Patent Publication Number: US-11654069-B2

Title: Systems for monitoring person lifting devices using load tension pins

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 15/967,973 filed on May 1, 2018, which claims priority to U.S. Provisional Application No. 62/513,711 filed on Jun. 1, 2017, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Field 
     The present specification generally relates to systems for monitoring person lifting devices, such as person lifting devices including mobile lifts and/or overhead lifts and, more particularly, to systems for monitoring person lifting devices having load tension pins that wirelessly communicate load information to a server. 
     Technical Background 
     Person lifting devices, such as mobile lifts and/or overhead lifts, may be used in hospitals, other health care facilities, and sometimes in home care settings to move a person from one location to another or to assist the person in moving. Conventional person lifting devices utilize various accessories that attach to the person lifting device. For example, a sling or other attachment may secure a person to the lifting device and to an actuator to lift the person to a higher elevation or lower the person to a lower elevation. In one typical example the caregiver operates the actuator to raise the patient off a bed, repositions the person by moving the lifting device to a desired location, and then operates the actuator again to lower the patient to the destination. 
     Information about how many times and how long person lifting devices are used is important to track. Accordingly, a need exists for monitoring the usage of person lifting devices in real time. 
     SUMMARY 
     In one embodiment, a multi-link device includes a load tension pin including a sensor configured to measure tension applied to the load tension pin, network interface hardware, one or more processors, and one or more memory modules storing computer readable and executable instructions which, when executed by the one or more processors, cause the multi-link device to: determine whether the tension measured by the load tension pin exceeds a threshold value; and transmit, by the network interface hardware, load event data to a receiver in response to determination that the tension exceeds the threshold value. 
     In another embodiment, a person lift device includes an actuator, a lift arm coupled to the actuator, and a multi-link device coupled to one end of the lift arm. The one end of the lift arm is configured to move vertically by the actuator. The multi-link device includes a load tension pin including a sensor configured to measure tension applied to the load tension pin, network interface hardware, one or more processors, and one or more memory modules storing computer readable and executable instructions which, when executed by the one or more processors, cause the multi-link device to: determine whether the tension measured by the load tension pin exceeds a threshold value, and transmit, by the network interface hardware, load event data to a receiver in response to determination that the tension exceeds the threshold value. The person lift device also includes a bar attached to the load tension pin. 
     In yet another embodiment, a lift data management system includes a receiver, a person lifting device, and a central server communicatively coupled to the receiver. The person lifting device includes an actuator, a lift arm coupled to the actuator, one end of the lift arm being configured to move vertically by the actuator, and a multi-link device coupled to the one end of the lift arm and communicatively coupled to the receiver. The multi-link device includes a load tension pin including a sensor configured to measure tension applied to the load tension pin, first network interface hardware, one or more processors, and one or more memory modules storing computer readable and executable instructions which, when executed by the one or more processors, cause the multi-link device to: determine whether the tension measured by the load tension pin is increased; and transmit, by the first network interface hardware, load event data to the receiver in response to determination that the tension is increased. The central server includes second network interface hardware configured to receive load event data from the receiver, one or more processors, and one or more memory modules storing usage information associated with the person lifting device and computer readable and executable instructions which, when executed by the one or more processors, cause the multi-link device to update the usage information based on the load event data. 
     Additional features of the person lifting devices and scale assemblies for person lifting devices and methods for operating the same described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    schematically depicts a front perspective view of a mobile lift according to one or more embodiments shown and described herein; 
         FIG.  2    schematically depicts a rear perspective view of a mobile lift according to one or more embodiments shown and described herein; 
         FIG.  3    schematically depicts a perspective view of an overhead lift according to one or more embodiments shown and described herein; 
         FIG.  4    schematically depicts an exploded view of the overhead lift of  FIG.  3   ; 
         FIG.  5    schematically depicts a carriage of the overhead lift of  FIGS.  3  and  4   ; 
         FIG.  6    schematically depicts a perspective view of an overhead lift according to another embodiment shown and described herein; 
         FIG.  7    schematically depicts an exemplary embodiment of a lift data management system including a multi-link device for providing load data to a central server in accordance with one or more embodiments shown and described herein; 
         FIG.  8    depicts a perspective view of an operator lifting a patient using the person lift system in accordance with one or more embodiments shown and described herein; 
         FIG.  9 A  depicts the person lift system lifting a patient in accordance with one or more embodiments shown and described herein; 
         FIG.  9 B  depicts the person lift system lifting a patient in accordance with one or more embodiments shown and described herein; 
         FIG.  10 A  depicts the load tension pin of the multi-link device when no object is hung on the sling bar or no object is placed on a sling attached to the load tension pin; 
         FIG.  10 B  depicts the load tension pin of the multi-link device when an object is hung on the sling bar or an object is placed on the sling attached to the load tension pin; 
         FIG.  11    depicts an exemplary graph showing changes of the tension applied to the load tension pin in accordance with one or more embodiments shown and described herein; and 
         FIG.  12    depicts collecting load information from a plurality of multi-link devices and a plurality of receivers in accordance with one or more embodiments shown and described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments of lift data management systems, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. In one embodiment, a multi-link device includes a load tension pin including a sensor configured to measure tension applied to the load tension pin, network interface hardware, one or more processors, and one or more memory modules storing computer readable and executable instructions which, when executed by the one or more processors, cause the multi-link device to: determine whether the tension measured by the load tension pin exceeds a threshold value; and transmit, by the network interface hardware, load event data to a receiver in response to determination that the tension exceeds the threshold value. Various embodiments of person lifting devices including the multi-link device will be described herein with specific reference to the appended drawings. 
