Abstract: A tower crane includes a tower on which a rotating portion is pivotally mounted and configurable between a service configuration in which the rotating portion can be rotatably driven by a motorized orientation system, and an out of service configuration in which the rotating portion is rotatably released to be able to be oriented in the direction of the wind. A control/command unit activates a monitoring mode in the out of service configuration to detect, depending on variations in the angle of orientation or the angular speed of the rotating portion, if the rotating portion is in one of the following movement states: an autorotation state corresponding to a rotary movement of the rotating portion in a given direction over at least one complete turn; or an oscillation state corresponding to a back and forth movement of the rotating portion about the orientation axis.

Abstract: The invention relates to a method of weathervaning a work machine in out-of-operation mode, in particular of weathervaning a revolving crane/revolving tower crane or a concrete spreader mast, wherein the work machine comprises at least one slewing part that is rotatable about a substantially vertical axis by means of a slewing gear, and wherein in a first step one or more wind data are measured by means of a measurement system arranged at the work machine; an optimum position of the slewing part is determined for an optimum weathervaning in dependence on the detected wind data; and the slewing gear drive is subsequently correspondingly actuated to bring the slewing part into the determined position.

Abstract: Aspects of the present disclosure relates to disruptive coupling systems and methods, and apparatus thereof, for subsea systems. The subsea systems may be subsea oil and gas systems. In one implementation, a subsea system includes a subsea component disposed in seawater, and a disruptive coupling device coupled to the subsea structure and/or surrounding fluid.

Abstract: A monitoring detection device and crane for displaying real-time hook bias angle, characterized in that a fixed pulley assembly a1 of a crane is hung on a lifting lug b2 of a crane boom b1 by a shackle a5 through a connector a3. the connector a3 is connected to the fixed pulley assembly a1 through a articulated shaft a2 which is arranged in a direction perpendicular to the axis of a fixed pulley; a platform surface perpendicular to a pulley block force application line or a line parallel to the pulley block force application line is arranged on the connector to be used to. Beneficial effects: the real-time hook bias angle can be accurately displayed when the crane is lifting: Beneficial effects: the real-time hook bias angle can be accurately displayed when the crane is lifting.

Abstract: Methods and systems for monitoring at least one crane, preferably two or more cranes, in particular revolving tower cranes, on a construction site, wherein one or more optical detection means are provided, and wherein a collision monitoring unit analyzes the recorded optical data to recognize a possible collision between at least one crane and one further crane and/or another projecting edge.

Abstract: A system and computer-implemented method is used for operating a crane on an offshore unit on which entities (e.g., personnel and/or equipment) operate. A dimensional map of the unit is created so locations of the entities can be tracked in the dimensional map of the unit. For example, wireless monitoring is received from wireless devices associated with both the entities and the offshore unit to perform the tracking. Dynamic operating parameters of the crane are also obtained while the crane is operating on the unit. These parameters can be received remotely from the crane. A programmable control device calculates a lifting zone that moves dynamically in the dimensional map based on the parameters, detect a conflict of a tracked location interfering with the zone, and outputs the detected conflict for appropriate action.

Abstract: A safety system and method of use is provided for a tow cable handling system. In use, the cable is from a winch and onto a sheave where a cable tension surge is transmitted to a meter and onto a software element. The software of a controller determines torque needed from a motor to increase winch speed to unreel cable to relieve the surge but not too much that the cable will unreel off the winch. Once the surge concludes, the motor reverses and decreases speed of the winch. If the tension surge is transient, then the motor can increase the winch speed and then slow down the winch before the cable completely unreels. The sheave is suspended by a spring and a dashpot for an over-damped response to increase the time for the winch to speed up to an acceptable speed.

Abstract: A computing system (CS) calculates a three-dimensional (3D) position of an origin of a 3D upperworks coordinate system for a crane based on local coordinates of the crane. The origin is located along an axis of rotation between an upperworks of the crane and a lowerworks of the crane that is rotatably coupled with the upperworks. The CS transforms the 3D position of the origin from the local coordinates to global 3D coordinates using absolute position sensing data from first and second positioning sensors attached to the crane and using global 3D coordinates specific to the jobsite where the crane is located. The CS computes positions of at least one movable component of the crane with respect to a tracked object on the jobsite. The CS utilizes the computed positions to provide assistance in maneuvering the crane with respect to the tracked object.

