientation of the boom assembly based on the operational condition of the boom assembly, and to control movement of the boom assembly to the resting orientation; and Figure 8 is a diagrammatic view of a software architecture that can be used by the control system of Figure 7. DETAILED DESCRIPTION Figure 1 shows a mobile elevating work platform (MEWP) 1 according to an embodiment of the invention. The MEWP 1 includes a base unit 3. The base unit 3 includes a chassis (sometimes referred to as a “frame”) 5, and a turntable 7, which is rotatably mounted on the chassis 5 via a bearing 9. The turntable 7 is arranged to rotate relative to the chassis 5 about an axis X-X. Typically the axis X-X is a vertical axis when the MEWP is located on horizontal ground. The chassis 5 includes ground contacting elements such as wheels 11 or tracks (not shown). The MEWP 1 includes a turntable drive system that is arranged to rotate the turntable 7 relative to the chassis 5, for example the turntable drive system can include a slew ring. The MEWP 1 includes a chassis drive system that is arranged to drive the base unit 3. The chassis drive system is arranged to control operation of the ground contacting elements to move the base unit over the ground. The base unit 3 includes a control panel 13, which is often referred to as “ground controls”. The control panel 13 enables an operator to control operation of the MEWP 1 from the ground. The MEWP 1 includes an extending structure, which includes a boom assembly 15. The boom assembly 15 is pivotally attached to the turntable 7 and is arranged to pivot relative the turntable 7 about an axis Y. Typically the axis Y is a horizontal axis when the MEWP is located on horizontal ground. The boom assembly 15 can be a telescopic boom assembly. For example, the telescopic boom assembly 15 can comprise a plurality of sections, such as an outer section boom 17 (hereinafter “outer boom 17”), which is pivotally attached to the turntable 7 or the extending structure member. The telescopic boom assembly 15 can include a tele section boom 19 (hereinafter “tele boom 19”, mounted within, and axially extendable beyond, the outer boom 15. Optionally, the telescopic boom assembly 15 can include at least one inner section boom 21 (hereinafter “inner boom 21”) located between the outer boom 17 and the tele boom 19. A jib 23 is connected to a distal end of the tele boom 19. The jib 23 comprises first and second jib arms 23a,23b. The first jib arm 23a is pivotally attached to the tele boom 19 at a first end of the jib arm 23a, and is arranged to pivot relative to the tele boom 19 about a pivot axis Zi. The second jib arm 23b is pivotally attached to the tele boom 19 at a first end of the jib arm 23b, and is arranged to pivot relative to the tele boom 19 about a pivot axis Z2. Typically, the pivot axes Zi,Z2 are horizontal axes. The first and second jib arms 23a,23b can be arranged parallel to one another. The first jib arm 23a is pivotally attached to a working platform assembly 25 at a second end of the jib arm 23a, for example via a rotator 24, and is arranged to pivot relative to the working platform assembly 25 about a pivot axis Z3. The second jib arm 23b is pivotally attached to the working platform assembly 25 at a second end of the jib arm 23b, for example via the rotator 24, and is arranged to pivot relative to the working platform assembly 25 about a pivot axis Z4. Typically, the pivot axes Z3,Z< are horizontal axes. The working platform assembly 25 includes a platform 27 on which an operator can stand, a safety cage 29 and a control panel 31. The control panel 31 enables the operator to control operation of the MEWP 1 from the platform 27. The MEWP 1 includes a boom drive system 33 that is arranged to control movement of the boom assembly 15, jib 23 and platform assembly 25. The boom drive system 33 is arranged to raise and lower the boom assembly 15, extend and retract the boom assembly 15, raise and lower the jib 23 and platform assembly 25. Typically, the boom drive system 33 includes a plurality of actuators that are arranged to achieve the desired movement. For example, the boom drive system 33 can include at least one actuator 35, such as a hydraulic cylinder, that is arranged to adjust the angle of inclination of the boom assembly 15 relative to the turntable 7 about axis Y. In some MEWPs 1, hydraulic fluid can be supplied to the cylinder 35 via a hydraulic pump 36 and a spool valve 38. The boom drive system 33 can include at least one actuator (not shown), such as a hydraulic cylinder, that is arranged to deploy and retract the boom assembly 15. The boom drive system 33 can include at least one actuator 37, such as a hydraulic cylinder, that is arranged to adjust the angle of inclination of the jib 23 relative to the tele boom 19 about axis Z. The boom drive system 33 can include a plurality of actuators 37, such that at least one actuator 37 is arranged to adjust the angle of inclination of the first jib arm 23a relative to the tele boom 19 about axis Zi, and at least one actuator 37 is arranged to adjust the angle of inclination of the second jib arm 23b relative to the tele boom 19 about axis Z2. It will be appreciated that as the first and second jib arms 23a,23b pivot with respect to tele boom 19 about axes Zi,Z2, the platform assembly 25 will pivot with respect to the first and second jib arms 23a,23b about axes Z3,Z<. The MEWP 1 includes a control system 39 that is arranged to control operation of the MEWP 1. Among other things, the control system 39 is arranged to control operation of the boom drive system 33, the turntable drive system and the chassis drive system. For example, the control system 39 can include a programmable logic controller (PLC) 41 that is arranged to control operation of the hydraulic pump 36 and spool valve 38. The ground control panel 13 and platform assembly control panel 31, each includes manually operable controls to enable an operate to control operation of the MEWP1, via the control system 39. For example, each control panel 13,31 can include a manually operable luffing control 40 arranged to enable an operator to adjust the angular orientation of the boom assembly 15 about the axis Y. Each control panel 13,31 can include a manually operable control 42 arranged to enable an operator to extend and retract the boom assembly 15. Each control panel 13,31 can include a manually operable control 44 arranged to enable an operator to adjust the angular orientation of the jib 23 about axes Zi,Z2. Each control panel 13,31 can include a manually operable control arranged to enable an operator to adjust the rotational orientation of the turntable 7. Each control panel 13,31 can include at