Lifting device for a wind turbine rotor blade

Abstract

A lifting system for a rotor blade of a wind turbine includes a lifting device having a structural frame body with a root end and a tip end. The root end supports a root cradle and the tip end supports a tip cradle. The root cradle and the tip cradle each have a profile corresponding to at least one outer surface of the rotor blade so as to receive and support at least a portion of the rotor blade. Due to the shape of the rotor blade, the rotor blade experiences asymmetric loads when the rotor blade is installed in the lifting device and lifted onto a tower. Accordingly, the lifting system further includes a variable airflow assembly coupled to the tip end of the lifting device. The variable airflow assembly includes at least one surface that is movable between a plurality of positions having different resistances so as to counteract the asymmetric loads.

Description

Technical Field

[0001] This disclosure relates generally to wind turbines, and more particularly to lifting devices for wind turbine rotor blades. Background Technology

[0002] Wind power is considered one of the cleanest and most environmentally friendly energy sources available today, and wind turbines are receiving increasing attention in this area. A modern wind turbine typically consists of a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture the kinetic energy of the wind using the known airfoil principle. The rotor blades transfer this kinetic energy as rotational energy, which in turn rotates the shaft that connects the rotor blades to the gearbox (or, if no gearbox is used, directly to the generator). The generator then converts the mechanical energy into electrical energy, which can be deployed to the public power grid.

[0003] The typical construction of a wind turbine involves erecting a tower and then attaching various other components to the erected tower. For example, rotor blades can be lifted to the appropriate height and attached to the tower after it has been erected. In some cases, each rotor blade is attached to a hub before lifting, and then the connected rotor blades and hubs are lifted and attached to the tower as units. However, the trend toward taller towers and larger rotor diameters, due to size and / or cost considerations, limits and / or excludes the lifting of such units to the tower. More specifically, as rotor diameter and / or mass, as well as hub height, increase, there are very few cranes (if any) capable of lifting such a structure. Furthermore, the sail area becomes so large that the available wind tunnel for performing such lifting approaches zero; that is, a crane cannot lift the rotor without tipping it over.

[0004] Therefore, current systems and methods for lifting rotor blades involve using clamping blade lifting tools, supports, or slings, such as those using a crane, to lift each rotor blade individually onto a tower. The individual rotor blades can then be attached to a hub.

[0005] When installing blades individually using this lifting tool, the blade's center of gravity must be located below the crane hook to maintain stability and suspension balance. However, due to the asymmetrical nature of wind turbine rotor blades, their center of gravity is not central. More specifically, when the blade is correctly positioned in the lifting device, there will be a short but very large diameter root section on one side of the tool, while on the other side there will be a very long but aerodynamically shaped section, resulting in asymmetrical loads. When exposed to a uniform airflow, the root section will generate higher drag than the longer blade section on the tip side, despite being much shorter. Simply put, the root section has a higher drag coefficient and therefore generates greater drag than the blade tip. This imbalance causes the entire system to rotate.

[0006] Therefore, conventional systems utilize one or more grab lines attached to the lifting tool, which can be held by an operator on the ground as the rotor blades are lifted onto the tower. However, as the rotor blades are lifted, load control via the grab lines becomes less effective. More specifically, as the load increases, the operator must apply increasingly greater force to the grab lines with decreasing effectiveness. Furthermore, due to the shape of the rotor blades (i.e., a thick, rounded root tapering to a long, slender tip), the blades are subjected to asymmetrical loads (e.g., due to wind) as they are lifted onto the tower.

[0007] In view of the above, an improved lifting device for lifting wind turbine rotor blades onto a tower is desired in the art. Summary of the Invention

[0008] The aspects and advantages of this disclosure will be set forth in part in the description which follows, or may be apparent from the description, or may be learned by practice of this disclosure.

[0009] On one hand, this disclosure relates to a lifting system for a rotor blade of a wind turbine. The lifting system includes a lifting device having a structural frame body having a blade root end and a blade tip end. A blade root support is supported at the blade root end, and a blade tip support is supported at the blade tip end. The blade root support and the blade tip support each have a profile corresponding to at least one outer surface of the rotor blade to receive and support at least a portion of the rotor blade. Therefore, due to the shape of the rotor blade, when the rotor blade is mounted in the lifting device and lifted onto a tower, the rotor blade may be subjected to asymmetrical loads. Therefore, the lifting system also includes a variable airflow assembly coupled to the blade tip end of the lifting device. The variable airflow assembly includes at least one surface that is movable between multiple locations with different resistances to counteract asymmetrical loads.

[0010] In an embodiment, the plurality of positions may include at least a first position and a second position. In one embodiment, the surface(s) may be one of a plurality of surfaces fitted to a frame member. In such an embodiment, the first position may be synonymous with the plurality of surfaces being in an open position relative to the frame member, and the second position may be synonymous with the plurality of surfaces being in a closed position relative to the frame member, wherein the open position provides a first resistance to asymmetric loads, and the closed position provides a second resistance to asymmetric loads. Furthermore, in such an embodiment, the second resistance is greater than the first resistance.

[0011] In another embodiment, one or more surfaces may be fixed to a hinge point. In such an embodiment, a first position may be synonymous with one or more surfaces being in a compressed position, and a second position may be synonymous with one or more surfaces being in an extended position from the hinge point, wherein the compressed position provides a first resistance to asymmetric loads, and the extended position provides a second resistance to asymmetric loads. Furthermore, in such an embodiment, the second resistance is greater than the first resistance.

[0012] In a further embodiment, the variable airflow assembly can be movably coupled to the blade tip of the lifting device, such that after the rotor blades have been installed on the tower, the variable airflow assembly can be moved to a concealed position relative to the main structural frame to minimize the impact of the variable airflow assembly.

[0013] In another embodiment, the lifting system may further include a gyroscope assembly having at least one gyroscope configured to change the orientation of the lifting device as it is lifted to or descends from the hub of the tower to which the wind turbine is mounted. In one embodiment, the gyroscope assembly may include multiple gyroscopes, such as a first gyroscope and a second gyroscope. In such an embodiment, the first and second gyroscopes may be coupled to at least one of the blade root and blade tip portions of the structural frame body, respectively, or coupled at an intermediate location along the structural frame body, such as at the center of the structural frame body.

