Patent Publication Number: US-2013253751-A1

Title: System and method for controllijng autonomous platform using wire

Description:
TECHNICAL FIELD 
     The present invention relates to a system for controlling an autonomous platform, more specifically to a system and method for controlling an autonomous platform using a wire. 
     BACKGROUND ART 
     As vessels become increasingly bigger, blocks that form the hull are also increasingly getting bigger. Generally, the hull of a large vessel is constructed by manufacturing the blocks, which constitute portions of the hull, and then assembling the blocks. In other words, after rust or foreign substances on surfaces of raw materials are blasted off and the raw materials are painted for prevention of corrosion, the raw materials are, for example, welded together to build the blocks, and the blocks are assembled with one another to complete the hull. 
     These blocks need to be welded, blasted and painted inside thereof. Accordingly, various tasks, such as collecting the grits used for blasting, drying/inspecting/measuring paint film after painting, etc., are also performed inside the blocks. Various kinds of automated preparations for welding, painting and inspection have been steadily developed in order to improve the work efficiency inside the blocks. Demanded as a result is an apparatus for freely moving the devices required for the tasks to desired positions inside the block so that the tasks performed inside the block can be easily carried out. The most well-known apparatus for freely moving inside the block is an autonomous platform using a wire. 
     The conventional autonomous platform using a tendon has not only a wider work radius than the Stewart platform using a linear actuator but also stronger characteristics against a very heavy load. 
     It has been only possible to control the position and posture of such an autonomous platform under a weightless condition (i.e. a condition in which no load is applied) in order to prevent the wire from being stretched. However, in the case that the autonomous platform using a wire is under a load, the wire becomes stretched due to the weight of the autonomous platform, making the wire to sag. If the autonomous platform is disturbed while the wire is sagged, it becomes difficult to maintain the position and posture of the autonomous platform. 
     Moreover, since the autonomous platform itself has its own weight while a load is applied, the wire gets stretched, and thus it is not easy to move the autonomous platform to a desired position and posture, thereby occurring errors when the welding, painting and inspection are performed. 
     DISCLOSURE 
     Technical Problem 
     An embodiment of the present invention provides a system and method for controlling an autonomous platform using a wire that can prevent the wire connected to the autonomous platform from sagging. 
     An embodiment of the present invention provides a system and method for controlling an autonomous platform using a wire that can control the tension acting on the wire. 
     An embodiment of the present invention provides a system and method for controlling an autonomous platform using a wire that can accurately determine a length of the wire fixed to the autonomous platform and a block. 
     An embodiment of the present invention provides a system and method for controlling an autonomous platform using a wire that can determine an accurate position and posture of the autonomous platform inside the block by use of the tension acting on the wire. 
     Technical Solution 
     An aspect of the present invention features a system for controlling an autonomous platform connected with a wire. 
     A system for controlling an autonomous platform connected with a wire in accordance with an embodiment of the present invention includes: a route setting unit configured to generate movement control information by using final position information and initial position information; a speed management unit configured to move the autonomous platform by controlling a speed of the autonomous platform by use of the movement control information; a processing unit configured to generate current position information by using a rotation angle measurement value with respect to the wire and the moved autonomous platform and configured to generate wire operation length information by using the current position information and the movement control information; and a sagging management unit configured to determine sagging of the wire by using measurement information of wire tension acting on the wire once the wire operation length information is generated and configured to adjust the wire by using the measurement information of wire tension if it is determined that the sagging of the wire has occurred. 
     The sagging management unit can set tension reference information, which becomes a reference for determining the sagging of the wire, and determine that the wire has sagged if the measurement information of wire tension is smaller than the tension reference information; and adjust the wire by using the wire tension measurement information. 
     The sagging management unit can generate tension comparison information by comparing the measurement information of wire tension with the tension reference information and pull the wire by using the tension comparison information. 
     The processing unit can include: a wire management module configured to generate current length information of the wire by setting a length of the wire by use of the rotation angle measurement value; a position management module configured to generate the current position information by using the current length information of the wire; a length management module configured to generate the wire operation length information by using the current position information and moved position information of the movement control information; and a winch control module configured to move the autonomous platform, for which the sagging of the wire is solved, by winding or unwinding the wire by controlling a winch by use of the wire operation length information. The moved position information can refer to a position and posture to which the autonomous platform needs to move per unit time. 
     The wire management module can include: a rotation angle analysis module configured to generate the current length information of the wire by using the rotation angle measurement value measured through an encoder that is conned to the wire; and a tension analysis module configured to generate tension measurement information by using a tension measurement value measured through a load cell that is connected to the wire. 
     The position management module can include: a prediction module configured to set arbitrary position information, which indicates an arbitrary position within a block in which the autonomous platform is placed, and arbitrary length information of the wire by using the arbitrary position information; and a generation module configure to the current position information by using the arbitrary length information of the wire and the current length information of the wire. 
     The generation module can generate a length difference value by comparing the arbitrary length information of the wire with the current length information of the wire, determine whether the length difference value is smaller than the length reference information, and generate the current position information with the arbitrary position information if the length difference value is determined to be smaller than the length reference information. 
     The generation module can re-set the arbitrary position information by using the length difference value if the length difference value is determined to be greater than or equal to the length reference information. 
     Moreover, an aspect of the present invention features a system for controlling an autonomous platform connected with a wire. 
     A system for controlling an autonomous platform connected with a wire in accordance with an embodiment of the present invention includes: a route setting unit configured to set movement control information by using final position information and initial position information; a speed management unit configured to move the autonomous platform by controlling a speed of the autonomous platform by use of the movement control information; a position management unit configured to generate current length information of the wire by using rotation angle measurement information with respect to the wire and the moved autonomous platform and by using wire tension information acting on the wire and configured to generate current position information of the moved autonomous platform by using the current length information of the wire; and a processing unit configured to generate wire operation length information by using the current position information and the movement control information and generate rotation angle control information by using the wire operation length information and the rotation angle measurement information. 
     The movement control information can include at least one of movement speed information, at which the autonomous platform needs to move per unit time, and moved position information. 
     The processing unit can include: an analysis module configured to generate the wire operation length information by using the current position information and the moved position information; a prediction module configured to generate rotation angle prediction information by using the wire operation length information; and a determination module configured to generate the rotation angle control information by comparing the rotation angle prediction information with the rotation angle measurement information. 
     The prediction module can generate tension prediction information corresponding to the wire operation length information and generate the rotation angle prediction information by using the wire operation length information and the tension prediction information. 
     The position management unit can include: a rotation angle analysis module configured to generate base length information of the wire by using the rotation angle measurement information that is measured through an encoder connected to the wire; a tension analysis module configured to generate the wire tension information by using tension measurement information that is measured through a load cell connected to the wire; and a length setting module configured to generate the current length information of the wire by setting a length of the wire by using the base length information of the wire and the wire tension information. 
     The position management unit can also include: an operation module configured to set arbitrary position information indicating a position where the autonomous platform is placed within a block and set arbitrary length information by using the arbitrary position information; and a generation module configured to generate a length difference value by comparing the arbitrary length information of the wire with the current length information of the wire and set the arbitrary position information as the current position information if the length difference value is smaller than length reference information. 
     The generation module can re-set the arbitrary position information by using the length difference value if the length difference value is greater than or equal to the length reference information. 
     An aspect of the present invention features a method for controlling an autonomous platform by a system for controlling the autonomous platform using a wire. 
     A method for controlling an autonomous platform using a wire by a system for controlling the autonomous platform using the wire in accordance with an embodiment of the present invention includes: (a) generating movement control information of the autonomous platform by using final position information and initial position information, and moving the autonomous platform by using the movement control information; (b) generating current position information by setting a position and posture of the autonomous platform by using a rotation angle measurement value of a winch connected to the wire; (c) generating wire operation length information by setting a length of the wire by using the current position information; (d) determining sagging of the wire by using measurement information of wire tension acting on the wire, and if the sagging of the wire occurs, adjusting the wire by using the measurement information of wire tension; and (e) moving the wire-sagging solved autonomous platform by controlling a speed of the autonomous platform by using the movement control information. 
     Said step (d) can include: generating the measurement information of wire tension by measuring a tension of the wire connected to the autonomous platform; setting tension reference information which becomes a reference for determining sagging of the wire; and determining that the wire is sagged if the measurement information of wire tension is smaller than the tension reference information, and adjusting the wire by using the measurement information of wire tension. 
     Said step (b) can include: (b1) generating current length information of the wire by setting a length of the wire by using the rotation angle measurement value; and (b2) generating the current position information through forward kinematics by using the current length information of the wire. 
     Said step (b2) can include: setting arbitrary position information indicating an arbitrary position within a block in which the autonomous platform is placed; setting arbitrary length information of the wire by using the arbitrary position information; and generating the current position information by using the arbitrary length information of the wire and the current length information of the wire. 
     The generating of the current position information by using the arbitrary length information of the wire and the current length information of the wire can include: generating a length difference value by comparing the arbitrary length information of the wire with the current length information of the wire; generating length determination result information by determining whether the length difference value is smaller than length reference information; and generating the current position information with the arbitrary position information if the length determination result information shows that the length difference value is smaller than the length reference information. 
     The generating of the current position information by using the arbitrary length information of the wire and the current length information of the wire can also include re-setting the arbitrary position information by using the length difference value if the length determination result shows that the length difference value is greater than or equal to the reference information. 
     Said step (c) can include generating the wire operation length information through inverse kinematics by using the current position information. 
     An aspect of the present invention features a method for controlling an autonomous platform by a system for controlling the autonomous platform using a wire. 
     A method for controlling an autonomous platform using a wire by a system for controlling the autonomous platform using the wire in accordance with an embodiment of the present invention includes: (a) setting movement control information by using final position information and initial position information, and moving the autonomous platform by using the movement control information; (b) generating current length information of the wire by using rotation angle measurement information with respect to the wire and the moved autonomous platform and wire tension information acting on the wire; (c) generating current position information of the moved autonomous platform by using the current length information of the wire; (d) generating wire operation length information by using the current position information and the movement control information; (e) moving the autonomous platform by using rotation angle control information setting the wire operation length information and the rotation angle measurement information. 
     Said step (a) can include: setting the movement control information comprising at least one of movement speed information, at which the autonomous platform needs to move per unit time, and moved position information by using the final position information and the initial position information; and moving the autonomous platform by using the movement control information. 
     Said step (e) can include: generating tension prediction information corresponding to the wire operation length information; generating rotation angle prediction information by using the wire operation length information and the tension prediction information; and generating the rotation angle control information by comparing the rotation angle prediction information with the rotation angle measurement information. 
     Said step (d) can include generating the wire operation length information through inverse kinematics by using the current position information and the moved position information. 
     Said step (b) can include: generating base length information of the wire by using the rotation angle measurement information measured through an encoder connected to the wire; generating the wire tension information by using tension measurement information measured through a load cell connected to the wire; and generating the current length information of the wire by setting a length of the wire by using the base length information of the wire and the wire tension information. 
     Said step (c) can include generating the current position information through forward kinematics by using the current length information of the wire. 
     Said step (c) can include: setting arbitrary position information where the autonomous platform is placed within a block; setting arbitrary length information of the wire by using the arbitrary position information; generating a length difference value by comparing the arbitrary length information of the wire with the current length information of the wire; and generating the current position information with the length difference value and the arbitrary position information if the length difference value is smaller than length reference information. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating a system for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
         FIG. 2  is a block diagram illustrating a detailed configuration of a processing unit of a system for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
         FIGS. 3 and 4  are detailed flow diagrams illustrating a method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
         FIG. 5  is a block diagram illustrating a system for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
         FIG. 6  is a block diagram illustrating a detailed configuration of a position management unit of the system for controlling an autonomous platform using a wire shown in  FIG. 5 . 
         FIG. 7  is a block diagram illustrating in detail a processing unit of the system for controlling an autonomous platform using a wire shown in  FIG. 5 . 
         FIGS. 8 and 9  are detailed flow diagrams illustrating a method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
         FIG. 10  shows an example of how current position information is generated in a method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
         FIG. 11  shows an example of how wire operation length information is generated in a method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
     