     As used herein, the term “longitudinal direction” refers to the forward-rearward direction of the components of the person lifting devices (i.e., in the +/−Y-direction as depicted). The term “lateral direction” refers to the cross-wise direction of the components of the person lifting devices (i.e., in the +/−X-direction as depicted), and is transverse to the longitudinal direction. The term “vertical direction” refers to the upward-downward direction of the components of the person lifting devices (i.e., in the +/−Z-direction as depicted). 
     Referring now to  FIGS.  1  and  2   , one embodiment of a person lifting device  100  is schematically illustrated. The person lifting device  100  generally comprises a base  102 , a lift mast  104  and a lift arm  106 . The base  102  comprises a pair of base legs  108 A,  108 B which are pivotally attached to a cross support  132  at base leg pivots  144 A,  144 B such that the base legs  108 A,  108 B may be pivotally adjusted with respect to the lift mast  104  as indicated by the arrows. The base legs  108 A,  108 B are pivoted with the base actuator  206  which is mechanically coupled to both base legs  108 A,  108 B with base motor linkages  125 ,  126 . In one embodiment, the base actuator  206  may comprise a linear actuator such as a motor mechanically coupled to telescoping threaded rods connected to the base motor linkages  125 ,  126  such that, when an armature of the motor is rotated, one of the threaded rods is extended or retracted relative to the other. For example, in the configuration shown in  FIGS.  1  and  2   , when the rods are extended, the base legs  108 A and  108 B are pivoted towards one another and, when the rods are retracted, the base legs  108 A and  108 B are pivoted away from one another. The base legs  108 A,  108 B additionally comprise a pair of front casters  130 A,  130 B and a pair of rear casters  128 A,  128 B. The rear casters  128 A,  128 B may comprise caster brakes (not shown). 
     The base further comprises a mast support  122  disposed on the cross support  132 . In one embodiment, the mast support  122  is a rectangular receptacle configured to receive the lift mast  104  of the person lifting device  100 . For example, a first end of the lift mast  104  may be adjustably received in the mast support  122  and secured with a pin, threaded fastener, or a similar fastener coupled to the adjustment handle  124 . The pin or threaded fastener extends through the mast support  122  and into a corresponding adjustment hole(s) (not shown) on the lift mast  104 . Accordingly, it will be understood that the position of the lift mast  104  may be adjusted vertically with respect to the base  102  by repositioning the lift mast  104  in the mast support  122 . The lift mast  104  further comprises at least one handle  118  coupled to the lift mast  104 . The handle  118  may provide an operator with a grip for moving the person lifting device  100  on the front casters  130 A,  130 B and the rear casters  128 A,  128 B. Accordingly, it should be understood that, in at least one embodiment, the person lifting device  100  is mobile. 
     The person lifting device  100  further comprises a lift arm  106  which is pivotally coupled to the lift mast  104  at the lift arm pivot  138  at a second end of the lift mast  104  such that the lift arm  106  may be pivoted (e.g., raised and lowered) with respect to the base  102 .  FIG.  1    shows the lift arm  106  in the fully raised position while  FIG.  2    shows the lift arm  106  in the fully lowered position. The lift arm  106  comprises at least one sling bar  136  coupled to the lift arm  106  with a multi-link device  148  such that the sling bar  136  is raised or lowered with the lift arm  106 . In the embodiment shown in  FIGS.  1  and  2   , the multi-link device  148  is pivotally attached to the lift arm  106  at an end of the lift arm  106  opposite the lift arm pivot  138 . In one embodiment, the multi-link device  148  is pivotally attached to the lift arm  106  at attachment pivot  142  such that the sling bar  136  may be pivoted with respect to the lift arm  106 . However, it should be understood that, in other embodiments, the multi-link device  148  may be fixedly attached to the lift arm  106 . The multi-link device  148  includes a load tension pin  149  to which the sling bar  136  may be attached. The load tension pin  149  is configured to measure load applied to the load tension pin  149  by the sling bar  136  and/or an object hanging on the sling bar  136 , which will be described in detail with reference to  FIGS.  9 A,  9 B,  10 A, and  10 B  below. 
     In the embodiments described herein, the person lifting device  100  is a mechanized lifting device. Accordingly, raising and lowering the lift arm  106  with respect to the base  102  may be achieved using an actuator such as a lift actuator  204 . In the embodiments shown, the lift actuator  204  is a linear actuator which comprises a motor  110  mechanically coupled to an actuator arm  114 . More specifically, the motor  110  may comprise a rotating armature (not shown) and the actuator arm  114  may comprise one or more threaded rods coupled to the armature such that, when the armature is rotated, the threaded rods are extended or retracted relative to one another and the actuator arm  114  is extended or retracted. In the embodiment shown in  FIG.  1   , the lift actuator  204  further comprises a support tube  116  disposed over the actuator arm  114 . The support tube  116  provides lateral support (e.g., support in the X and/or Y directions) to the actuator arm  114  as the actuator arm  114  is extended. The lift actuator  204  (and base actuator  206 ) are coupled to an electronic control unit  202  which facilitates actuation and control of both the lift actuator  204  and the base actuator  206 . 
     In the embodiment shown in  FIGS.  1  and  2   , the lift actuator  204  is fixedly mounted on the lift mast  104  and pivotally coupled to the lift arm  106 . In particular, the lift mast  104  comprises a bracket  150  to which the motor  110  of the lift actuator  204  is attached while the actuator arm  114  is pivotally coupled to the lift arm  106  at the actuator pivot  140 . Accordingly, it should be understood that, by actuating the lift actuator  204  with the motor  110 , the actuator arm  114  is extended or retracted thereby raising or lowering the lift arm  106  relative to the base  102 . In one embodiment, the lift actuator  204  further comprises an emergency release  112 . The emergency release  112  facilitates the manual retraction of the actuator arm  114  in the event of a mechanical or electrical malfunction of the lift actuator  204 . 
     While the embodiments described herein refer to the lift actuator  204  as comprising a motor  110  and an actuator arm  114 , it will be understood that the actuator may have various other configurations and may include a hydraulic or pneumatic actuator comprising a mechanical pump or compressor, or a similar type of actuator. Further, in other embodiments, where the lifting device is a cable-based lift system, the actuator may be a motor which pays out and/or takes-up cable thereby raising and/or lowering an attached load. Accordingly, it will be understood that various other types of actuators may be used to facilitate raising and lowering the lift arm  106  and/or an attached load with respect to the base  102 . 
