Vestibular Dynamic Inclinometer for Gravity-Independent Inclination Measurement
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Solution Overview
Problem
Existing methods for measuring inclination parameters of a body, such as those used in robotics and biomechanics, face challenges with accuracy under non-gravity conditions and require complex integration and differentiation techniques, leading to errors and the need for precise sensor placement.
Innovation Solution
The use of a Vestibular Dynamic Inclinometer (VDI) and Planar Vestibular Dynamic Inclinometer (pVDI) systems, which employ strategically placed multi-axis linear accelerometers and a single-axis gyroscope to directly measure inclination parameters like angle, angular velocity, and acceleration, avoiding integration and differentiation errors and not requiring system dynamics modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If tri-axial accelerometer is used to measure inclination angle, then measurement is simple, but accuracy deteriorates under non-gravity acceleration conditions
Solution Approach 1:
The patent combines multiple accelerometers (two dual-axis accelerometers) with a single-axis gyroscope to form an integrated measurement system. This merging of sensors allows the system to distinguish between gravity and non-gravity accelerations by comparing measurements from different sensor locations, thereby maintaining measurement simplicity while improving accuracy under dynamic conditions.
Solution Approach 2:
The patent segments the acceleration measurement function by placing accelerometers at different locations (symmetrically positioned at distance d/2 from point P) and using a gyroscope for angular velocity measurement. This segmentation allows the system to separate gravitational acceleration from non-gravitational acceleration components, enabling accurate inclination measurement even during dynamic motion.
2Adaptability or versatility
If strapdown integration algorithm is used to estimate inclination angle from angular velocity, then dynamic motion can be captured, but integration errors accumulate
Solution Approach 1:
The patent uses feedback by continuously monitoring angular velocity from the gyroscope and using it to correct inclination angle estimates. The system integrates angular velocity to get angle changes but uses the known relationship between acceleration measurements and inclination to provide feedback correction, preventing error accumulation while maintaining dynamic motion capture capability.
3Measurement precision
If conventional IMU with three single-axis accelerometers and three single-axis gyroscopes is used, then complete inclination parameters can be estimated, but device complexity increases
Solution Approach 1:
The patent extracts only the essential measurement components needed for planar motion inclination estimation. Instead of using three dual-axis accelerometers and three gyroscopes as in conventional IMUs, it uses only two dual-axis accelerometers and one single-axis gyroscope, removing redundant sensors while maintaining the ability to estimate inclination parameters for planar motion.
Solution Approach 2:
The patent makes the two dual-axis accelerometers perform multiple functions: measuring linear acceleration at different locations for both gravity detection and dynamic acceleration analysis. This multi-functionality allows the reduced sensor set to provide complete inclination parameter estimation for planar motion, matching the capability of more complex conventional IMUs.
4Measurement precision
If magnetometer is used for inclination estimation, then low frequency component can be obtained, but errors increase near ferromagnetic materials
Solution Approach 1:
The patent replaces the magnetometer-based magnetic field sensing approach with a purely mechanical/inertial sensing approach using accelerometers and a gyroscope. This substitution eliminates susceptibility to ferromagnetic interference while maintaining the ability to estimate low frequency inclination components through acceleration analysis and integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These systems provide accurate and reliable measurements of inclination parameters independent of gravity, with low computation costs and flexible sensor placement, suitable for dynamic and large-angle applications, and can be used for robots and human body analysis.
Implementation Method 1
a single-axis gyroscope to directly measure inclination parameters like angle, angular velocity, and acceleration
Implementation Method 2
strategically placed multiple inertial sensors i.e. multi-axis linear accelerometers
Data Source
AI summary
A method of determining orientation parameters of a rigid body, including: associating at least two multi-axis accelerometers with the rigid body, wherein the body has a base end, a distal end, and a line of symmetry between the base end and the distal end. The two first multi-axis accelerometers are disposed at a first point along the line of symmetry between the base end and the distal end. Each first multi-axis accelerometer is disposed at equal distances from the line of symmetry. The line of symmetry and both first multi-axis accelerometers lie in a first plane. The method further includes: associating a gyroscope with the body at the first point, equally between both first multi-axis accelerometers; gathering measured data from the two first multi-axis accelerometers and the gyroscope; and applying analysis free of calculus to determine a first inclination angle, of the body from a stable orientation.