least one manually operable control arranged to drive the base unit 3. The manually operable controls can be in the form of paddles. The control system 39 is arranged to provide a “virtual boom rest” for the boom assembly 15, that is, the control system 39 is arranged to bring the boom assembly 15 to a resting orientation RO without the need for a mechanical stop. The resting orientation RO of the boom assembly 15 is a notional level NL that can be parallel to a chassis inclination axis, wherein the chassis inclination axis passes through the centres of the front and rear wheel axles (see Figures 2 and 3). Typically, the notional level NL is approximately horizontal in a condition wherein the MEWP 1 is located on flat horizontal ground. In some embodiments, the resting orientation RO of the boom assembly 15 deviates from the notional axis by an angle P, wherein the angle P is typically in the range ±5° from the notional level NL. The main purpose of the virtual boom rest is to prevent the working platform assembly 25 from accidentally crashing into the ground. The control system 39 includes a sensor 43, such as a rotary angle sensor, that is arranged to monitor the angle of inclination of the boom assembly 15 about axis Y. The sensor 43 can be arranged to monitor angular movement of the boom assembly 15 directly, or alternatively can be arranged to monitor operation of the boom angle control paddle 40, and determine the angle of the boom assembly 15 based on movement of the control paddle 40. Output signals from the sensor 43 can be provided to the PLC 41. The PLC 41 is able to determine angle of inclination of the boom assembly 15 about axis Y from the signals received from the sensor 43. The control system 39 can include at least one further sensor, for example the control system 39 can include a sensor 45, such as a boom switch, that is arranged to determine if the boom assembly 15 is in an extended or retracted condition. The sensor 45 can be arranged to monitor telescopic movement of the boom assembly directly, or alternatively can be arranged to monitor operation of the boom extension control paddle 42, and determine the operational condition of the boom assembly 15 based on movement of the control paddle 42. Signals from the sensor 45 can be provided to the PLC 41. The PLC 41 is arranged to determine from the signals received the sensor 45 if the boom assembly 15 is in an extended or retracted state, and in some embodiments the sensor 45 can be arranged to determine the extent to which the boom assembly 15 is extended. From this determination, the PLC 41 is arranged to select the resting orientation for the boom assembly 15 by adjusting the angle p. It will be appreciated that when the boom assembly 15 is in an extended condition, there is a greater risk of the platform assembly 25 colliding with the ground than in a condition wherein the boom assembly 15 is retracted. Accordingly, the PLC 41 determines a suitable resting orientation angle p according to the operating conditions of the boom assembly 15. For example, in one embodiment the angle P can be a negative value (an angle below the horizontal) when the boom assembly 15 is in a retracted condition (shown diagrammatically in Figure 2), and the angle P can be a positive value (an angle above the horizontal) in a condition when the boom assembly 15 is in an extended condition (shown diagrammatically in Figure 3). A typical value for angle P when the boom assembly is in a retracted condition can be, for example -3°. In a condition wherein the jib 23 is oriented downwards to its fullest extent, a typical distance from the ground to the platform 27 can be around 0.5m. A typical value for angle P when the boom assembly 15 is in an extended condition can be, for example +1°. In a condition wherein boom assembly 15 is extended and the jib 23 is oriented downwards to its fullest extent, a typical distance from the ground to the platform 27 can be around 0.6m to Im depending on the extent to which the boom assembly 15 is extended. Generally, the aim is to enable the working platform 27 to be as close to the ground as possible to enable easy access to the platform 27 for the operator, but at the same time minimising the possibility of the platform colliding with the ground. Thus, the PLC 41 is able to determine a first virtual resting orientation ROi for the boom assembly 15 in a condition wherein the boom assembly 15 is fully retracted, and a second virtual resting orientation RO2 for the boom assembly 15 in a condition wherein the boom assembly 15 is fully extended. In some embodiments, in a condition wherein the boom assembly 15 is in a partially extended condition, the PLC 41 can select either one of the first virtual resting orientation ROi and the second virtual resting orientation RO2 at which to rest the boom assembly 15. In some embodiments, in a condition wherein the boom assembly 15 is in a partially extended condition, the PLC 41 can be arranged to determine at least one third virtual resting orientation RO3, wherein the third virtual resting orientation is located between the first virtual resting orientation ROi and the second virtual resting orientation RO2. In some embodiments, the third virtual resting orientation RO3 can vary according to the extent to which the boom assembly 15 is deployed. The control system 39 can include a sensor 47, such as a tilt or inclination sensor, that is arranged to determine the angle of the chassis, for example relative to the horizontal. The control system 39 can include a sensor 49, such as a rotary angle sensor, that is arranged to determine the angle of the jib 23, for example relative to the fly boom 19. The control system 39 can include a sensor 51, such as a scales or load cell, that is arranged to determine the mass loaded on to the platform 27. The control system 39 can include a sensor 53, such as a rotary angle sensor, that is arranged to determine the angular orientation of the turntable 7. On MEWPs with an extending structure comprising a plurality of articulating booms or links, the control system 39 can include at least one sensor 55, such as a rotary angle sensor, that is arranged to determine a links position. The output from at least one of the aforementioned sensors 47,49,51,53,55 separately, or any combination of the aforementioned sensors, can be provided to the PLC 41. The PLC 41 can be arranged to determine at least one of the first virtual resting orientation ROi, second virtual resting orientation RO2 and third virtual resting orientation RO3 of the boom assembly 15, at least in part, based on signals received from any one, or any combination, of the following sensors: the sensor 47 arranged to determine the