    
    
     MODE FOR INVENTION 
     Hereinafter, a system and method for controlling an autonomous platform using a wire in accordance with an embodiment will be described with reference to the accompanying drawings. In describing the embodiment with reference to the accompanying drawings, any identical or similar elements will be given same reference numerals, and the description thereof will not be redundantly provided. 
     Hereinafter, a system for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention will be described with reference to  FIG. 1  and  FIG. 2 . 
       FIG. 1  is a block diagram illustrating a system for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
     Referring to  FIG. 1 , a system for controlling an autonomous platform using a wire  100  (referred to as “autonomous platform control system” hereinafter) uses the wire to move the autonomous platform within a block. Here, the autonomous platform  10  is fixed by the wire  20  within the block  50 , as illustrated in  FIG. 11 , and is movable by a plurality of connected wires  20 . 
     Such an autonomous platform  10  can include a mobile platform and a working apparatus, and the working apparatus can include a working robot and a base. Accordingly, the autonomous platform  10  can easily perform welding, blasting, painting and surfacing tasks inside the block  50  while freely moving inside the block  50 , which is a work space. Here, the autonomous platform  10  can have eight wires  20  connected thereto. 
     One end of the wire  20  is coupled with the block  50 , and the other end of the wire  20  is coupled to a winch (not shown) that is installed in the autonomous platform  10 . Here, the winch can adjust a length of the wire  20  precisely by winding or unwinding the wire  20 . Accordingly, the autonomous platform  10  can adjust the length of the wire  20  by use of the winch to be precisely moved to a desired position inside the block  50 . 
     Referring to  FIG. 1  again, the autonomous platform control system  100  includes an input unit  110 , a route setting unit  120 , a speed management unit  130 , a processing unit  200 , a sagging management unit  170 , a display unit  150  and a storage unit  160 . 
     The input unit  110  can have final position information inputted by a user. Here, the final position information indicates a position and posture to which the autonomous platform  10  needs to move eventually in the block  50 . 
     Here, the position of the autonomous platform  10  can be expressed as a coordinate value including x, y and z to indicate where the autonomous platform  10  is positioned in the block  50 . 
     Here, the posture of the autonomous platform  10  can be expressed as an Euler angle including ψ, θ and φ to indicate an angle by which the autonomous platform  10  is tilted with respect to the position of the autonomous platform  10  in the block  50 . 
     That is, the final position information can express the position and posture, to which the autonomous platform  10  needs to move eventually in the block  50 , as x, y, z, ψ, θ and φ. The final position information can include at least one of a local coordinate value, which is based on the autonomous platform  10 , and a global coordinate value, which is based on any one point within the block  50 . 
     The input unit  110  is a user interface (UI) for having various data inputted by the user, and there is no restriction on how the input unit  110  is realized. For example, the input unit  110  can be any means, such as a keyboard, a touch-pad, a mouse, a key-pad, etc., which can have data inputted thereto. 
     Meanwhile, the input unit  110  can have the final position information inputted through a macro generated using, for example, CAD/CAM (Computer Aided Design/Computer Aided Manufacturing). Hereinafter, it will be described that the final position information is inputted through the input unit  110  by the user. 
     The route setting unit  120  generates movement control information of the autonomous platform  10  by use of the final position information and initial position information. Here, the movement control information refers to control information required for moving the autonomous platform  10  from the initial position information to the final position information. 
     Specifically, the route setting unit  120  generates the initial position information indicating the position and posture of the autonomous platform  10  prior to moving. That is, the initial position information refers to the position and posture before the autonomous platform  10  is repositioned, and a coordinate value including x, y and z can be expressed to indicate the position where the autonomous platform  10  is positioned within the block  50 , and an Euler angle including ψ, θ and φ can be expressed to indicate the posture which is an angle by which the autonomous platform  10  is tilted in the block  50 . 
     The route setting unit  120  can use a sensor value inputted through a sensor unit  60  or wire initial length information provided by the processing unit  200  to generate the initial position information. 
     Here, the sensor unit  60  can be any device that can generate a sensor value by measuring a position and posture in a space. For example, the sensor unit  60  can be at least one of the global positioning system (GPS), an indoor GPS (IGPS) and an ultrasonic sensor. 
     The route setting unit  120  uses the final position information and the initial position information to determine a movement route through which the autonomous platform  10  needs to move. Here, the movement route refers to a route through which the autonomous platform  10  needs to move from the initial position information to the final position information. 
     The route setting unit  120  generates movement speed information indicating a speed at which the autonomous platform  10  needs to move through the movement route per unit time. The route setting unit  120  can set acceleration section information, constant speed section information and deceleration section information. The route setting unit  120  generates the movement speed information that includes the acceleration section information, the constant speed section information and the deceleration section information. Here, the route setting unit  120  can set the acceleration section information, the constant speed section information and the deceleration section information by receiving an input from the user through the input unit  110  or by using a predetermined algorithm (e.g., a program, a probability model, etc.). 
     The route setting unit  120  sets moved position information which indicates a position and posture to which the autonomous platform  10  needs to move per unit time. That is, the moved position information refers to the position and posture to which the autonomous platform  10  needs to have moved after a unit time. 
     The route setting unit  120  generates the movement control information that includes at least one of the movement speed information and the moved position information. Moreover, the route setting unit  120  can set position unit information, which indicates a position and posture to which the autonomous platform  10  needs to move per unit time, and have the position unit information included in the movement control information. Here, the position unit information refers to information on how much the autonomous platform  10  needs to move per unit time according to the movement speed information. 
     The speed management unit  130  uses the movement control information to generate wire unit length information to be provided to the processing unit  200  to move the autonomous platform  10 . In other words, the speed management unit  130  generates the wire unit length information by setting a length of the wire  20  per unit time, based on the movement control information. The speed management unit  130  provides the wire unit length information to the processing unit  200 , which moves the autonomous platform  10  by winding or unwinding the wire  20  connected to a winch  70  by use of the wire unit length information. 
     Moreover, the speed management unit  130  generates the wire unit length information so as for the sagging management unit  170  to solve sagging of the wire  20  or, if the wire  20  does not sag, uses the movement control information to allow the autonomous platform  10  to move toward the final position information. 
     The processing unit  200  uses a rotation angle measurement value, from a measured rotation angle of the winch  70  (shown in  FIG. 2 ), to generate current length information of the wire, current position information and wire operation length information. Here, the rotation angle measurement value indicates an angle of the winch  70  when the winch  70  is wound or unwound by the wire  20 . In other words, the processing unit  200  uses the rotation angle measurement value of the winch  70  to configure the length of the wire  20  that is unwound from the winch  70  to generate the current length information of the wire. 
     Here, the current length information of the wire indicates the length of the wire  20  that is unwound from the winch  70 , which is the length of the wire  20  connecting between the autonomous platform  10  and the block  50 . The current length information of the wire can include a length for each of the plurality of wires  20  connected to the autonomous platform  10 . The processing unit  200  that generates the current length information of the wire will be described in detail with reference to  FIG. 2 . 
     Moreover, the processing unit  200  uses the current length information of the wire to configure a position and posture of the autonomous platform  10  and generate the current position information. Here, the current position information refers to a position and posture of the autonomous platform  10  that is moved by the speed management unit  130  within the block  50 . The current position information can be expressed with a coordinate value such as x, y and z to indicate the position of the autonomous platform  10  and with an Euler angle such as ψ, θ and φ to indicate the posture of the autonomous platform  10 . 
     The processing unit  200  uses the current position information and the movement control information to generate the wire operation length information. Here, the wire operation length information refers to a length of the wire  20  corresponding to a position and posture to which the autonomous platform  10  needs to move based on the current position information and the movement control information. The processing unit  200  will be described in more detail with reference to  FIG. 2 . 
     The sagging management unit  170  uses measurement information of wire tension to determine whether the wire  20  is sagging or not and, if sagging of the wire  20  occurs, adjusts the wire by use of the wire tension measurement information. 
     Specifically, the sagging management unit  170  has the measurement information of wire tension provided thereto from the processing unit  200 . Here, the measurement information of wire tension refers to a tension applied to the wire  20  and can include tension information for each of the plurality of wires  20  connected to the autonomous platform  10 . 
     The sagging management unit  170  sets tension reference information that becomes a reference for a tension applied to the wire  20  in order to determine the sagging of the wire  20 . The sagging management unit  170  can set the tension reference information by either receiving the tension reference information from the input unit  100  or using a pre-determined algorithm. For example, the sagging management unit  170  can set the tension reference information by using block design information. 
     Here, the block design information refers to information configured when the block  50  is designed in order to fix the autonomous platform  10  in the block, and can include a wire fixing position value for a position at which the wire  20  is fixed to the autonomous platform  10 , a block fixing position value for a position at which the wire  20  is fixed to the block  50 , and physical property information such as the size of the autonomous platform  10 . The block design information can be set by having the block design information inputted from the user through the input unit  110  or set by the sagging management unit  170  after receiving the block design information from an external device (not shown) that is connected with the autonomous platform control system  100 . 
     The sagging management unit  170  uses the measurement information of wire tension and the tension reference information to determine the sagging of the wire  20 . Specifically, the sagging management unit  170  determines that the wire  20  is sagged if the measurement information of wire tension is smaller than the tension reference information. Since the tension reference information refers to a minimum tension to be applied to the wire in order not to have any sagging occur in the wire  20 , it can be determined that the wire  20  is sagged if the measurement information of wire tension is smaller than the tension reference information. 
     The sagging management unit  170  generates tension comparison information by comparing the measurement information of wire tension with the tension reference information. The sagging management unit  170  provides the tension comparison information to the processing unit  200 . Here, the processing unit  200  can use the tension comparison information to pull the wire  20  and prevent the wire  20  from sagging. 
