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## Patent Application Titled "Method of Calculating Step Length" Published Online

February 6, 2014

By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C. , by VerticalNews journalists, a patent application by the inventors LAN, Kun-Chan ( Tainan , TW); SHIH, Wen-Yuah (New Taipei, TW), filed on July 5, 2013 , was made available online on January 23, 2014 . No assignee for this patent application has been made. Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to an indoor positioning system, and more particularly to a method of calculating a step length. "GPS (Global Positioning System) is widely used in navigation of vehicle, and in present days, some mobile devices, such as smart phone, are equipped with GPS for positioning and navigation of people. However, GPS only works outdoors because the satellite signals can't get through the buildings. Therefore, if a person walks in a spacious room, such as an exhibition hall or a museum, GPS is insufficient to navigate him/her. Some techniques such as A-GPS provide indoor positioning functions; however, those techniques can only provide rough positioning. Until now, there still is no positioning system has the ability to perform accurate indoor navigation." In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "In view of the above, the primary objective of the present invention is to provide a method of calculating a step length while walking, which could be used for accurate navigation. "The present invention provides a method of calculating a step length, which comprises the steps of: A. Input a leg length of a user; B. Obtain a vertical acceleration when the user is walking; C. Do double integral on the vertical acceleration to obtain a vertical displacement for one step of the user; D. Calculate a step length according to the vertical displacement and the leg length. "In an embodiment, the leg length is a distance between a hip joint and a sole of a foot of the user. "In an embodiment, the step B comprises the steps of obtaining a static acceleration by an accelerometer when the user is standing still; obtaining a moving acceleration by the accelerometer when the user is walking; and then removing the static acceleration from the moving acceleration to obtain the vertical acceleration. "In an embodiment, an equation of calculating the vertical acceleration is An=(R-M).times.sec(cos.sup.-1(M/9.8)), where An is the vertical acceleration, R is the moving acceleration, and M is the static acceleration. "In an embodiment, the method further comprising the step of low-pass filtering after the step B, to filter out low frequency waves of the vertical acceleration generated by vibration. "In an embodiment, the step C comprises the steps of doing integral on the vertical acceleration to obtain a vertical velocity; and then doing another integral on an absolute value of the vertical velocity; and then a result of the second integral is divided by two to obtain the vertical displacement. "In an embodiment, the vertical acceleration is obtained via an accelerometer, and the vertical velocity is reset to zero when the accelerometer is at a highest position and a lowest position. "In an embodiment, a movement of the accelerometer is simulated as Simple Harmonic Motion (SHM). "In an embodiment, the step C comprises the steps of doing integral on the vertical acceleration to obtain a vertical velocity, and then doing another integral on an absolute value of the vertical velocity to obtain the vertical displacement for the step when the user starts to walk or stops walking. "In an embodiment, the vertical acceleration is obtained via an accelerometer, and the vertical velocity is reset to zero when the accelerometer is at a lowest position. "In an embodiment, an equation of calculating the step length in the step D is D=2.times. {square root over (L.sup.2-(L-h).sup.2)}, where D is the step length, L is the leg length, and h is the vertical displacement. "In an embodiment, the method further comprises a turning angle by using a gyroscope to calculate a coordinate of the user in a 2D space, wherein the step length is combined with the turning angle to obtain a trajectory of the user in the 2D space. "In an embodiment, a X coordinate of the coordinate is obtained via an equation .sup.X.sup.n.sup.=X.sup.n-1.sup.+D.times.cos.theta., and a Y coordinate of the coordinate is obtained via an equation .sup.Y.sup.n.sup.=Y.sup.n-1.sup.+D.times.sin.theta., where X.sub.n is the current X coordinate, X.sub.n-1 is the previous X coordinate, Y.sub.n is the current Y coordinate, Y.sub.n-1 is the previous Y coordinate; and .theta. is the turning angle, wherein X.sub.n-1 and Y.sub.n-1 are zero if this is the first step. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS "The present invention will be best understood by referring to the following detailed description of some illustrative embodiments in conjunction with the accompanying drawings, in which "FIG. 1 is a flowchart of a preferred embodiment of the present invention; "FIG. 2 is a diagram of the relation between the vertical acceleration and time; "FIG. 3 is a sketch diagram, showing a user standing and walking; "FIG. 4 is a sketch diagram, showing the stride taken by the user." For more information, see this patent application: LAN, Kun-Chan; SHIH, Wen-Yuah. Method of Calculating Step Length. Filed July 5, 2013 and posted January 23, 2014 . Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1065&p=22&f=G&l=50&d=PG01&S1=20140116.PD.&OS=PD/20140116&RS=PD/20140116 Keywords for this news article include: Patents. Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC

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Source: Politics & Government Week

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