angle of the chassis; the sensor 49 arranged to determine the angle of the jib 23; the sensor 51 arranged to determine the mass loaded on to the platform 27; the sensor 53 arranged to determine the angular orientation of the turntable 7; and the sensor 55 arranged to determine a links position or height of the extending structure. In some embodiments, the PLC 41 is arranged to determine at least one of the first virtual resting orientation ROi, second virtual resting orientation RCh and third virtual resting orientation RO3 of the boom assembly 15 based on signals from the sensor 45 that is arranged to determine if the boom assembly 15 is in an extended or retracted condition and signals received from any one, or any combination, of the following sensors: the sensor 47 arranged to determine the angle of the chassis; the sensor 49 arranged to determine the angle of the jib 23; the sensor 51 arranged to determine the mass loaded on to the platform 27; the sensor 53 arranged to determine the angular orientation of the turntable 7; and the sensor 55 arranged to determine a links position or height of the extending structure. In some embodiments the PLC 41 is arranged to determine at least one, and preferably each, of the virtual resting orientations RO of the boom assembly 15 based on signals received from the sensor 45 that is arranged to determine if the boom assembly 15 is in an extended or retracted condition, the sensor 49 arranged to determine the angle of the jib 23, and the mass loaded on to the platform 27. In some embodiments, the PLC 41 is arranged to determine at least one, and preferably each, of the virtual resting orientations RO of the boom assembly 15 based on signals received from the sensor 45 that is arranged to determine if the boom assembly 15 is in an extended or retracted condition, the sensor 49 arranged to determine the angle of the jib 23, and the sensor 47 arranged to determine the angle of the chassis. In some embodiments, the PLC 41 is arranged to determine at least one, and preferably each, of the virtual resting orientations of the boom assembly 15 based on signals received from the sensor 45 that is arranged to determine if the boom assembly 15 is in an extended or retracted condition, the sensor 49 arranged to determine the angle of the jib 23, the sensor 51 arranged to determine the mass loaded on to the platform 2, and the sensor 47 arranged to determine the angle of the chassis. Thus, any one of the aforementioned sensors 45,47,49,51,53,55, or any suitable combination of the aforementioned sensors 45,47,49,51,53,55, can be used with the sensor 43 that is arranged to monitor the angle of inclination of the boom assembly 15 about axis Y, in order to determine the virtual resting orientations RO of the boom assembly 15 and to control movement of boom assembly 15 about the axis Y in order to arrest movement of the boom assembly 15 at the resting orientation RO. When the operator actuates the manually operable luffing control to move the boom assembly 15 to the resting orientation RO, the PLC 41 is arranged to control operation of the hydraulic pump 36 and spool valve 38 to automatically arrest pivoting movement of the boom assembly 15 as the boom assembly 15 reaches the resting orientation RO. To ensure that the boom assembly 15 is braked smoothly the PLC 41 calculates the angular distance from the resting orientation RO at which when to commence a braking operation in order to provide a sufficient braking distance to allow the boom assembly 15 to reach the rest orientation RO in a condition wherein the angular speed is equal to zero. The braking distance will vary based on the current angular speed of the boom assembly 15. To calculate the braking distance, the following equation can be used, based on the graph shown in Error! Reference source not found.: ml — m2 where m is the braking slope, m2 is the angular speed of the boom assembly 15 when moving towards the resting orientation RO, ml is the final speed (zero) at the resting orientation RO, 02 is the angle read by the angle sensor 45 when the boom assembly 15 is at the resting orientation, and 01 is the braking angle, that is, the angle at which the PLC 41 should start the braking operation to reach the resting orientation RO smoothly. The slope (m) can be either calculated based on the parameters of a ramping module or obtained through fine tuning. Solving for the braking distance (A0) we obtain: -m2 02- 01 =--- m After calculating the braking distance, the PLC 41 calculates the braking angle: 0)2 01 =--1-02 m When the boom assembly 15 reaches the braking angle 01 the PLC 41 begins the braking process for the boom assembly 15. In some embodiments, the rest of the MEWP 1 shall be allowed to continue moving without any restriction while braking of the boom assembly 15 takes place. When the resting orientation RO is reached, the control system 39 preferably issues a visual and / or audio notification to the operator, for example on a display screen and / or speaker 50. In some embodiments, the control system is arranged such that it is necessary for the operator to move the luffing manually operable control through a neutral position before the boom assembly 15 can move again, either upwards or downwards, beyond the resting orientation RO of the boom assembly 15. The PLC 41 can be arranged to control downward pivoting movement of the boom assembly 15, about pivot axis Y, from the resting orientation RO to the boom assembly lower limit LL in a reduced speed mode. This helps to ensure that the platform assembly 25 does not crash into the ground, since it provides more time for the operator to realise that a collision may occur. The arcuate zone from the resting orientation RO to the boom assembly lower limit LL can notionally be split into a plurality of sub zones. A first sub zone can extend from the resting orientation RO through an angle a, to a notional boundary line BL. A second sub zone can extend from the notional boundary line BL to the boom assembly lower limit LL. Typically, the first sub zone extends approximately two thirds of the angular distance between the resting orientation RO to the boom assembly lower limit LL, and the second sub zone extends approximately one third of the angular distance between the resting orientation RO to the boom assembly lower limit LL. The PLC 41 can be arranged to control the speed of pivoting movement of the boom assembly 15, while the boom assembly 15 is located in the first sub zone at a normal pivoting speed. The PLC 41 can be arranged to control the speed of pivoting movement of the boom assembly 15, while the boom assembly 15 is located in the second sub zone at a reduced pivoting speed. This arrangement