[0014] In another embodiment, the lifting system may further include a drive mechanism for driving the variable airflow assembly and / or the gyroscope assembly. For example, in one embodiment, the drive mechanism may include a generator, an integrated motor, or a separate motor.

[0015] In yet another embodiment, the lifting system may include a controller configured to control a drive mechanism of at least one of a variable airflow component or a gyroscope component. For example, in one embodiment, the controller may include a remote controller, a turbine controller for a wind turbine, or a controller separate from the wind turbine. Furthermore, in embodiments, the lifting system may include one or more sensors communicatively coupled to the controller to monitor the orientation of the lifting device as it is lifted to or descends from a hub mounted on a tower. In such embodiments, as an example, the sensors(s) ...

[0016] In another aspect, this disclosure relates to a method for controlling the orientation of a lifting device for a wind turbine rotor blade as the lifting device is lifted to or lowered from a hub mounted on a tower of a wind turbine. The method includes securing a variable airflow assembly to the blade tip of a structural frame body of the lifting device. The structural frame body supports a blade root support and a blade tip support. The variable airflow assembly includes at least one surface movable between multiple locations with different resistances to counteract asymmetric loads on the lifting device. The method also includes securing the rotor blades to the top of the blade root and blade tip supports of the lifting device. Furthermore, the method includes raising or lowering the lifting device between a ground location and the hub while varying between multiple locations on the surface(s) to counteract asymmetric loads.

[0017] It should be understood that the methods described herein may further include any of the additional steps and / or features as described herein. Furthermore, in embodiments, securing the variable airflow assembly to the blade tip of the structural frame body of the lifting device may include movably securing the variable airflow assembly to the blade tip of the structural frame body.

[0018] For example, in one embodiment, the method may include moving the variable airflow assembly relative to the structural frame body to a concealed position after the rotor blades have been removed from the lifting device, in order to minimize the impact of the variable airflow assembly. In some embodiments, as examples, moving the variable airflow assembly to the concealed position may include folding the variable airflow assembly against the structural frame body, sliding the variable airflow assembly toward the center of the structural frame body, compressing the variable airflow assembly, or receiving the variable airflow assembly within a recess in the structural frame body.

[0019] Furthermore, in embodiments, the method may include coupling a gyroscope assembly having at least one gyroscope to the lifting device, and fine-tuning the orientation of the lifting device when it is mounted onto the hub of a tower fitted to a wind turbine.

[0020] In yet another embodiment, the method may include automatically controlling at least one of a variable airflow component or a gyroscope component via the controller's processor to change the orientation of the lifting device as it is lifted to or descends from a hub mounted on the tower.

[0021] These and other features, aspects, and advantages of this disclosure will become more readily understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. Attached Figure Description

[0022] The complete and implementable disclosure (including its best mode) of this disclosure is set forth in the description with reference to the accompanying drawings, in which:

[0023] Figure 1 A perspective view of one embodiment of a wind turbine according to the present disclosure is shown;

[0024] Figure 2 A side view of one embodiment of a rotor blade according to the present disclosure is shown;

[0025] Figure 3 A perspective view of one embodiment of the lifting system according to the present disclosure is shown;

[0026] Figure 4 A perspective view of one embodiment of the lifting device according to the present disclosure is shown;

[0027] Figure 5 A perspective view of one embodiment of a gyroscope according to the present disclosure is shown;

[0028] Figure 6 A perspective view of an embodiment of a lifting system for rotor blades of a wind turbine is shown, with particular emphasis on a first and a second gyroscope mounted at opposite ends of the lifting device of the lifting system.

[0029] Figure 7 A schematic diagram of an embodiment of a lifting system for rotor blades of a wind turbine is shown, particularly showing a first gyroscope and a second gyroscope with opposite tilt angles mounted on opposite ends of the lifting device of the lifting system.

[0030] Figure 8 A perspective view of an embodiment of the variable airflow assembly according to the present disclosure is shown, particularly showing multiple surfaces of the variable airflow assembly in the open position;

[0031] Figure 9 It shows Figure 8 A perspective view of the variable airflow assembly, particularly showing multiple surfaces of the variable airflow assembly in the closed position;

[0032] Figure 10 A perspective view of another embodiment of the variable airflow assembly according to the present disclosure is shown, particularly showing the surface of the variable airflow assembly in a compressed position;

[0033] Figure 11 It shows Figure 10 A perspective view of the variable airflow assembly, particularly showing the surface of the variable airflow assembly in the extended position;

[0034] Figure 12A and 12BA schematic diagram of one embodiment of the variable airflow assembly according to the present disclosure is shown, particularly showing the variable airflow assembly in an active position and a hidden position, respectively;

[0035] Figure 13A and 13B A schematic diagram of another embodiment of the variable airflow assembly according to the present disclosure is shown, particularly showing the variable airflow assembly in an active position and a hidden position, respectively;

[0036] Figure 14 A simplified block diagram of one embodiment of suitable components that may be included in a controller according to the present disclosure is shown;

[0037] Figure 15 A schematic diagram of one embodiment of a fail-safe operating mode implemented by a controller of a lifting system according to the present disclosure is shown;

[0038] Figure 16 A schematic diagram of another embodiment of a fail-safe operating mode implemented by a controller of a lifting system according to the present disclosure is shown;

[0039] Figure 17 A schematic diagram of yet another embodiment of a fail-safe operating mode implemented by a controller of a lifting system according to the present disclosure is shown;

[0040] Figure 18 A schematic diagram of yet another embodiment of a fail-safe operation mode implemented by a controller of a lifting system according to the present disclosure is shown; and,

[0041] Figure 19 A flowchart of one embodiment of the method according to the present disclosure is shown, which is used to control the orientation of the lifting device for the rotor blades of a wind turbine when the lifting device is lifted to or from the hub of the tower to which it is mounted. Detailed Implementation

[0042] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. Each example is provided in a manner that explains the disclosure and not limits it. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the disclosure without departing from its scope or spirit. For example, features shown or described as part of one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, the present disclosure is intended to cover such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0043] When an asymmetrical load is lifted from a crane hook in an open environment with wind, the load generates torque and begins to rotate due to the wind vane effect. An example of such an asymmetrical load includes wind turbine rotor blades being lifted onto a tower. This effect is typically compensated for using at least one grab stabilizing cable. However, as the rotor blade is lifted, control of the load via the grab stabilizing cable(s) becomes less effective. More specifically, as the load is lifted, the operator must apply increasingly greater force to the grab stabilizing cable with decreasing effectiveness. Furthermore, due to the shape of the rotor blades (i.e., a thick, rounded root that tapers to a long, slender tip), the blades are subjected to asymmetrical loads (e.g., due to oncoming wind) as they are lifted onto the tower.

