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US 2018/0231393 A1Published application
Method for Calibrating Local Coordinates and Force Reference of Motion and Ground Reaction Force Analysis System
AssigneeIPComm
InventorsStanislaw Czaja, Lora O'Leary
Life of this patent
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Abstract
A method of calibration correcting inaccuracies in measurement of force, acceleration and orientation vectors introduced during fabrication of motion and ground reaction forces analysis system embedded in footwear insoles.
Claims17
A method to calibrate a motion and force analysis system embedded in footwear insoles to obtain a local coordinate system and reference of ground reaction force, wherein said calibration method compensates for:
- inaccuracies arising from manufacturing and assembly of motion processing element comprising of micro-electro-mechanical (MEMS) accelerometer, gyroscope and magnetometer sensors;
- inaccuracies in orientation of the installation of the motion processing element inside the insole;
- inaccuracies in azimuth between the left foot and right foot motion processing elements;
- inaccuracies arising from manufacturing of force processing element comprising multiplicity of force sensors;
- inaccuracies arising from assembly of the force processing elements in the insole;
- inaccuracies arising from assembly of the insoles into the user footwear;
- contribution of user body weight on the estimation of ground reception force;
- and
- wherein the motion and force analysis system comprising:
- motion processing element comprising a three-axis accelerometer and a three-axis gyroscope;
- force processing element comprising multiplicity of force sensors;
- a smart-phone based analysis application in communication with the motion and force processing elements using wireless radio interface;
- is designed to analyze motion and balance of user by estimating location of Center of Pressure (COP), timing of the COP location change and the user's feet motion in relation to ground reaction force.
10 more elements
A non-transitory computer accessible memory medium for storing program instructions pertaining to method of calibration orientation of motion processing elements and a reference of ground reaction force of a motion and force analysis system embedded in a footwear insoles, wherein said program instructions performs all of the following:
- maintaining communication with the motion and force processing elements embedded in the footwear insoles;
- providing user with calibration procedure instructions;
- obtaining reference offset of local coordinate system by:
- obtaining multiplicity of independent data samples from three-axis accelerometer sensor, and three-axis gyroscope sensor of each motion processing element;
- averaging said independent data samples;
- store values of the averaged data samples as an offset for each of the accelerometer and the gyroscope axis of each motion processing element;
- obtaining reference offset of ground reaction force by:
- retrieving user's weight parameter stored in first information and converting said parameter to Newton units;
- obtaining multiplicity of independent values of data samples from each force sensor of each force processing element;
- adding said averaged force sensor data sample to ½ of the user's weight parameter value, and storing results as offsets of related force sensor of each force processing element;
- subtracting positive offset values of the accelerometer x-axis and y-axis from each sample of the accelerometer x-axis and y-axis data, and adding negative offset values of the accelerometer x-axis and y-axis to each sample of the accelerometer x-axis and y-axis data and storing results as calibrated data samples of the accelerometer x-axis and y-axis;
- subtracting constant value of 0.98066, or value of gravity present at the GPS coordinates of measurement location from the accelerometer z-axis offset value from each sample of the accelerometer z-axis data, before storing results as calibrated data samples of the accelerometer x-axis;
- subtracting positive offset values of the gyroscope x-axis and y-axis from each sample of the gyroscope x-axis and y-axis data, and adding negative offset values of the gyroscope x-axis and y-axis to each sample of the gyroscope x-axis and y-axis data and storing results as calibrated data samples of the gyroscope x-axis and y-axis;
- subtracting positive offset of second gyroscope z-axis from each z-axis data sample received from the second gyroscope z-axis data, and adding negative offset of the second gyroscope z-axis to each z-axis data sample received from the second gyroscope, before storing data sample as a calibrated z-axis data sample of the second gyroscope;
- and
- provide heading information of first insole using first gyroscope z-axis calibrated data sample and difference between heading of the first gyroscope and second gyroscope calibrated data samples as a difference in heading between the first and the second insole.
13 more elements
Dependencies are inferred from the claim text.