Abstract: A lifting hook bias angle monitoring apparatus, a vertical hoisting monitoring apparatus, and a mobile crane. One method is that a lifting hook assembly serially connects connecting plates (b3) provided with hinge connection shafts (b2, b4) at two ends to a movable pulley component (b1) which bears a pulling force and a lifting hook component (b7) which bears a pulling force, and is also provided with a biaxial inclinometer (b9) on a platform surface (b8) of the connecting plates (b3) which is perpendicular to a lifting force line of action of the lifting pulley component, so as to detect a real-time lifting hook bias angle, and accordingly be developed into a mobile crane having a vertical hoisting monitoring function.

Abstract: The present invention relates to a vessel comprising:-a hull,-a support structure connected to said hull, the support structure configured for supporting the mass, the support structure being constructed to allow the mass to make a back and forth movement relative to said hull along a trajectory between opposite ends of said trajectory,-a damping device configured to dampen the movement of the mass relative to said hull. The present invention also relates to a method for damping the movements of a vessel or of a mass.

Abstract: The present disclosure relates to a method for controlling the orientation of a crane load, wherein a manipulator for manipulating the load is connected by a rotator unit to a hook suspended on ropes and the skew angle ?L of the load is controlled by a control unit of the crane, characterized in that the control unit is an adaptive control unit wherein an estimated system state of the crane system is determined by use of a nonlinear model describing the skew dynamics during operation.

Abstract: Disclosed in the present invention is a crane, method and apparatus for monitoring the swing angle, weight or gesture of the crane load, belonging to the technical field of crane; the purpose of the present invention is provide an apparatus for monitoring the swing angle, weight or gesture for the crane's hoisting, and to provide a crane which comprises aforesaid apparatus; when hoisting a load, the swing angle, weight or gesture are displayed in both the native crane cab and the collaborative crane cab by wireless transmission and switching channels in the cab; then, not only can the drivers operate the cranes to eliminate the deflection of load and achieve the vertical hoisting according to the load's swing angle of each crane displayed on the screen, but also operate the cranes to make balance of weight distribution according to the real-time ratio of load weight or load gesture.

Abstract: The various embodiments of the present disclosure relate generally to crane control systems. An exemplary embodiment of the present invention provides a crane control system comprising a real-time position-location module, an on-off controller module, and an input-shaper module. The real-time position-location module generates a position signal indicative of the distance between crane trolley and a desired location of safety. The on-off controller module maps the position signal to a velocity command signal, wherein the velocity command signal comprises instructions for the crane trolley to move in a vector relative to the desired location in at least a first velocity only if the distance between the crane trolley and the desired location is greater than a cut-off threshold 150. The at least a first velocity is a substantially constant. The input shaper module manipulates the velocity command signal mapped by the on-off controller module to dampen payload oscillations.

Abstract: A device associated with a crane is described for the control of unwanted movements of a load that is connected to a hoisting line (14) via a number of branch hoisting wires (28, 29), and it is characterised in that the crane derrick comprises means that are arranged to push against the branch wires to dampen and eliminate the unwanted movements. According to the invention the device is used to control rotary movements of a container with four hoisting wires connected to a hook (36) at the end of the main hoisting wire (14) and the arm (22) is unfolded into an approximately vertical position, the two branch arms (28, 29) are folded out into a T-shape (FIG. 5), the arm is rotated further so that the branch arms (30, 32) push against the branch wires (28, 29) with a power sufficient to prevent the container from moving in unwanted ways. According to one variant, a device associated with a crane is proposed for the control of the hoisting line (13) itself for a load.

Abstract: A machine including an implement system pivotably mounted on the machine, a thumb member mounted on an arm of the implement system for free dampened back and forth pivotable movement, the thumb member being controllably pivotable into selectable pivot positions via controlled pivoting of one or the other or both of the arm and a bucket member, a dampener being interconnected between the thumb member and the arm in an arrangement where the dampener dampens free pivoting movement of the thumb member.

Abstract: A hoisting assembly for lifting or lowering a heavy object includes an upper fixed block, an upper movable block being suspended from the upper fixed block by at least one first rope which is reeved into one or more first rope lengths between the upper fixed block and the upper movable block, a lower movable block being connected to the upper movable block by at least one second rope which is reeved into one or more second rope lengths between the upper fixed block and the upper movable block. The first and second ropes are reeved in such a way that in use the upper movable block can be positioned at a distance greater than zero from the upper fixed block and at a distance greater than zero from the lower movable block by controlling the lengths of the first and second ropes.