[0044] Generally, this disclosure relates to a lifting system for wind turbine rotor blades and a method for controlling the ascent and descent of the rotor blades, whether loaded or unloaded into the lifting system, without the assistance of grab stabilizing cables or grab stabilizing cable personnel. More specifically, this disclosure relates to a system and method for eliminating undesirable torque by utilizing surfaces or guide vanes of variable size and / or aerodynamic drag to generate compensating torque in opposite directions. Thus, by using surfaces of variable size and / or aerodynamic drag, equal but opposite torques can be generated to counteract undesirable rotation of the lifting device, thereby stabilizing the load on its path to the tower.

[0045] Furthermore, in one embodiment, the lifting system of this disclosure is also equipped with a positioning control device having at least one gyroscope suspended in a gimbal, which allows the generation of a force produced by gyro precession to allow for precise positioning of the load. More specifically, the precession force allows the load to be precisely positioned to facilitate the assembly of the object to be lifted into the support structure. As generally understood, a gyroscope tends to maintain its position in space, or in other words, maintain the axis around which it rotates, and tends to resist changes in its orientation due to external influences. Conversely, if an external force causes a change in the position of the axis, a reaction force is generated in a plane perpendicular to the plane of the external force. Thus, this disclosure utilizes this gyroscopic behavior, also known as precession. For example, a pair of gyroscopes are configured to spin in a vertical plane. More specifically, the gyro wheel is suspended in a manner that allows it to tilt about a horizontal axis. If the gyroscopes tilt in opposite directions, the resulting precession force generates a torque that causes the lifting device to rotate. Furthermore, when the gyroscope tilts, a single force is applied, which is related to the degree and speed of the gyroscope's tilt. Once this force is applied, the system glides to a stop until the gyroscope tilts again when another force is applied. Therefore, by tilting the gyroscope, more direct control of the load is achieved compared to the input from the grab stabilizing cable from ground personnel.

[0046] Now refer to the attached diagram, Figure 1 A perspective view of one embodiment of a wind turbine 10 according to this disclosure is shown. As shown, the wind turbine 10 includes a tower 12, on which a nacelle 14 is mounted. A plurality of rotor blades 16 are mounted to a rotor hub 18, such as via the blade roots (discussed below), which in turn is connected to a main flange that rotates a main rotor shaft (not shown). The wind turbine power generation and control components are generally housed within the nacelle 14 and / or the tower 12. Figure 1 The view Figure 1 This disclosure is provided for illustrative purposes only, placing it within an exemplary field of use. It should be understood that this disclosure is not limited to any particular type of wind turbine configuration.

[0047] Now for reference Figure 2 This shows the following according to the present disclosure Figure 1 A perspective view of one of the rotor blades 16. As shown, the rotor blade 16 includes an outer surface defining a pressure side 22 and a suction side 24 extending between a leading edge 26 and a trailing edge 28, and extending from the blade tip 32 to the blade root 34. As is known in the art, the outer surface can be a generally aerodynamic surface having a generally aerodynamic profile. In some embodiments, the rotor blade 16 may include a plurality of individual blade segments aligned end-to-end from the blade tip 32 to the blade root 34. Each of the individual blade segments may be uniquely configured such that the plurality of blade segments define a complete rotor blade 16 having a designed aerodynamic profile, length, and other desired characteristics. For example, each of the blade segments may have an aerodynamic profile corresponding to the aerodynamic profile of an adjacent blade segment. Thus, the aerodynamic profiles of the blade segments may form a continuous aerodynamic profile of the rotor blade 16. Alternatively, the rotor blade 16 may be formed as a single integral blade having a designed aerodynamic profile, length, and other desired characteristics.

[0048] In an exemplary embodiment, the rotor blade 16 may be curved. Bending the rotor blade 16 may require bending it along a generally flap-wise direction and / or a generally edge-wise direction. The flap-wise direction can generally be interpreted as the direction (or opposite direction) along which aerodynamic lift acts on the rotor blade 16. The edge-wise direction is generally perpendicular to the flap-wise direction. The flap-wise curvature of the rotor blade 16 is also referred to as pre-bending, and the edge-wise curvature is also referred to as sweep (or sweep). Therefore, the curved rotor blade 16 may be pre-bent and / or swept. Bending allows the rotor blade 16 to better withstand loads in both the flap-wise and edge-wise directions during wind turbine 10 operation and can further provide clearance between the rotor blade 16 and the tower 12 during wind turbine 10 operation.

[0049] Still referencing Figure 2 The rotor blades 16 can further define the chord 42 and the wingspan 44. Furthermore, as... Figure 2 As shown, the chord 42 can vary over the entire span 44 of the rotor blade 16. Therefore, a local chord can be defined for the rotor blade 16 at any point along the span 44. As discussed above, the outer surface can extend generally along the span direction between the blade tip 32 and the blade root 34.

[0050] Now for reference Figures 3 to 7 This illustrates various components of the lifting system 50 for the rotor blades 16 of a wind turbine 10 according to this disclosure. For example... Figure 3 and 4 As shown, the lifting system 50 includes a lifting device 52 configured to support at least a portion of the rotor blade 16. More specifically, as shown, the lifting device 52 includes at least one support 54, 56, which will be described in more detail below. For example, as shown, the lifting device 52 includes a root support 54 and a tip support 56 for supporting portions of the blade 16 near the blade root 34 and the blade tip 32, respectively. Furthermore, in some embodiments, each of the supports 54, 56 generally has a profile corresponding to at least one of the outer surfaces of the rotor blade 16 to support at least a portion of the rotor blade 16. For example, as... Figure 3 and 4 As shown, the blade root support 54 has a profile that generally corresponds to the blade root 34 of the rotor blade 16, while the blade tip support 56 has a profile that generally corresponds to the blade tip 32 of the rotor blade 16.

