Capacitive Ground Reaction Sensor Cluster for Pedestrian Navigation
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Solution Overview
Problem
In GPS-denied environments, traditional inertial motion units (IMUs) lose accuracy over short periods, failing to precisely determine user navigation due to limitations in detecting zero velocity points and bearing changes.
Innovation Solution
A ground reaction sensor cluster (GRSC) with an array of capacitive pressure and shear sensors distributed along a shoe's contact portion, detecting changes in capacitance to determine zero velocity points and bearing changes, which are then communicated to an IMU for refined navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional IMUs are used to determine user navigation in GPS-denied environments, then the system can operate without GPS signals, but the measurement precision of zero velocity points and bearing changes deteriorates over short periods
Solution Approach 1:
The patent combines IMU data with ground reaction force sensor data to create a hybrid navigation system. The IMU provides continuous navigation data while the ground reaction sensors provide periodic correction measurements at zero velocity points, merging inertial navigation with force-based position verification to maintain both reliability and precision.
Solution Approach 2:
The system uses ground reaction force measurements to detect zero velocity points and bearing changes, then feeds this information back to correct IMU drift. This feedback mechanism allows the system to identify when the user is stationary or changing direction and use these moments to recalibrate the navigation solution, maintaining measurement precision over time.
2Measurement precision
If ground reaction sensor clusters with capacitive pressure and shear sensors are used, then the measurement precision of zero velocity points and bearing changes is improved, but the device complexity increases
Solution Approach 1:
The ground reaction sensor cluster is divided into multiple discrete capacitive pressure and shear sensors distributed across the shoe sole. Each sensor independently measures local ground reaction forces, and the system processes these segmented measurements to determine overall foot contact state, zero velocity points, and bearing changes, reducing the complexity of any single sensor while maintaining high measurement precision.
Solution Approach 2:
The ground reaction sensor cluster serves multiple functions: detecting zero velocity points, measuring bearing changes, and providing ground contact information. By making the sensor system multi-functional, the patent reduces the need for separate specialized sensors, thereby managing device complexity while achieving high measurement precision across multiple navigation parameters.
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
The GRSC enhances navigation accuracy by precisely determining zero velocity points and bearing changes, allowing for reliable pedestrian navigation in GPS-denied areas until GPS signals are restored.
Implementation Method 1
The array includes multiple flexible capacitive sensor cells that detect changes in capacitance in response to a footstep. Each cell of the array includes multiple overlapping, fingered capacitors that detect pressure and shear force by determining the change in capacitance in each fingered capacitor.
Data Source
AI summary
Embodiments are directed to a ground reaction sensor cluster (GRSC) and to methods for precisely determining zero velocity points and bearing changes using a GRSC and for navigating using a GRSC and an inertial motion unit (IMU) in a global positioning satellite (GPS)-denied environment. The GRSC device itself includes an array of capacitive pressure and shear sensors. The array includes multiple flexible capacitive sensor cells that detect changes in capacitance in response to a footstep. Each cell of the array includes multiple overlapping, fingered capacitors that detect pressure and shear force by determining the change in capacitance in each fingered capacitor. The GRSC device also includes a multiplexing receiver that receives the capacitance inputs from each of the capacitive sensor cells. The multiplexing receiver and other electronic elements further process the received capacitance inputs to determine, based on the pressure and shear forces, the direction and bearing of the footstep.