     The display unit  150  can display steps carried out and results outputted by the input unit  110 , the route setting unit  120 , the speed management unit  130 , the processing unit  200  and the sagging management unit  170  and can display data stored in the storage unit  160 . 
     For example, the display unit  150  can display a user interface in order to have movement initial information inputted by the user. The user can check displayed information through the display unit  150  and input the movement initial information through the input unit  110 . 
     In another example, the display unit  150  can display the steps and results of having the initial position information set and the movement control information generated by the route setting unit  120 . 
     In another example, the display unit  150  can display the steps and results of having the current length information of the wire, the current position information and the wire operation length information generated by the processing unit  200 . 
     In another example, the display unit  150  can display the sensor value measured by the sensor unit  60 . 
     Moreover, the display unit  150  can display any error occurred in the input unit  110 , the route setting unit  120 , the speed management unit  130 , the processing unit  200  and the sagging management unit  170 . Accordingly, the user can check the error displayed through the display unit  150  and solve the error. 
     The display unit  150  can be any one of a cathode ray tube, a liquid crystal display (LCD), an organic light emitting display (OLED), a light emitted diode (LED), an electrophoretic display (EPD), a plasma display panel (PDP), etc. or can be a computer having a display device. Moreover, the display unit  150  can be realized integrally with the input unit  110  by use of, for example, a touch screen. 
     The storage unit  160  stores data required by the input unit  110 , the route setting unit  120 , the speed management unit  130 , the processing unit  200  and the sagging management unit  170  of the autonomous platform  100  and data generated by the input unit  110 , the route setting unit  120 , the speed management unit  130 , the processing unit  200  and the sagging management unit  170 . 
     For example, the storage unit  160  can store the final position information inputted from the input unit  110  and store the initial position information configured by and the movement control information generated by the route setting unit  120 . 
     In another example, the storage unit  160  can store the sensor value measured by the sensor unit  60  and store the current length information of the wire, the current position information and the wire operation length information generated by the processing unit  200 . 
     The storage unit  160  can provide data required by a request of the input unit  110 , the route setting unit  120 , the speed management unit  130 , the processing unit  200 , the sagging management unit  170  and the display unit  150 . The storage unit  160  can be provided as a unified memory or constituted with a plurality of memories. For example, the storage unit  160  can be constituted with Read Only Memory (ROM), Random Access Memory (RAM), flash memory, etc. 
       FIG. 2  is a block diagram illustrating a detailed configuration of the processing unit of the system for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
     Referring to  FIG. 2 , the processing unit  200  includes a wire management module  210 , a position management module  250  and a length management module  280 . 
     The wire management module  210  uses the rotation angle measurement value to configure the length of the wire  20  and generate the current length information of the wire. This wire management module  210  includes a rotation angle analysis module  220 , a tension analysis module  230  and a winch control module  240 . 
     The rotation angle analysis module  220  uses the rotation angle measurement value of the winch  70  that is measured by an encoder  80  to generate the current length information of the wire that indicates the length of the wire  20  unwound from the winch  70 . 
     For example, the rotation angle analysis module  220  can express a relation between the rotation angle measurement value and length information of the wire  20  as a function and insert the rotation angle measurement value in the function to generate the current length information of the wire. It is also possible for the rotation angle analysis module  220  to generate the current length information of the wire by use of a length table in which lengths of the wire  20  are matched to rotation angle measurement values. The rotation angle analysis module  220  provides the current length information of the wire to the position management module  250 . 
     Here, the encoder  80  is connected to the winch  70  and generates the rotation angle measurement value through a rotation of the winch  70 . Moreover, the encoder  80  is connected to a pulley (not shown) that discharges the wire  20  to measure how much the pulley is rotated or to generate the rotation angle measurement value by measuring an amount of the discharged wire  20 . 
     Moreover, once a length request signal is received from the route setting unit  120 , the rotation angle analysis module  220  generates the wire initial length information by use of the rotation angle measurement value of the encoder  80  connected to the wire  20  of the autonomous platform  10  before moving. 
     The tension analysis module  230  generates the measurement information of wire tension by use of a tension measurement value measured at a load cell  90 . 
     For example, the tension analysis module  230  can express a relation between the tension measurement value measured at the load cell  90  and a wire tension acting on the wire  20  as a linear or non-linear function and can generate the measurement information of wire tension by inserting the tension measurement value in the function. It is also possible for the tension analysis module  230  to generate the tension measurement information by use of a tension table in which wire tensions are matched to tension measurement values. 
     Here, the load cell  90  is connected to the wire  20  and generates the tension measurement value by measuring the tension acting on the wire  20 . The load cell  90  is accessed to the processing unit  200  and sends the tension measurement value to the tension analysis module  230  of the processing unit  200 . 
     The winch control module  240  is accessed with the winch  70  and controls the winch  70  on which the wire  20  is wound to adjust the length of the wire  20  and move the autonomous platform  10  connected to the wire  20 . For example, the winch control module  240  can use the wire unit length information provided by the speed management unit  130  to control the winch  70  and move the autonomous platform  10  by winding or unwinding the wire  20 . The winch control module  240  can use the tension comparison information provided by the sagging management unit  170  to solve the sagging of the wire  20  by winding or unwinding the wire  20  connected to the winch  70 . 
     The position management module  250  uses the current length information of the wire to generate the current position information. For this, the position management module  250  includes a prediction module  260  and a generation module  270 . 
     The prediction module  260  uses arbitrary position information to set arbitrary length information of the wire. That is, the prediction module  260  sets the arbitrary position information in order to assume that the autonomous platform  10  is at the arbitrary position within the fixed block  50 . Here, the arbitrary position information is expressed as a coordinate value to indicate a position at which the autonomous platform  10  is virtually positioned within the block  50 . The arbitrary position information can be any position in the block  50  as long as the autonomous platform  10  can move within the block  50 . The arbitrary position information can be set by the prediction module  260  by having the arbitrary position information inputted by the user through the input unit  110  or by using a predetermined algorithm. 
     The prediction module  260  uses the arbitrary position information to set the arbitrary length information through inverse kinematics. Here, the arbitrary length information of the wire refers to a length of the wire  20  connecting the block  50  to the autonomous platform  10  that is placed at the arbitrary position information. 
     The generation module  270  uses the arbitrary length information of the wire and the current length information of the wire to generate the current position information through forward kinematics. That is, the generation module  270  generates a length difference value by comparing the arbitrary length information of the wire and the current length information of the wire. The generation module  270  sets length reference information, which is a reference for tolerating an error. Here, the generation module  270  can set the length reference information by having the length reference information inputted by the user through the input unit  110  or by using a predetermined algorithm. 
     The generation module  270  can generate length determination result information by determining whether the length difference value is smaller than the length reference information. The generation module  270  generates the current position information to be the arbitrary position information if the length determination result information shows that the length difference value is smaller than the length reference information. 
     The generation module  270  generates the current position information by re-setting the arbitrary position information if the length determination result information shows that the length difference value is greater than or equal to the length difference information. 
     The length management module  280  uses the current position information and the movement control information to generate the wire operation length information. That is, the length management module  280  generates position difference information by comparing the current position information with the moved position information included in the movement control information in order to determine whether the autonomous platform  10  has moved based on the movement control information set by the route setting unit  120 . 
     The length management module  280  generates the wire fixing position value by adding the current position information, the position difference information and the position unit information with one another. Moreover, the length management module  280  can substitute the wire fixing position value in inverse kinematics to generate the wire operation length information. 
     The length management module  280  uses the wire operation length information to generate rotation angle prediction information. Here, the rotation angle prediction information refers to a rotation angle of the winch  70  for moving the autonomous platform  10 . The length management module  280  generates the movement control information by comparing the rotation angle measurement value with the rotation angle prediction information in order to move the autonomous platform  10  from the current position and posture of the autonomous platform  10  to a position and posture to which the autonomous platform  10  needs to move. 
     A method for allowing the autonomous platform control system using a wire in accordance with an embodiment of the present invention to control the autonomous platform will be described with reference to  FIGS. 3 and 4 . 
       FIGS. 3 and 4  are detailed flow diagrams illustrating a method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
     Referring to  FIGS. 3 and 4 , the autonomous platform control system  100  generates the initial position information, using a sensor value measured by the sensor unit  60  or the wire initial length information (S 310 ). 
     The autonomous platform control system  100  generates the movement control information including at least one of the movement speed information, the moved position information and the position unit information, using the final position information and the initial position information (S 320 ). 
     Then, the autonomous platform control system  100  uses the movement control information to generate the wire unit length information and moves the autonomous platform  10  by loosening or pulling the plurality of wires  20  connected to the autonomous platform  10  according to the wire unit length information. 
     The autonomous platform control system  100  generates the current length information of the wire, using the rotation angle measurement value of the winch  70  (S 330 ). 
     The autonomous platform control system  100  sets arbitrary position information that indicates an arbitrary position at which the autonomous platform  10  is positioned in the block  50  (S 340 ). 
     The autonomous platform control system  100  sets the arbitrary length information of the wire by substituting the arbitrary position information in inverse kinematics (S 350 ). 
     The autonomous platform control system  100  generates the length difference value by comparing the current length information of the wire with the arbitrary length information of the wire (S 360 ). Specifically, the generation module  270  can define the length difference value as shown in [Equation 1]. 
         D=L   m   −L   k   [Equation 1]
 
