Mobile Robot ToF Sensor Layout With Non-Overlapping Coverage

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Solution Overview

Problem

Existing robotic systems face a tradeoff between sensor accuracy and cost, with overlapping sensor coverage leading to inefficiency and the need for extra sensors to achieve desired precision in obstacle detection.

Innovation Solution

The use of non-overlapping, one-dimensional (1D) time-of-flight (ToF) sensors mounted at fixed positions and orientations on a mobile robotic device, combined with a three-dimensional (3D) lidar sensor for front obstacle detection, minimizes the number of sensors required while ensuring comprehensive coverage and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If overlapping sensor coverage is used to improve detection precision, then measurement precision improves, but device complexity and cost increase due to requiring extra sensors

Engineering Contradiction:
Improveobstacle detection precisionVSAvoidnumber of sensors
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the detection space into distinct non-overlapping zones, with each 1D ToF sensor responsible for a specific sector. This segmentation eliminates redundant coverage while maintaining comprehensive detection, resolving the contradiction between detection precision and sensor quantity by ensuring each sensor contributes uniquely to overall coverage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from traditional overlapping 2D sensor coverage to a structured angular segmentation approach, where sensors are positioned at specific angles (e.g., 45-degree intervals) to create non-overlapping conical coverage zones. This dimensional reorganization of sensor placement optimizes coverage efficiency without sacrificing detection precision.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If more sensors are added to achieve desired detection precision, then measurement precision improves, but manufacturing cost increases

Engineering Contradiction:
Improveobstacle detection precisionVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

By segmenting the detection environment into non-overlapping angular zones and assigning one sensor per zone, the system achieves comprehensive coverage with minimal sensors. This eliminates the need for redundant sensors that would increase manufacturing costs while maintaining the required detection precision for safe operation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the coverage parameter from overlapping to non-overlapping angular sectors, optimizing the sensor count. By carefully selecting sensor angles and fields of view to create adjacent而非overlapping coverage zones, the system achieves complete 360-degree detection with fewer sensors, directly reducing manufacturing costs.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If non-overlapping sensor coverage is used to reduce sensor quantity, then device complexity decreases, but detection precision may worsen due to coverage gaps

Engineering Contradiction:
Improvenumber of sensorsVSAvoidobstacle detection precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent addresses potential coverage gaps by transitioning to three-dimensional spatial reasoning, where the 3D LiDAR provides comprehensive front coverage and the 1D ToF sensors provide complementary lateral and rear detection. This multi-dimensional sensor arrangement ensures no detection gaps exist while maintaining non-overlapping coverage efficiency.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent merges different sensor types (1D ToF sensors for lateral/rear detection and 3D LiDAR for front detection) with complementary fields of view. This combination creates unified non-overlapping coverage across all directions, eliminating gaps while keeping the total sensor count minimal, thus maintaining both low complexity and high detection precision.

Inventive Principle:
Principle #5Merging (Combining)

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 arrangement provides efficient and cost-effective obstacle detection by avoiding redundant coverage areas, allowing for predictable detection of objects and ensuring safety by detecting potential hazards, such as operator presence, while utilizing a 3D lidar for front obstacles.

Implementation Method 1

a plurality of one-dimensional (1D) time-of-flight (ToF) sensors for obstacle detection

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 2

a three-dimensional lidar sensor oriented to detect obstacles in front of the mobile robotic device

Methodology Applied
Scientific EffectLight flight time sensing: Time of Flight

Data Source

PatentEP3972785B1Mobile robot sensor configuration
Publication Date: 2026.03.25 GDM HOLDING LLC
  • EP3972785B1 patent drawingFigure 1
  • EP3972785B1 patent drawingFigure 2
  • EP3972785B1 patent drawingFigure 3

AI summary

A mobile robotic device (100) is disclosed which includes a plurality of one-dimensional (ID) time-of-flight (ToF) sensors (502-518, 602-618). Each ID ToF sensor of the plurality of ID ToF sensors may be mounted at a fixed position and orientation on the mobile robotic device. Each pair of ID ToF sensors of the plurality of ID ToF sensors may be fixed at respective positions and orientations relative to each other such that respective cones of coverage of the pair of ID ToF sensors are non-overlapping.