has the benefit of reducing the risk of the platform assembly 25 crashing into the ground, since the pivoting speed of the boom assembly 15 is reduced at the critical time, while moving the boom assembly 15 into position more quickly since the boom assembly 15 is able to pivot downwards through the first sub zone at a normal pivoting speed. In some embodiments the reduced speed mode can be selected for the first sub zone and the second sub zone. In some embodiments, a first reduced speed mode can be selected for downward pivoting movement of the boom assembly 15 in the first sub zone and a second reduced speed can be selected for downward pivoting movement of the boom assembly in the second sub zone, wherein second reduced speed mode operates at a lower speed than the first reduced speed mode. For at least some operating conditions wherein the boom assembly 15 is oriented below the resting orientation RO, and an operator actuates the manually operable control 42 arranged to control telescopic extension and retraction of the boom assembly, the PLC 41 can be arranged to drive telescopic adjustment of the boom assembly in a reduced speed mode. For example, the reduced speed mode can be selected by the PLC 41 when the boom assembly 15 reaches the second sub zone. For at least some operating conditions wherein the boom assembly 15 is oriented below the resting orientation RO, the PLC 41 can be arranged to drive the base unit 3 across the ground in a reduced speed mode. For example, in a condition wherein the boom assembly 15, jib 23 and work platform assembly 25 are in a lowered travel position configuration, the PLC 41 selects the reduced driving speed mode for driving the base unit 3. For example, the reduced speed mode can be selected by the PLC 41 in a condition wherein the boom assembly 15 reaches the second arcuate zone. It is to be noted that other operations can take place at normal speed, for example when starting from a position wherein the boom assembly 15 is located in the first sub zone, a command to raise the boom assembly 15 upwards will typically take place at normal operating speed. A possible software architecture is shown in Figure 8 that can be used for the control system 39 shown in Figure 7. The software architecture includes a Virtual Boom Rest module 57, which is arranged to determine the resting orientation RO for the boom assembly 15, and to control operation of the drive system 33 to brake pivoting movement of the boom assembly 15 at an appropriation rotational position to arrest pivoting movement at the resting orientation RO smoothly. The Virtual Boom Rest module 57, is also arranged to issue the alert to the operator when the boom assembly reaches the resting orientation RO, and to select the reduced speed mode for movement of the boom assembly below the resting orientation RO. An advantage of having a virtual boom rest is that it enables an operator to drive the boom assembly 15 beyond the boom rest orientation into a lower position, for example using an override mode. In other operational conditions, for example when the jib 23 is raised (when the risk of collision is reduced). The control system 39 can be arranged to automatically change speed mode when the boom is below the boom rest angle and / or send an audible or visual warning to the operator to alert them of an increased risk of collision. The control system 39 can be arranged such that the operator has to acknowledge a warning message before the control system allows the boom assembly to move past the boom resting orientation RO into a lower position. The description presents exemplary embodiments and, together with the drawings, serves to explain principles of the invention. However, the scope of the invention is not intended to be limited to the precise details of the embodiments or exact adherence with all method installation steps, since variations will be apparent to a skilled person and are deemed also to be covered by the claims. For example, in some embodiments the extending structure includes links booms and links knuckles, and the boom assembly is pivotally attached to at least one links boom and / or at least one links knuckle. At least one of the links booms can be pivotally attached to the mobile base unit. Thus the invention is applicable to MEWPs 1 that include a links structure, and wherein the boom assembly is pivotally attached to the links structure either directly or indirectly. The boom assembly can be moveable independently of at least one links boom and / or at least one links knuckle. Terms for components used herein should be given a broad interpretation that also encompasses equivalent functions and features. In some cases, several alternative terms (synonyms) for structural features have been provided but such terms are not intended to be exhaustive. Descriptive terms should also be given the broadest possible interpretation; e g. the term "comprising" as used in this specification means "including" such that interpreting each statement in this specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. Directional terms such as “vertical”, “horizontal”, “up”, “down”, “upper” and “lower” may be used for convenience of explanation usually with reference to the illustrations and are not intended to be ultimately limiting if an equivalent function can be achieved with an alternative dimension and / or direction. The description herein refers to embodiments with particular combinations of configuration steps or features, however, it is envisaged that further combinations and cross-combinations of compatible steps or features between embodiments will be possible. Indeed, isolated features may function independently as an invention from other features and not necessarily require implementation as a complete combination. Any feature from an embodiment can be isolated from that embodiment and included in any other embodiment. The term “at least one of’ is to be interpreted in the sense of “and / or”. For example, the term “at least one of the first sensor and the second sensor” is to be interpreted as meaning any one of the following: the first sensor alone; the second sensor alone; or a combination of the first sensor and the second sensor. As another example, the term “at least one of the first sensor, the second sensor and the third sensor” is to be interpreted as meaning any one of the following: the first sensor alone; the second sensor alone; the third sensor alone; the combination of the first sensor and the second sensor; the combination of the first sensor and the third sensor; the combination of the second sensor and the third sensor; or the combination of the first sensor, the second sensor and the third sensor.