     Still referring to  FIGS.  1  and  2   , the person lifting device  100  further comprises an electronic control unit  202 . The electronic control unit  202  comprises a battery  146  and is electrically coupled to the lift actuator  204  and the base actuator  206 . The electronic control unit  202  may be operable to receive an input from an operator via a control device coupled to the electronic control unit  202 . In some embodiments, the control device comprises a wired controller and/or one or more wireless controllers. For example, in one embodiment, the control device is a wired controller (such as a pendant or the like) or, alternatively, a controller integrated into the electronic control unit  202 . In another embodiment, the controller is a wireless controller such as a wireless hand control and/or a wireless diagnostic monitor/control. Based on the input received from the control device, the control unit is programmed to adjust the position of the lift arm  106  and/or the position of the base legs  108 A,  108 B by sending electric control signals to the lift actuator  204  and/or the base actuator  206 . The electronic control unit  202  may communicate with the multi-link device  148  via a wireless or wired connection. For example, the electronic control unit  202  may communicate identification information or location information of the person lifting device  100  to the multi-link device  148 . 
     While  FIGS.  1  and  2    depict the person lifting device  100  as a mobile person lift, it should be understood that the lift control systems and methods for operating a person lifting device described herein may be used in conjunction with other person lifting devices having various other configurations including, without limitation, stationary lifting devices and overhead lifting devices. Further, it should also be understood that, while specific embodiments of the person lifting device described herein relate to person lifting devices used for raising and/or lowering patients, the lift control systems described herein may be used with any lifting device which is operable to raise and lower a load. 
     For example,  FIG.  3    depicts another embodiment in which the person lifting device  300  is a rail-mounted lift system. In this embodiment, the person lifting device  300  generally comprises a lift unit  304  which is slidably coupled to a rail  302  with a carriage  306 . The lift unit  304  may be used to support and/or lift a patient with a lift arm, for example, a lifting strap  308  that is coupled to a lift actuator, in this case a motor, contained within the lift unit  304 . The lift actuator facilitates paying-out or taking-up the lifting strap  308  from the lift unit  304  thereby raising and lowering a patient attached to the lifting strap  308 . In some embodiments, an end of the lifting strap  308  includes a multi-link device  148  to which a sling bar  136  may be attached. In the embodiments described herein, the lift unit  304  further includes a battery which is housed in the lift unit  304  and electrically coupled to the lift actuator thereby providing power to the lift actuator. However, it should be understood that, in other embodiments, the lift unit  304  may be constructed without the battery, such as when the lift actuator is directly wired to a power source. The person lifting device  300  further includes an electronic control unit  202  which is communicatively coupled to the lift actuator and facilitates actuation and control of the lift actuator, specifically paying out and taking up the lifting strap  308 . In some embodiments, the electronic control unit  202  wirelessly communicates with the multi-link device  148 . For example, in some embodiments, the electronic control unit  202  communicates identification information or location information of the person lifting device  300  to the multi-link device  148 . 
     In the embodiment of the person lifting device shown in  FIG.  3   , a person may be attached to the lifting strap  308  with a sling bar  136  attached to the lifting strap  308 . For example, the sling bar  136  may be attached to a harness or sling in which the person is positioned to facilitate the lifting operation. The lift unit  304  may be actuated with the electronic control unit  202  to pay out or take up the lifting strap  308  from the lift unit  304 . In the embodiment shown in  FIG.  3   , the electronic control unit  202  is directly wired to the lift unit  304 . However, it should be understood that, in other embodiments, the electronic control unit  202  may be wirelessly coupled to the lift unit  304  to facilitate remote actuation of the lift unit  304 . 
     Referring now to the exploded view of the person lifting device  300  schematically depicted in  FIG.  4   , the lift unit  304  is mechanically coupled to a carriage  306  which facilitates slidably positioning the lift unit  304  along rail  302 . In the embodiments of the lift unit  304  described herein, the lift unit  304  includes a connection rail  318  which is mounted to the top surface of the lift unit  304 . The connection rail  318  facilitates connecting and securing the lift unit  304  to the carriage  306 . In the embodiment of the lift unit  304  shown in  FIG.  4   , the connection rail  318  has a T-shaped configuration and the carriage  306  has a receiving slot  342  with a complimentary configuration for receiving the connection rail  318 . In some embodiments, the carriage  306  is secured to the connection rail  318  with a fastener  319 , such as a bolt and nut as depicted in  FIG.  4   , which extends transversely through openings in the carriage  306  and a corresponding opening in the connection rail  318 . 
     Referring now to  FIG.  5   , the carriage  306  generally comprises a carriage body  340  to which a plurality of support wheels  344   a ,  344   b ,  344   c , and  344   d  are rotatably attached for supporting the carriage  306  in the rail. The support wheels  344   a ,  344   b ,  344   c , and  344   d  facilitate positioning the carriage  306  and lift unit along the length of the rail. In the embodiments described herein, the carriage  306  is depicted with four support wheels. However, it is contemplated that the carriage  306  may be constructed with fewer than 4 support wheels. For example, in some embodiments, the carriage may be constructed with one or two support wheels (i.e., a pair of support wheels). Accordingly, it should be understood that the carriage  306  includes at least one support wheel. The support wheels  344   a - d  are positioned on axles  320  which extend transversely through the carriage body  340 . Each support wheel is secured to the axle  320  with a fastener, such as retaining clips  322 , such that the support wheels are rotatable on the axle  320 . 
     In the embodiment of the carriage  306  depicted in  FIG.  5   , the support wheels  344   a ,  344   b ,  344   c , and  344   d  are passive (i.e., the support wheels are not actively driven with a motor or a similar drive mechanism) and the lift unit is manually traversed along the rail. However, in alternative embodiments (not shown), the support wheels may be actively driven such as when the support wheels are coupled to a motor or a similar mechanism. In such embodiments, the drive mechanism may be communicatively coupled to an electronic control unit (such as electronic control unit  202  shown in  FIG.  3   ) which actuates the drive mechanism and facilitates traversing the lift unit along the rail with the drive mechanism. 
