# US 10,309,983 B2 · Systems and methods for motion detection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,309,983 B2 - Document ID: US10309983B2 - Status: Granted - Kind: B2 - Application number: 15/461,761 - Filed: 2017-03-17 - Published: 2018-09-20 - Granted: 2019-06-04 - Earliest claimed: 2017-03-17 - Assignees: InvenSense, Inc. - Applicants: InvenSense, Inc. - Inventors: William Kerry Keal - Web page: https://patentgrep.com/patent/US10309983B2 ## CPC - G01P 13/00: Indicating or recording presence, absence, or direction, of movement (electric switches H01H; counting moving objects G06M7/00) - G01P 21/00: Testing or calibrating of apparatus or devices covered by the preceding groups - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) ## Abstract Systems and methods are disclosed for characterizing motion of a device by taking the difference between pairs of sensor signal samples and comparing an expected higher order moment for the differences determined from an observed first order moment for the differences and/or an observed second order moment for the differences and the observed higher order moment for the differences. A determination of whether the device is experiencing motion may be made based on a comparison of the difference of the moments to a threshold. ## Claims ### Claim 1 A method for characterizing a motion of a device, comprising: obtaining a data signal from a motion sensor of the device, wherein the data signal comprises a plurality of samples provided at a sampling frequency; computing differences between pairs of the plurality of samples; performing a calculation corresponding to subtracting an expected higher order moment for the differences from an observed higher order moment for the differences to obtain a difference of the moments, wherein the expected higher order moment is based at least in part on an observed first order moment for the differences and an observed second order moment for the differences; and determining whether the device is experiencing motion based at least in part on a comparison of the difference of the moments to a threshold. ### Claim 2 (depends on 1) The method of claim 1, wherein the higher order moment is a fourth order moment for the differences. ### Claim 3 (depends on 2) The method of claim 2, wherein the difference of the moments is equal to the observed fourth order moment for the differences minus three times the observed second order moment for the differences squared. ### Claim 4 (depends on 1) The method of claim 1, wherein the higher order moment for the differences is an even order moment greater than a fourth order moment for the differences. ### Claim 5 (depends on 1) The method of claim 1, wherein the samples of each pair are spaced a fixed number of samples apart. ### Claim 6 (depends on 5) The method of claim 5, wherein the spacing is based at least in part on an expected frequency of motion of the device. ### Claim 7 (depends on 6) The method of claim 6, wherein the spacing is configured to oppose the phase of the expected frequency of motion of the device. ### Claim 8 (depends on 6) The method of claim 6, wherein the fixed number of samples is based at least in part on a reciprocal of the expected frequency of motion multiplied by the sampling frequency divided by two. ### Claim 9 (depends on 6) The method of claim 6, wherein the expected frequency of motion is approximately 7 Hz. ### Claim 10 (depends on 6) The method of claim 6, wherein the expected frequency of motion is based at least in part on a use case for the device. ### Claim 11 (depends on 10) The method of claim 10, wherein the use case for the device is determined based at least in part on a data signal from the motion sensor. ### Claim 12 (depends on 1) The method of claim 1, wherein the samples of each pair are spaced a varying number of samples apart. ### Claim 13 (depends on 12) The method of claim 12, wherein the varying number of samples corresponds to a bandwidth associated with expected frequencies of motion. ### Claim 14 (depends on 1) The method of claim 1, further comprising making an initial no motion determination by comparing a difference between two samples to a threshold. ### Claim 15 (depends on 1) The method of claim 1, wherein the threshold is based at least in part on a standard deviation of the motion sensor. ### Claim 16 (depends on 1) The method of claim 1, further comprising making an initial no motion determination based on an output of a different motion sensor. ### Claim 17 (depends on 1) The method of claim 1, further comprising determining the motion sensor is working properly when the result of the subtraction is within the threshold and it is known the device is not moving. ### Claim 18 (depends on 1) The method of claim 1, further comprising calculating an accelerometer bias when the result of the subtraction exceeds a threshold. ### Claim 19 (depends on 1) The method of claim 1, further comprising characterizing a behavior of a user of the device based at least in part on the determination of whether the device is experiencing motion. ### Claim 20 (depends on 1) The method of claim 1, wherein the motion sensor is a gyroscope. ### Claim 21 (depends on 20) The method of claim 20, further comprising calibrating at least a parameter of the gyroscope. ### Claim 22 (depends on 21) The method of claim 21, further comprising determining a gyroscope bias when the result of the subtraction is within the threshold. ### Claim 23 (depends on 20) The method of claim 20, further comprising setting a gyroscope temperature compensation learning term when the result of the subtraction is within the threshold. ### Claim 24 (depends on 1) The method of claim 1, wherein the motion sensor is an accelerometer. ### Claim 25 (depends on 1) The method of claim 1, wherein the motion sensor is a magnetometer. ### Claim 26 A sensor device comprising; at least one motion sensor outputting a data signal, wherein the data signal comprises a plurality of samples provided at a sampling frequency; and a motion detection module configured to: compute differences between pairs of the plurality of samples; perform a calculation corresponding to subtracting an expected higher order moment for the differences from an observed higher order moment for the differences to obtain a difference of the moments, wherein the expected higher order moment is based at least in part on an observed first order moment for the differences and an observed second order moment for the differences; and determine whether the device is experiencing motion based at least in part on a comparison of the difference of the moments to a threshold. ### Claim 27 (depends on 26) The sensor device of claim 26, wherein the motion sensor is a gyroscope. ### Claim 28 (depends on 27) The sensor device of claim 27, further comprising a calibration module configured to determine at least a parameter of the gyroscope. ### Claim 29 (depends on 28) The sensor device of claim 28, further comprising determining a gyroscope bias when the result of the subtraction is within the threshold. ### Claim 30 (depends on 28) The sensor device of claim 28, wherein the device further comprises an additional motion sensor and wherein the motion detection module is further configured to make an initial motion detection before performing the calculation. ### Claim 31 (depends on 26) The sensor device of claim 26, wherein the at least one motion sensor and the motion detection module are implemented on a single substrate. ### Claim 32 An integrated sensor processing unit characterizing a motion of a device, comprising: at least one motion sensor outputting a data signal, wherein the data signal comprises a plurality of samples provided at a sampling frequency; and a processor configured to: compute differences between pairs of the plurality of samples; compute a first order moment for the differences; compute a second order moment for the differences; derive a higher order moment for the differences using only the computed first order moment and the computed second order moment; estimate a higher order moment for the differences using only an average of the differences taken to a power corresponding to the higher order moment; subtract the derived higher order moment for the differences from the estimated higher order moment for the differences; and determine wherein the device is experiencing motion based at least in part on a comparison of the result of the subtraction to a threshold.