Patent Publication Number: US-9886803-B2

Title: Crane monitoring system

Description:
REFERENCE TO EARLIER FILED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/644,797, filed May 9, 2012, and titled “CRANE MONITORING SYSTEM,” which is incorporated, in its entirety, by this reference. 
     The present application relates to the field of crane service, and more particularly to systems and methods for determining the service conditions of a crane component. 
    
    
     BACKGROUND 
     Cranes have numerous components that are subject to wear as cranes age. The health of linearly extending components, such as a boom extension or outrigger extension, may be difficult to determine without physically disassembling the component. For example, wear pads are disposed internal to the linearly extending component and may not be accessible for inspection. Similarly, seals within a hydraulic cylinder and not visible with the cylinder in operation. To physically inspect these parts requires disassembly of the components which entails a stoppage of work. This inspection is typically done when the crane is not in service to avoid disruptions at the job site and is performed at pre-determined intervals. Because of the difficulty is disassembling the components and the stoppage of work, the parts are typically replaced at this time, even if they still have usable life remaining. 
     The pre-determined interval is typically based on an amount of time, such as the age of the components or the service hours of the component. The average lifetime of the parts can be found based on past usage and a service interval can be set to ensure that the parts will be replaced before failure. Because not all parts last the average lifetime, the service interval is typically less than the average lifetime of the part. This results in the majority of the parts being replaced prior to their end of life. 
     It would be useful to have a system capable of determining the service condition of the components without requiring the disassembly of the component. This would enable the components to operate for longer periods of time before requiring service and would reduce the number of service parts required during the life of the crane. It would be useful for such a system to be a part of the crane itself, as well as a separate service tool for cranes not having the system. 
     SUMMARY 
     Embodiments of the invention include a crane monitoring system having a sensor, a processing unit operably coupled to the sensor, and a data store. The sensor is adapted to sense a sequence of accelerations of a linearly extending component and output a signal representative of the sequence of accelerations. The data store stores computer executable instructions that, when executed by the processing unit, cause the processing unit to perform a plurality of functions including determining at least one crane service condition utilizing a signal received from the sensor. 
     Embodiments further include a method for determining at least one service condition of a linearly extending crane component utilizing a service tool. A sensor is coupled to the linearly extending crane component. The sensor is adapted to sense an acceleration of the linearly extending crane component and output a signal representative of the acceleration. The linearly extending crane component is operated through a predetermined operating procedure and a signal is received at the tool from the sensor representative of a series of accelerations of the linearly extending crane component during the predetermined operating procedure. The received signal is then analyzed to determine the at least one service condition for the linearly extending crane component. 
     In another embodiment, a system for tracking service conditions of a fleet of cranes includes a plurality of crane sensors adapted to sense an acceleration of a crane component, a plurality of communication links operably coupled to the plurality of crane sensors, a data warehouse operably coupled to the plurality of communication links, and a processing unit operably coupled to the data warehouse. The processing unit has computer readable storage memory storing instructions that, when executed by the processing unit, cause the processing unit to analyze data previously received from the plurality of communication links to determine a baseline for determining a crane service need. 
     In another embodiment, a service tool for determining at least one service condition of a crane includes a housing, a first communication interface adapted to communicate with a sensor, a second communication interface adapted to communicate with a crane control system, a computer processer disposed within the housing and operably coupled to the communication interface, and computer readable storage media operably coupled to the computer processor. The computer readable storage media stores data for determining the at least one service condition and computer executable instructions. The computer executable instructions, when executed by the computer processor, cause the computer processor to implement functions including a function for receiving a signal from the sensor through the first communication link, a function for communicating with a crane control system through the second communication link, and a function for determining the at least one service condition of the crane based on the signal. 
     In another embodiment, a crane includes a crane body, a crane component coupled to the crane body, a sensor coupled to the crane component and adapted to sense a sequence of accelerations of the crane component and output a signal representative of the sequence of accelerations, a processing unit operably coupled to the sensor and adapted to receive the signal, and a data store storing computer executable instructions that, when executed by the processing unit, cause the processing unit to perform a plurality of functions. The functions include a function to determine at least one service condition dependent upon the signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To further clarify the above and other advantages and features of the one or more present inventions, reference to specific embodiments thereof are illustrated in the appended drawings. The drawings depict only typical embodiments and are therefore not to be considered limiting. One or more embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  is a perspective view of a mobile crane illustrating components of an embodiment of a crane service management system. 
         FIG. 2  is a perspective view of another mobile crane illustrating components of another embodiment of a crane service management system. 