     Referring to  FIG.  3   , in some embodiments, the multi-link device  148  is disposed at a different location of the person lifting device  300  than a joint of the lifting strap and the sling bar  136 . The multi-link device  148  may be disposed in any location where a load is applied to the load tension pin  149  of the multi-link device  148  in response to lifting operations. For example, as shown in  FIG.  6   , two multi-link devices  148  may be disposed between the sling bar  136  and the lifting hooks  139 A and  139 B. When the person lifting device  300  lifts a patient sitting on a sling attached to the sling bar  136 , a load is applied to the load tension pins  149 . In some embodiment, only one multi-link device  148  is disposed between the sling bar  136  and the lifting hook  139 A or  139 B. As another example, the multi-link device  148  is disposed at a joint between the rail  302  and the lift unit  304 . In some embodiments, the multi-link  148  may be disposed at any other location on a load path, for example, at the axle  320  on the carriage  306 , at the bolt on the carriage  306  or the lift unit  304 , at the bolt on the lift arm  106 , at the lift arm pivot  138 , at the actuator pivot  140 , at the attachment pivot  142 , etc. 
       FIG.  7    schematically depicts an exemplary embodiment of a lift data management system  700  including a multi-link device  702  for providing load data to a server  740  in accordance with one or more embodiments shown and described herein. The multi-link device  702  may correspond to the multi-link device  148  in  FIG.  1    or the multi-link device  148  in  FIG.  3   . The multi-link device  702  includes a controller  704 , one or more sensors  710 , network interface hardware  712 , a power source  714 , and a communication path  716 . The various components of the multi-link device  702  will now be described. 
     The controller  704  includes one or more processors  706  and one or more memory modules  708  to which various components are communicatively coupled, as will be described in further detail below. In some embodiments, the one or more processors  706  and the one or more memory modules  708  and/or the other components are included within a single device. In other embodiments, the one or more processors  706 , the one or more memory modules  708  and/or the other components are distributed among multiple devices that are communicatively coupled. 
     The controller  704  includes the one or more memory modules  708  that store a set of machine readable instructions. The one or more processors  706  execute the machine readable instructions stored in the one or more memory modules  708 . The one or more memory modules  708  may comprise RAM, ROM, flash memories, hard drives, or any device capable of storing machine readable instructions such that the machine readable instructions can be accessed by the one or more processors  706 . The machine readable instructions comprise logic or algorithm(s) written in any programming language of any generation (e.g., 1GL, 2GL, 3GL, 4GL, or 5GL) such as, for example, machine language that may be directly executed by the one or more processors  706 , or assembly language, object-oriented programming (OOP), scripting languages, microcode, etc., that may be compiled or assembled into machine readable instructions and stored in the one or more memory modules  708 . Alternatively, the machine readable instructions may be written in a hardware description language (HDL), such as logic implemented via either a field-programmable gate array (FPGA) configuration or an application-specific integrated circuit (ASIC), or their equivalents. Accordingly, the methods described herein may be implemented in any conventional computer programming language, as pre-programmed hardware elements, or as a combination of hardware and software components. The one or more memory modules  708  may be implemented as one memory module or a plurality of memory modules. 
     The one or more memory modules  708  include instructions for executing the functions of the multi-link device  702 . The instructions may include instructions for determining whether a tension measured by the one or more sensors  710  becomes greater or less than a threshold value, instructions for determining whether a tension measure by the one or more sensors  710  is increased or decreased, and/or instructions for transmitting signal to a receiver  720 . The one or more sensors  710  may be strain gauges included within the load tension pin  149  in  FIG.  1  or  3   . In some embodiments, if it is determined that the tension measured by the one or more sensors  710  becomes greater than a threshold value, the controller  704  instructs the network interface hardware  712  to send to the receiver  720  load event data indicating that an object is loaded on the multi-link device  702 . For example, the network interface hardware  712  transmits load event data (e.g., a binary code of one) to the receiver  720  when it is determined that the tension measured by the one or more sensors  710  becomes greater than a threshold value. The network interface hardware  712  transmits unload event data (e.g., a binary code of zero) to the receiver  720  when it is determined that the tension measured by the one or more sensors  710  becomes less than the threshold value. The one or more memory modules  708  may store the load event data and the unload event data along with the time of the events occurred. 
     In some embodiments, if it is determined that the tension measured by the one or more sensors  710  is increased by a certain amount, the controller  704  instructs the network interface hardware  712  to send to the receiver  720  load event data indicating that an object is loaded on the multi-link device  702 . If it is determined that the tension measured by the one or more sensors  710  is decreased by a certain amount, the controller  704  instructs the network interface hardware  712  to send to the receiver  720  unload event data indicating that an object is unloaded from the multi-link device  702 . For example, the network interface hardware  712  transmits a binary code of one to the receiver  720  when it is determined that the tension measured by the one or more sensors  710  is increased by a certain amount. The network interface hardware  712  transmits a binary code of zero to the receiver  720  when it is determined that the tension measured by the one or more sensors  710  is decreased by the certain amount. 
     The one or more processors  706  may be any device capable of executing machine readable instructions. For example, the one or more processors  706  may be an integrated circuit, a microchip, a computer, or any other computing device. The one or more memory modules  708  and the one or more processors  706  are coupled to a communication path  716  that provides signal interconnectivity between various components and/or modules of the multi-link device  702 . Accordingly, the communication path  716  may communicatively couple any number of processors with one another, and allow the modules coupled to the communication path  716  to operate in a distributed computing environment. Specifically, each of the modules may operate as a node that may send and/or receive data. As used herein, the term “communicatively coupled” means that coupled components are capable of exchanging data signals with one another such as, for example, electrical signals via conductive medium, electromagnetic signals via air, optical signals via optical waveguides, and the like. 