     Here, D is a length difference value, and L m  is current length information of the wire, and L k  is arbitrary length information of the wire. Accordingly, the generation module  270  of the autonomous platform control system  100  generates the length difference value by inputting the current length information of the wire generated by the rotation angle analysis module  220  in L m  of [Equation 1] and inputting the arbitrary length information of the wire set by the prediction module  260  in L k  of [Equation 1]. Here, the generation module  270  can generate the length difference value to correspond to each of the plurality of wires  20  connected to the autonomous platform  10 . 
     The autonomous platform control system  100  determines whether the length difference value is smaller than the length reference information (S 370 ). 
     The autonomous platform control system  100  can re-set the arbitrary position information by returning to step S 340  if the length difference value is determined to be greater than or equal to the length reference information (S 380 ). 
     The autonomous platform control system  100  generates the current position information by use of the arbitrary position information and the length difference value if the length difference value is determined to be smaller than the length reference information (S 390 ). 
     That is, the generation module  270  of the autonomous platform control system  100  can generate the current position information by use of [Equation 2]. 
         X   k+1   =X   k   +JM   #   [D]   [Equation 2]
 
     Here, X k+1  refers to a position and posture to which the autonomous platform  10  moves using the movement control information with respect to X k , which is arbitrary position information, and JM is the Jacobian matrix that is determined by the kinematic shape of the wire  20 , and D is a length difference value. 
     The generation module  270  can convert [Equation 2] to [Equation 3]. 
         JM   X   {dot over (X)}=JM   L   {dot over (L)}   [Equation 3]
 
     Here, JM X {dot over (X)} means that a value obtained by subtracting X k  from X k+1  is differentiated, and JM L {dot over (L)} means that a value obtained by subtracting L k  from L m  is differentiated. Afterwards, the generation module  270  can convert [Equation 3] to [Equation 4] in order to generate the current position information. 
     