Abstract: The present invention relates to a crane for handling a load hanging on a load cable, comprising a slewing gear for rotating the crane, a luffing gear for luffing up the boom, and a hoisting gear for lowering or lifting the load hanging on the load cable, with a control unit for calculating the actuation of slewing gear, luffing gear and/or hoisting gear, wherein the calculation of the actuation commands for actuating slewing gear, luffing gear and/or hoisting gear is effected on the basis of a desired movement of the load indicated in Cartesian coordinates.

Abstract: For load compensation, different kinds of elastomeric load compensators are placed at various locations on the crane for increased flexibility and for shock and vibration absorption. The elastomeric load compensators employ elastomeric tension elements, elastomeric torsion elements, or elastomeric shear elements. Elastomeric tension elements can be simply inserted in series with the main hoist rope. An elastomeric load compensator employing elastomeric torsion elements is mounted to the underside of the boom for receiving the live end of the main hoist rope. A single stack of elastomeric shear elements is suitable for mounting a hoist or winch or an idler sheave to the crane structure. For additional load compensation, the hoist, winch, and idler sheaves are mounted on rails for increased displacements under heave loads, and the increased displacements are compensated by elongated elastomeric tension elements or multiple elastomeric tension, torsion or shear elements in series.

Abstract: Disclosed is an apparatus, system, and method for sensing the current supplied to a motorized hoist for raising a maintenance platform and providing an estimate of the operating status of the motor, for example, as stopped, starting, stalled or operating as expected. In various embodiments, measures of voltage and current may be used to determine the operating condition of the hoist and to estimate the magnitude of the applied load. Unintended modes of operation can then be determined so that the conditions can be indicated to the operator and protective measures taken.

Abstract: The present invention relates to a crane control for the control of a hoisting gear of a crane which takes account of oscillation dynamics based on the elasticity of the hoist rope on the control of the hoisting gear and reduces them by a suitable control of the hoisting gear.

Abstract: The present invention relates to a crane having a load hook directly/indirectly fastened to the crane hoist rope and having a frame suspended at the load hook for taking up a special load, in particular for taking up a rotor blade of a wind turbine, wherein the control element(s) of a frame suspended at the load hook is/are guided along a guider rope region of the crane hoist rope.

Abstract: A method for reducing resonant vibrations and dynamic loads of cranes, whose horizontal and vertical motion of the pay load are controlled by a boom winch controlling the luffing motion of a pivoting boom and a hoist winch controlling the vertical distance between a boom tip and the load. Where the method includes determining the resonance frequencies of the coupled crane boom and load system, either experimentally or theoretically at least from data on inertia of the boom and stiffness of at least a boom rope, a hoist rope, a pedestal and an A-frame. The method further includes automatically generating a damping motion in at least one of said winches, that counteracts dynamic oscillations in the crane, and adding this damping motion to the motion determined by a crane operator.

Abstract: In a method and apparatus for moving a free-swinging load that is suspended relative to a suspension point, a first path along which the load should be moved from a starting point to a destination, with a first location-dependent velocity, is provided to a processor. In the processor, a second path is automatically determined along which the suspension point should be moved with a second location-dependent velocity to cause the load to move along the first path from the starting point to the destination with the first location-dependent velocity. A movement-imparted mechanism, connected to the suspension point, is automatically controlled from the processor to move the freely-suspended load from the starting point to the destination by moving the suspension point along the second path with the second location-dependent velocity.

Abstract: A system and method for using a gantry crane to efficiently and safely transport loads such as containers and ship hatch covers from one location to another along a known path while avoiding collisions between the loads and obstructing objects which may be situated in the known path. A transceiver emitting laser beams may be used to establish both the position of the spreader and its load and the profile of the known path. Continuous comparisons are made by computer between the location of a dynamic digital protective envelope constructed around the crane spreader and its load, if any, and a digital representation of the profile of the known path to be traveled by the spreader and its load, if any. In the event, the comparison indicates intersection of the protective envelope and the path profile, a speed limit is imposed on the motor controlling the movement in the X axis of the trolley or in the Z axis of the spreader, as required to prevent a collision.

