Patent Description:
Reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge.

Warning devices to signal or to correct an unsafe lifting condition in the use of cranes are known.

One such dangerous condition involves lifting, when the crane boom is misaligned vertically with the radius of the load whereupon the crane and associated components would become overloaded, or more critically, the resulting swinging action of the load could cause the crane to be overturned.

Crane operators with many years of experiences are generally proficient in visually identifying an overloaded crane boom. However, after attachment of the lift cable hook to the load point and slack is taken up in the lift cable, the lift cable can remain out of plumb by several degrees. Such a situation can lead to an unsafe operating condition with the result that when the load is lifted, it suddenly swings, causing equipment damage or injury to people in the surrounding area.

The difficulty of accurately identifying problems with the crane boom is increased when the boom is particularly long and/or elevated to a high angle and can be further complicated when a prevailing wind is present.

Furthermore, in some situations, the load to be lifted is out of view by a crane operator and the operator must rely solely upon instructions issued by a third party, such as a Rigger or Dogman.

<CIT> discloses a luffing crane according to the preamble of claim <NUM>. More in detail, it relates to crane load space swing angle detection technology and an apparatus thereof, wherein the apparatus comprises a measurement box and a signal receiving processor. According to the technology, a sensor in the measurement box arranged on a lifting hook/load measures a spatial attitude of the lifting hook/load relative to a geodetic coordinate, the signal receiving processor arranged on a crane body/boom measures a spatial attitude of the crane body/boom relative to the geodetic coordinate based on the sensor, a spatial attitude parameter of the crane load relative to the crane body/boom can be calculated through coordinate transformation, and the calculated parameter can be transmitted to a crane control box through a bus control unit to automatically control. With the present invention, a spatial swing condition of the crane load can be accurately measured so as to help the crane to achieve anti-swing control and improve safety production efficiency.

It is an aim of this invention to provide a sensing device for assisting crane riggers which overcomes or ameliorates one or more of the disadvantages or problems described above, or which at least provides a useful commercial alternative.

Other preferred objects of the present invention will become apparent from the following description.

The invention resides in a sensing device for a crane for detecting unsafe operating conditions comprising:.

The sensing device is adapted to activate an alert element if the deviation of the hook is within a predefined range.

The sensing device is adapted to indicate a plumb or an out of plumb lift cable attached to a load.

The inertial measurement unit comprises an electronic gyroscope adapted to measure orientation of the hook and obtain orientation data. Preferably, the inertial measurement unit further comprises an accelerometer adapted to measure orientation of the hook and obtain orientation data. Preferably, the gyroscope and the accelerometer are adapted to measure deviation from vertical pitch of the hook.

The inertial measurement unit comprises a magnetometer adapted to measure changes of the hook relative to magnetic north. The magnetometer is adapted to measure yaw of the hook.

The sensing device further comprises a microcontroller. the microcontroller is arranged to calculate a compensation factor for the magnetometer. Preferably, the microcontroller is arranged to calculate the compensation factor to compensate for heavy iron present in the hook.

The microcontroller is arranged to combine orientation data measured by the accelerometer and the gyroscope with a statistical estimation filter. Preferably, the statistical estimation filter comprises a Kalman filter. the microcontroller is arranged to use the combination of the orientation data with the statistical estimation filter to determine deviation from the plumb position.

Preferably, the sensing device comprises a housing. Preferably, the housing is waterproof. Preferably, the inertial measurement unit is located within the housing.

Preferably, the sensing device is removably attached to a collar of the hook.

Preferably, the inertial measurement unit is adapted to measure the deviation of the hook in degrees.

Preferably, the sensing device is connected to a graphical display device. Preferably, the sensing device is wirelessly connected to the graphical display device.

Preferably, the sensing device is arranged to operate the graphical display device to display a visual indication of the hook in relation to the plumb position on the graphical display device.

Preferably, the sensing device is connected to a crane sensor bus. Preferably, the sensing device is arranged to read one or more of a load weight, a boom radius, a boom length and a total weight from the crane sensor bus.

Preferably, the alert element is in the form of an audible signal generator or a visual signal generator, such as a flashing light or a pop-up on a graphic display.