Claims

1. A mobile elevating work platform, including: a mobile base unit; an adjustable extending structure comprising a boom assembly, wherein the boom assembly is pivotally attached to the mobile base unit or an extending structure member at a pivot axis; a drive system arranged to adjust the angular orientation of the boom assembly about the pivot axis; and a control system having at least one controller arranged to control operation of the drive system, the control system including a first sensor arranged to determine the angular orientation of the boom assembly about the pivot axis, and at least one further sensor arranged to determine an operating condition of the mobile elevating work platform, wherein the controller is arranged to receive signals from the first sensor and the at least one further sensor, to determine a resting angular orientation for the boom assembly based, at least in part, on the signals received from the at least one further sensor, and to control operation of drive system to automatically arrest pivoting movement of the boom assembly at the resting angular orientation based, at least in part, on signals received from the first sensor.

2. A mobile elevating work platform of claim 1, wherein the boom assembly is telescopically adjustable and the at least one further sensor includes a sensor that is arranged to determine the telescopic operating condition of the boom assembly.

3. The mobile elevating work platform of claim 2, wherein, in a first condition wherein the boom assembly is fully telescopically retracted, the controller is arranged to determine a first resting angular orientation for the boom assembly, and in a second condition wherein the boom assembly is in a fully telescopically extended condition, the controller is arranged to determine a second resting angular orientation for the boom assembly, wherein the second resting angular orientation is different from the first resting angular orientation.

4. The mobile elevating work platform of claim 3, wherein a distal end of the boom assembly is positioned vertically higher from the ground in the second resting angular orientation than in the first resting angular orientation.

5. The mobile elevating work platform of claim 3 or 4, wherein, in a third condition wherein the boom assembly is partially telescopically extended, the controller is arranged to determine a third resting angular orientation for the boom assembly, wherein the third resting angular is located between the first resting angular orientation and the second resting angular orientation.

6. The mobile elevating work platform of claim 3 or 4, wherein, in a third condition wherein the boom assembly is partially telescopically extended, the controller is arranged to select one of the first resting angular orientation and the second resting angular orientation for the boom assembly.

7. The mobile elevating work platform of any one of claims 3 to 6, wherein, in the first resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, is oriented within ±5° of a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground.

8. The mobile elevating work platform of any one of claims 3 to 7, wherein, in the first resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, is inclined downwards through an angle P below a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground.

9. The mobile elevating work platform of any one of claims 3 to 8, wherein, in the second resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, is oriented within ±5° of a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground.

10. The mobile elevating work platform of any one of claims 3 to 9, wherein, in the second resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, is inclined upwards through an angle P above a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground.

