Leg Landing Time Detection Using Acceleration Sensor Candidate Groups
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Solution Overview
Problem
Existing methods face challenges in accurately determining the point of time when a patient's leg lands during walking, especially at low speeds or in varying environments, leading to difficulties in accurately estimating step length due to small changes in acceleration and angular velocity.
Innovation Solution
An information processing apparatus and method that acquires measurement data from sensors on the patient's legs, identifies candidate points for leg landing, combines these candidates into groups, calculates step length, and evaluates the likelihood of landing positions within predetermined ranges to select the most accurate candidate group for output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods using acceleration sensors are used to detect leg landing time, then the system is simple and easy to operate, but measurement precision deteriorates when walking speed is low or environmental conditions vary
Solution Approach 1:
The patent segments the leg landing detection process into multiple candidate time points (first candidate, second candidate, third candidate) based on different acceleration characteristics. By dividing the detection into discrete candidate points with specific selection criteria, the system achieves higher precision without requiring complex continuous analysis, thus resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent performs preliminary identification of multiple candidate leg landing time points before final determination. By pre-identifying potential landing times based on acceleration patterns and then selecting the most accurate candidate through additional criteria, the system improves measurement precision while maintaining operational simplicity, avoiding the need for complex real-time continuous monitoring.
2Measurement precision
If multiple sensors are used to improve measurement accuracy, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent enables a single acceleration sensor to perform multiple functions by analyzing different characteristics of the acceleration signal (vertical acceleration peaks, travel direction acceleration, angular velocity changes). The sensor essentially serves itself by extracting multiple pieces of information from its own output, eliminating the need for additional sensors while maintaining high measurement precision for leg landing time and step length estimation.
Solution Approach 2:
The acceleration sensor is designed to perform multiple detection functions: detecting vertical acceleration for candidate time identification, detecting travel direction acceleration for step length calculation, and working in conjunction with angular velocity data. This multi-functionality allows one sensor to replace what would traditionally require multiple specialized sensors, reducing device complexity while improving overall measurement precision.
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
This approach improves the accuracy of specifying the point of time for leg landing and estimating step length, reducing the burden on patients and the need for multiple sensors, while maintaining ease of use and cost-effectiveness.
Implementation Method 1
the number of steps and a walking cycle obtained when a walker walks are detected on the basis of vertical acceleration obtained by a three-axis acceleration sensor, and a travel direction acceleration per step is measured by the acceleration sensor
Implementation Method 2
a point of time at which each leg lands is estimated by gyro sensors attached to both the legs, and a change in angle between the points of time of landing is measured
Data Source
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AI summary
An information processing apparatus (100) acquires measurement information regarding movement of each leg of a patient. Based on the acquired measurement information, the information processing apparatus (100) specifies, for each step in a walking period of the patient, one or more candidates for a point of time corresponding to landing of a leg serving as a swing leg of the patient. The information processing apparatus (100) specifies a plurality of candidate groups obtained by selecting one of the one or more candidates specified for each step in the walking period and combining the selected candidates. Based on the cumulative travel distance calculated for each step in the walking period, the information processing apparatus (100) evaluates, for each candidate group, a degree of appearance of a predetermined relationship between the landing positions of both the legs of the patient in the walking period. The information processing apparatus (100) selects one of the plurality of candidate groups on the basis of the evaluation result and outputs the selected one of the candidate group.