The invention further resides in a method for detecting an unsafe operating lifting condition for a crane, the method comprising the steps of:.

Preferably, the method comprises the further step of determining if the deviation of the hook from the plumb position is less than or greater than a predetermined limit.

Preferably, the step of determining a deviation of the hook comprises calculating an angle of pitch of the hook using the inertial measurement unit. Preferably, the step of determining a deviation further comprises calculating the angle of yaw of the hook using the inertial measurement unit.

Preferably, if the deviation of the hook is greater than a predetermined limit, the method comprises the further step of operating an alert element to indicate that the deviation of the hook is greater than the predetermined limit. Preferably, the alert element indicates that the operating condition of the crane is unsafe.

Preferably, the method comprises the further step of determining if the hook is in a plumb or out of plumb position.

Preferably, if the deviation of the hook is less than the predetermined limit, the method comprises the further step of operating an alert element to indicate that the deviation of the hook is less than the predetermined limit. Preferably, the alert element indicates that the operating condition of the crane is safe or within the predetermined limit.

Preferably, the alert element comprises a display device of an operator of the crane and/or a rigger.

Preferably, the step of calculating the angle of the pitch plane comprises comparing data obtained from a gyroscope and an accelerometer with a gravity vector. Preferably, the data from the gyroscope comprises the angular momentum of the hook. Preferably, a statistical estimation filter is applied to the data obtained from the gyroscope and the accelerometer.

Preferably, the method further comprises the step of calculating yaw of the hook. Preferably, yaw of the hook is calculated by a magnetometer. Preferably, the magnetometer compensates for any twist in the cables attached to the hook.

Preferably, the alert element is in the form of an audible signal generator or a visual signal generator, such as a flashing light or graphic display element.

Preferably, the alert element is received by a graphical display device. Preferably, the alert element is transmitted to and received by the graphical display device wirelessly over a Low-Power Wide-Area Network (LPWAN) for long range communication.

In another form, the invention resides in a system for determining deviation of a hook from a plumb position, the system comprising:.

Further features and advantages of the present invention will become apparent from the following detailed description.

By way of example only, preferred embodiments of the invention will be described more fully hereinafter with reference to the accompanying drawings, which are as follows:.

<FIG>, <FIG> and <FIG> illustrate a crane hook sensing device <NUM> for detecting an unsafe, out of plumb, lifting hook <NUM> of a luffing type crane <NUM> (shown in <FIG>).

The crane hook sensing device <NUM> calculates angles and deviations from inertial axes to determine the optimal rigging application of a load <NUM> engaged by hoist cables <NUM> of the crane <NUM>.

Turning to <FIG>, there is illustrated a system <NUM> including the crane hook sensing device <NUM>, the cabin processor assembly <NUM> and rigger display device <NUM>.

The crane hook sensing device <NUM> comprises a microcontroller board <NUM> which includes a microcontroller <NUM> that accesses a digital memory <NUM> that stores firmware <NUM> containing instructions to calculate the angle θ<NUM> of deviation from a vertical axis (or plumb position) of the hook <NUM> relative to the boom head <NUM>, as well as compensation for any twist of the hook <NUM>. Twisting of the hook <NUM> typically occurs when a hook block is reeved with an odd number of falls of hoist rope or wind loading and affects the horizontal orientation (yaw) of the hook <NUM> which will affect the accuracy of calculations of existing systems.

The plumb position is defined by a vertical line <NUM> (seen in <FIG>) extending from the ground to the boom head <NUM>.

The microcontroller <NUM> also operates radio communications Tx/Rx unit <NUM> to establish radio communications with Tx/Rx unit <NUM> of between the crane cabin <NUM> and rigger display <NUM> using a long range radio technology, such as Low-Power Wide-Area Network (LPWAN) for example.

The crane hook sensing device <NUM> includes an inertial measurement unit (IMU) <NUM> in communication with microcontroller <NUM>. The IMU <NUM> measures the <NUM>-axis orientation of the hook <NUM> (i.e. pitch, roll and yaw). The IMU <NUM> includes a gyroscopic sensor <NUM> (such as an electronic gyroscope) for providing long term orientation data and an accelerometer <NUM> for providing short term orientation data combined with a Kalman filter (or other suitable statistical estimation filter) to accurately determine the variation from the gravity vector.