11. The mobile elevating work platform of any one of the preceding claims, wherein the controller is arranged to calculate a braking distance for the boom assembly based on the pivoting speed of the boom assembly.

12. The mobile elevating work platform of any one of the preceding claims, wherein the controller is arranged to calculate the pivoting angle of the boom assembly at which braking of the boom assembly commences in order to arrest pivoting movement of the boom assembly at the resting angular orientation.

13. The mobile elevating work platform of any one of the preceding claims, wherein the first sensor comprises a rotary angle sensor, which is arranged to monitor the angle of the boom assembly.

14. The mobile elevating work platform of any one of the preceding claims, wherein the at least one further sensor comprises at least one boom switch sensor.

15. The mobile elevating work platform of any one of the preceding claims, wherein the mobile base unit includes a chassis and a turntable, the turntable is arranged to pivot relative to the chassis about a turntable pivot axis.

16. The mobile elevating work platform of claim 15, wherein the at least one further sensor includes a chassis level sensor, and the controller is arranged to receive signals from the chassis level sensor and is arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the chassis levelsensor.

17. The mobile elevating work platform of claim 15 or 16, wherein the at least one further sensor includes a turntable angle sensor, which is arranged to determine the angular orientation of the turntable with respect to the chassis about the turntable pivot axis, wherein the controller is arranged to receive signals from the turntable angle sensor and is arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the turntable angle sensor.

18. The mobile elevating work platform of any one of the preceding claims, including a jib having a first end pivotally attached to a distal end of the boom assembly, and a second end connected to a working platform assembly, and preferably pivotally connected to the working platform.

19. The mobile elevating work platform of claim 18, wherein the at least one further sensor includes a jib angle sensor, which is arranged to determine the angular orientation of the jib with respect to the boom assembly, for example the fly boom, about the jib pivot axis, wherein the controller is arranged to receive signals from the jib angle sensor and is arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the jib angle sensor.

20. The mobile elevating work platform of claim 18 or 19, wherein the at least one further sensor includes a weight sensor, which is arranged to determine a weight value for a mass loaded on to the working platform assembly, wherein the controller is arranged to receive signals from the mass sensor and is arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the weight sensor.

21. The mobile elevating work platform of any one of the preceding claims, wherein the extending structure includes at least one links boom and the at least one further sensor includes a links position sensor, wherein the controller is arranged to receive signals from the links position sensor and is arranged to determine the resting angularorientation of the boom assembly, at least in part, based on signals received from the links position sensor.

22. The mobile elevating work platform of any one of the preceding claims, wherein control system includes a manually operable control arranged to control pivoting movement of the boom assembly about the pivot axis; and / or the control system includes a manually operable control arranged to control telescopic extension and retraction of the boom assembly; and / or the control system includes a manually operable control arranged to control pivoting movement of the jib relative to the boom assembly; and / or the control system includes a manually operable control arranged to control movement of the links booms.

23. The mobile elevating work platform of any one of the preceding claims, wherein the drive system is arranged to pivot the boom assembly downwards beyond the resting orientation of the boom assembly.

24. The mobile elevating work platform of claim 23, wherein the controller is arranged to operate the drive system to pivot the boom assembly downwards beyond the resting orientation only in a condition wherein the manually operable control for controlling pivoting movement of the boom assembly is moved to a neutral position subsequent to the boom assembly stopping at the resting orientation, and the control for controlling pivoting movement of the boom assembly is subsequently actuated to recommence downward movement of the boom assembly.

25. The mobile elevating work platform of claim 23 or 24, wherein the boom assembly is arranged to pivot downwardly about the pivot axis through an arc from the resting orientation to a lower limit, and the controller is arranged to drive the boom assembly in a reduced speed mode through at least part of the arc.

26. The mobile elevating work platform of claim 25, wherein the arc is split into a plurality of arcuate zones, including a first arcuate zone located adjacent the resting orientation and a second arcuated zone located adjacent to the lower limit, wherein thecontroller is arranged to operate downward pivoting movement of the boom assembly in the second arcuate zone at the reduced speed.

27. The mobile elevating work platform of any one of claims 23 to 26, wherein for at least some operating conditions wherein the boom assembly is oriented below the resting orientation, and an operator actuates the manually operable control arranged to control telescopic extension and retraction of the boom assembly, the controller is arranged to drive telescopic adjustment of the boom assembly in a reduced speed mode.

28. The mobile elevating work platform of any one of claims 23 to 27, wherein for at least some operating conditions wherein the boom assembly is oriented below the resting orientation, the controller is arranged to drive the base unit across the ground in a reduced speed mode.

29. The mobile elevating work platform of any one of the preceding claims, wherein the control system is arranged to issue an alert to an operator, for example via a display and / or a speaker, which notifies the operator that the boom assembly has reached the resting orientation.