       
         
           
             
               
                 
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     Here, JM L  is a unit matrix (l), and, as shown in  FIGS. 5 and 6 , s n  is a unit vector from A n , which is a position at which the “n”th wire  20  is fixed to the autonomous platform  10 , to B n , which is a position at which the “n”th wire  20  is fixed to the block  50 , and b n  is a vector from a center of a robot to A n , and N is a natural number. Therefore, the generation module  270  calculates s n  and b n  by use of the length difference value and the block fixing position value of the block design information. Moreover, the generation module  270  generates the current position information by substituting the calculated s n  and b n  into [Equation 4]. 
     The autonomous platform control system  100  generates the position difference information by comparing the current position information with the moved position information of the movement control information and generates the wire operation length information by use of the position difference information (S 410 ). 
     That is, the length management module  280  of the autonomous platform control system  100  can define the wire operation length information as [Equation 5]. 
         L   n   =∥A   n   −B   n ∥=√{square root over (( w   X   n − w   x   n ) 2 +( w   Y   n − w   y   n ) 2 +( w   Z   n − w   z   n ) 2 )}{square root over (( w   X   n − w   x   n ) 2 +( w   Y   n − w   y   n ) 2 +( w   Z   n − w   z   n ) 2 )}{square root over (( w   X   n − w   x   n ) 2 +( w   Y   n − w   y   n ) 2 +( w   Z   n − w   z   n ) 2 )}  [Equation 5]
         whereas, A n =( w x n ,  w y n ,  w z n ),B n =( w X n ,  w Y n ,  w Z n )       

     Here, L is wire operation length information, and, as shown in  FIG. 6 , A n  is a wire fixing position value at which the “n”th wire  20  is fixed to the autonomous platform  10 , and B n  is a block fixing position value at which the “n”th wire  20  is fixed to the block  50 , and N is a natural number that indicates the number of wires  20  connected to the autonomous platform  10 .  w x n ,  w y n ,  w z n  is a wire fixing position value defined in a global coordinate system at which the “n”th wire  20  is fixed to the autonomous platform  10 , and  w X n ,  w Y n ,  w Z n  is a block fixing position value defined in the global coordinate system at which the “n”th wire  20  is fixed to the block  50 . Here, since B n  is a position at which the “n”th wire  20  is fixed to the block  50  and thus does not change even if the autonomous platform  10  moves, B n  can be checked using the block fixing position value of the block design information. 
     The length management module  280  can define A as shown in [Equation 6]. 
     
       
         
           
             
               
                 
                   
                     
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     Here, R is a rotation matrix, and T is a translation matrix.  b x n ,  b y n  and  b z n  are platform fixing position values defined in a local coordinate system at which the “n”th wire  20  is fixed to the autonomous platform  10 . Here, since  b x n ,  b y n  and  b z n  determine fixing position points of the wire  20  with reference to the autonomous platform  10  and thus do not change even if the autonomous platform moves,  b x n ,  b y n  and  b z n  can be checked using the platform fixing position values included in the block design information. c θ  and s θ  can be cos θ and sin θ. P x , P y  and P z  indicate the position and posture of the autonomous platform  10  in the global coordinate system. 
     Accordingly, the length management module  280  generates wire fixing position value A n  by substituting the platform fixing position values of the block design information in  b x n ,  b y n  and  b z n  and substituting information obtained by adding the current position information, the position difference information and the position unit information with one another in P x , P y  and P z . 
     The length management module  280  generates the wire operation length information by substituting the generated wire fixing position value in A n  and substituting the block fixing position value of the block design information in B n  of [Equation 5]. 
     The autonomous platform control system  100  generates the measurement information of wire tension that indicates the tension acting on the wire  20  (S 420 ). 
     The autonomous platform control system  100  sets the tension reference information that becomes a reference for determining sagging of the wire  20  (S 430 ). 
     The autonomous platform control system  100  determines whether the measurement information of wire tension is smaller than the tension reference information (S 440 ). 
     If the measurement information of wire tension is determined to be equal to or greater than or equal to the tension reference information, the sagging management unit  170  of the autonomous platform control system  100  determines that no sagging has occurred in the wire  20  and adjusts the length of the wire  20  in order to move the autonomous platform  10  (S 450 ). A method of adjusting the length of the wire  20  will be described in detail with reference to step S 470 . 
     If the measurement information of wire tension is determined to be smaller than the tension reference information, the autonomous platform control system  100  adjusts the wire  20  by use of the tension comparison information generated by comparing the measurement information of wire tension with the tension reference information (S 460 ). For example, the sagging management unit  170  of the autonomous platform control system  100  can define the tension comparison information as shown in [Equation 7]. 
         TS=K   t *(( T   n ) t −( T   n ) c )  [Equation 7]
 
     Here, TS is tension comparison information, and K t  is a tension proportional gain for compensating tension information, and (T n ) t  is tension reference information, and (T n ) c  is wire tension measurement information. Here, the sagging management unit  170  can set the tension proportional gain by having the tension proportional gain inputted by the user or by using a predetermined algorithm. 
     The sagging management unit  170  sets the tension comparison information by substituting the tension reference information in (T n ) t  of [Equation 7] and substituting the measurement information of wire tension in (T n ) c . The autonomous platform control system  100  can use the tension comparison information to solve the sagging occurred in the wire  20 . 
     The autonomous platform control system  100  generates the rotation angle prediction information by using the wire operation length information and adjusts the length of the wire  20  by using the movement control information generated by comparing the rotation angle prediction information with the rotation angle measurement value (S 470 ). 
     That is, the length management module  280  of the autonomous platform control system  100  can define the movement control information as shown in [Equation 8]. 
         CL=K   p *(( J   n ) t −( J   n ) c )  [Equation 8]
 