Abstract: Disclosed are various embodiments of methods and systems related to double-pendulum crane control. In one embodiment for determining a specified insensitivity (SI) input shaper for a double-pendulum crane, the method using a processor system to implement the steps including determining a plurality of insensitivity ranges based upon operational parameters associated with the double-pendulum crane; and determining SI input shaper parameters based upon tolerances corresponding to the plurality of insensitivity ranges, the SI input shaper parameters including an amplitude and a time corresponding to each impulse of the SI input shaper.

Abstract: A method for mounting a wind turbine blade to a wind turbine hub by use of a crane boom is provided. The orientation of the blade is kept substantially horizontal when the blade is lifted off the ground and mounted to the rotor hub. Control wires which connect the blade via the crane boom to a winch arrangement are used for keeping the blade orientation substantially horizontal in addition to at least one bearing wire for bearing the blade weight.

Abstract: A method and a system for controlling a crane drive unit so as to suppress sway of a load suspended by a rope of a crane, which sway occurs when the load has been transported from a first position to a second position, the control being made by operating a controller having a filter unit by using a feedforward control program.

Abstract: A device associated with a crane is described for the control of unwanted movements of a load that is connected to a hoisting line (14) via a number of branch hoisting wires (28, 29), and it is characterised in that the crane derrick comprises means that are arranged to push against the branch wires to dampen and eliminate the unwanted movements. According to the invention the device is used to control rotary movements of a container with four hoisting wires connected to a hook (36) at the end of the main hoisting wire (14) and the arm (22) is unfolded into an approximately vertical position, the two branch arms (28, 29) are folded out into a T-shape (FIG. 5), the arm is rotated further so that the branch arms (30, 32) push against the branch wires (28, 29) with a power sufficient to prevent the container from moving in unwanted ways. According to one variant, a device associated with a crane is proposed for the control of the hoisting line (13) itself for a load.

Abstract: The lifting gear comprises two motors (1, 1?) that are connected to a transmission (6) via respective drive shafts (2, 2?), couplings (3, 3?), with fitted brake disks (4, 4?) or brake drums, brakes (14, 14?) and transmission input shafts (5, 5?). The transmission (6) drives cable drums (9, 9?) via transmission output shafts (7, 7?) and couplings (8, 8?). The cable drums have a cable pull (12, 12?) and fitted brake disks (10, 10?) or brake drums and safety brakes (11, 11?). The inventive lifting gear is characterized by comprising, in the drive shafts (2, 2?), devices (13, 13?) that completely or partially disconnect the motors (1, 1?) from the transmission (6) when an excess load exceeds the predetermined load. They are monitored on both sides of the devices (13, 13?) and the brakes (14, 14?) and/or safety brakes (11, 11?) are activated in the event of disconnection.

Abstract: This invention provides a device for preventing sway of a suspended load, which does not require complex calculation for eliminating frictional resistance components. The device is equipped with a speed control device (14) for outputting a torque command based on a speed command, a torque command filter (16), and a load torque observer (4) for estimating the load torque, and configured to output a value obtained by adding a load torque estimation signal to an output of the torque command filter (16). The device is further equipped with a high-pass filter (32) for outputting a signal TRFLHPF in which a frictional resistance component is eliminated from the load torque estimation signal and a sway angle calculator (33) for outputting a sway angle estimation calculated value ?e obtained by multiplying a sway angle calculator factor by the output signal TRFLHPF.

Abstract: The present invention relates to a crane control for the control of a hoisting gear of a crane which takes account of oscillation dynamics based on the elasticity of the hoist rope on the control of the hoisting gear and reduces them by a suitable control of the hoisting gear.

Abstract: The present invention comprises a method for the control of a drive of a crane, in particular of a slewing gear and/or of a luffing mechanism, wherein a desired movement of the boom tip serves as an input value on the basis of which a control parameter for the control of the drive is calculated, characterized in that the oscillation dynamics of the system comprising the drive and the crane structure are taken into account in the calculation of the control parameter to reduce natural oscillations. The present invention furthermore comprises a method for the control of a hoisting gear of a crane, wherein a desired hoisting movement of the load serves as an input value on the basis of which a control parameter for the control of the drive is calculated.

Abstract: The invention relates to a method for the transfer of a load hanging at a load rope of a crane or excavator comprising a slewing gear, a luffing mechanism and a hoisting gear comprising a computer-controlled regulator for the damping of the load oscillation which has a trajectory planner, a disturbance observer and a state regulator with a pre-control, wherein the working space is first fixed by selection of two points, with one of the two points being fixed as the destination point by direction presetting by means of the hand lever and with the nominal speeds for the slewing gear and the luffing mechanism being preset by the hand lever signals.