30. A mobile elevating work platform, including: a mobile base unit; an adjustable extending structure comprising a boom assembly, wherein the boom assembly is pivotally attached to the mobile base unit or an extending structure member at a pivot axis, and the boom assembly is telescopically adjustable; a drive system arranged to adjust the angular orientation of the boom assembly about the pivot axis and to adjust a length of the boom assembly by telescopically extending and retracting the boom assembly; and a control system having at least one controller arranged to control operation of the drive system, the control system including a first sensor arranged to determine the angular orientation of the boom assembly about the pivot axis, and a second sensor arranged to determine the telescopic operating condition of the boom assembly, wherein the controller is arranged to receive signals from the first sensor and the second sensor, to determine a resting angular orientation for the boom assemblybased, at least in part, on the signals received from the second sensor, and to control operation of drive system to automatically arrest pivoting movement of the boom assembly at the resting angular orientation based, at least in part, on signals received from the first sensor.Amendments to the Claims have been filed as follows:18 07 2532CLAIMS1. A mobile elevating work platform, including: a mobile base unit; an adjustable extending structure comprising a boom assembly, wherein the boom assembly is pivotally attached to the mobile base unit or an extending structure member at a pivot axis; a drive system arranged to adjust the angular orientation of the boom assembly about the pivot axis; and a control system having at least one controller arranged to control operation of the drive system, the control system including a first sensor arranged to determine the angular orientation of the boom assembly about the pivot axis, and at least one further sensor arranged to determine an operating condition of the mobile elevating work platform, wherein the controller is arranged to receive signals from the first sensor and the at least one further sensor, to determine a resting angular orientation for the boom assembly based, at least in part, on the signals received from the at least one further sensor, and to control operation of drive system to automatically arrest pivoting movement of the boom assembly at the resting angular orientation based, at least in part, on signals received from the first sensor; wherein the drive system is arranged to pivot the boom assembly downwards beyond the resting orientation of the boom assembly.

2. A mobile elevating work platform of claim 1, wherein the boom assembly is telescopically adjustable and the at least one further sensor includes a sensor that is arranged to determine the telescopic operating condition of the boom assembly.

3. The mobile elevating work platform of claim 2, wherein, in a first condition wherein the boom assembly is fully telescopically retracted, the controller is arranged to determine a first resting angular orientation for the boom assembly, and in a second condition wherein the boom assembly is in a fully telescopically extended condition, the controller is arranged to determine a second resting angular orientation for the boom assembly, wherein the second resting angular orientation is different from the first resting angular orientation.18 07 254. The mobile elevating work platform of claim 3, wherein a distal end of the boom assembly is positioned vertically higher from the ground in the second resting angular orientation than in the first resting angular orientation.

5. The mobile elevating work platform of claim 3 or 4, wherein, in a third condition wherein the boom assembly is partially telescopically extended, the controller is arranged to determine a third resting angular orientation for the boom assembly, wherein the third resting angular is located between the first resting angular orientation and the second resting angular orientation.

6. The mobile elevating work platform of claim 3 or 4, wherein, in a third condition wherein the boom assembly is partially telescopically extended, the controller is arranged to select one of the first resting angular orientation and the second resting angular orientation for the boom assembly.

7. The mobile elevating work platform of any one of claims 3 to 6, wherein, in the first resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, is oriented within ±5° of a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground.

8. The mobile elevating work platform of any one of claims 3 to 7, wherein, in the first resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, is inclined downwards through an angle P below a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground.

9. The mobile elevating work platform of any one of claims 3 to 8, wherein, in the second resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, is oriented within ±5° of a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground.18 07 2510. The mobile elevating work platform of any one of claims 3 to 9, wherein, in the second resting angular orientation, a central longitudinal axis of the boom assembly, which passes through the pivot axis, is inclined upwards through an angle P above a horizontal plane passing through the pivot axis, in a condition wherein the base unit is located on flat horizontal ground.

11. The mobile elevating work platform of any one of the preceding claims, wherein the controller is arranged to calculate a braking distance for the boom assembly based on the pivoting speed of the boom assembly.

12. The mobile elevating work platform of any one of the preceding claims, wherein the controller is arranged to calculate the pivoting angle of the boom assembly at which braking of the boom assembly commences in order to arrest pivoting movement of the boom assembly at the resting angular orientation.

13. The mobile elevating work platform of any one of the preceding claims, wherein the first sensor comprises a rotary angle sensor, which is arranged to monitor the angle of the boom assembly.

14. The mobile elevating work platform of any one of the preceding claims, wherein the at least one further sensor comprises at least one boom switch sensor.

15. The mobile elevating work platform of any one of the preceding claims, wherein the mobile base unit includes a chassis and a turntable, the turntable is arranged to pivot relative to the chassis about a turntable pivot axis.

16. The mobile elevating work platform of claim 15, wherein the at least one further sensor includes a chassis level sensor, and the controller is arranged to receive signals from the chassis level sensor and is arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the chassis levelsensor.18 07 2517. The mobile elevating work platform of claim 15 or 16, wherein the at least one further sensor includes a turntable angle sensor, which is arranged to determine the angular orientation of the turntable with respect to the chassis about the turntable pivot axis, wherein the controller is arranged to receive signals from the turntable angle sensor and is arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the turntable angle sensor.