         FIG. 3  is a perspective view of another mobile crane illustrating components of another embodiment of a crane service management system. 
         FIG. 4  is a perspective view of another mobile crane illustrating components of another embodiment of a crane service management system. 
         FIG. 5  is a system diagram of an embodiment of a crane service management system. 
         FIG. 6  is a chart illustrating acceleration measurements of a linearly extending crane component. 
         FIG. 7 a    is an illustration of a crane boom having new wear pads. 
         FIG. 7 b    is an illustration of a crane boom having worn wear pads. 
         FIG. 8  is a chart of a crane boom deflection angle plotted over time. 
         FIG. 9  is an illustration of a crane service database and a blank record of the database. 
         FIG. 10  is an illustration of a service tool for determining service conditions of a crane. 
         FIG. 11  is a second illustration of a service tool for determining service conditions of a crane. 
     
    
    
     The drawings are not necessarily to scale. 
     DETAILED DESCRIPTION 
     Embodiments of the invention include systems and methods for determining the service requirements of a mobile crane. Embodiments of the present invention will now be further described in relation to the figures. In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous. 
     Referring to  FIG. 1 , an embodiment of a crane  100  is depicted. The crane  100  is comprised of a chassis  106  and a superstructure  108  coupled to the chassis  106 . The superstructure  108  is adapted to rotate about the chassis  106 , but in some embodiments may be fixed in a single orientation. The superstructure  108  includes a boom  102  that is designed to lift and move a load (not shown). Collectively, the chassis  106  and superstructure  108  of the crane  100  may be referred to as the crane body. 
     The boom  102  is connected to the superstructure  108  at a pivot that allows the boom  102  to angle up and down. A driving device, such as a hydraulic cylinder  110   b  and piston  110   a , extends and retracts to cause the boom  102  to rotate about the pivot point, thereby angling the boom  102  up and down. Additionally, the boom  102  is designed to extend in length in a generally linear direction depicted by arrows  104 . A second hydraulic cylinder and piston (not shown) is configured to cause the boom  102  to extend and retract. The boom  102  may have multiple segments such that the boom  102  can be extended in multiple steps. 
     A cable  112  is secured to the boom  102  and is used to couple the boom  102  to the load. The cable  112  is attached to a winding drum (not shown) disposed on the superstructure  108 . The cable  112  extends from the winding drum along the boom  102  to an end  114  of the boom  102 . From the end  114  of the boom  102  the cable  112  extends to a hook  115 . The cable  112  may be coupled to the hook  115  through a lower sheave  160  and multiple segments of the cable  112  may support the hook  115  through a block and tackle type pulley system comprised of multiple sheaves. 
     The boom  102  has a number of linearly extending components associated with it that are subject to wear. Each segment of the boom  102  has at least one wear pad between it and an adjacent boom segment that reduces friction between adjacent boom segments. Each hydraulic cylinder, such as cylinder  110   b , has an associated seal that retains the hydraulic fluid while allowing the piston, such as piston  110   a , to translate linearly. 
     A sensor assembly  116  is disposed proximate a linearly extending component. The sensor assembly  116  does not need to be placed directly on the linearly extending component so long as it is able to detect acceleration from the movement of the linearly extending component. Furthermore, a single sensor assembly  116  may detect the acceleration caused by multiple component interactions; each component may have an associated sensor assembly  116 ; or some combination of multiple sensor assemblies may be used. 
     The sensor assembly  116  in the embodiment of  FIG. 1  comprises sensors  118 , a radio module  120 , a micro-controller  122 , and an analog to digital converter (ADC)  123 . The sensors  118  are adapted to detect and measure accelerations. One example of a sensor particularly suited to detecting acceleration is an accelerometer and, more particularly, a multi-axis accelerometer. The ADC  123  converts an analog signal from the sensors  118  to a digital signal suitable for communication with a processing unit. The radio module  120  communicates with a second radio module  128  and delivers the digital signal from the ADC  123 . The micro-controller  122  manages the sensor assembly  116 . 
     The sensor assembly  116  may be designed to power on only when an operating condition is taking place that is relevant to a desired acceleration measurement. For example, the sensor assembly  116  may power on immediately prior to a component moving, or immediately after a component begins to move. The sensor assembly  116  may receive a signal indicating an operation is about to be performed or may detect the operation by some other means. By powering on only when a relevant operation is being performed, the battery life of the sensor assembly  116  is increased. 