     Accordingly, the communication path  716  may be formed from any medium that is capable of transmitting a signal such as, for example, conductive wires, conductive traces, optical waveguides, or the like. Moreover, the communication path  716  may be formed from a combination of mediums capable of transmitting signals. In some embodiments, the communication path  716  comprises a combination of conductive traces, conductive wires, connectors, and buses that cooperate to permit the transmission of electrical data signals to components such as processors, memories, sensors, input devices, output devices, and communication devices. Additionally, it is noted that the term “signal” means a waveform (e.g., electrical, optical, magnetic, mechanical or electromagnetic), such as DC, AC, sinusoidal-wave, triangular-wave, square-wave, vibration, and the like, capable of traveling through a medium. 
     As schematically depicted in  FIG.  7   , the communication path  716  communicatively couples the one or more processors  706  and one or more memory modules  708  with a plurality of other components of the multi-link device  702 . For example, the multi-link device  702  depicted in  FIG.  7    includes the one or more processors  706  and the one or more memory modules  708  communicatively coupled with the one or more one or more sensors  710 , and the network interface hardware  712 . 
     The one or more sensors  710  may be one or more strain gauges that measures strain applied to the multi-link device  702 . For example, the one or more sensors  710  may be one or more strain gauges included within the load tension pin  149 . When an electrical conductor of the strain gauge is stretched within the limits of its elasticity, the electrical conductor will become narrower and longer and increase its electrical resistance end-to-end. In contrast, when the electrical conductor of the strain gauge is compressed, the electrical conductor will broaden and shorten and decrease its electrical resistance end-to-end. From the measured electrical resistance of the strain gauge, the amount of induced strain may be inferred. The detailed operations of the strain gauge will be described with reference to  FIGS.  10 A,  10 B , and  11  below. 
     The multi-link device  702  includes network interface hardware  712  for communicatively coupling the multi-link device  702  to the receiver  720 . The network interface hardware  712  can be communicatively coupled to the communication path  716  and can be any device capable of transmitting and/or receiving data to and from the receiver  720 . Accordingly, the network interface hardware  712  can include a communication transceiver for sending and/or receiving any wired or wireless communication. For example, the network interface hardware  712  may include an antenna, a modem, LAN port, Wi-Fi card, WiMax card, an RFID transmitter, mobile communications hardware, near-field communication hardware, satellite communication hardware and/or any wired or wireless hardware for communicating with other networks and/or devices. In one embodiment, the network interface hardware  712  includes hardware configured to operate in accordance with the Bluetooth wireless communication protocol. 
     The multi-link device  702  includes the power source  714  which is housed in the multi-link device  702  and electrically coupled to the components of the multi-link device  702  thereby providing power to the components of the multi-link device  702 . However, it should be understood that, in other embodiments, the multi-link device  702  may be constructed without the power source, such as when the multi-link device  702  is directly wired to an external power source. 
     While  FIG.  7    depicts the one or more processors  706 , the one or more memory modules  708 , and the one or more sensors  710 , it should be understood that one or more of these components may be distributed among multiple devices in a variety of configurations. 
     The receiver  720  may be communicatively coupled to the server  740  by a network  730 . In embodiments, the receiver  720  includes one or more processors similar to the one or more processors  706 , one or more memory modules similar to the one or more memory modules  708 , and network interface hardware similar to the network interface hardware  712 . The one or memory modules of the receiver  720  may include location information about the receiver  720  and/or the multi-link device  702 . 
     In one embodiment, the network  730  may include one or more computer networks (e.g., a personal area network, a local area network, or a wide area network), cellular networks, satellite networks and/or a global positioning system and combinations thereof. Accordingly, the receiver  720  can be communicatively coupled to the network  730  via a wide area network, via a local area network, via a personal area network, via a cellular network, via a satellite network, etc. Suitable local area networks may include wired Ethernet and/or wireless technologies such as, for example, wireless fidelity (Wi-Fi). Suitable personal area networks may include wireless technologies such as, for example, IrDA, Bluetooth, Wireless USB, Z-Wave, ZigBee, and/or other near field communication protocols. Suitable cellular networks include, but are not limited to, technologies such as LTE, WiMAX, UMTS, CDMA, and GSM. In some embodiments, the lift data management system  700  may not include the receiver  720  and the multi-link device  702  may be communicatively coupled to the server  740  by the network  730 . 
     The server  740  may include one or more processors  742 , one or more memory modules  744 , a network interface hardware  746 , a display  748 , and a communication path  750 . The one or more processors  742  may be processors similar to the one or more processors  706  described above. The one or more memory modules  744  may be memories similar to the one or more memory modules  708  described above. The network interface hardware  746  may be interface hardware similar to the network interface hardware  712  described above. The communication path  750  may be a communication path similar to the communication path  716  described above. The display  748  may include any medium capable of transmitting an optical output such as, for example, a cathode ray tube, a light emitting diode (LED) display, an organic light emitting diode (OLED) display, a liquid crystal display, a plasma display, or the like. 
     The one or more processors  742  can execute logic to communicate with the multi-link device  702  and/or the receiver  720 . The server  740  may be configured with wired and/or wireless communication functionality for communicating with the multi-link device  702 . In some embodiments, the server  740  may perform one or more elements of the functionality described herein, such as in embodiments in which the functionality described herein is distributed between the multi-link device  702  and the server  740 . In some embodiments, the server  740  may provide a user interface through which one or more settings or configurations of the multi-link device  702  may be altered. 
     In embodiments, the multi-link device  702  transmits load event data or unload event data to the server  740 . For example, the multi-link device  702  detects a load event or unload event using the one or more sensors  710 , and transmits the load event data or unload event data to the receiver  720 . The receiver  720  relays the received load event data or unload event data to the server  740  through the network  730 . In some embodiments, the multi-link device  702  communicates directly with the receiver  720  through the network  730 . For example, when the multi-link device  702  detects a load event or unload event by the one or more sensors  710 , it transmits the load event data or unload event data to the server  740  through the network  730  without transmitting the data to the receiver  720 . 
