Method and apparatus for measuring reaction forces
Inventors
Ronchi, Daniel Matthew • Ronchi, Andrew James • Charry, Edgar • Chhikara, Aakanksha • Hu, Wenzheng
Assignees
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Publication Number
US-10568550-B2
Publication Date
2020-02-25
Expiration Date
Abstract
Apparatus is disclosed for monitoring, measuring and/or estimating a force applied to a body or body part of a vertebral mammal. The apparatus includes an acceleration sensor for measuring acceleration of the body or body part relative to an inertial frame of reference and for providing data indicative of the acceleration. The acceleration sensor includes at least one inertial sensor, a memory device adapted for storing the data, and a processor adapted for processing the data to evaluate a reaction force that correlates to the data. The processor may be configured to execute an algorithm for evaluating the reaction force, based on one or more correlation components such as mass, speed and/or velocity associated with the body or body part. A method of monitoring and/or estimating a force applied to a body or body part of a vertebral mammal is also disclosed.
Core Innovation
The invention provides an apparatus and method for monitoring, measuring and/or estimating a force applied to a body or body part of a vertebral mammal by using acceleration sensors. Acceleration is measured relative to an inertial frame of reference, acceleration data is provided from a single sensor, and the acceleration data is stored in a memory device and processed by a processor using only the data indicative of acceleration to evaluate a reaction force that correlates to the acceleration data.
The processor is configured to process the acceleration data according to a non-linear relationship function between the acceleration data and the reaction force. The relationship function is substantially logarithmic and includes one or more correlation coefficients including mass, speed and/or velocity associated with the body or body part. The reaction force is evaluated by executing an algorithm that causes the processor to evaluate a reaction force correlated to the acceleration data using said correlation coefficients.
In the disclosed reaction-force correlation model, the reaction-force estimate is provided as a correlation with a reaction force GRFPeak(acc,m). The equation is GRFPeak(acc,m)=a(m)*[log2(acc+b)]+c(m), wherein m denotes body mass of a mammal subject and acc denotes acceleration data measured by the acceleration sensor. The “b” term is a fixed coefficient to compensate accelerations lower than 0 g, and “a” and “c” denote a slope and an offset associated with the logarithmic function, with mass-dependent coefficients including a(m) and c(m).
Claims Coverage
The independent claims in the provided list are clm-00001, clm-00012, clm-00023, and clm-00027, each directed to an apparatus or a method for evaluating a reaction force correlated to acceleration data using a substantially logarithmic, non-linear relationship function parameterized by correlation coefficients including mass and at least one of speed and/or velocity, or in equation-based forms, parameters a, b, and c with mass dependence.
Substantially logarithmic correlation from single-sensor acceleration to reaction force
Processing acceleration data indicative of acceleration according to a non-linear relationship function between the acceleration data and a reaction force, wherein the relationship function is substantially logarithmic.
Use of correlation coefficients including mass and speed/velocity
Evaluating the reaction force based on one or more correlation coefficients including mass, speed and/or velocity associated with the body or body part, wherein the relationship function is substantially logarithmic and includes said one or more correlation coefficients.
Reaction force evaluation using only acceleration data
Evaluating a reaction force that correlates to said data by processing only said data indicative of said acceleration, wherein the processor executes an algorithm for evaluating said reaction force based on the specified relationship function and correlation coefficients.
Mass-dependent logarithmic equation GRFPeak(acc,m)=a(m)*[log2(acc+b)]+c(m)
Providing a correlation with a reaction force GRFPeak(acc,m) according to GRFPeak(acc,m)=a(m)*[log2(acc+b)]+c(m), where m denotes body mass and acc denotes acceleration data measured by the acceleration sensor.
Logarithmic equation parameterized with fixed coefficient b for accelerations below 0 g
Using “b” as a fixed coefficient to compensate accelerations lower than 0 g in the substantially logarithmic correlation, with “a” denoting a slope of a logarithmic function and “c” denoting an offset associated with the logarithmic function.
Explicit mass-dependent forms for slope and offset (a(m) and c(m))
Configuring the correlation so that a(m) and c(m) follow the specified mass-dependent linear relationships.
Fixed coefficient b set to 1
Configuring the correlation so that the fixed coefficient b is set to 1.
Single-sensor acceleration measured relative to an inertial frame
Using an acceleration sensor to measure acceleration of the body or body part relative to an inertial frame of reference and to provide data indicative of said acceleration from a single sensor.
Store acceleration data and process with a processor to evaluate reaction force
Storing the acceleration data in a memory device and processing the acceleration data by a processor to evaluate a reaction force that correlates to said data.
AMTI force plate comparability of evaluated reaction force
Configuring the reaction force generated by the processor to be substantially comparable to a ground reaction force measured using an AMTI force plate.
Acceleration along orthogonal axes
Using an acceleration sensor configured to measure acceleration along one or more orthogonal axes.
Overall, the independent claims cover apparatus and methods that evaluate a reaction force correlated to acceleration using a substantially logarithmic, non-linear relationship function. The claims ground the correlation in an equation-based GRFPeak(acc,m) formulation with mass-dependent parameters and a fixed coefficient “b” to compensate accelerations lower than 0 g, with additional constraints in dependent members including explicit mass-dependent coefficient forms, a fixed b value of 1, comparability to an AMTI force plate, and acceleration measurement along orthogonal axes.
Stated Advantages
Substantially comparable to a ground reaction force measured using an AMTI force plate.
Documented Applications
Walking/running/sprinting/hopping/landing/jumping.
Computation of an asymmetry index (ASI) from left and right GRF measures.
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