Abstract: A crane having an upper block, a lower block, a drum, and two ropes. The upper block includes an equalizer having a yoke to which the ropes are connected. The connections between the ropes and the yoke include load cells that measure the forces carried by each of the ropes. The upper block includes a fail-safe system that prevents failure of the upper block in overload conditions.

Abstract: A rotary part of a crane is associated with an electric slewing mechanism including at least one geared electric motor unit of which the electric motor is powered in such a way as to produce a slewing torque having a certain maximum value. When the crane is in use and for conditions such as windspeed greater than a given value, jib length greater than a given value and moment of the lifted load greater than a given value, the maximum value of a slewing torque produced by the electric motor is increased. The crane thus becomes easier to drive, particularly in the phases during which the jib is adopting a “windward trend”.

Abstract: A crane having an upper block, a lower block, a drum, and two ropes. The upper block includes an equalizer having a yoke to which the ropes are connected. The connections between the ropes and the yoke include load cells that measure the forces carried by each of the ropes. The upper block includes a fail-safe system that prevents failure of the upper block in overload conditions.

Abstract: A gantry with a buffering structure cooperates with a base and comprises a gantry and a buffering structure. Both ends of the gantry are provided with a connecting portion, respectively. One of the connecting portions is fixed on the base, and the buffering structure is disposed between the other connecting portion of the gantry and the base. Thereby, when the gantry moves along with the base, the gantry can absorb the inertial strength caused by displacement and the deformation caused by thermal expansion and contraction by the flexibility of the buffering structure.

Abstract: The present invention shows a crane control of a crane which includes at least one cable for lifting a load, wherein at least one sensor unit is provided for determining a cable angle relative to the direction of gravitational force. Furthermore, there is shown a crane control for driving the positioners of a crane which includes at least one first and one second strand of cables for lifting the load, with a load oscillation damping for damping spherical pendular oscillations of the load, wherein first and second sensor units are provided, which are associated to the first and second strands of cables, in order to determine the respective cable angles and/or cable angular velocities, and the load oscillation damping includes a control in which the cable angles and/or cable angular velocities determined by the first and second sensor units are considered. Furthermore, a corresponding crane and a method are shown.

Abstract: The invention refers to a crane or excavator for the transaction of a load, which is carried by a load cable with a turning mechanism for the rotation of the crane or excavator, a seesaw mechanism for the erection or incline of an extension arm and a hoisting gear for the lifting or lowering of the load which is carried by a cable with an actuation system. The crane or excavator has, in accordance with the invention, a track control system, whose output values are entered directly or indirectly as input values into the control system for position or speed of the crane or excavator, whereas the set points for the control system in the track control are generated in such a way that a load movement results from it with minimized oscillation amplitudes.

Abstract: An apparatus including a main housing including a generally horizontal platform, a boom extending from the platform, a bucket suspended from the boom, and a mast extending from the platform. The apparatus further includes a boom support strand extending between and attached to the mast and the boom, and a boom support strand oscillation dampening mechanism. The boom support strand oscillation dampening mechanism comprises a left brace and a right brace spaced apart from the left brace, and a polyester rope extending between each of the braces and the boom. Each of the ropes is attached to the boom. A device attaches the rope to the brace, and a boom support strand clamp mechanism is connected to the brace and includes a first clamp block, a second clamp block, and a flexible enclosure placed between the first clamp block and the second clamp block.

Abstract: The present disclosure relates to a method of operating a crane whose safe working load depends on one or more changeable parameters, with the change of at least one of the parameters being made such that the speed of the parameter change is reduced continuously or step-wise before a parameter value is reached at which the safe working load corresponds to the actual working load.

Abstract: A crane having an upper block, a lower block, a drum, and two ropes. The upper block includes an equalizer having a yoke to which the ropes are connected. The connections between the ropes and the yoke include load cells that measure the forces carried by each of the ropes. The upper block includes a fail-safe system that prevents failure of the upper block in overload conditions.

Abstract: Systems, methods and computer program code for the measurement and control of sway in load transportation systems are provided which include using Micro-Electro-Mechanical Systems (MEMS) devices to measure and control the sway of suspended loads such as loads suspended from cranes.