     Here, CL is movement control information, and K p  is a rotation angle proportional gain for compensating rotation angle information, (J n ) t  rotation angle prediction information, and (J n ) c  a rotation angle measurement value. Here, the length management module  280  can set length proportional gain by having the length proportional gain inputted by the user or by using a predetermined algorithm. 
     The length management module  280  sets the movement control information by substituting the rotation angle prediction information in (J n ) t  of [Equation 8] and substituting rotation angle measurement information in (J n ) c . 
     The autonomous platform control system  100  controls the speed of the autonomous platform  10  and moves the autonomous platform  10  by using the movement control information and the movement speed information of the movement control information (S 480 ). 
     Afterwards, the speed management unit  130  of the autonomous platform control system  100  stops moving the autonomous platform  10  if the measurement information of wire tension is greater than the tension reference information and a comparison value between the current position information and the final position information is smaller than position reference information. Here, the position reference information is a reference for determining a tolerable error by comparing the position and posture to which the autonomous platform needs to move with the current position and posture of the autonomous platform, and can be set by having the position reference information inputted by the user or by using a predetermined algorithm. 
     Hereinafter, a system for controlling an autonomous platform using a wire in accordance with an embodiment will be described with reference to  FIGS. 5 to 7 . 
       FIG. 5  is a block diagram illustrating a system for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
     Referring to  FIG. 5 , an autonomous platform control system  100  includes an input unit  110 , a route setting unit  120 , a speed management unit  130 , a winch control unit, a position management unit  300 , a processing unit  200 , a display unit  150  and a storage unit  160 . 
     The input unit  110  can have final position information inputted by a user. Here, the final position information indicates a position and posture to which an autonomous platform  10  needs to move eventually in a block  50 . Here, the position of the autonomous platform  10  can be expressed as a coordinate value including x, y and z to indicate where the autonomous platform  10  is positioned in the block  50 . Here, the position of the autonomous platform  10  indicates where the autonomous platform  10  is positioned in the block  50 . The posture of the autonomous platform  10  can be expressed as an angle by which the autonomous platform  10  is tilted by a wire  20 . The final position information can include at least one of a local coordinate value, which is based on the autonomous platform  10 , and a global coordinate value, which is based on any one point within the block  50 . 
     Moreover, the input unit  110  can have block design information inputted therein by the user. Here, the block design information can include a wire fixing position value for a position at which the wire  20  is fixed to the autonomous platform  10 , a block fixing position value for a position at which the wire  20  is fixed to the block  50 , and physical property information such as the size of the autonomous platform  10 . The block design information can be received from an external device (not shown) that is connected with the autonomous platform control system  100 . 
     The route setting unit  120  generates movement control information of the autonomous platform  10  by use of the final position information and initial position information. Here, the initial position information refers to a position and posture of the autonomous platform  10  before the autonomous platform  10  is moved, and is expresses as a coordinate value, like the final position information. The movement control information refers to control information required for moving the autonomous platform  10  from the initial position information to the final position information. 
     Specifically, the route setting unit  120  sets the initial position information indicating the position and posture of the autonomous platform  10  prior to moving. The route setting unit  120  can set the initial position information by using a sensor value inputted through a sensor unit  60  or by using wire initial length information provided by the position management unit  300 . Here, the wire initial length information refers to a length of the wire  20  unwound from the winch  70  before the autonomous platform  10  is moved. 
     The route setting unit  120  uses the final position information and the initial position information to determine a movement route through which the autonomous platform  10  needs to move. Here, the movement route refers to a route through which the autonomous platform  10  needs to move from the initial position information to the final position information. 
     The route setting unit  120  generates movement speed information indicating a speed at which the autonomous platform  10  needs to move through the movement route per unit time. The route setting unit  120  generates the movement speed information that includes acceleration section information, constant speed section information and deceleration section information. Here, the route setting unit  120  can set the acceleration section information, the constant speed section information and the deceleration section information by receiving an input from the user through the input unit  110  or by using a predetermined algorithm (e.g., a program, a probability model, etc.). 
     The route setting unit  120  sets moved position information which indicates a position and posture to which the autonomous platform  10  needs to move per unit time. That is, the moved position information refers to the position and posture to which the autonomous platform  10  needs to have moved after a unit time. 
     The route setting unit  120  sets the movement control information that includes at least one of the movement speed information and the moved position information. Moreover, the route setting unit  120  can set position unit information, which indicates a position and posture to which the autonomous platform  10  needs to move per unit time, and have the position unit information included in the movement control information. Here, the position unit information refers to information on how much the autonomous platform  10  needs to move per unit time according to the movement speed information. 
     The route setting unit  120  sets rotation angle processing information corresponding to the final position information. Here, the rotation angle processing information can show a rotation angle of the winch  70  corresponding to the position and posture to which the autonomous platform  100  needs to move per unit time. 
     The speed management unit  130  uses the movement control information to move the autonomous platform  10 . In other words, the speed management unit  130  can generate wire unit length information by setting a length of the wire  20  per unit time based on the movement speed information. The speed management unit  130  provides the wire unit length information to the winch control unit  140 . 
     The winch control unit  140  is accessed with the winch  70  and adjusts the length of the wire  20  by controlling the winch  70 , on which the wire  20  is wound, to move the autonomous platform connected with the wire  20 . For instance, the winch control unit  140  can control the winch  70  by use of the wire unit length information provided by the speed management unit  130  to wind or unwind the wire  20  to move the autonomous platform  10 . 
     The position management unit  300  uses rotation angle measurement information and wire tension information to generate current position information. In other words, the position management unit  300  generates current length information of the wire by using the rotation angle measurement information for the wire  20  and the autonomous platform  10  and the wire tension information acting on the wire  20 . 
     Here, the rotation angle measurement information refers to an angle of the winch  70  when the winch  70  winds or unwinds the wire  20 . The wire tension information refers to a tension acting on the wire  20  and can include tension information for each of a plurality of wires  20  connected to the autonomous platform  10 . The current length information of the wire refers to a length of the wire  20  that is unwound from the winch  70 , which is a length of the wire  20  connecting the autonomous platform  10  with the block  50 . The current length information of the wire can include lengths for each of the plurality of wires  20  connected to the autonomous platform  10 . 
     The position management unit  300  uses the current length information of the wire to generate the current position information. Here, the current position information can refer to a position and posture at which the autonomous platform  10  is currently placed within the block  50 . The position management unit  300  will be described in more detail with reference to  FIG. 2 . 
     The processing unit  200  uses the current position information to generate wire operation length information and rotation angle control information. That is, the processing unit  200  generates the wire operation length information, which indicates a length of the wire  20  at a position and posture to which the autonomous platform  10  needs to move, by using the current position information and the moved position information of the movement control information. Here, the rotation angle control information refers to a rotation angle of the winch  70  for moving the autonomous platform  10  to the moved position information. The processing unit will be described in more detail with reference to  FIG. 3 . 
     The display unit  150  can display steps carried out and results outputted by the input unit  110 , the route setting unit  120 , the speed management unit  130 , the winch control unit  140 , the position management unit  300  and the processing unit  200  and can display data stored in the storage unit  160 . 
     For example, the display unit  150  can display a user interface in order to have movement initial information inputted by the user. The user can check displayed information through the display unit  150  and input the movement initial information through the input unit  110 . 
     In another example, the display unit  150  can display the steps and results of having the initial position information and the movement control information set by the route setting unit  120  and display the sensor value measured by the sensor unit  60 . 
     In another example, the display unit  150  can display the steps and results of having the current length information and the current position information generated by the position management unit  300  and display the steps and results of having the wire operation length information generated by the processing unit  200 . 
     Moreover, the display unit  150  can display any error occurred in the input unit  110 , the route setting unit  120 , the speed management unit  130 , the winch control unit  140 , the position management unit  300  the processing unit  200 . Accordingly, the user can check the error displayed through the display unit  150  and solve the error. 
     The storage unit  160  stores data required or generated for moving the autonomous platform  10 . That is, the storage unit  160  can store data required or generated by the input unit  110 , the route setting unit  120 , the speed management unit  130 , the winch control unit  140 , the position management unit  300  and the processing unit  200 , which are component elements of the autonomous platform control system  100 . 
     For example, the storage unit  160  can store the final position information inputted through the input unit  110  and the sensor value measured through the sensor unit  60 . 
     In another example, the storage unit  160  can store the current length information and the current position information generated by the position management unit  300  and store the wire operation length information generated by the processing unit  200 . 
     Moreover, the storage unit  160  can provide data required according to a request of the input unit  110 , the route setting unit  120 , the speed management unit  130 , the winch control unit  140 , the position management unit  300 , the processing unit  200  or the display unit  150 . 
       FIG. 6  is a block diagram illustrating a detailed configuration of the position management unit of the system for controlling an autonomous platform using a wire shown in  FIG. 5 . 
     Referring to  FIG. 6 , the position management unit  300  includes a rotation angle analysis module  220 , a tension analysis module  230 , a length setting module  310 , an operation module  320  and a generation module  330 . 
     The rotation angle analysis module  220  uses rotation angle measurement value of the winch  70  that is measured by an encoder  80  to generate base length information of the wire that indicates the length of the wire  20  unwound from the winch  70 . 
     For example, the rotation angle analysis module  220  can express a relation between the rotation angle measurement information and length information of the wire  20  as a function and insert the rotation angle measurement information in the function to generate the base length information of the wire. It is also possible for the rotation angle analysis module  220  to generate the base length information of the wire by use of a length table in which lengths of the wire  20  are matched to rotation angle information. 
     Here, the encoder  80  is connected to the winch  70  and generates the rotation angle measurement information through a rotation of the winch  70 . Moreover, the encoder  80  is connected to a pulley (not shown) that discharges the wire  20  to measure how much the pulley is rotated or to generate the rotation angle measurement information by measuring an amount of the discharged wire  20 . 
     Moreover, once a length request signal is received from the route setting unit  120 , the rotation angle analysis module  220  generates the wire initial length information by measuring the rotation angle measurement information of the winch  70 , prior to moving, mounted in the autonomous platform, through the encoder  80  connected to an axle of the winch  70 . Moreover, the rotation angle analysis module  220  provides the wire initial length information to the route setting unit  120 . 
     The tension analysis module  230  generates the wire tension information by use of tension measurement information measured at a load cell  90 . 
     For example, the tension analysis module  230  can express a relation between the tension measurement information measured at the load cell  90  and a wire tension acting on the wire  20  as a linear or non-linear function and can generate the wire tension information by inserting the tension measurement information in the function. It is also possible for the tension analysis module  230  to generate the wire tension information by use of a tension table in which wire tensions acting on the wire  20  are matched to the tension measurement information. 
     Here, the load cell  90  is connected to the wire  20  and generates the tension measurement information by measuring the tension acting on the wire  20 . The load cell  90  is accessed to the tension analysis module  230  and sends the tension measurement information to the tension analysis module  230 . 
     The length setting module  310  uses the base length information of the wire and the wire tension information to generate the current length information of the wire. In other words, the length setting module  310  can generate the current length information of the wire by reflecting the wire tension information in the base length information of the wire. 
     Therefore, the autonomous platform control system  100  using the wire  20  in accordance with the present invention can determine a precise position and posture of the autonomous platform  10  in the block  50  because the current length information of the wire is generated using the tension acting on the wire  20 . 
     The operation module  320  sets arbitrary position information of the autonomous platform  10  and then sets arbitrary length information for the arbitrary position information. Specifically, the operation module  320  sets the arbitrary position information in order to assume that the autonomous platform  10  is placed at an arbitrary position within the block  50  to which the autonomous platform  10  is fixed. Here, the arbitrary position information refers to a position where the autonomous platform  10  is virtually placed within the block  50  and can be expressed as a coordinate value. The arbitrary position information can be any place as long as the autonomous platform can be moved to such a place within the block  50 . The arbitrary position information can be set by the operation module  320  by having the arbitrary position information inputted by the user through the input unit  110  or by use of a predetermined algorithm. 
     The operation module  320  uses the arbitrary position information to set the arbitrary length information through inverse kinematics. Here, the arbitrary length information of the wire can refer to a length of the wire  20  unwound from the winch  70  with respect to the arbitrary position information and can include lengths of the plurality of wires  20  connected to the autonomous platform  10 . 
     The generation module  330  uses the arbitrary length information of the wire and the current length information of the wire to generate the current position information through forward kinematics. In other words, the generation module  330  generates a length difference value by comparing the arbitrary length information of the wire and the wire operation length information. The generation module  270  can set length reference information, which is a reference for tolerating an error, by comparing the arbitrary length information of the wire with the current length information of the wire. Here, the generation module  330  can set the length reference information by having the length reference information inputted by the user through the input unit  110  or by using a predetermined algorithm. 
     The generation module  330  determines whether the length difference value is smaller than the length reference information. If the length difference value is determined to be smaller than the length reference information, the generation module  330  generates the current position information with the arbitrary position information. 
     If, however, the length difference value is determined to be greater than or equal to the length reference information, the generation module  330  can generate the current position information by re-setting the arbitrary position information by use of the length difference value. 
       FIG. 7  is a block diagram illustrating in detail the processing unit of the system for controlling an autonomous platform using a wire shown in  FIG. 5 . 
     Referring to  FIG. 7 , the processing unit  200  includes a length analysis module  211 , a prediction module  212  and a determination module  213 . 
     The length analysis module  211  uses the current position information and the movement control information to generate the wire operation length information. That is, the length analysis module  211  generates position difference information by comparing the current position information with the moved position information included in the movement control information in order to determine whether the autonomous platform  10  has moved based on the movement control information set by the route setting unit  120 . 
     Moreover, the length analysis module  211  generates the wire operation length information by adding the current position information, the position difference information and position unit information included in the movement control information with one another. Here, the wire operation length information refers to a length of the wire  20  connecting the block  50  with the autonomous platform  10  that is placed at a position and posture to which the autonomous platform  10  needs to move per unit time. Meanwhile, the length analysis module  211  can generate the wire operation length information by using the current position information, the position difference information and the movement control information through inverse kinematics. 
     The prediction module  212  uses the wire operation length information to generate rotation angle prediction information, which refers to a rotation angle of the autonomous platform  10  and the winch  70  for moving the autonomous platform  10 . 
     In other words, the prediction module  212  can generate tension prediction information corresponding to the wire operation length information. The prediction module  212  uses the wire operation length information and the tension prediction information to generate the rotation angle prediction information. For example, the prediction module  212  can express a relation between the rotation angle information and length information of the wire  20  as a function and input the wire operation length information in the function to generate the rotation angle prediction information. Moreover, it is also possible for the prediction module  212  to generate the rotation angle prediction information by using the rotation angle information that is matched to the wire operation length information in the length table. 
     The determination module  213  uses the rotation angle measurement information and the rotation angle prediction information to generate the rotation angle control information. That is, the determination module  213  can generate the rotation angle control information by comparing the rotation angle measurement information with the rotation angle prediction information in order to move the autonomous platform  10  from a position and posture at which the autonomous platform  10  is currently placed in the block  50  to a position and posture to which the autonomous platform  10  needs to move. 
     A method for allowing the autonomous platform control system using a wire in accordance with an embodiment of the present invention to control the autonomous platform will be described with reference to  FIGS. 8 and 9 . 
       FIGS. 8 and 9  are detailed flow diagrams illustrating a method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention. 
     Referring to  FIGS. 8 and 9 , the autonomous platform control system  100  sets the initial position information indicating the position and posture of the autonomous platform before the autonomous platform  10  is moved (S 810 ). 
     The autonomous platform control system  100  sets the movement control information including at least one of the movement speed information, the moved position information and the position unit information, using the final position information and the initial position information (S 820 ). Then, the autonomous platform control system  100  uses the movement speed information of the movement control information to generate the wire unit length information and moves the autonomous platform  10  by loosening or pulling the plurality of wires  20  connected to the autonomous platform  10  by use of the movement speed information and the wire unit length information. 
     The autonomous platform control system  100  generates the base length information of the wire by use of the rotation angle measurement information of the winch  70  (S 830 ). 
     The autonomous platform control system  100  generates the wire tension information acting on the wire  20  (S 840 ). 
     The autonomous platform control system  100  generates the current length information of the wire by use of the base length information of the wire and the wire tension information (S 850 ). 
     The autonomous platform control system  100  sets the arbitrary position information of the autonomous platform  10  in order to assume that the autonomous platform  10  is placed at an arbitrary position within the block  50  (S 860 ). 
     The autonomous platform control system  100  sets the arbitrary length information of the wire by substituting the arbitrary position information in inverse kinematics (S 870 ). 
     The autonomous platform control system  100  generates the length difference value by comparing the current length information of the wire with the arbitrary length information of the wire (S 880 ). 
     Specifically, the generation module  330  of the autonomous platform control system  100  can define the length difference value as shown in [Equation 9]. 
         D=L   m   −L   k   [Equation 9]
 