     A crane controller assembly is  124  disposed within the superstructure  108  of the crane  100 . In some embodiments, the crane controller assembly  124  may be within a cab  126  of the crane  100 , or in other embodiments the crane controller assembly  124  may be located elsewhere. The crane controller assembly  124  is comprised of the second radio module  128  for communicating with the radio module  120  of the sensor assembly  116 , a crane controller  130  for implementing computer executable instructions, a user input interface  132 , a user output interface  134 , and a telematics control unit  136 . 
     The second radio module  128  communicates with the radio module  120  to receive sensor data. In some embodiments, the second radio module  128  may send a signal to the radio module  120  to cause the sensor assembly  116  to power on from a low power mode. The second radio module  128  communicates with the radio module  120  using any commonly available radio communication protocol, but is not limited to commonly available protocols. Other communications are possible and fall within the scope of the invention so long as a wireless communication is affected between the radio module  120  and the second radio module  128 . 
     The telematics control unit  136  communicates with a remote computing system  138  through an external communications network  140 . The external communications network  140  may include the internet, a phone network, a satellite network, or other type of network. The telematics control unit  136  sends the sensor data to the remote computing system  138  for analysis. The crane controller  130  may send all received acceleration data to the remote computing system  138  through the telematics control unit  136 , or the crane controller  130  may send selective subsets of the received acceleration data. In addition to the acceleration data, the telematics control unit  136  typically sends other information to the remote computing system  138  such as an identifier, location information, crane model, or other information. 
     The crane controller  130  is comprised of computer readable storage memory  142  and a computer processor  145 . The computer readable storage memory  142  stores instructions that when executed by the computer processor  145  cause the computer processor  145  to perform functions. The computer readable storage memory  142  may be volatile memory where the instructions are stored only when the crane controller  130  is powered on, or it may be nonvolatile where the information remains through power cycling. The computer readable storage memory  142  may further save information such as the sensor data from the sensor assembly  116 , information from the telematics control unit  136 , or other operating information. 
     A user interacts with the crane controller  130  through the user input interface  132  and the user output interface  134 . The user input interface  132  and user output interface  134  may be combined in a single device such as a touchscreen, or may be separate such as a display and a keyboard. Other types of input and output are possible and one of ordinary skill in the art would recognize various user inputs and outputs that are suitable for use with embodiments of the invention. Examples of other suitable user inputs include one or more of pushbuttons, joysticks, jog dials, foot pedals, switches, touch screen, keypads, buttons, microphones, mice, track pads, and the like, and combinations thereof. Examples of other suitable user outputs include one or more of heads up displays, speakers, visual indicators, and the like, and combinations thereof. 
     The remote computing system  138  interacts with the crane controller  130  through the external communications network  140 . The remote computing system  138  may comprise a single computer, or it may be a network of computers working together. In the embodiment shown in  FIG. 1 , the remote computing system  138  comprises a network of computers  144 ,  146 ,  148  working together. 
     A first computing system  144  is responsible for communication with the crane controller assembly  124  through the telematics control unit  136 . The first computing system  144  may communicate with a large number of other crane control systems associated with other cranes that are not shown. The first computing system  144  communicates with a second computing system  146  that stores information related to a crane&#39;s history such as service records  150 , warranty records  152 , and other records  154 . The remote computing system  138  uses the information delivered to the first computing system  144  from the crane controller assembly  124  in combination with the records of the second computing system  146  to extract, transform, and load information relevant to the service condition of the crane  100 . 
     For example, the service record  150  and warranty record  152  may indicate that for a particular model of crane, a wear pad should be checked to determine its service condition. This information in combination with the information received from the crane controller assembly  124  at the first computing system  144  may then be used to extract information specific to that service condition. The extracted data can be used in numerous ways. In one embodiment, the extracted information can be used to determine the current service condition of the crane  100 . In another embodiment, the extracted information may be saved to a data store as part of a baseline measurement for future use. 
     A data warehouse  158  may be part of the remote computing system  138 , the first computing system  144 , the second computing system  146 , or some other computing system operably coupled to with the remote computing system  138 . The data warehouse  158  stores information related to the service of cranes. 