       FIG.  8    depicts a perspective view of an operator  802  lifting a patient  804  using the person lifting device  300  in accordance with one or more embodiments shown and described herein. In  FIG.  8   , a sling  808  is hung on the sling bar  136  of the person lifting device  300  and the patient  804  sits on the sling  808 . The operator  802  may be a caregiver, a nurse, or a technician testing or fixing the person lifting device  300 . The operator  802  may manipulate the electronic control unit  202  to heighten or lower the sling bar  136  in order to lift or lower the patient  804 . When the sling  808  is lifted such that the patient  804  is lifted off of a patient support system  806 , a tension is applied to the load tension pin  149  (see  FIG.  3   ) of the multi-link device  148 . 
     In some embodiments, the multi-link device  148  determines whether the tension becomes greater or less than a threshold value. The multi-link device  148  transmits load event data to the receiver  720  if it is determined that the tension becomes greater than the threshold value. For example, in some embodiments, the multi-link device  148  may transmit a binary code of one to the receiver  720  when it is determined that the tension becomes greater than the threshold value. The multi-link device  148  transmits unload event data to the receiver  720  if it is determined that the tension becomes less than the threshold value. For example, the multi-link device  148  may transmit a binary code of zero to the receiver  720  when it is determined that the tension becomes less than the threshold value. As for another example, the multi-link device  148  may transmit one type of data if it is determined that the tension becomes greater than the threshold value, and transmit another type of data if it is determined that the tension becomes less than the threshold value. 
     In some embodiments, if it is determined that the tension applied to the load tension pin is increased by a certain amount, the multi-link device  148  transmits to the receiver  720  load event data indicating that an object is loaded on the multi-link device  148 . If it is determined that the tension applied to the load tension pin is decreased by a certain amount, the multi-link device  148  transmits to the receiver  720  unload event data indicating that an object is unloaded from the multi-link device  148 . For example, the multi-link device  148  transmits a binary code of one to the receiver  720  when it is determined that the tension measured by the multi-link device  148  is increased by a certain amount. The multi-link device  148  transmits a binary code of zero to the receiver  720  when it is determined that the tension measured by the multi-link device  148  is decreased by a certain amount. Although  FIG.  8    illustrates the person lifting device  300  shown in  FIG.  3   , the mobile person lifting device  100  in  FIG.  1    may be used to lift the patient  804 . 
     In some embodiments, the multi-link device  148  may transmit identification information about the person lifting device  300  to the receiver  720  along with load event data or unload event data. For example, the multi-link device  148  receives identification information of the person lifting device  300  from the electronic control unit  202 , and stores the identification number of the person lifting device  300  in the one or more memory modules  708 . When there is a change in the tension applied to the multi-link device  148 , the multi-link device  148  transmits load event data or unload event data along with the identification information. 
     In some embodiments, the multi-link device  148  also transmits location information to the receiver  720 . For example, the multi-link device  148  receives the location information of the person lifting device  300  from the electronic control unit  202 , and stores the location information of the person lifting device  300  in the one or more memory modules  708 . When the load applied to the multi-link device  148  is changed, the multi-link device  148  transmits load event data or unload event data along with the identification number. In another embodiment, the receiver  720  may store location information, e.g., a room number where the person lifting device  300  or the receiver  720  is located. 
     As described with reference to  FIG.  7   , the receiver  720  transmits load event data or unload event data, the identification, and/or the location information to the server  740  via the network  730 . In this regard, the server  740  may receive information about where the person lifting device  300  is used and how many times the person lifting device  300  is used. 
       FIGS.  9 A and  9 B  depict the person lifting device  300  lifting a patient in accordance with one or more embodiments shown and described herein. In  FIG.  9 A , no object is hung on the sling bar  136 . As another example, a sling may be hung on the sling bar  136  without a patient sitting on the sling. Thus, only the weight of the sling bar  136  and optionally the sling  808  is applied the load tension pin  149 . The load applied by the sling bar  136  and the sling  808  may be set as a default load by the multi-link device  148 . 
       FIG.  10 A  depicts the load tension pin  149  of the multi-link device  148  when no object is hung on the sling bar  136  or no object is placed on the sling  808 , as shown in  FIG.  9 A . The load tension pin  149  may include one or more strain gauges. For example, in  FIG.  10 A , the load tension pin  149  includes two strain gauges  1010 . When no object is hung on the sling bar  136  or no object is placed on the sling  808 , the load tension pin  149  is not substantially deformed. Accordingly, the strain gauges  1010  are also not substantially deformed. 
     Referring now back to  FIG.  9 B , the patient  804  sits on the sling  808  that is hung on the sling bar  136 . The person lifting device  300  lifts the patient  804  by lifting the multi-link device  148  using the lifting strap  308 . When the patient  804  is lifted off a patient support system, e.g., a patient bed, the weight of the patient  804  is applied to the load tension pin  149 .  FIG.  10 B  depicts the load tension pin  149  when the patient  804  sitting on the sling  808  is lifted off as shown in  FIG.  9 B . The load tension pin  149  is deformed in −y direction by the tension applied by the weight of the patient. Particularly, the center of the load tension pin  149  is deformed in −y direction, whereas both sides of the load tension pin  149  are fixed. Accordingly, the strain gauges  1010  are also deformed in a similar way as the load tension pin  149 . Based on the degree of deformation of the strain gauges  1010 , the load tension pin  149  measures the tension applied to the load tension pin  149 . Specifically, when electrical conductors of the strain gauges  1010  are stretched within the limits of its elasticity, the electrical conductor becomes narrower and longer and increases its electrical resistance end-to-end. When the electrical conductors of the strain gauges  1010  are compressed, the electrical conductor broadens and shortens and decreases its electrical resistance end-to-end. Based on the measured electrical resistance of the strain gauges  1010 , the amount of induced tension may be inferred. 
