Vehicle Self-Localization Using Vertical Acceleration and Terrain Elevation
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Solution Overview
Problem
Existing self-localization methods for vehicles in environments without GNSS data reception and terrain prone to slipping or getting stuck suffer from accuracy issues due to unreliable vehicle speed and acceleration measurements.
Innovation Solution
Estimate vehicle altitude based on initial altitude and time series data of vertical acceleration, and match this altitude to terrain elevation data to determine vehicle position, independent of horizontal speed and acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-localization is performed based on detected vehicle speed or acceleration in horizontal direction, then self-localization can be performed without GNSS data, but accuracy deteriorates in terrain where slipping or getting stuck is likely to occur
Solution Approach 1:
The patent replaces the mechanical measurement system (accelerometers and speed sensors measuring horizontal acceleration and speed) with an alternative approach using vertical acceleration sensors combined with terrain elevation data. This substitution avoids the reliability issues of horizontal measurements in slippery terrain by using a different physical measurement basis (vertical acceleration integrated with terrain database) that is not affected by horizontal wheel slip.
Solution Approach 2:
The patent introduces a terrain database as an intermediary element between the vehicle and the localization system. By comparing integrated altitude (derived from vertical acceleration) with terrain elevation data from the database, the system determines vehicle position without relying on direct horizontal motion measurements. The terrain database acts as a reference map that translates altitude information into position information, bypassing the unreliable horizontal sensors.
2Device complexity
If vehicle speed and acceleration sensors are used for self-localization, then the system remains simple, but measurement reliability deteriorates on slippery terrain
Solution Approach 1:
The patent makes the vertical acceleration sensor serve multiple functions: it not only measures vertical motion for comfort control but also provides the basis for altitude integration and subsequent position determination through terrain database matching. This multi-functionality eliminates the need for separate horizontal acceleration sensors, maintaining device simplicity while improving reliability on slippery terrain.
Solution Approach 2:
The patent changes the measurement parameter from horizontal acceleration (unreliable on slippery terrain) to vertical acceleration (reliable and unaffected by wheel slip). By integrating vertical acceleration to obtain altitude and then matching with terrain elevation data, the system transforms a reliable measurement (vertical acceleration) into position information, bypassing the unreliable horizontal parameters entirely.
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
Enables high-accuracy self-localization even in environments where GNSS data is unavailable and slipping or getting stuck is likely, by minimizing the influence of horizontal vehicle speed and acceleration.
Implementation Method 1
an acceleration sensor (Z-axis accelerometer) that detects acceleration of the vehicle in a vertical direction
Data Source
AI summary
A self-localization method according to the present disclosure includes the following first to fourth steps. The first step is acquiring terrain data in which a position and an elevation of a ground surface on a traveling area of the vehicle are managed. The second step is acquiring time series data of acceleration in a vertical direction of the vehicle. The third step is estimating an altitude of the vehicle based on an initial altitude of the vehicle and the time series data of acceleration. The fourth step is estimating a vehicle position based on the position of the ground surface at which the elevation of the ground surface approximates the estimated altitude of the vehicle.