       FIG. 2  illustrates a crane  200 , which may be identical to the crane  100  of  FIG. 1 . The crane  200  includes a sensor assembly  202  and a crane controller assembly  212 . Like sensor assembly  116  of the crane  100  of  FIG. 1 , the sensor assembly  202  includes a radio module  203 , one or more sensors  204 , such as an accelerometer, an analog to digital converter  206 , and a micro controller  208 . Similarly, the crane controller assembly  212 , like the crane controller assembly  124  of  FIG. 1 , includes a second radio module  214  adapted to communicate with the radio module  203 , a telematics unit  222 , a user input  218 , a user output  220 , and a crane controller  216 . The system shown in  FIG. 2  differs from the system of  FIG. 1  in part because it does not include the external communications network  140  and remote computing system  138  present in the system of  FIG. 1 . The crane  200  is functional without the presence of the external communications network  140  and the remote computing system  138 . The crane controller assembly  212  may store information related to determining the cranes service condition in a computer readable storage medium. The crane controller assembly  212  may store the information representing the data measured by the sensor assembly  202 . This information may be stored and then diagnosed by the crane controller assembly  212  for direct operator use. Alternatively, the crane controller assembly  212  may communicate with a remote computing system, such as the remote computing system  138  of  FIG. 1  at pre-determined intervals or in response to an event. The information may be stored and transmitted over an external network to the remote computing system for further diagnostics. 
       FIG. 3  illustrates an embodiment of a crane  300  in which a sensor assembly  302  is hard wired to a crane control system  304 . In all other respects the embodiment of  FIG. 3  functions similarly to the embodiment of  FIG. 2 , with the exception that the no radio module is present within the sensor assembly  302 , or the crane control system  304 . Instead, the sensor assembly  302  is connected directly to the crane control system  304  through a wired connection  306 . In some embodiments the crane control system  304  may supply power to the sensor assembly  302  in addition to communicating with the sensor assembly  302 . The wired connection  306  between the sensor assembly  302  and the crane control system may be adapted to change in length as the boom  308  extends or retracts. This length change may be effected by a spool  312  that winds the wired connector  306 . The embodiment of  FIG. 3  includes a telematics control unit  310  that is adapted to communicate with the remote computer system  138  of  FIG. 1 . 
       FIG. 4  illustrates an embodiment of a crane  400  in which sensors  402  communicate directly with a crane control system  404  over a wired connection  406  similar to the embodiment of  FIG. 3 . However, in the embodiment of  FIG. 4  no microprocessor or analog to digital converter is utilized on the crane boom. Instead, the sensors  402  communicate the raw signal over the wired connection  406  to the crane control system  404 . At the crane control system  404  the raw signal is processed into a digital signal by an analog to digital convertor  408 . Like the embodiments of  FIGS. 1 through 3 , the crane control system  404  may include a telematics control unit  410  that is adapted to communicate with the remote computer system  138  of  FIG. 1 . 
       FIG. 5  illustrates a high level block diagram of an embodiment of a crane monitoring system  500 . The crane monitoring system  500  is comprised of a remote sensor module  502 , a crane controller  504 , a telematics controller  506 , a remote computing system  508  such as a back office/business intelligence system, and end use applications  510 . This crane monitoring system  500  encompasses each of the previously described embodiments of mobile cranes. 
     The remote sensor module  502  is adapted to measure boom accelerations, noises, and other sensor modalities that can be monitored and analyzed for wear indicating patterns. For accelerations, sensors  512  such as an accelerometer or accelerometers may be rigidly attached to the boom. The sensors  512  measures boom vibration during crane operations such as telescoping and lifting. The sensor  512  produces a signal representative of the measured variables. 
     The signal produced by the sensor  512  is typically an analog signal which is then converted to a digital signal by an analog to digital converter  514 . A microcontroller  516  manages the remote sensor module  502  and may perform tasks such as power management of the sensors, data filtering of the digital signal, and other management tasks. It is beneficial to convert the analog signal to the digital signal near the sensor  512  before the signal is attenuated or additional noise is introduced. Digital signals are less susceptible to noise and interference and can be retransmitted with no degradation. In embodiments in which the microcontroller  516  filters the data, less data may be sent to the crane controller  504 . This reduces the bandwidth necessary for communications and saves power. 
     The remote sensor module  502  includes a communications component  518  that transmits and receives data. The communications component  518  may be powered on at all times, or may be powered on selectively by a clock, an event detector, or the microprocessor. In some embodiments the communications component  518  may be a wired connection. In such embodiments data is transmitted over the wire to the crane controller  504 . The wired connection may additionally provide power to the remote sensor module  502 . In other embodiments, the communication component  518  may be a wireless connection such as a Bluetooth, Wi-Fi, or other data connection. In such embodiments the remote sensor module  502  may contain its own power source such as a battery. To preserve battery power, such embodiments may power down when no measurements are taking place. The wireless connection may remain powered on in a low power state and wake in response to a signal from the crane controller  504 . In other embodiments the remote sensor module  502  may receive power from a local power generator, such as the power generator disclosed in U.S. patent application Ser. No. 12/762,186 filed on Apr. 16, 2010, entitled, “Power and Control for Wireless Anti-Two Block System.” 