       FIG.  11    depicts an exemplary graph showing changes of the tension applied to the load tension pin  149  in accordance with one or more embodiments shown and described herein. Prior to time t 1 , the tension applied to the load tension pin  149  starts increasing, e.g., by lifting a patient using the person lifting device  300 . At time t 1 , the tension applied to the load tension pin  149  exceeds the threshold value T th . The controller  704  of the multi-link device  148  determines that the tension measured by the load tension pin  149  becomes greater than the threshold value T th , and sends load event data to receiver  720  indicating that the load tension pin  149  is loaded, e.g., a binary code of one. The multi-link device  148  may send the load event data to the server  740  through the network  730  without communicating with the receiver  720 . In another embodiment, the controller  704  of the multi-link device  148  determines that the tension measured by the load tension pin  149  is increased by a certain amount, and sends load event data to receiver  720  indicating that the load tension pin  149  is loaded. 
     Prior to time t 2 , the tension applied to the load tension pin  149  starts decreasing when the person lifting device  300  puts the patient down on a patient support system. At time t 2 , the tension applied to the load tension pin  149  becomes less than the threshold value T th . The controller  704  of the multi-link device  148  determines that the tension measured by the load tension pin  149  becomes less than the threshold value T th , and sends unload event data to receiver  720  indicating that the load tension pin  149  is unloaded, e.g., a binary code of zero. In another embodiment, the controller  704  of the multi-link device  148  determines that the tension measured by the load tension pin  149  is decreased by a certain amount, and sends unload event data to the receiver  720  indicating that the load tension pin  149  is unloaded. That is, the multi-link device  148  sends two types of data: load event data indicating that the load tension pin  149  is loaded, and unload event data indicating that the load tension pin  149  is unloaded. In another embodiment, the multi-link device  148  sends only load event data indicating that the load tension pin  149  is loaded, and does not send unload event data indicating that the load tension pin  149  is unloaded. 
     Prior to time t 3 , the tension applied to the load tension pin  149  again starts increasing, e.g., by lifting another patient using the person lifting device  300 . At time t 3 , the tension applied to the load tension pin  149  exceeds the threshold value T th . The controller  704  of the multi-link device  148  determines that the tension measured by the load tension pin  149  becomes greater than the threshold value T th , and sends another load event to receiver  720  indicating that the load tension pin  149  is loaded, e.g., a binary code of one. The multi-link device  148  may send the load event data to the server  740  through the network  730  without communicating with the receiver  720 . In another embodiment, the controller  704  of the multi-link device  148  determines that the tension measured by the load tension pin  149  is increased by a certain amount, and sends load event data to receiver  720  indicating that the load tension pin  149  is loaded. 
     Prior to time t 4 , the tension applied to the load tension pin  149  starts decreasing when the person lifting device  300  puts down the patient on, e.g., a patient support system. At time t 4 , the tension applied to the load tension pin  149  becomes less than the threshold value T th . The controller  704  of the multi-link device  148  determines that the tension measured by the load tension pin  149  becomes less than the threshold value T th , and sends a wireless signal to receiver  720  indicating that the load tension pin  149  is unloaded, e.g., a signal of binary code 0. In another embodiment, the controller  704  of the multi-link device  148  determines that the tension measured by the load tension pin  149  is decreased by a certain amount, and sends unload event data to receiver  720  indicating that the load tension pin  149  is unloaded. 
     Between t 5  and t 6 , the tension applied to the load tension pin  149  increases and decreases. However, the maximum of the tension between t 5  and t 6  does not exceed the threshold value T th . Accordingly, the multi-link device  148  does not send load event data or unload event data. In this regard, the multi-link device  148  sends load event data or unload event data only when a significant change of the tension applied to the load tension pin  149  occurs. 
       FIG.  12    depicts collecting load information from a plurality of multi-link devices and a plurality of receivers in accordance with one or more embodiments shown and described herein. The person lifting devices  300   a ,  300   b ,  300   c ,  300   d , and  300   e  are present at rooms of a hospital or any other facilities. For example, the person lifting device  300   a  is located at Room A and communicates with a receiver  720   a  that is also located within Room A. Similarly, the person lifting device  300   b  is located at Room B and communicates with a receiver  720   b  that is located in Room B, the person lifting device  300   c  is located at Room C and communicates with a receiver  720   c  that is located in Room C, the person lifting device  300   d  is located at Room D and communicates with a receiver  720   d  that is located in Room D, and person lifting device  300   e  is located at Room E and communicates with a receiver  720   e  that is located in Room E. The person lifting devices  300   a ,  300   b ,  300   c ,  300   d , and  300   e  may be either the person lifting device  100  in  FIG.  1    or the person lifting device  300  in  FIG.  3   , or a combination of the two. The person lifting devices  300   a ,  300   b ,  300   c ,  300   d , and  300   e  include multi-link devices  148   a ,  148   b ,  148   c ,  148   d , and  148   e , and load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e , respectively. Although  FIG.  12    illustrates five person lift systems, more than or less than five lift systems may communicate with the server  740 . 
     Each of the load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e  detects load events or unload events and transmits load event data or unload event data to the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e , respectively. Each of the load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e  may also communicate identification information about the person lifting devices  300   a ,  300   b ,  300   c ,  300   d , and  300   e  to the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e , respectively. The receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e , in turn, transmit the load event data or unload event data and/or the identification information to the server  740  through the network  730 . The receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e  may also transmit the locations of the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e  or the load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e  to the server  740  through the network  730 . 
     The server  740  receives the load information, identification information, and/or the location information from the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e  or the load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e , and stores the information in a database as illustrated in Table 1 below. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Device ID 
                 Location 
                 Event 
                 Time 
               