[0051] In addition, such as Figure 3 and 4As shown, the lifting device 52 may include a structural frame body 55 for connecting and supporting the blade root support 54 and the blade tip support 56. More specifically, as shown, the structural frame body 55 may include one or more support members 57 configured to support each of the blade root support 54 and the blade tip support 56, respectively. Thus, as shown, the blade root support 54 and the blade tip support 56 may be fitted to the corresponding ends of the structural frame body 55, namely, the blade root end 65 and the blade tip end 67 of the structural frame body 55. Furthermore, the support members 57 may be connected or linked together via a main support member 59 or a beam. Therefore, in another embodiment, the lifting system 50 may also include a crane (not shown) and crane cables or slings 58 (…). Figure 3 and 4 In such an embodiment, the crane may be coupled to a cable or sling 58, which is secured to the structural frame body 55, such that the crane can raise and / or lower the rotor blades 16 between the hub 18 and the tower 12. More specifically, the crane cable or sling 58 may include synthetic fiber slings and / or a central attachment point to provide stability to the lifting device 52 during raising and / or lowering.

[0052] The crane described herein can be any suitable machine known in the art for the general lifting of equipment and / or materials, such as a mobile crane, floating crane, overhead crane, or stationary crane (e.g., a tower crane). Furthermore, crane cables or slings 58 can be connected to the crane, and the crane can control the movement of the crane cables or slings 58 as known in the art.

[0053] like Figure 3 As shown, due to the shape of the rotor blades 16, when the rotor blades 16 are installed in the lifting device 52 and lifted onto the tower, the rotor blades 16 will be subjected to asymmetrical loads. Therefore, as Figure 3-13B As shown, the lifting system 50 may further include a variable airflow assembly 100 coupled to the blade tip 67 of the lifting device 52. The variable airflow assembly 100 includes at least one surface 102 that can operate between multiple locations with different drags (i.e., different aerodynamic drag coefficients) to counteract asymmetric loads. For example, as... Figure 8-9 As shown in 10-11, in an embodiment, the plurality of positions may include at least a first position ( Figure 8-10 ) and second position ( Figure 9 and Figure 11 ).

[0054] Furthermore, the surfaces 102 of the variable airflow assembly 100 described herein can have a variety of suitable configurations. For example, in one embodiment, such as Figure 8As shown, the variable airflow assembly 100 may include a plurality of surfaces 102 fitted to the frame member 104. More specifically, as Figure 8 and 9 As shown, surface 102 can be a guide vane or a louver (or skylight). Furthermore, in such embodiments, as... Figure 8 As shown, the first position can be synonymous with the plurality of surfaces 102 being in an open position relative to the frame member 104. Furthermore, as... Figure 9 As shown, the second position can be synonymous with the plurality of surfaces 102 being in a closed position relative to the frame member 104. Therefore, the open position provides a first resistance to asymmetric loads, while the closed position provides a second resistance to asymmetric loads. In such an embodiment, the second resistance is greater than the first resistance.

[0055] In certain embodiments, one or more surfaces 102 of the variable airflow assembly 100 may resemble an HVAC louver system. Accordingly, in some embodiments, the position of the louvers may be controlled by various devices such as damper actuators, motors, plungers, etc. More specifically, in some embodiments, such as Figure 9 As shown, the louvers 104 can be controlled by a programmable logic controller (PLC) 105 with analog outputs (such as 4-20 mA outputs) or by a safety-rated fieldbus (such as CAN or ProfiNet). Therefore, in such an embodiment, one or more surfaces 102 of the variable airflow assembly 100 can utilize a safety PLC with outputs (safety-rated fieldbus or conventional analog outputs) to maintain the last known position of the louvers in the event of a power failure or emergency stop engagement.

[0056] Now for reference Figure 10 and 11 In another embodiment, one or more surfaces 102 of the variable airflow assembly 100 may extend from the hinge point 106. In such an embodiment, as Figure 10 As shown, the first position can be synonymous with surface 102 being in a compressed position. Furthermore, as... Figure 11 As shown, the second position can be synonymous with surface 102 being in the extended position. Therefore, the compressed position provides a first resistance relative to the asymmetric load, and the extended position provides a second resistance relative to the asymmetric load. Furthermore, in such an embodiment, the second resistance is greater than the first resistance.

[0057] In a further embodiment, the variable airflow assembly 100 may be movably coupled to the blade tip 67 of the lifting device 52 such that after the rotor blades 16 have been removed from the lifting device 52 (e.g., after the rotor blades 16 have been installed on the tower), the variable airflow assembly 100 may be moved to a concealed position relative to the structural frame body 55 to minimize the impact of the variable airflow assembly 100. In some embodiments, such as Figure 12A and 12B As shown, the variable airflow assembly 100 can be moved to a hidden position by abutting against the structural frame body 55 folding assembly 100 (e.g., by rotating the variable airflow assembly 100 about hinge point 108 so that the variable airflow assembly 100 is flush with the structural frame body 55). Alternatively, as Figure 6 As shown, the variable airflow assembly 100 can be moved to a hidden position by sliding it toward the center of the structural frame body 55, for example, via the track system 110. In yet another embodiment, as Figure 10 and 11 As shown, the variable airflow assembly 100 can be moved to a concealed position by compressing it from an extended position to a compressed position. In such an embodiment, the compressed surface assembly 100 can then also be folded against the structural frame body 55. In yet another embodiment, as... Figure 13A and 13B As shown, the variable airflow assembly 100 can be moved to a hidden position by receiving the variable airflow assembly 100 in the recess 112 of the structural frame body 55, i.e., when the surface assembly 100 is no longer in use or needed.

[0058] Still referencing Figure 3-7 The lifting system 50 may also include a gyroscope assembly 60 having at least one gyroscope 62 coupled to the lifting device 52. As used herein, a gyroscope generally refers to a device used to measure or maintain orientation and angular velocity. More specifically, such as Figure 5 The diagram shows a perspective view of one embodiment of the gyroscope 62. As shown, the illustrated gyroscope 62 includes a spin wheel 66 or disk, which is mounted in a manner such as a fork to allow the wheel 66 to rotate about a rotation axis 74 and about the axis of the fork. Thus, when the device 52 is lifted onto or lowered from the hub 20 mounted on the tower, the rotation of the gyroscope 62 can be used to change the orientation of the lifting device 52.