     The crane controller  504  communicates with the remote sensor module  502  through a communications component  520  compatible with the communications component  518  of the remote sensor module  502 . For example, if a remote sensor module  502  has a wireless communication component  518 , the crane controller  504  will likewise. In some embodiments the crane controller  504  may have multiple communications components  520  such that it could communicate with both wireless communication components and wired communication components. The crane controller  504  further includes a controller  522  for implementing functions and an operator input and output  524  for interacting with a user. 
     The telematics controller  506  includes a local communication component  526  adapted to communicate with the communications component  520  of the crane controller  504 . A remote communications component  530  is adapted to communicate with a remotes system such as the remote computing system  508 . A microcontroller  528  may control the operation of the local communications component  526  and the remote communications component  530 . 
     The remote computing system  508  is comprised of a remote communications component  532  adapted to communicate with a remote system such as the crane controller  504  by way of the remote communication component  530 . A processor  534  implements computer executable instructions that may include instruction for determining the service conditions of a crane. The processor  534  is operably coupled to a database  536  that may store information related to service conditions for one or more cranes. A business intelligence unit  538  may be operably connected to the database  536  and be configured to make decisions about crane service conditions based on information contained in the database  536 . Each of the components of the remote computing system  508  may be implemented individually on a single computing device or application, may be implemented as a system of computing devices or applications, or may be implemented together with one or more other component of the remote computing system. 
     End use applications  510  are operably coupled to the remote computing system  508  and may include mobile devices  540  configured to access information stored in the database  536  and/or access business intelligence decisions from the business intelligence unit  538 . End use applications  510  may also include an end user computer  542  configured to access information stored in the database  536  and/or access business intelligence decisions from the business intelligence unit  538 . The end use application  510  may be implemented on many different mobile devices, computers, web based applications, and combinations of the same. 
       FIG. 6  is a chart  600  illustrating accelerations measured during a crane operation. The chart  600  will be described with relation to the crane  100  of  FIG. 1 . The vertical axis  602  of the chart  600  represents accelerations as measured by a 3-axis accelerometer  118  located on the boom end  114  of the crane  100 . The horizontal axis  604  represents time. The accelerations have been filtered using a band pass filter so that only accelerations within a pass band of frequencies are shown. A typical pass band would include frequencies from 0.5 Hertz to 5.0 Hertz, although other ranges are feasible. 
     The chart  600  has three different plots corresponding to each of the three different axis of the 3-axis accelerometer  118 . The first plot line  606  represents lateral or side to side accelerations of the boom end  114 . The second plot  608  represents longitudinal accelerations of the boom end  114 . The third plot  610  represents perpendicular accelerations at the boom end  114  that are perpendicular to the lateral and longitudinal axes. 
     Initially, at time zero  612 , the measured accelerations are small. At time  614  the crane operator begins a predetermined crane operation. In the example of chart  600 , the predetermined crane operation is telescoping the boom  102  out and back in, however other operations are feasible. As can be seen by the second plot line  608 , the boom  102  experiences accelerations primarily in the longitudinal direction as the boom  102  extends. At time  616  the boom  102  has been fully extended. The longitudinal accelerations are now small in comparison to lateral accelerations, which decrease as time passes. At time  618  the operator retracts the boom  102 . Transient accelerations similar to those present when the boom  102  is extended are present in the longitudinal axis. Additionally, the lateral accelerations are significantly greater than when the boom  102  is extended. At time  620  the boom is fully retracted. Once the boom  102  is fully retracted, the primary accelerations occur in the perpendicular axis and decrease as time passes. 
     The data comprising the chart  600  of  FIG. 6  may be used to determine the service conditions of the boom  102  and or verify and improve its design. The crane service condition may be determined using the crane controller assembly  124  or it may be determined by the remote computing system  138 . Examples of a processor determining crane service conditions include a processor comparing the data with historical data to determine any abnormalities. For example, the amount of time required for the longitudinal accelerations to stop could be compared against a determined normal value. If the amount of time was greater than the normal value, it may indicate that a wear pad of the boom  102  is worn, allowing excessive vibration. In another example, the longitudinal acceleration transients while retracting or extending could be greater than a baseline value, indicating a problem with the hydraulic seal of the extension mechanism. Other techniques for determining wear are possible and do not necessarily require comparing a value against a baseline. In some embodiments, wear may be determined using a combination of measurements or historical trends. The measured accelerations and calculated service conditions could be compared to historical and theoretical data to verify and improve designs. 
