Hand Orientation Detection Using ToF Surface Geometry

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Solution Overview

Problem

Current user input devices struggle to accurately distinguish between a user's left and right hand, especially in applications like vehicle interfaces, where differentiation is crucial for driver and passenger operations, due to limited detection range and false detection risks.

Innovation Solution

A method and user input device utilizing a sensor, such as a ToF camera, to detect the palm's surface points and thumb position, determining hand orientation by analyzing convex and concave surfaces, allowing for efficient recognition of hand alignment and preventing misuse through minimal surface point evaluation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional sensors are used for hand detection, then the device complexity is low, but the measurement precision and detection range are insufficient to distinguish left and right hands

Engineering Contradiction:
Improvehand orientation detection accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transitions from 2D image analysis to 3D spatial analysis by utilizing depth information from a ToF camera. This dimensional change enables the system to detect hand orientation and distinguish between left and right hands by analyzing the three-dimensional positions of surface points, thereby improving measurement precision without requiring multiple cameras or complex sensor arrays.

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

Solution Approach 2:

The patent creates a digital 3D model (point cloud) of the hand by capturing depth information from multiple surface points. This digital copy of the hand's geometry allows the evaluation unit to analyze hand orientation and orientation without physical contact, improving detection accuracy while keeping the physical sensor system relatively simple.

Inventive Principle:
Principle #26Copying

2Measurement precision

If all surface points of the hand are evaluated to determine orientation, then the measurement precision improves, but the processing time and computational load increase

Engineering Contradiction:
Improvehand orientation accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the essential information needed for hand orientation detection by identifying and evaluating specific surface points that are most informative for determining palm orientation. Instead of processing all captured surface points, the system selectively uses a subset of points that provide sufficient information for accurate orientation determination, thereby reducing computational load and processing time while maintaining measurement precision.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by evaluating only the necessary portion of surface points required for hand orientation detection. The system identifies key surface points on the palm and uses these partial data points to determine overall hand orientation, avoiding the computational overhead of processing every captured surface point while still achieving accurate detection.

Inventive Principle:
Principle #16Partial or excessive action

3Ease of operation

If the detection range is extended to capture hands from a distance, then the ease of operation improves, but the reliability of hand distinction decreases due to reduced detection precision

Engineering Contradiction:
Improvegesture input convenienceVSAvoidhand distinction accuracy
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent uses the depth dimension provided by the ToF camera to maintain reliable hand distinction even at extended detection ranges. By analyzing the three-dimensional spatial relationships between surface points rather than relying solely on 2D image features, the system can accurately determine hand orientation and distinguish between left and right hands regardless of distance, thereby maintaining reliability while improving ease of operation.

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

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 reliable and efficient differentiation between left and right hands, reducing false detection and enhancing ergonomic design by using fewer surface points for quick orientation estimation, thus improving user interface functionality in transportation and other applications.

Implementation Method 1

DE 10 2013 010 932 B4 discloses a gesture-based user interface which has a time-of-flight (ToF) camera as a sensor. The image data created in this way represent three-dimensional information containing spatial coordinates of individual surface sections of the at least one gesturing arm.

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Data Source

PatentEP3232372B1Method, user input device and computer program for recognizing an orientation of a hand of a user
Publication Date: 2021.06.09 VOLKSWAGEN AG
  • EP3232372B1 patent drawingFigure 1~8
  • EP3232372B1 patent drawingFigure 2

AI summary

A user interface, a computer program product, a signal sequence, a means of locomotion, and a method for detecting a user's hand (1) are proposed. The method comprises the steps of: - detecting the user's hand (1) using a sensor, - identifying a plurality of surface points (6, 7) of the hand (1) in the sensor signal, - detecting a palm (8) facing the sensor if the surface points (6, 7) lie substantially on a surface concave with respect to the sensor, and/or - detecting a back of the hand facing the sensor if the surface points (6, 7) lie substantially on a surface convex with respect to the sensor.