[0059] In a further embodiment, the gyroscope assembly 60 may include a plurality of gyroscopes 62, 64. For example, as particularly in Figure 3-4As shown in Figures 6-8, the gyroscope assembly 60 may include a first gyroscope 62 and a second gyroscope 64. More specifically, as shown in the illustrated embodiment, the first gyroscope 62 and the second gyroscope 64 may be coupled to opposite ends (i.e., the blade root end 65 and the blade tip end 67 of the structural frame body 55). It should be understood that the first gyroscope 62 and the second gyroscope 64 may be assembled with any suitable assembly orientation. For example, as shown, the first gyroscope 62 and the second gyroscope 64 may be assembled generally parallel to the top beam extension of the structural frame body 55. Alternatively, as... Figure 4 As shown, the first gyroscope 62 and the second gyroscope 64 can be assembled as a top beam extension substantially perpendicular to the structural frame body 55. In another embodiment, the first gyroscope 62 and the second gyroscope 64 can be assembled in any other orientation relative to the structural frame body 55. Furthermore, the first gyroscope 62 and the second gyroscope 64 can be located at any suitable position along the structural frame body 55. For example, as... Figure 3 As shown, the first gyroscope 62 and the second gyroscope 64 can be uniformly spaced from the center position of the structural frame body 55 (e.g., as indicated by the distance r). Alternatively, as... Figure 4 As shown, the first gyroscope 62 and the second gyroscope 64 can be mounted at the center of the structural frame body 55 or toward that center.

[0060] In another embodiment, such as Figure 3 and 4 As shown, the lifting system 50 may include one or more drive mechanisms 80 for driving the variable airflow assembly 100 and / or the gyroscope assembly 60. For example, in some embodiments, the drive mechanism 80 may be a generator, an integrated motor, a separate motor, or any other suitable power device. For example, in one embodiment, the first gyroscope 62 and the second gyroscope 64 may each be controlled via speed motors 63, 65 and / or tilt motors 67, 69. In such embodiments, where the first gyroscope 62 and the second gyroscope 64 are controlled by corresponding speed motors 63, 65, the speed motors 63, 65 may be controlled by speed control drivers, which may be safety-rated to a predetermined Safety Integrity Level (SIL) rating by establishing a safe speed shutdown definition therein. In such embodiments, the safe speed typically refers to the maximum speed of the gyroscope motors 63, 65. For a safety drive, the safe speed may be equal to a certain percentage of the maximum speed rating. In further embodiments, the motors 63, 65 need not be controlled by a driver, but rather the safety shutdown mechanism may be implemented through a relay logic arrangement equivalent to the driver's SIL rating.

[0061] In a further embodiment, the tilt motors 67, 69 can be controlled by a position control driver or a servo motor. This allows the driver to be safety-rated and a safe position shut-off definition to be programmed therein. The safe position could be, for example, the final position of the tilt motors 67, 69. Therefore, when power is lost or an emergency stop is engaged, the brakes on the motors 67, 69 can be applied, and one or more drivers remain in the final position. Similarly, the tilt motors 67, 69 do not necessarily have to be controlled by a driver, and the safety shut-off mechanism can still be implemented using a relay logic arrangement equivalent to the driver's SIL rating.

[0062] Therefore, as Figure 8-9 As shown in 10-11, the drive mechanism 80 described herein can be configured to move the surface 102 of the variable airflow assembly 100 between the plurality of locations described herein. Furthermore, as... Figure 6 and 7 As shown, the drive mechanism 80 can be configured to orient the tilt angles / directions 76, 78 of the first gyroscope 62 and the second gyroscope 64 in opposite directions. Therefore, as shown, the lifting device 52 can rotate about a single suspension point (i.e., the crane hook), while the tilt angles of the first gyroscope 62 and the second gyroscope 64 are configured to be opposite to generate a torque T. Figure 6 and 7 ( ), to stop the rotation of the lifting device 52 and / or reverse the direction of rotation of the lifting device 52.

[0063] Furthermore, as shown in the figure, the lifting system 50 may also include a controller 82 communicatively coupled to one or more sensors 90, 92, such as a drive mechanism 80 for monitoring and controlling the variable airflow assembly 100 and / or the gyroscope assembly 60, and various motors described herein. Additionally, in some embodiments, the sensors 90, 92 may be used to measure one or more wind conditions, such as wind speed and / or wind direction. In such embodiments, the lifting system 50 may include (as an example) a GPS system located at one or more ends of the structural frame body 55 for detecting and / or counteracting motion, as well as wind condition sensors. Therefore, the controller 82 may be configured to utilize various inputs to determine how to actuate the variable airflow assembly 100 and / or the gyroscope assembly 60. By detecting wind speed and / or wind direction, the GPS system can quickly detect changes in the system 50 as it is raised and / or lowered.

[0064] The controller 82, as described herein, can be incorporated into a suitable control system of the wind turbine 10 (not shown), a handheld remote control, a personal digital assistant, a cellular phone, a separate controller or computer having one or more processors and associated storage devices. Furthermore, in certain embodiments, as an example, one or more sensors 90, 92 may include a Global Positioning Sensor (GPS) sensor, an accelerometer, a smart sensor, and combinations thereof. Thus, in certain embodiments, when the lifting device 52 approaches the hub 18, the controller 82 can, via a first gyroscope 62 and a second gyroscope 64, allow the Z-coordinate of the structural frame body 55 to change vertically up to a predetermined height, while maintaining the X and Y coordinates of the structural frame body 55.

[0065] In another embodiment, the controller 82 can control the lifting system 50 and the drive mechanism 80 by receiving multiple sensor signals from one or more sensors 90, 92, respectively, to change the position of one or more surfaces 102 and / or gyroscopes 62, 64 based on the sensor signals. More specifically, in one embodiment, the controller 82 can turn one or more surfaces 102 on or off and / or reverse the tilt angles of the first gyroscope 62 and the second gyroscope 64 to stop the rotation of the lifting device 52 and / or reverse the direction of rotation of the lifting device 52.