               
                   
               
             
            
               
                 300a 
                 Room A 
                 Load 
                 2:00 pm, May 1, 2017 
               
               
                 300a 
                 Room A 
                 Unload 
                 2:01 pm, May 1, 2017 
               
               
                 300b 
                 Room B 
                 Load 
                 2:10 pm, May 1, 2017 
               
               
                 300b 
                 Room B 
                 Unload 
                 2:12 pm, May 1, 2017 
               
               
                 300e 
                 Room E 
                 Load 
                 2:15 pm, May 1, 2017 
               
               
                 300c 
                 Room C 
                 Load 
                 2:15 pm, May 1, 2017 
               
               
                 300e 
                 Room E 
                 Unload 
                 2:18 pm, May 1, 2017 
               
               
                 300c 
                 Room C 
                 Unload 
                 2:19 pm, May 1, 2017 
               
               
                 300a 
                 Room A 
                 Load 
                 2:50 pm, May 1, 2017 
               
               
                 300a 
                 Room A 
                 Unload 
                 2:52 pm, May 1, 2017 
               
               
                   
               
            
           
         
       
     
     Table 1 shows exemplary load or unload events that occurred between 2 pm and 3 pm on May 1, 2017. The server  740  stores the events based on the information received from the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e  or the load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e . For example, at 2:00 pm, May 1, 2017, the server  740  receives load event data, e.g., a binary code of one, location information (Room A), and identification information about the person lifting device  300   a  from the receiver  720   a . At 2:01 pm, May 1, 2017, the server  740  receives unload event data, e.g., a binary code of zero, location information (Room A), and identification information about the person lifting device  300   a . At 2:50 pm, May 1, 2017, the server  740  receives load event data, location information (Room A), and identification information about the person lifting device  300   a  from the receiver  720   a . At 2:52 pm, May 1, 2017, the server  740  receives unload event data, location information (Room A), and identification information about the person lifting device  300   a . In some embodiments, the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e  store the timings of receiving load event data and/or unload event data, and transmit the timings to the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e , respectively. 
     Based on the received information, the server  740  can determine how many times each of the person lifting devices  300   a ,  300   b ,  300   c ,  300   d , and  300   e  is lifted, and how long the person lifting devices  300   a ,  300   b ,  300   c ,  300   d , and  300   e  is lifted during a certain period of time. For example, between 2 pm and 3 pm on May 1, 2017, the person lifting device  300   a  is lifted two times, and the person lifting device  300   a  is lifted for three minutes (between 2:00 pm and 2:01 pm and between 2:50 pm and 2:52 pm). 
     The server  740  may also maintain an exemplary database as illustrated in Table 2 below. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Device ID 
                 No. of Load Events 
                 Total Usage Time 
                 Time of First Lift 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 300a 
                 3,164 
                 4,587 minutes  
                 January 2012 
               
               
                 300b 
                 12 
                   15 minutes 
                 July 2016 
               
               
                 300c 
                 3 
                    5 minutes 
                 March 2017 
               
               
                 300d 
                 367 
                  695 minutes 
                 February 2017 
               
               
                 300e 
                 893 
                 1,234 minutes  
                 June 2013 
               
               
                   
               
            
           
         
       
     
     The database stores the device ID, the number of load events, total usage time, and the time of first lift. The server  740  updates the database whenever it receives information from the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e  or the load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e . For example, when the server  740  receives load event data from the receiver  720   a , the server  740  increases the number of load events for the person lifting device  300   a  by one. When the server  740  receives unload event data from the receiver  720   a , the server calculates usage time based on the time when the load event occurred and the time when the unload event occurred, and updates the total usage time. The updated database may be provided to a facility manager via output devices, for example, the display  748  of the server  740 . 
     Based on the database, the server  740  may determine whether a certain person lift system should be replaced or repaired. For example, if the number of load events for a certain person lift system exceeds a threshold value, the server  740  may provide an alert to a facility manager that the person lift system should be replaced or repaired. In some embodiments, the server  740  may communicate the alert to the receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e  or the load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e  through the network  730 . The receivers  720   a ,  720   b ,  720   c ,  720   d , and  720   e  or the load tension pins  149   a ,  149   b ,  149   c ,  149   d , and  149   e , in turn, may communicate the alert to the electronic control unit  202  of the person lifting devices  300   a ,  300   b ,  300   c ,  300   d , and  300   e , respectively. 
     Based on the foregoing, it should be understood that a lift data management system includes a receiver, a person lifting device, and a central server. The person lifting device includes an actuator, a lift arm coupled to the actuator, one end of the lift arm being configured to move vertically by the actuator, and a multi-link device coupled to the one end of the lift arm and communicatively coupled to the receiver. The multi-link device includes a load tension pin including a sensor configured to measure tension applied to the load tension pin, network interface hardware, one or more processors, and one or more memory modules storing computer readable and executable instructions which, when executed by the processors, cause the multi-link device to: determine whether the tension is increased, and transmit, by the network interface hardware, load event data to the receiver in response to determination that the tension is increased. The central server receives the load event data from the receiver, and update usage information associated with the person lifting device based on the load event data. 
     By transmitting load or unload events associated with person lifting devices to a central server in real time, the multi-link devices allow centralized management of multiple person lifting devices distributed over many areas. The multi-link device also provide accurate and fast information about how many times and how long each of the person lift devices are used. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.