     In some embodiments, the data may be decomposed into frequency content. This may be done using a fast Fourier transform. The frequency data can then be evaluated to determine unusual frequencies or amplitudes which may indicate a service condition. Historical data obtained from similar cranes may be used to determine frequencies and amplitudes indicating particular service conditions. For example, the remote computing system  508  may have historical records of cranes in need of service. These historical records can be analyzed to determine common frequencies and amplitudes not present in normally operating cranes. Then the processing unit can be instructed to look for these conditions. 
     The sensor  118  may also be used to measure an angle relative to gravity.  FIG. 7 a    and  FIG. 7 b    illustrate a simplified view of a boom  700 . The boom is comprised of a stationary arm  702  and an extending arm  704 . The extending arm  704  is supported within the stationary arm  702  by wear pads  706 . A load  708  at the end of the extending arm has a normal component  710  and a tangential  712  component. The load  708  is the result of gravitational acceleration, but may also include other forces such as wind loads. The normal component  710  causes a moment  714  in the boom  700 . 
     In a boom  700  having new wear pads  706 , the moment  714  causes little orthogonal displacement of the extending arm  704  as shown in  FIG. 7 a   . If the wear pads  706  are worn, as shown in  FIG. 7 b   , the moment  714  results in the extending arm displacing at a displacement angle  716 . An arm angle at the end of the boom  700  can be determined using the accelerometer  118 . The accelerometer  118  measures the direction of gravitational acceleration, which can be broken into a tangential component and a normal component. The arm angle is equal to the inverse tangent of the ratio of the tangential component of the gravitational acceleration and the normal component of the gravitational acceleration. The displacement angle  716  can be found by calculating the difference in the arm angle with the extending arm retracted and the arm angle with the extending arm extended. Furthermore, the orthogonal displacement distance can be calculated from the boom length and displacement angle using trigonometry. 
       FIG. 8  is a chart  800  of the arm angle  802  calculated from inverse tangent of the ratio of the tangential component of the gravitational acceleration to the normal component of the gravitational acceleration of an accelerometer placed on the extending arm  704  versus time  804 . At point  806  the extending arm  704  is retracted and has an arm angle of about 2.5 degrees. As the extending arm  704  extends towards point  808 , the arm angle decreases to about 1.5 degrees. A spike near point  806  is the result of the arm accelerating as it extends and the spike reflects measurement noise, not an actual arm angle  802 . Similarly, spikes near points  808 ,  810 , and  812  are the result of the extending arm accelerating and are not indicative of the actual arm angle  802 . The extending arm  704  is held at a constant length between points  808  and  810 . As such, the arm angle  802  remains relatively constant between point  808  and point  810 . At point  810 , the extended arm is retracted. After point  810 , the arm angle  802  gradually increases until the extending arm  704  is fully retracted at point  812 . During this process, the arm angle of the stationary arm is held constant. 
     The service condition of the linearly extending arm component can be determined by monitoring the displacement of the extending arm. The amount of displacement may be increased by having a known load on the extending arm. Like the frequency data, the displacement data may be stored, transmitted, used to determine a baseline, and used to determine service conditions. 
     The acceleration sensors may also be used to calculate the velocity of the boom as it extends. The velocity may be found by integrating the acceleration along the boom. A change in velocity could indicate wear in a component such as pumps, seals, and actuators. The velocity component may additionally be used to weight the accelerations measurements. For example, higher accelerations are likely if the boom is fully extended to a hard stop at a high velocity, since more kinetic energy is dissipated in stopping. The velocity can be further integrated to calculate the extension of the boom. In some embodiments, an accurate, response length sensor may be used to calculate the velocity and acceleration at the boom end. 
     Another useful characteristic for detecting service conditions is to measure the horizontal displacement of the boom end. Horizontal displacement of the boom end may be indicative of wear and, upon exceeding a threshold, may be used to trigger a service condition such as a need for preventative maintenance. The horizontal displacement may be found by twice integrating the horizontal accelerations. 
     The crane controller  504  may receive baseline data from the database  536 , or it may calculate its own baseline data based on past measurements. The baseline data is stored in memory and used to compare the baseline to the measured data. 