[0066] In addition, such as Figure 14 The diagram illustrates a block diagram of one embodiment of various components of a controller 82 according to the present disclosure. As shown, the controller 82 may include one or more processors 83 and associated storage devices 85, configured to perform various computer-implemented functions (e.g., performing the methods, steps, calculations, etc. disclosed herein and storing related data). Additionally, the controller 82 may include a communication module 87 to facilitate communication between the controller 82 and various components of the variable airflow assembly 100 and / or the gyroscope assembly 60. Furthermore, the communication module 87 may include a sensor interface 89 (e.g., one or more analog-to-digital converters) to allow signals transmitted from sensors 90, 92 to be converted into signals that can be understood and processed by the processor 83. It should be understood that sensors 90, 92 may be communicatively coupled to the communication module 87 in any suitable manner. For example, as... Figure 14 As shown, sensors 90 and 92 are connected to sensor interface 89 via a wired connection. However, in other embodiments, sensors 90 and 92 may be connected to sensor interface 89 via a wireless connection, such as by using any suitable wireless communication protocol known in the art.

[0067] As used herein, the term "processor" refers not only to integrated circuits known in the art as contained in a computer, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits. Additionally, storage device(s) 85 may typically include storage elements(s) including, but not limited to, computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, optical disc read-only memory (CD-ROM), magneto-optical discs (MOD), digital versatile discs (DVDs), and / or other suitable storage elements. Such storage device(s) 85 may typically be configured to store suitable computer-readable instructions that, when implemented by processor(s) 58, configure controller 82 to perform various functions.

[0068] In a further embodiment, the controller 82 is also configured to operate in a fail-safe mode upon engaging an emergency stop or power failure. For example, in such an embodiment, the fail-safe mode may include maintaining the gyroscope motor at its maximum speed, maintaining the gyroscope tilt motor at its last known position, and / or maintaining the blinds at their last known position. Specifically, as... Figure 15 The diagram illustrates an embodiment of a fail-safe mode or safe shutdown procedure implemented by controller 82. As shown, Figure 15 The failure-safe mode activation is generally illustrated, with controller 82 communicatively coupled to the system's motor 122 or converter 124. Additionally, as shown, the system may also include one or more batteries 126. Therefore, as shown, controller 82 is configured to control automatic transfer switch 120 to activate emergency stop 114. Emergency stop 114 can thus engage safety relay 116 (e.g., during a power outage) and reset 118 (e.g., when power is restored).

[0069] Now for reference Figure 16 The fail-safe mode of controller 82 may also include holding the blinds 102 in their last known position. For example, as shown, in the event of an engagement emergency stop or power failure, controller 82 may be configured to receive a signal 128 associated with the last known position of each of the blinds 102. Thus, controller 82 may, for example, actuate and / or hold each of the blinds in its last known position via a plurality of actuators until the power failure is restored.

[0070] Now for reference Figure 17 The fail-safe mode of controller 82 may also include maintaining the speed of gyroscope motors 63 and 65 at a predetermined speed. Similarly, as Figure 18As shown, the fail-safe mode of controller 82 can also maintain the angles of the first and second gyroscopes, for example, at the last known position, via tilt motors 67 and 69.

[0071] Now for reference Figure 19 A flowchart of one embodiment of method 100 is shown, which is used to control the orientation of a lifting device for a wind turbine rotor blade when the lifting device is lifted to or lowered from a hub mounted on or from a tower of a wind turbine. Generally, method 200 will be referenced herein. Figures 1 to 18 The wind turbine 10 and lifting system 50 shown are described herein. However, it should be understood that the disclosed method 200 can be implemented with wind turbines having any other suitable configuration. Furthermore, although... Figure 19 The steps performed in a particular order are depicted for illustrative and discussion purposes, but the methods discussed herein are not limited to any particular order or arrangement. Those skilled in the art using the disclosure provided herein will understand that various steps of the methods disclosed herein may be omitted, rearranged, combined, and / or adapted in various ways without departing from the scope of this disclosure.

[0072] As shown at (202), method 200 may include securing a variable airflow assembly 100 to the blade tip 67 of the structural frame body 55 of the lifting device 52. As mentioned, the structural frame body 55 supports the blade root support 54 and the blade tip support 56. Furthermore, as mentioned, the variable airflow assembly 100 includes at least one surface 102 operable between multiple locations with different resistances to counteract asymmetric loads on the lifting device 52. In an embodiment, for example, the variable airflow assembly 100 may be movably secured to the blade tip 67 of the structural frame body 55 of the lifting device 52. As shown at (204), method 200 also includes securing rotor blades 16 to the top of the blade root support 54 and the blade tip support 56 of the lifting device 52. In an alternative embodiment, it should be understood that the lifting device 52 may also be lifted to or lowered from the hub without the rotor blades 16 installed. As shown at (206), method 200 may include raising or lowering the lifting device 52 between the ground position and the hub 18, while changing between multiple positions on the surface(s) 102 to counteract asymmetrical loads.

[0073] In some embodiments, once the rotor blades 16 are removed from the lifting device 52, method 200 may further include moving the variable airflow assembly 100 relative to the structural frame body 55 to a concealed position, i.e., to minimize the aerodynamic effects of the variable airflow assembly 100. In some embodiments, as an example, method 200 may include folding the variable airflow assembly 100 against the structural frame body 55. Furthermore, in embodiments, method 200 may include sliding the variable airflow assembly 100 toward a central position of the structural frame body 55. In yet another embodiment, method 200 may include compressing the variable airflow assembly 100. In still another embodiment, method 200 may include receiving the variable airflow assembly 100 within a recess in the structural frame body 55.

[0074] Other aspects of the invention are provided by the subject matter of the following provisions:

[0075] Clause 1. A lifting system for rotor blades of a wind turbine, the lifting system comprising:

[0076] A lifting device includes a structural frame body having a blade root end and a blade tip end, a blade root support supporting a blade root bracket at the blade root end, and a blade tip support supporting a blade tip bracket at the blade tip end. Each of the blade root bracket and blade tip bracket includes a profile corresponding to at least one outer surface of a rotor blade to receive and support at least a portion of the rotor blade. The rotor blade is subjected to asymmetrical loads when it is mounted in the lifting device and lifted onto a tower.

[0077] A variable airflow assembly, coupled to the blade tip of a lifting device, includes at least one surface that can move between multiple locations with different resistances to counteract asymmetrical loads.

[0078] Clause 2. The lifting system according to Clause 1, wherein the plurality of positions includes at least a first position and a second position.