A magnetometer <NUM> of the IMU <NUM> measures the yaw changes of the hook <NUM> relative to magnetic north, with calculations in accordance with firmware <NUM> made to compensate for the heavy iron of the hook <NUM> which the sensing device <NUM> is mounted upon.

The hook sensing device <NUM> is housed within a waterproof housing <NUM> having a mounting bracket which is removably affixed to the collar <NUM> of the hook <NUM> inside the cheekbones <NUM> of the hook block. Advantageously, the sensing device <NUM> can be removed from the hook <NUM> for recharging and maintenance, as required.

The sensing device <NUM> is powered by a battery <NUM> located within the housing <NUM>. In some preferable embodiments, the battery <NUM> is a rechargeable battery that can be recharged using a standard USB charging cable.

Located in the cabin <NUM> of the crane <NUM> is a cabin processor assembly <NUM> connected to the crane sensor bus <NUM> and coupled to cabin radio Tx/Rx unit <NUM>. The assembly <NUM> reads lift specific data streams from the existing crane sensors S1,. ,Sn including the following: load weight, boom radius, boom length and total weight.

The extraction of this data from the crane sensors S1,. Sn is make and model dependent and relies on integration technology in the cabin processor assembly <NUM> that can handle different connections and data formats for different cranes.

A display <NUM> within the cabin <NUM> provides the operator <NUM> with a graphical view of the orientation of the hook in relation to the centre of the load <NUM> as a bird's eye view of the horizontal plane. The display <NUM> uses a microprocessor programmed with software to extract the crane data as well as draw the display. Hardware specific to the integration required to extract the crane data is used to connect the display <NUM> to the existing crane sensors S1,.

The Rigger <NUM> also has a display assembly <NUM>. The Rigger display assembly <NUM> includes a radio receiver <NUM> that receives the data stream sent by the radio Tx/Rx unit <NUM> of sensing device <NUM> which includes the real time calculation results that the Rigger <NUM> can use to adjust the load <NUM> for optimal lifting. The format of the display <NUM> can vary, from smart phones to smart glasses, or specifically designed display apparatus that is appropriate for onsite construction use.

The Rigger display <NUM> provides a graphical plumb gauge that highlights the deviation in degrees (from +<NUM>° to -<NUM>°) from the vertical as well as other data from the crane sensors S1,. Sn like weight and other indications relevant to the Rigger <NUM>.

The radio Tx/Rx unit <NUM> comprises long range radios for bidirectional communication between the sensing device <NUM>, the radio Tx/Rx unit <NUM> of the crane cabin <NUM> and the radio receiving unit <NUM> of the Rigger display apparatus <NUM>. Suitably, the radio Tx/Rx unit <NUM> has long range capability to ensure the signal is transferred successfully between the radio Tx/Rx unit <NUM>, the sensing device <NUM> and the Rigger display apparatus <NUM> to cater for varying on-site conditions which can adversely affect signal conditions. The system uses a data transfer protocol that is specifically designed to ensure the correct information is received for the crane operator <NUM> and rigger display apparatus <NUM> and is resilient to errors in transmission.

As mentioned above, the sensing device <NUM> measures the deviation in degrees from vertical orientation (indicated by plumb line <NUM>) of the hook <NUM> underneath the boom <NUM> which is referred to as "plumb" calibrated to suit by the Rigger <NUM> at the commencement of lifting. This information is sent via long range radio frequency to a radio Tx/Rx unit <NUM> in the crane operator's cabin <NUM> and to a radio Tx/Rx unit assembly <NUM> of rigger display <NUM> to display to rigger <NUM>.

In use, the sensing device <NUM> is attached to the hook <NUM> of the crane <NUM>. The hook <NUM> is then attached to the load <NUM> in preparation for lifting.