18. The mobile elevating work platform of any one of the preceding claims, including a jib having a first end pivotally attached to a distal end of the boom assembly, and a second end connected to a working platform assembly, and preferably pivotally connected to the working platform.

19. The mobile elevating work platform of claim 18, wherein the at least one further sensor includes a jib angle sensor, which is arranged to determine the angular orientation of the jib with respect to the boom assembly, for example the fly boom, about the jib pivot axis, wherein the controller is arranged to receive signals from the jib angle sensor and is arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the jib angle sensor.

20. The mobile elevating work platform of claim 18 or 19, wherein the at least one further sensor includes a weight sensor, which is arranged to determine a weight value for a mass loaded on to the working platform assembly, wherein the controller is arranged to receive signals from the mass sensor and is arranged to determine the resting angular orientation of the boom assembly, at least in part, based on signals received from the weight sensor.

21. The mobile elevating work platform of any one of the preceding claims, wherein the extending structure includes at least one links boom and the at least one further sensor includes a links position sensor, wherein the controller is arranged to receive signals from the links position sensor and is arranged to determine the resting angular18 07 25orientation of the boom assembly, at least in part, based on signals received from the links position sensor.

22. The mobile elevating work platform of any one of the preceding claims, wherein the control system includes a manually operable control arranged to control telescopic extension and retraction of the boom assembly; and / or the control system includes a manually operable control arranged to control pivoting movement of the jib relative to the boom assembly; and / or the control system includes a manually operable control arranged to control movement of the links booms.

23. The mobile elevating work platform of any one of the preceding claims, wherein the control system includes a manually operable control arranged to control pivoting movement of the boom assembly about the pivot axis, and the drive system is arranged to pivot the boom assembly downwards beyond the resting orientation of the boom assembly in response to signals received from the manually operable control arranged to control pivoting movement of the boom assembly about the pivot axis.

24. The mobile elevating work platform of claim 23, wherein the controller is arranged to operate the drive system to pivot the boom assembly downwards beyond the resting orientation only in a condition wherein the manually operable control for controlling pivoting movement of the boom assembly is moved to a neutral position subsequent to the boom assembly stopping at the resting orientation, and the control for controlling pivoting movement of the boom assembly is subsequently actuated to recommence downward movement of the boom assembly.

25. The mobile elevating work platform of any one of the preceding claims, wherein the boom assembly is arranged to pivot downwardly about the pivot axis through an arc from the resting orientation to a lower limit, and the controller is arranged to drive the boom assembly in a reduced speed mode through at least part of the arc.

26. The mobile elevating work platform of claim 25, wherein the arc is split into a plurality of arcuate zones, including a first arcuate zone located adjacent the resting18 07 25orientation and a second arcuated zone located adjacent to the lower limit, wherein the controller is arranged to operate downward pivoting movement of the boom assembly in the second arcuate zone at the reduced speed.

27. The mobile elevating work platform of any one of claims 23 to 26, wherein for at least some operating conditions wherein the boom assembly is oriented below the resting orientation, and an operator actuates the manually operable control arranged to control telescopic extension and retraction of the boom assembly, the controller is arranged to drive telescopic adjustment of the boom assembly in a reduced speed mode.

28. The mobile elevating work platform of any one of the preceding claims, wherein for at least some operating conditions wherein the boom assembly is oriented below the resting orientation, the controller is arranged to drive the base unit across the ground in a reduced speed mode.

29. The mobile elevating work platform of any one of the preceding claims, wherein the control system is arranged to issue an alert to an operator, for example via a display and / or a speaker, which notifies the operator that the boom assembly has reached the resting orientation.

30. A mobile elevating work platform, including: a mobile base unit; an adjustable extending structure comprising a boom assembly, wherein the boom assembly is pivotally attached to the mobile base unit or an extending structure member at a pivot axis, and the boom assembly is telescopically adjustable; a drive system arranged to adjust the angular orientation of the boom assembly about the pivot axis and to adjust a length of the boom assembly by telescopically extending and retracting the boom assembly; and a control system having at least one controller arranged to control operation of the drive system, the control system including a first sensor arranged to determine the angular orientation of the boom assembly about the pivot axis, and a second sensor arranged to determine the telescopic operating condition of the boom assembly, wherein the controller is arranged to receive signals from the first sensor andthe second sensor, to determine a resting angular orientation for the boom assembly based, at least in part, on the signals received from the second sensor, and to control operation of drive system to automatically arrest pivoting movement of the boom assembly at the resting angular orientation based, at least in part, on signals received from the first sensor; wherein the control system includes a manually operable control arranged to control pivoting movement of the boom assembly about the pivot axis, and the drive system is arranged to pivot the boom assembly downwards beyond the resting orientation of the boom assembly in response to signals received from the manually operable control arranged to control pivoting movement of the boom assembly about the pivot axis.LDCM

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