     Here, D is a length difference value, and L m  is current length information of the wire, and L k  is arbitrary length information of the wire. Accordingly, the generation module  330  generates the length difference value by inputting the current length information of the wire generated by the length setting module  310  in L m  of [Equation 1] and inputting the arbitrary length information of the wire set by the operation module  320  in L k  of [Equation 1]. Here, the generation module  330  can generate the length difference value to correspond to each of the plurality of wires  20  connected to the autonomous platform  10 . 
     The autonomous platform control system  100  determines whether the length difference value is smaller than the length reference information (S 890 ). 
     The autonomous platform control system  100  re-sets the arbitrary position information by returning to step S 860  and using the length difference value if the length difference value is determined to be greater than or equal to the length reference information (S 910 ). 
     The autonomous platform control system  100  generates the current position information by inputting the arbitrary position information in forward kinematics if the length difference value is determined to be smaller than the length reference information (S 920 ). 
     That is, the generation module  330  of the autonomous platform control system  100  can generate the current position information by use of [Equation 10]. 
         X   k+1   =X   k   +JM   #   [D]   [Equation 10]
 
     Here, X k+1  refers to a position and posture to which the autonomous platform  10  moves using the movement control information with respect to X k , which is arbitrary position information, and JM is the Jacobian matrix that is determined by the kinematic shape of the wire  20 , and D is a length difference value. 
     The generation module  330  can convert [Equation 10] to [Equation 11]. 
         JM   X   {dot over (X)}=JM   L   {dot over (L)}   [Equation 11]
 
     Here, JM X {dot over (X)} means that a value obtained by subtracting X k  from X k+1  is differentiated, and JM L {dot over (L)} means that a value obtained by subtracting L k  from L m  is differentiated. Afterwards, the generation module  330  can convert [Equation 11] to [Equation 12] in order to generate the current position information. 
     