     The data may be transmitted to the remote computing system  508  over the external communications network. The data may be transmitted immediately, or it may be stored in memory and transmitted at a later time. The crane controller  504  may determine the service of the crane using the data and a baseline previously stored in memory. In some embodiments the baseline may be retrieved over the external communications network for use by the crane controller  504 . In still other embodiments, the remote computing system  508  may make the determination of crane service condition using the data transmitted by the crane controller  504 . In such embodiments the remote computer system  508  may then send a status identifier indicating at least one crane service condition back to the crane control system. The remote computing system  508  may also send an updated baseline to the crane controller  504  for future use. 
     The crane controller  504  may prompt a crane operator to operate the crane through a known crane operation. For instance, the crane controller  504  may prompt the operator to angle the boom at a 45 degree angle and extend the boom, hold the extension for a minute, and then retract the boom. Having the crane operator perform a known crane procedure allows for simpler identification of crane service conditions. The crane controller  504  may record the operators input, verifying that the operator performed the known operation. 
     In some embodiments the crane may include at least one additional sensor adapted to communicate with the crane controller  504 . The at least one additional sensor may sense an additional crane state such as the boom length, a crane load, a boom position, or a boom angle. This information may be stored by the crane controller  504  and may be used to verify that the crane performed the known crane operation. The information may also be used in conjunction with the sensor data to verify the service condition of the crane. 
     When the crane controller  504  sends the data to the remote computing system  508 , it may include other data such as a crane identifier, a time, a location, ambient conditions, and other data. The remote computing system  508  stores the data in a service database. One example of the service database is shown in  FIG. 9 . In  FIG. 9  the database  900  is comprised of a plurality of service records  902 . Each service record  902  stores the crane model  904 , serial number  906 , boom model  908 , data record  910 , service data  912 , and warranty data  914 . This list of data fields is illustrative and embodiments are not limited to this example. 
     The remote computing system  508  may use the information contained in the database  900  to determine service conditions for the crane based on the data received from the crane. For example, the crane may send data representing the accelerations measured at the boom, along with the crane serial number. Other data may be sent including information such as the linear extending component extension length and displacement angle as previously described. The remote computing system  508  may then find all prior records of the crane based on the serial number and compare past acceleration data, or other data, to the received data. Or, the remote computing system  508  may develop a baseline for that particular model of crane based on the data records of plurality cranes of that model. In some embodiments the baseline may be calculated prior to receiving the data from the crane. The baseline may be stored in the data record for the crane on the crane controller  504 . 
     In some embodiments, a service warning could be triggered from a weighted sum of an occurrence of events detected by the sensor. For instance, in one example a check could be triggered by a formula such as (number of type 1 events)/N1+(number of type 2 events)/N2+(number of type 3 events)/N3&gt;=1 where N1, N2, and N3 are weighting factors and N1&gt;N2&gt;N3. (I.E. 10 type 1 events, 1,000 type 2 events, or 100,000 type 3 events or a sufficiently weighted combination trips the warning check.) The events may be differing thresholds of a single type of event. For example, a vibration may have three different thresholds with the lowest threshold corresponding to a minor event and the highest threshold corresponding to a major event. In such a system a lot of minor vibrations would be allowable before a service warning was activated, or relatively few major vibrations would result in a service warning. For example, a minor vibration may be associated with a normally worn wear pad, while a major vibration may be associated with a failed wear pad. The actual storage and calculating of the data can be performed at the crane controller  504 , or the events may be sent to the remote computing system  508  for calculating. 
     Many preventative maintenance schedules are based simply on calendar time. Others try to use data more indicative of expected wear, such as by logging the number of hours an engine is running. The present invention can be used to keep track of actual usage of a given crane component, such as the actual usage of the components that can wear during extension and retraction of a telescopic boom. In such an embodiment, a measured metric could be the weighted distance traveled. For example the sum of extension and or retract cycles under load conditions can be calculated. The sensor  512  would be able to detect the actuation of the linearly extending component and could determine the distance traveled. The crane controller  504  typically has a sensor  512  measuring the load on linearly extending component. A metric might be (number of type 1 loads retracted)/N1R+(number of type 1 loads extended)/N1E+(number of type 2 loads retracted)/N2R+(number of type 2 loads extended)/N2E+(number of type 3 loads extended)/N3R+(number of type 3 loads extended)/N3E where N1R, N1E, N2R, N2R, N3E, and N3R are weighing factors and N1E&gt;N2E&gt;N3E and N1R&gt;N2R&gt;N3R. For example a type 1 load could be a load of at least 67% capacity, and a type 2 load could range from 33% to 66% of capacity. The number of loads could be fractional if the linearly extending component did not complete an extension or retraction. The sensor  512  may also be used to determine the actual distance traveled and use that measurement. Again the actual storage and calculating of the data can be performed at the crane controller  504 , or the events may be sent to the remote computing system  508  for calculating. These metrics would prove an accurate indication of expected wear on parts that would then be replaced in a preventative maintenance procedure. 
