Indoor Ultrasonic Positioning Using Surface-Aware Cost Terms
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Solution Overview
Problem
Existing positioning systems using ultrasonic signals for mobile units in indoor environments can be inaccurate due to reliance on range data alone, which is prone to noise and inconsistencies, and fail to account for the influence of environmental surfaces effectively.
Innovation Solution
Incorporating a cost term in the optimization problem that considers the distance between the mobile receiver unit and environmental surfaces, such as walls and objects, to refine position estimation by influencing the position estimate based on likelihood and surface proximity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If positioning is based solely on range data from transmitter units, then the positioning system is simple to implement, but positioning accuracy deteriorates due to noise and inconsistencies in range data
Solution Approach 1:
The patent introduces environmental surfaces (walls, objects) as intermediary elements that mediate between the transmitter units and the mobile receiver unit. These surfaces provide additional geometric constraints that help resolve positioning ambiguities and reduce the impact of noise in range data, thereby improving positioning accuracy without requiring additional transmitters or receivers
Solution Approach 2:
The patent transitions from traditional 2D positioning (using only horizontal range data) to 3D positioning by incorporating vertical surface information. The cost term evaluates the mobile unit's position in three-dimensional space relative to environmental surfaces, adding a vertical dimension that provides additional geometric constraints and improves accuracy
2Measurement precision
If geometric multilateration is used to determine position from signal arrival times, then the positioning method is computationally simple, but positioning accuracy deteriorates when range data contains noise or inconsistencies
Solution Approach 1:
The patent implements a feedback mechanism where the cost term continuously evaluates the plausibility of the estimated position against known environmental surface geometry. This feedback loop allows the system to iteratively refine position estimates by comparing predicted range data with actual measurements and adjusting the position estimate to minimize inconsistencies, thereby improving accuracy in the presence of noisy range data
Solution Approach 2:
The patent performs preliminary action by pre-storing environmental surface data (wall positions, object locations) before the positioning process begins. This pre-established geometric model serves as a reference framework that guides the position estimation process, allowing the system to quickly evaluate candidate positions against known environmental constraints rather than discovering geometry in real-time
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
Improves positioning accuracy by allowing estimates to account for environmental changes and surface interactions, providing a more realistic and accurate representation of the mobile unit's movement within the environment.
Implementation Method 1
transmitting locating signals from a plurality of transmitter units; receiving the locating signals at a mobile receiver unit
Data Source
AI summary
In a positioning system, a plurality of transmitter units (2, 3, 4, 5) transmit respective locating signals which are received at a mobile receiver unit (7). A processing system (7; 9) identifies the transmitter unit that transmitted each locating signal, and determines, for each transmitter unit, range data representative of a respective distance between the transmitter unit and the mobile receiver unit. The processing system determines a position estimate for the mobile receiver unit (7) by solving an optimisation problem that depends on i) the range data determined for the plurality of transmitter units, ii) data representative of the positions of the plurality of transmitter units in an environment (1), and iii) data representative of a position of a surface (1a, 1b, 1c, 1d, 1e; 601, 602) in the environment, by optimising for an objective function comprising a cost term that depends on a distance between the surface and the position estimate.