Prior to lifting, the sensing device <NUM> calculates the angle of the pitch plane in real time based on a comparison of the gravity vector measured by the accelerometer of the IMU <NUM> and compensated by the angular momentum of the gyroscope of the IMU <NUM> using modified Kalman equations. In addition, due to the accuracy of the angle measurement in the pitch plane decreasing if the hook <NUM> is twisted, the magnetometer of the IMU <NUM> (preferably a compass) is used to calculate and compensate for the twist, allowing for high accuracy when calculating the pitch angle for a large number of crane lifting situations. In the event that the hook <NUM> has deviated beyond a predetermined limit, such as <NUM>° for example, an alert or indication that the hook <NUM> is currently in an unsafe operating condition can be issued to the operator <NUM> in the crane cabin <NUM> by means of display <NUM> and/or the display device <NUM> of the Rigger <NUM> so that the lifting operation may be appropriately adjusted. Alternatively, or additionally, if the hook <NUM> is within a predetermined range (i.e. not beyond the allowable deviation limit), an alert or indication that the hook is currently in a safe operation condition can be issued to the operator <NUM> in the crane cabin <NUM> through alert generator <NUM> and/or the display device <NUM> of the Rigger <NUM>.

The alert generator <NUM> is under the control of cabin processor <NUM> for producing visual and/or audible signals as instructed by the sensing device <NUM>.

The alert for an unsafe condition can be in the form of a visual element, such as a red flashing light, or an audible signal, such as a siren. Once a safe operating condition has been achieved, the light may change to green, or another colour predetermined to signal a safe condition. Additionally, the audible signal could be a bell chime or other predetermined sound which signifies the safe condition.

An example of the sensing device <NUM> in use is shown in <FIG>. The sensing device <NUM>, located adjacent the hook <NUM> of the crane <NUM>, is measuring the difference in degrees from the plumb position of the hook <NUM>, illustrated by plumb line <NUM> and deviation line <NUM>.

In the illustrated situation, an alert would be issued to the operator <NUM> in the cabin <NUM> of the crane <NUM> by means of display <NUM> and/or alert generator <NUM> and the display device <NUM> of rigger <NUM>. Upon receiving the alert, the operator <NUM> and rigger <NUM> are immediately made aware of an unsafe condition and are able to readily correct the situation by manipulation of the crane controls to achieve a safe operation condition, which can also be detected and indicated by the sensing device.

While the illustration only shows a load with a perfect rigging arrangement (i.e. all lifting equipment having the same length), the sensing device can also be calibrated to allow for an "offset" plumb for situations where a portion of the load has been taken by the crane. This is particularly useful when rigging has different lengths and configurations of both sides of the load.

Advantageously, the sensing device can effectively compute any lateral orientation changes in a hook or hookblock of a crane, such as a specific number of falls of hoist rope in crane configuration or specific rigging applications causing torque, or high winds.

In another advantage, the use of existing crane sensors improves calculations for better guidance to move the jib back or forward.

Another advantage lies in the ability to indicate both safe and unsafe operating conditions of a lifting operation.

In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step, etc..

The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, as defined by the appended claims.

Claim 1:
A sensing device (<NUM>) for a luffing crane for detecting unsafe operating conditions comprising:
an inertial measurement unit (<NUM>) for measuring pitch and yaw of a hook (<NUM>) of a crane attached to a load (<NUM>), the inertial measurement unit (<NUM>) comprises:
an electronic gyroscope;
an accelerometer (<NUM>), wherein the electronic gyroscope and the accelerometer (<NUM>) are adapted to measure orientation of the hook (<NUM>) and obtain orientation data to measure deviation from a plumb position of the hook (<NUM>);
a magnetometer (<NUM>) adapted to measure yaw of the hook (<NUM>) and adapted to measure changes of the hook (<NUM>) relative to magnetic north and obtain yaw data, and characterised by a microcontroller (<NUM>) arranged to:
calculate a compensation factor from yaw data measured by the magnetometer (<NUM>);
combine the orientation data measured by the electronic gyroscope and the accelerometer (<NUM>) with a statistical estimation filter; and
determine deviation of the hook (<NUM>) of the crane from the plumb position before commencement of lifting the load (<NUM>) attached to the hook (<NUM>) using the combination of the orientation data with the statistical estimation filter and the compensation factor,
wherein the inertial measurement unit (<NUM>) is adapted to activate an alert element if the deviation of the hook (<NUM>) exceeds a predetermined limit.