     In the embodiment of  FIG. 10  a service tool  1000  is depicted. The service tool  1000  has a housing  1002  that is portable. Within the housing  1002  the service tool contains a first communication interface  1004  adapted to communicate with a sensor  1006 , such as an accelerometer. The first communication interface  1004  may have an external wireless receiver  1008  adapted to communication with the sensor  1006 . A second communication interface  1010  is adapted to communicate with a crane control system. The first communication interface  1004  and the second communication interface  1010  may be wired or wireless, or a combination of the two. The communication interfaces  1004 ,  1010  may use different communication protocols. 
     A computer processor is operably coupled to the first communication interface  1004  and the second communication interface  1010  such that the computer processor is able to communicate with the first communication interface  1004  and the second communication interface  1010 . A computer readable storage media is operably coupled to the computer processor. Examples of computer readable storage media include hard disk, flash drive, optical disks, tape drives, or any other media that stores computer readable data. The computer readable storage media stores computer executable instructions, that, when executed by a computer processor, cause the computer processor to implement functions. Such functions include a function for receiving a signal from the sensor  1006  through the first communication interface  1004 , a function for communication with the crane control system through second communication interface  1010 , and a function for determining at least one service condition of the crane based on a received signal. 
     The computer readable storage media also stores data for determining the service conditions of the crane. The data for determining the cranes service condition may include data related to a plurality of crane models and the functions implemented by the computer processor may further include a function for selecting data relating to a given crane model from the plurality of crane models. In some embodiments the functions may include a function for detecting a crane model from the plurality of crane models. For example, the service tool may have a Radio Frequency Identification Data (RFID) tag scanner operably coupled to the computer processor through a communication interface, or a bar code scanner operably coupled to the computer processor through a communication interface. The crane or crane components may have an RFID tag or a barcode that identifies the crane or crane component to the service tool. 
     In another embodiment the service tool  1000  includes a third communication interface adapted to communicate with a remote data warehouse such as the remote computing system  508  of  FIG. 5 . The functions of the service tool  1000  may include a function for sending data representative of the received sensor signal through the third interface to the data warehouse and a function for receiving update data for updating the data for determining a crane&#39;s service condition. In some embodiments the service tool  1000  may receive an indication of the cranes service condition from the remote data warehouse over the third communication interface. The data for determining the service conditions of the crane may comprise the indication of the crane&#39;s service condition received from the remote data warehouse. 
     In some embodiments the service tool  1000  includes a sensor  1006 , such as an accelerometer. The sensor  1006  is configured to couple to a crane component and to communicate with the computer processor over the first communications interface  1004 . The housing  1002  may have a holder sized and shaped to receive the sensor  1006 . In such embodiments the sensor  1006  is stored in the holder and can be removed to couple the service tool  1000  to a crane component. 
       FIG. 11  illustrates another embodiment of a service tool  1100 . Service tool  1100  is similar to the service tool of  FIG. 10  and includes a housing  1102  having a processor, computer readable storage media, a first communication interface  1104 , and a second communication interface  1110 . However, the first communication interface  1104  of service tool  1100  is a wireless interface whereas the first communication interface  1004  of service tool  1000  is a wired connection communicatively coupled to a wireless receiver  1008 . The first communication interface  1104  communicates with a sensor  1106  using a wireless communication protocol. Second communications interface  1110  is a wired interface that communicates with the crane controller. In some embodiments the service tool  1100  may communicate with both the sensor and the crane controller over a single wireless interface. In such instances, the single wireless interface may be considered to be both the first communication interface  1004  and the second communication interface  110 . 
     Embodiments have been described in relation to a crane boom, but are applicable to any vibrating component of a crane. For example, a lattice boom, a lattice jib, an outrigger beam, and an outrigger jack may have their service conditions determined using embodiments of the invention. In such embodiments, records within the database would contain additional fields to record the accelerations association with the component. Based on accelerations previously provided by cranes of the same model, appropriate baselines can be developed for the components. 
     Furthermore, other measurements may be used in conjunction with the acceleration data to determine crane service needs. For example, sensors may monitor temperature and noise for use in determining a cranes service conditions. It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. For example, the invention may also be used on an outrigger or hydraulic cylinder. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.