       
         
           
             
               
                 
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     Here, JM L  is a unit matrix (l), and, as shown in  FIGS. 6 and 7 , s n  is a unit vector from A n , which is a position at which the wire  20  is fixed to the autonomous platform  10 , to B n , which is a position at which the wire  20  is fixed to the block  50 , and b n  is a vector from a center of a robot to A n , and N is a natural number. 
     Therefore, the generation module  330  calculates s n  and b n  by use of the length difference value and the block fixing position value of the block design information. Moreover, the generation module  330  generates the current position information by substituting the calculated s n  and b n  into [Equation 12]. 
     The autonomous platform control system  100  generates the wire operation length information by adding the current position information, the position difference information and the position unit information of the movement control information with one another and inputting said addition to inverse kinematics (S 930 ). 
     That is, the length analysis module  211  of the autonomous platform control system  100  can define the wire operation length information as [Equation 13]. 
         L   n   =∥A   n   −B   n ∥=√{square root over (( w   X   n − w   x   n ) 2 +( w   Y   n − w   y   n ) 2 +( w   Z   n − w   z   n ) 2 )}{square root over (( w   X   n − w   x   n ) 2 +( w   Y   n − w   y   n ) 2 +( w   Z   n − w   z   n ) 2 )}{square root over (( w   X   n − w   x   n ) 2 +( w   Y   n − w   y   n ) 2 +( w   Z   n − w   z   n ) 2 )}  [Equation 13]
         whereas, A n =( w x n ,  w y n ,  w z n ),B n =( w X n ,  w Y n ,  w Z n )       

     Here, L is wire operation length information, and, as shown in  FIG. 7 , A n  is a wire fixing position value at which the wire  20  is fixed to the autonomous platform  10 , and B n  is a block fixing position value at which the wire  20  is fixed to the block  50 , and N is a natural number that indicates the number of wires  20  connected to the autonomous platform  10 .  w x n ,  w y n ,  w z n  is a wire fixing position value defined in a global coordinate system at which the “n”th wire  20  is fixed to the autonomous platform  10 , and  w X n ,  w Y n ,  w Z n  is a block fixing position value defined in the global coordinate system at which the “n”th wire  20  is fixed to the block  50 . Here, since B n  is a position at which the wire  20  is fixed to the block  50  and thus does not change even if the autonomous platform  10  moves, B n  can be checked using the block fixing position value of the block design information. 
     The length analysis module  211  can define A n  as shown in [Equation 14]. 
     
       
         
           
             
               
                 
                   
                     
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     Here, R is a rotation matrix, and T is a translation matrix.  b x n ,  b y n  and  b Z n  are platform fixing position values defined in a local coordinate system at which the “n”th wire  20  is fixed to the autonomous platform  10 . Here, since  b x n ,  b y n  and  b Z n  determine fixing position points of the wire  20  with reference to the autonomous platform  10  and thus do not change even if the autonomous platform moves,  b x n ,  b y n  and  b Z n  can be checked using the platform fixing position values included in the block design information. c θ  and s θ  are cos θ and sin θ, respectively. P x , P y  and P z  indicate the position and posture of the autonomous platform  10  in the global coordinate system. 
     Accordingly, the length analysis module  211  generates wire fixing position value A n  by substituting the platform fixing position values of the block design information in  b x n ,  b y n  and  b Z n  and substituting information obtained by adding the current position information, the position difference information and the position unit information with one another in P x , P y  and P z . The length analysis module  211  generates the wire operation length information by substituting the generated wire fixing position value in A n  and substituting the block fixing position value of the block design information in B, of [Equation 13]. 
     The autonomous platform control system  100  generates the tension prediction information corresponding to the wire operation length information (S 940 ). 
     The autonomous platform control system  100  generates the rotation angle prediction information by using the wire operation length information and the tension prediction information (S 950 ). 
     The autonomous platform control system  100  generates the rotation angle control information by comparing the rotation angle measurement information with the rotation angle prediction information (S 960 ). 
     That is, the prediction module  212  of the autonomous platform control system  100  can define the rotation angle control information as shown in [Equation 15]. 
         CL=K   p *(( J   n ) t −( J   n ) c )  [Equation 15]
 
     Here, CL is rotation angle control information, and K p  is a rotation angle proportional gain for compensating rotation angle information, (J n ) t  rotation angle prediction information, and (J n ) c  rotation angle measurement information. Here, the prediction module  212  can set the rotation angle proportional gain by having the rotation angle proportional gain inputted by the user or by using a predetermined algorithm. 
     The prediction module  212  sets the rotation angle control information by substituting the rotation angle prediction information in (J n ) t  of [Equation 15] and substituting the rotation angle measurement information in (J n ) c . 
     The autonomous platform control system  100  moves the autonomous platform  10  toward the final position information by using the rotation angle control information and the movement speed information of the movement control information (S 970 ). 
     The autonomous platform control system  100  determines whether rotation angle difference information is smaller than rotation angle reference information (S 980 ). That is, the route setting unit  120  of the autonomous platform control system  100  can set the rotation angle difference information by subtracting the rotation angle prediction information from rotation angle process information in order to determine whether the autonomous platform  10  has arrived at the final position information. The route setting unit  120  determines whether the rotation angle difference information is smaller than the rotation angle reference information. Here, the rotation angle reference information is information that becomes a reference for determining whether the autonomous platform  10  has arrived at the final position information and can be set by the route setting unit  120  by having the rotation angle reference information inputted by the user or by use of a predetermined algorithm. 
     If the rotation angle difference information is determined to be smaller than the rotation angle reference information by the route setting unit  120  of the autonomous platform control system  100 , the autonomous platform  10  stops moving because the autonomous platform has arrived at the final position information (S 990 ). 
     If the rotation angle difference information is determined to be greater than or equal to the rotation angle reference information by the route setting unit  120  of the autonomous platform control system  100 , the autonomous platform  10  has not arrived at the final position information, and thus the method can be repeated from step S 80  to move the autonomous platform  10  until the rotation angle difference information becomes smaller than the rotation angle reference information (S 1010 ). 
     Although certain embodiments of the present invention have been described, it shall be appreciated by those who are ordinarily skilled in the art to which the present invention pertains that various modifications and permutations of the present invention are possible without departing from the technical ideas and scope of the present invention that are defined in the claims appended below. 
     INDUSTRIAL APPLICABILITY 
     The system and method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention can prevent the wire connected to the autonomous platform from sagging. 
     Moreover, the system and method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention can control the tension acting on the wire so as to prevent the wire from sagging. 
     Moreover, the system and method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention can control the speed of the wire and thus can move the autonomous platform to a desired position and posture. 
     Moreover, the system and method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention can precisely determine the length of the wire fixed within the block. 
     Moreover, the system and method for controlling an autonomous platform using a wire in accordance with an embodiment of the present invention can precisely determine the length of the wire fixed to the autonomous platform and the block by use of the tension acting on the wire.