[0079] Clause 3. The lifting system according to Clause 2, wherein the at least one surface is one of a plurality of surfaces fitted to a frame member, a first position is synonymous with the plurality of surfaces being in an open position relative to the frame member, and a second position is synonymous with the plurality of surfaces being in a closed position relative to the frame member, wherein the open position provides a first resistance relative to an asymmetric load, and the closed position provides a second resistance relative to an asymmetric load, the second resistance being greater than the first resistance.

[0080] Clause 4. The lifting system according to Clause 2, wherein the at least one surface is fixed to a hinge point, a first position is synonymous with at least one surface being in a compressed position, and a second position is synonymous with at least one surface being in an extended position from the hinge point, wherein the compressed position provides a first resistance relative to an asymmetric load, and the extended position provides a second resistance relative to an asymmetric load, the second resistance being greater than the first resistance.

[0081] Clause 5. The lifting system according to any one of the preceding clauses, wherein the variable airflow assembly is movably coupled to the blade tip of the lifting device such that the variable airflow assembly can be moved to a concealed position relative to the structural frame body after the rotor blades have been installed on the tower, in order to minimize the impact of the variable airflow assembly.

[0082] Clause 6. The lifting system according to any one of the preceding clauses further includes a gyroscope assembly, the gyroscope assembly including at least one gyroscope configured to change the orientation of the lifting device when the lifting device is lifted to or from the hub of the tower to which the wind turbine is mounted.

[0083] Clause 7. The lifting system according to Clause 6, wherein at least one gyroscope includes a first gyroscope and a second gyroscope, the first gyroscope and the second gyroscope being respectively connected to at least one of the blade root end and the blade tip end of the structural frame body, or connected at a midpoint along the structural frame body.

[0084] Clause 8. The lifting system according to Clause 6 further includes a drive mechanism for driving at least one of the variable airflow assembly or the gyroscope assembly, the drive mechanism including at least one of a generator, an integrated motor or a separate motor.

[0085] Clause 9. The lifting system according to Clause 8 further includes a controller configured to control a drive mechanism of at least one of the variable airflow assembly or the gyroscope assembly.

[0086] Clause 10. The lifting system according to Clause 8, wherein, in the event of a power failure or the initiation of an emergency stop, the controller is configured to operate in a fail-safe mode, wherein, in the fail-safe mode, at least one of the speed of at least one gyroscope, the tilt of at least one gyroscope, or the position of the surface is controlled to a predetermined safety threshold.

[0087] Clause 11. The lifting system as described in Clause 9, wherein the controller comprises at least one of a remote controller, a turbine controller for a wind turbine, or a controller separate from the wind turbine.

[0088] Clause 12. The lifting system according to Clause 9 further includes one or more sensors communicatively coupled to the controller for monitoring the orientation of the lifting device as it is lifted to or descends from a hub mounted on the tower, wherein the one or more sensors include at least one of a Global Positioning Sensor (GPS) sensor, an accelerometer, a smart sensor, or a combination thereof.

[0089] Clause 13. A method for controlling the orientation of a lifting device for a wind turbine rotor blade as the lifting device is lifted to or from a hub mounted on or lowered from a tower of a wind turbine, the method comprising:

[0090] The variable airflow assembly is fixed to the tip of the blade of the structural frame body of the lifting device, which supports the blade root support and the blade tip support. The variable airflow assembly includes at least one surface that can operate between multiple locations with different resistances in order to counteract the asymmetric load of the lifting device.

[0091] The rotor blades are fixed to the top of the blade root support and blade tip support of the lifting device; and the lifting device is raised or lowered between the ground position and the hub, while changing between multiple positions on at least one surface to counteract asymmetrical loads.

[0092] Clause 14. The method according to Clause 13, wherein the at least one surface is one of a plurality of surfaces fitted to a frame member, a first position is synonymous with the plurality of surfaces being in an open position relative to the frame member, and a second position is synonymous with the plurality of surfaces being in a closed position relative to the frame member, wherein the open position provides a first resistance relative to an asymmetric load, and the closed position provides a second resistance relative to an asymmetric load, the second resistance being greater than the first resistance.

[0093] Clause 15. The method according to Clauses 13-14, wherein the at least one surface is fixed to the hinge point, a first position is synonymous with at least one surface being in a compressed position, and a second position is synonymous with at least one surface being in an extended position from the hinge point, wherein the compressed position provides a first resistance relative to an asymmetric load, and the extended position provides a second resistance relative to an asymmetric load, the second resistance being greater than the first resistance.

[0094] Clause 16. The method described in accordance with Clauses 13-15 further includes moving the variable airflow assembly relative to the structural frame body to a concealed position after the rotor blades have been removed from the lifting device, in order to minimize the impact of the variable airflow assembly.

[0095] Clause 17. The method according to Clause 16, wherein moving the variable airflow assembly to the concealed position comprises at least one of the following: folding the variable airflow assembly against the structural frame body, sliding the variable airflow assembly toward the center position of the structural frame body, compressing the variable airflow assembly, or receiving the variable airflow assembly in a recess of the structural frame body.

[0096] Clause 18. The method described pursuant to Clauses 13-17 further includes:

[0097] A gyroscope assembly having at least one gyroscope is connected to the lifting device; and,

[0098] When the lifting device is installed onto the hub of the tower that is fitted to the wind turbine, the orientation of the lifting device is finely adjusted.

[0099] Clause 19. The method according to Clauses 13-18 further includes automatically controlling at least one of the variable airflow assembly or gyroscope assembly via the processor of the controller to change the orientation of the lifting device when the lifting device is lifted to or from the hub mounted on the tower.

[0100] Clause 20. The method according to Clauses 13-19, wherein, in the event of a power failure or emergency stop start, at least one of the variable airflow assembly or the gyroscope assembly is operated via a controller in fail-safe mode, wherein, in fail-safe mode, at least one of the speed of the at least one gyroscope, the tilt of the at least one gyroscope, or the position of the surface is controlled to a predetermined safety threshold.

