Device and method for combining samples from an inertial measurement sensor cluster

Abstract

Device and method for providing inertial indications with high accuracy using micro inertial sensors with inherent very small size and low accuracy. The device and method of the invention disclose use of the cluster of multiple micro inertial sensors to receive from the multiple sensors an equivalent single inertial indication with high accuracy based on the multiple independent indications and mathematical manipulations for averaging the plurality of single readings and for eliminating common deviations based, for example, on measurements of the deviation of the single readings.

1 . An inertial measurement device comprising at least one sensor cluster, the sensor cluster comprising a plurality of micro inertial sensors to sample movement with respect to at least one axis of axes x, y and z; and
 a summing unit to receive samples from at least some of said plurality of sensors indicative of said movement with respect to said at least one axis and to sum said samples to an equivalent vector indicative of a sampled movement.   
     
     
         2 . The device of  claim 1 , further comprising a computing unit to receive said equivalent vector and to compensate said equivalent vector based on stored data representing pre-measured misalignment of said equivalent vector. 
     
     
         3 . The device as claimed in  claim 1 , wherein said plurality of micro inertial sensors is of the micro-electromechanical sensors type. 
     
     
         4 . The device as claimed in  claim 1 , wherein said plurality of micro inertial sensors comprise more than one accelerometer sensor. 
     
     
         5 . The device as claimed in  claim 1 , wherein said plurality of micro inertial sensors comprise more than one gyroscope sensor. 
     
     
         6 . The device as claimed in  claim 1 , wherein at least some of said plurality of micro inertial sensors is substantially aligned with one axis of a reference frame. 
     
     
         7 . The device as claimed in  claim 1 , wherein at least some of said plurality of micro inertial sensors are substantially aligned with each one of the axes of a three dimensional reference frame. 
     
     
         8 . The device as claimed in  claim 1 , wherein said plurality of micro inertial sensors comprises an integrated sensor cluster. 
     
     
         9 . The device as claimed in  claim 1 , wherein at least some of said micro inertial sensor of said plurality of micro inertial sensors are spatially displaced from a pivot axis of the sensor cluster each one by a known amount. 
     
     
         10 . The device as claimed in  claim 1 , wherein the orientation of an axis of each micro inertial sensor of said plurality of micro inertial sensors angularly misaligned with respect to an axis of the sensor cluster each one by a known amount. 
     
     
         11 . The device as claimed in  claim 2 , wherein said computing unit is programmed to combine separate outputs of said plurality of micro inertial sensors to yield compensated output for each of said at least one sensor clusters. 
     
     
         12 . The device as claimed in  claim 11  wherein said device communicates with at least one additional device from a list comprising Global Positioning System receiver and a zero-velocity update sensor. 
     
     
         13 . The device as claimed in  claim 11 , wherein the device is worn or carried by a person. 
     
     
         14 . An inertial measurement method comprising:
 reading separate output of at least some of a plurality of micro inertial sensors of a sensor cluster; and   combining the separate outputs to yield a single output of the sensor cluster.   
     
     
         15 . The method as claimed in  claim 14 , further comprising the steps of:
 estimating an error in said single output of the sensor cluster, said error is estimated according to sensor's error model using external data sources;   calculating a correction to compensate for the error; and   applying the correction to said single output of the sensor cluster to yield a corrected value.   
     
     
         16 . The method as claimed in  claim 15 , further comprising the steps of:
 reading the output of at least one additional device from a list comprising Global Positioning System receiver and a zero-velocity update sensor;   utilizing said output of said at least one additional device in estimating said error in said single output of the sensor cluster.   
     
     
         17 . The method as claimed in  claim 14 , further comprising the steps of:
 providing the amount of displacement of each micro inertial sensor of said plurality of micro-electromechanical inertial sensors from a pivot axis of said sensor cluster, each of said amount of displacement being stored by a computer; and   adjusting said separate output of each of said plurality of micro inertial sensors in accordance with each of said amount of displacement.   
     
     
         18 . The method as claimed in  claim 14 , further comprising the steps of:
 providing the amount of deviation of the axis of each micro inertial sensor of said plurality of micro-electromechanical inertial sensors from the axis of the sensor cluster, the amount being stored by the computer; and   adjusting said separate output of each of said plurality of micro inertial sensors in accordance with each of said amount of deviation.