Monocular Camera Distance Detection for Mobile Objects

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Solution Overview

Problem

The existing Structure from Motion (SfM) algorithm cannot detect distance to stationary objects when a vehicle is stationary, limiting its effectiveness in controlling vehicle movement safely, as it requires the vehicle to travel a predetermined distance before obtaining a valid distance detection result.

Innovation Solution

A mobile object control system that calculates a second stop position closer than the first stop position, allowing the vehicle to stop and start from this position, enabling distance detection using the SfM algorithm before reaching the initial stop position, thereby improving safety and reducing costs by using a monocular camera instead of a stereo camera.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a monocular camera with SfM algorithm is used for distance detection, then the cost is reduced compared to stereo camera, but the distance to stationary objects cannot be detected when the vehicle stops

Engineering Contradiction:
ImprovecostVSAvoiddistance detection capability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The vehicle performs a preliminary movement of a predetermined distance L before reaching the stop position, enabling the SfM algorithm to capture sufficient image data for distance detection. This preliminary action ensures that distance detection can be performed reliably while still stopping at the intended position, resolving the contradiction between cost reduction and detection reliability.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the vehicle stops at the first stop position, then the safety criterion is satisfied, but the SfM algorithm cannot provide distance detection results until the vehicle travels a predetermined distance L

Engineering Contradiction:
Improvesafety criterionVSAvoidtime for distance detection
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary distance detection and environment assessment during the approach phase, before the vehicle reaches the stop position. This allows the SfM algorithm to generate distance detection results in advance, eliminating the time delay that would occur if detection were postponed until after stopping.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The stop position is dynamically adjusted based on real-time distance detection results from the SfM algorithm. The vehicle may stop before, at, or after the original stop position depending on the detected distance to obstacles, allowing flexible adaptation to ensure safety while minimizing detection time loss.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If the vehicle travels ahead of the stop position to enable SfM distance detection, then distance detection results can be obtained, but the vehicle travels in a state of insufficient environmental grasp

Engineering Contradiction:
Improvedistance detection resultVSAvoidinsufficient environmental awareness
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The vehicle travels a predetermined distance L as a preliminary action to enable SfM processing, but this distance is carefully controlled to be sufficient for algorithm convergence while remaining short enough to maintain safety. The predetermined distance is optimized to balance detection precision requirements with safety constraints.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors distance detection results and uses this feedback to adjust vehicle control. If distance detection becomes reliable, the system can safely stop at or near the intended position. This closed-loop control ensures that the vehicle does not travel excessive distances while maintaining environmental awareness.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3438779B1Mobile object control system, mobile object control method, and program
Publication Date: 2022.08.31 RENESAS ELECTRONICS CORP
  • EP3438779B1 patent drawingFigure 1
  • EP3438779B1 patent drawingFigure 2
  • EP3438779B1 patent drawingFigure 3

AI summary

A mobile object control system has an SfM unit detecting distance to an object imaged by a monocular camera by using the SfM algorithm, a first-stop-position output unit outputting a first stop position, a second-stop-position calculating unit calculating a second stop position closer than the first stop position, and a control unit controlling travel of a mobile object. The control unit controls the mobile object so as to stop at the second stop position. When a predetermined starting condition is satisfied, the control unit controls the mobile object so as to start. The SfM unit detects the distance to an object by using an image captured by the monocular camera after the mobile object starts. When a result of detection of the distance of the object by the SfM unit is obtained, the control unit uses the detection result for control of the travel.