[0101] This written description uses examples to disclose this disclosure, including best practices, and also enables any person skilled in the art to practice this disclosure, including making and using any device or system and performing any incorporated methods. The patentable scope of this disclosure is defined by the claims, but may include other examples that would occur to a person skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A lifting system for rotor blades of a wind turbine, the lifting system comprising: A lifting device includes a structural frame body having a blade root end and a blade tip end, the blade root end supporting a blade root support, and the blade tip end supporting a blade tip support. Each of the blade root support and the blade tip support includes a profile corresponding to at least one outer surface of the rotor blade to receive and support at least a portion of the rotor blade. The rotor blade is subjected to asymmetrical loads when it is mounted in the lifting device and lifted onto a tower. A variable airflow assembly, coupled to the blade tip of the lifting device, includes at least one surface capable of moving between multiple locations with different resistances to counteract the asymmetric load. The variable airflow assembly is movably coupled to the blade tip of the lifting device such that after the rotor blades have been installed on the tower, the variable airflow assembly can be moved to a concealed position relative to the main structural frame to minimize the impact of the variable airflow assembly.

2. The lifting system according to claim 1, characterized in that, The plurality of positions includes at least a first position and a second position.

3. The lifting system according to claim 2, characterized in that, The at least one surface is one of a plurality of surfaces fitted to a frame member, the first position being synonymous with the plurality of surfaces being in an open position relative to the frame member, and the second position being synonymous with the plurality of surfaces being in a closed position relative to the frame member, wherein the open position provides a first resistance relative to the asymmetric load, and the closed position provides a second resistance relative to the asymmetric load, the second resistance being greater than the first resistance.

4. The lifting system according to claim 2, characterized in that, The at least one surface is fixed to a hinge point, the first position being synonymous with the at least one surface being in a compressed position, and the second position being synonymous with the at least one surface being in an extended position from the hinge point, wherein the compressed position provides a first resistance relative to the asymmetric load, and the extended position provides a second resistance relative to the asymmetric load, the second resistance being greater than the first resistance.

5. The lifting system according to claim 1, characterized in that, It also includes a gyroscope assembly comprising at least one gyroscope configured to change the orientation of the lifting device when the lifting device is lifted to or from the hub of the tower to which the wind turbine is mounted.

6. The lifting system according to claim 5, characterized in that, The at least one gyroscope includes a first gyroscope and a second gyroscope, which are respectively connected to at least one of the leaf root end and the leaf tip end of the structural frame body, or connected at a position along the middle of the structural frame body.

7. The lifting system according to claim 5, characterized in that, It also includes a drive mechanism for driving at least one of the variable airflow assembly or the gyroscope assembly, the drive mechanism comprising at least one of a generator, an integrated motor, or a separate motor.

8. The lifting system according to claim 7, characterized in that, It also includes a controller configured to control the drive mechanism of at least one of the variable airflow assembly or the gyroscope assembly.

9. The lifting system according to claim 8, characterized in that, When a power outage or emergency stop-start occurs, the controller is configured to operate in a fail-safe mode, in which at least one of the speed of the at least one gyroscope, the tilt of the at least one gyroscope, or the position of the surface is controlled to a predetermined safety threshold.

10. The lifting system according to claim 8, characterized in that, The controller includes at least one of a remote controller, a turbine controller of the wind turbine, or a controller separate from the wind turbine.

11. The lifting system according to claim 8, characterized in that, It also includes one or more sensors communicatively coupled to the controller for monitoring the orientation of the lifting device as it is lifted to or from a hub mounted on the tower, wherein the one or more sensors include at least one of a global positioning sensor (GPS) sensor, an accelerometer, a smart sensor, or a combination thereof.

12. A method for controlling the orientation of a lifting device for rotor blades of a wind turbine as the lifting device is lifted to or lowered from a hub mounted on or from a tower of a wind turbine, the method comprising: A variable airflow assembly is fixed to the tip of the blade of the structural frame body of the lifting device, the structural frame body supporting the blade root support and the blade tip support. The variable airflow assembly includes at least one surface that is operable between multiple locations with different resistances in order to counteract the asymmetric load of the lifting device. The rotor blades are fixed to the top of the blade root support and blade tip support of the lifting device; as well as, The lifting device is raised or lowered between its ground position and the hub, while simultaneously varying its position between multiple locations on at least one surface to counteract the asymmetric load. The method further includes moving the variable airflow assembly relative to the structural frame body to a hidden position after the rotor blades have been removed from the lifting device, in order to minimize the impact of the variable airflow assembly.

13. The method according to claim 12, characterized in that, The at least one surface is one of a plurality of surfaces fitted to a frame member, a first position of the plurality of positions being synonymous with the plurality of surfaces being in an open position relative to the frame member, and a second position of the plurality of positions being synonymous with the plurality of surfaces being in a closed position relative to the frame member, wherein the open position provides a first resistance relative to the asymmetric load, and the closed position provides a second resistance relative to the asymmetric load, the second resistance being greater than the first resistance.

14. The method according to claim 12, characterized in that, The at least one surface is fixed to a hinge point, a first position of the plurality of positions is synonymous with the at least one surface being in a compressed position, and a second position of the plurality of positions is synonymous with the at least one surface being in an extended position from the hinge point, wherein the compressed position provides a first resistance relative to the asymmetric load, and the extended position provides a second resistance relative to the asymmetric load, the second resistance being greater than the first resistance.

15. The method according to claim 12, characterized in that, Moving the variable airflow assembly to the hidden position includes at least one of the following: folding the variable airflow assembly against the structural frame body, sliding the variable airflow assembly toward the center of the structural frame body, compressing the variable airflow assembly, or receiving the variable airflow assembly in a recess of the structural frame body.

16. The method according to claim 12, characterized in that, Further includes: A gyroscope assembly having at least one gyroscope is connected to the lifting device; as well as, When the lifting device is installed onto the hub of the tower that is mounted on the wind turbine, the orientation of the lifting device is finely adjusted.

17. The method according to claim 16, characterized in that, It also includes automatically controlling at least one of the variable airflow assembly or the gyroscope assembly via the controller's processor to change the orientation of the lifting device when the lifting device is lifted to or from the hub mounted on the tower.

18. The method according to claim 16, characterized in that, When a power outage or emergency stop-start occurs, at least one of the variable airflow assembly or the gyroscope assembly is operated in fail-safe mode via the controller. In fail-safe mode, at least one of the speed of the at least one gyroscope, the tilt of the at least one gyroscope, or the position of the surface is controlled to a predetermined safety threshold.

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