Heuristic Correction Values for A* Route Determination
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Solution Overview
Problem
Vehicle navigation systems using the A* algorithm face inefficiencies in route calculation due to inaccurate estimation functions, leading to prolonged computation times when the heuristic values do not represent real route conditions accurately.
Innovation Solution
The method involves determining correction values based on digital map data, which include nodes, connections, and edge costs, using a destination-node-based correction value to improve route determination efficiency by adjusting the heuristic values and reducing the number of calculation steps required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the A* algorithm uses a simple estimation function (heuristics) to reduce run-time, then the calculation speed is improved, but the accuracy of route determination deteriorates when the heuristic values do not represent real route conditions
Solution Approach 1:
The patent pre-calculates correction values for nodes based on historical route data and stores them in the digital map data. These correction values are computed in advance to compensate for inaccuracies in heuristic estimations, allowing the A* algorithm to maintain both speed and accuracy without real-time complex calculations
Solution Approach 2:
The patent modifies the total cost calculation by introducing correction values that adjust the heuristic estimates. The formula becomes f(n) = g(n) + h(n) + correction_value(n), where the correction value dynamically adjusts the heuristic component based on pre-analyzed route characteristics, balancing speed and accuracy
2Measurement precision
If correction values are pre-calculated and stored for all nodes to improve route determination accuracy, then the accuracy is improved, but the storage requirements increase
Solution Approach 1:
The patent applies correction values selectively based on local route characteristics. Instead of uniformly applying corrections to all nodes, the system calculates and stores correction values only for nodes where heuristic inaccuracies are significant, tailored to local geographic and routing conditions
Solution Approach 2:
The patent implements a compromise where correction values are stored for a subset of nodes rather than all nodes. The system calculates correction values for nodes that are strategically important or exhibit high heuristic error, accepting partial correction coverage to balance accuracy improvement with storage constraints
Data Source
AI summary
The route from a prescribed starting node to a prescribed destination node is determined on the basis of digital map data stored in a memory unit such that, for possible expansion of a respective current node, total costs are determined for the current node on the basis of a sum of edge costs for an optimum route from the starting node to the current node and a destination-node-related heuristic value for the current node and a prescribed destination-node-related correction value. The destination-node-related correction value is in this case representative of a mean value for cost ratios for respective nodes in a prescribed set, wherein the respective cost ratios are dependent on the edge costs of the connections that are situated between the current node and the respective node in the set and that represent an optimum route between the current node and this node in the set and on a heuristic value for the current node in relation to this node in the set.