Abstract: A steering system (10) for a vehicle, such as a gantry crane (12). The gantry crane (12) generally includes a support structure (14) having a first front wheel (32) and a second opposing front wheel (36) connected proximate a front portion of the crane (12), and a first rear wheel (30) and a second opposing rear wheel (34) connected proximate a rear portion of the crane (12). A control system connected to the crane includes a user interface (111) electronically coupled to a command potentiometer (114) and a programmable controller responsive to the command potentiometer for controlling the angular position of each of the first front wheel (32), the second front wheel (36), the first rear wheel (30) and the second rear wheel (34) to effect a steering mode selected through the user interface (111).

Abstract: A rack serving unit comprises a carriage which may be moved along a rack aisle on substantially horizontal carrying rails. Carried along by the carriage there is a lifting platform which is suspended on the carriage by way of at least two traction mechanisms, preferably cables, and may be moved in the vertical direction with respect to the carriage. To stabilise the lifting platform against undesired lateral movements, a stabilising device is provided which comprises at least one guide element extending substantially horizontally parallel to the translatory movement path of the lifting platform. This guide element is in constant engagement with the lifting platform in such a way that the position of this latter in the direction of the translatory movement is constantly defined. Provided at both ends of the translatory movement path, there is a lifting device for each guide element by means of which the guide element may be moved synchronously with the lifting platform in the vertical direction.

Abstract: A steering system (10) for a vehicle, such as a gantry crane (12). The gantry crane (12) generally includes a support structure (14) having a first front wheel (32) and a second opposing front wheel (36) connected proximate a front portion of the crane (12), and a first rear wheel (30) and a second opposing rear wheel (34) connected proximate a rear portion of the crane (12). A control system connected to the crane includes a user interface (111) electronically coupled to a command potentiometer (114) and a programmable controller responsive to the command potentiometer for controlling the angular position of each of the first front wheel (32), the second front wheel (36), the first rear wheel (30) and the second rear wheel (34) to effect a steering mode selected through the user interface (111).

Abstract: A sway dampener is provided for reducing sway motion of a gantry crane spreader that is suspended from hanger chains. The sway dampener is configured to resist motion of the hanger chain relative to the spreader, thereby retarding sway. The dampener includes first and second portions that are movable relative to each other in a resistive fashion, for example a piston-cylinder structure. The first portion is mounted to the spreader and the second portion is mounted to the hanger chain at an attachment point located a vertical distance above a point at which the hanger chain is pivotally mounted to the spreader so that horizontal sway motion of the attachment point relative to the spreader displaces the first and second portions.

Abstract: An applicator boom apparatus comprises an applicator boom extending laterally from a vehicle, and pivotally attached to the vehicle such that the boom can pivot up and down with respect to the vehicle. A kit provides a gauge member adapted to ride along a surface of the ground and support an outer portion of the boom such that the boom moves up and down with the gauge member as the gauge member rides along the ground, and also provides an active hydraulic source powering the shoulder hydraulic cylinder of the apparatus such that the shoulder hydraulic cylinder exerts an upward force on the boom such that a downward force exerted on the gauge member by the boom is reduced.

Abstract: The invention concerns a method for stabilizing the motion of an articulated chain of a chain block, especially to prevent the formation of resonance oscillation of the chain, in which an articulated chain is led across a polygonal chain wheel with non-uniform pitch, which is driven by an electric motor. In order to create a method to prevent the formation of a resonance oscillation of the articulated chain, it is proposed that a periodic and/or stochastic and dampening actuating variable is superimposed on the velocity of the chain wheel (4) and the dampening actuating variable produces a change in the chain velocity so as to prevent a formation of a resonance oscillation. The chain drive with reduced polygon effect is characterized in that an electronic damper (8) is hooked up in front of the electric motor (2), which produces a control of the electric motor (2) such that a formation of a resonance oscillation of the articulated chain (5) is prevented.

Abstract: A system and process are provided for controlling motion of a grappler of a gantry crane to avoid damaging an object to be lifted. In an embodiment, a speed of grappler movement is automatically reduced when in close proximity to the object. Furthermore, the grappler automatically stops when positioned appropriately to permit a latching mechanism to engage the object for lifting. Normal speed grappler motion is restored when the latching mechanism is fully engaged. In a particular embodiment, the grappler includes a plurality of height sensors at various positions along the grappler to determine the respective height of the grappler above a top of the object. Vertical motion of front and rear ends of the grappler are independently actuated and controlled to permit appropriate control when the grappler and/or the object are not level.