High Precision Trajectory and Speed Sensor and Measuring Method

Patent metadata

Field	Value
Publication number	US-2018292429-A1
Application number	US-201615569386-A
Country	US
Kind code	A1
Filing date	Apr 28, 2016
Priority date	Apr 28, 2015
Publication date	Oct 11, 2018
Grant date	—

Abstract

A method for contactlessly determining an exact passage of an athlete at points placed along a track in sports, wherein the method comprises gearing the athlete with a wearable magnetometer sensor unit, whereby the magnetometer sensor unit is equipped with at least a magnetic sensor, a processing unit, and a storage medium; placing at each point at least a permanent magnet in proximity of a track surface of the track. When the athlete moves along the track, the method further comprises recording at the magnetic sensor a signal; detecting for each permanent magnet a disturbance of a local magnetic field generated by the permanent magnet in the recorded signal and measuring the disturbance; mapping of the measured disturbance to a movement speed of the athlete and a distance of the athlete to the magnet corresponding to the local magnetic field; and correcting the movement speed and the distance for a time offset between the magnet passage of an athlete's center of mass and the magnetometer sensor unit.

First claim

1 - 19 . (canceled)

20 . A method for contactlessly determining a passage of an athlete at a plurality of points along a track, the athlete being equipped with a wearable magnetometer sensor unit having a magnetic sensor, at each point a permanent magnet is located at or in proximity of the track, the method comprises the steps of:
recording a signal with the magnetic sensor; detecting a disturbance of a local magnetic field generated by passing by a permanent magnet in the recorded signal and measuring the disturbance with a processing unit; mapping of the measured disturbance to a movement speed of the athlete and a distance between the athlete and the permanent magnet corresponding to the local magnetic field by the processing unit; and correcting the movement speed and the distance by the processing unit for a time offset between a passage of the athlete at the permanent magnet and the magnetometer sensor unit.

21 . The method of claim 20 , wherein the magnetometer sensor unit is fixed to a trunk of the athlete and further includes a 3D accelerometer and 3D gyroscope, the method further comprising the steps of:
measuring 3D accelerations and 3D angular velocities at the magnetometer sensor unit; computing a trunk orientation based on the measured 3D accelerations and 3D angular velocities; and using the trunk orientation to report the measured 3D acceleration and 3D angular velocities in a global reference frame, to remove a gravity of earth from the measured acceleration, and to estimate a turn radius and to provide data expressing the measured quantities along the trajectory frame.

22 . The method of claim 21 , further comprising the step of:
calculating a speed by integrating the 3D acceleration; and correcting a speed drift based on the calculated speed at point passage and at beginning and end of the passage of the athlete along the track.

23 . The method of claim 22 , further comprising the step of
integrating the speed to obtain a movement trajectory.

24 . The method of claim 20 , wherein the permanent magnets are placed at gates along a skiing race track, each permanent magnet integrated in a pole of the respective gates.

25 . The method of claim 20 , wherein the permanent magnets are placed at gates along a skiing race track on or buried in snow.

26 . The method of claim 20 , wherein the permanent magnets are placed at regular intervals along a marked line on the track.

27 . The method of claim 20 , wherein each permanent magnet includes two smaller permanent magnets spaced apart by an iron yoke or a non-magnetic spacing material.

28 . The method of claim 20 , wherein the magnetometer sensor unit further includes a communication device for transmitting recorded data wirelessly to a base station.

29 . A method for determining a skiing trajectory of an athlete, the skiing trajectory defined as a trajectory of the athlete, the athlete equipped with an instrumented back protector, the back protector including
an active Global Navigation Satellite System (GNSS) antenna, the GNSS antenna arranged at the back protector such that the GNSS antenna is located between shoulder blades of the athlete when the back protector is worn, GNSS sensor unit having a global navigation satellite system receiver, an inertial sensor unit with 3D accelerometers and 3D gyroscopes, a processing unit, and a storage medium, wherein the method comprises the steps of: computing a trunk orientation based on measured 3D accelerations and 3D angular velocities; translating the measured 3D accelerations and 3D angular velocities to a GNSS antenna position and expressing the GNSS antenna positions in a global reference frame; removing a gravity of earth from the measured acceleration to obtain inertial measurement unit-derived antenna kinematics; fusing the inertial measurement unit-derived antenna kinematics with navigation information from the GNSS receiver to obtain final antenna kinematics, including at least one of acceleration, speed, position, angular velocity, and orientation; and translating the antenna kinematics to the athlete to obtain the final kinematics.

30 . The method of claim 29 , wherein the athlete further wears a magnetometer sensor unit including a magnetic sensor, and
wherein the GNSS sensor unit further includes a synchronization module to achieve a sample-by-sample electronic and automatic synchronization between the GNSS sensor unit and the magnetometer sensor unit, one of the GNSS sensor unit and the magnetometer unit acting as a master unit and the other one as a slave unit, and emitting a synchronization signal in regular intervals, the synchronization signal being received, processed and recorded by the slave unit to synchronize an internal clock with the master unit.

31 . The method of claim 30 , further comprising
translating the measured inertial data of at least one of the GNSS sensor unit and the magnetometer sensor unit to the other unit, comparing inertial data from each sensor unit in a common reference frame to determine differences, relating the differences to an orientation estimation drift, and correcting orientation estimation drift in both sensor units in a recursive or iterative manner.

32 . The method of claim 30 , further comprising the steps of:
improving a precision of the skiing trajectory estimated with the GNSS system by
estimating a magnet position of each passed permanent magnet,
comparing the estimated magnet positions with true magnet positions, obtaining an initial trajectory estimation error for each magnet, from a result of the comparing, and
interpolating between each estimation error and subtraction of an error curve from the initial trajectory estimation to obtain a precision improved skiing trajectory estimation.

33 . The method of claim 32 , further comprising the step of
estimating the true magnet positions of the permanent magnets based on averaging estimated magnet position from a plurality of passages.

34 . The method of claim 31 , wherein the GNSS sensor unit further includes a communication device for transmitting recorded data wirelessly to a base station.

35 . A system configured to contactlessly determine an exact passage of an athlete at points placed along a track, the system comprising:
a gearing to be worn by the athlete, the gearing including a wearable magnetometer sensor unit including a magnetic sensor; a processing unit in communication with the wearable magnetometer sensor unit, the processing unit having a storage unit; and permanent magnets located at each point at or in proximity of the track; wherein the processing unit is configured to
when the athlete moves along the track, record a signal in the storage unit to detect, for each permanent magnet, a disturbance of a local magnetic field generated by the permanent magnet in the recorded signal and to measure the disturbance,
map the measured disturbance to a movement speed of the athlete and a distance between the athlete and the magnet corresponding to the local magnetic field, and
correct the movement speed and the distance for a time offset between the magnet passage of the athlete and the magnetometer sensor unit.

36 . The system of claim 35 , wherein the magnetometer sensor unit further includes a 3D accelerometer and 3D gyroscope, wherein the magnetometer sensor unit is further configured to
measure 3D accelerations and 3D angular velocities, and compute a trunk orientation based on the measured 3D accelerations and 3D angular velocities, by using the trunk orientati

Assignees

• Ecole Polytechnique Fed Lausanne Epfl

Inventors

• Fasel Benedikt
• Aminian Kamiar

Classifications

• A63B2220/836

  Sensors arranged on the body of the user · CPC title

• G01P15/14

  by making use of gyroscopes (gyroscopes per se G01C19/00) · CPC title

• A63B69/18

  for skiing · CPC title

• A63B2220/12

  Absolute positions, e.g. by using GPS · CPC title

• A63B2209/08

  magnetic · CPC title