Capacitive Handle Sensing for Safe Teleoperation Control Input
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Solution Overview
Problem
Existing teleoperated control systems face safety risks due to unintentional motion of control input devices, which can lead to unintended motion of manipulator devices, and current hand presence detection methods, such as optical sensors, suffer from errors like false negatives and false positives.
Innovation Solution
A capacitive sensing system is implemented in the control input device, where the handle is isolated from electrical ground using insulative elements like bearings and gear mechanisms, allowing the capacitive sensor circuit to detect hand presence by sensing capacitance changes, thereby enabling accurate activation and deactivation of the controlling mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors are used to detect hand presence, then hand presence can be detected, but false detections occur due to sensitivity to dust, scratches, and reflectivity
Solution Approach 1:
The patent replaces optical sensing systems with capacitive sensing technology. The capacitive sensor detects changes in electrical capacitance caused by the proximity or contact of the user's hand, eliminating the problems associated with optical sensors such as sensitivity to dust, scratches, and reflectivity. This substitution provides more reliable and accurate hand presence detection.
Solution Approach 2:
The patent changes the detection parameter from optical properties (light reflection, absorption) to electrical properties (capacitance). By measuring capacitance changes rather than optical signals, the system becomes insensitive to surface conditions like dust and scratches, while remaining highly responsive to the dielectric properties of human tissue, thereby improving both accuracy and reliability.
2Measurement precision
If optical beam-break sensors are used to detect hand presence, then hand contact can be detected, but false negatives occur when the handle occludes the user's hand from detection
Solution Approach 1:
The patent replaces optical beam-break sensors with capacitive sensors that directly measure electrical field changes. This eliminates the line-of-sight requirement inherent in optical systems, allowing detection of hand presence even when partially occluded by the handle or in various hand poses, thereby eliminating false negatives.
Solution Approach 2:
The patent transitions from a spatial/optical detection approach (requiring line-of-sight) to an electrical field-based approach that penetrates through and around objects. The capacitive sensor detects changes in the electrical field caused by the hand's proximity or contact, regardless of visual occlusion, adding a new dimension of detection capability.
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
The capacitive sensing system effectively reduces safety risks by reliably detecting hand presence, minimizing false detections, and ensuring safe operation of teleoperated systems by accurately determining when the user's hand is in contact with the control input device.
Implementation Method 1
a capacitive sensor circuit electrically coupled to the handle. The handle is isolated from electrical ground and is an antenna for the capacitive sensor circuit
Data Source
AI summary
Implementations relate to capacitive sensing of hand presence at a control input device. In some implementations, a control input device includes a support structure, a handle moveable in one or more degrees of freedom with reference to the support structure, and a capacitive sensor circuit electrically coupled to the handle. The handle is isolated from electrical ground and is an antenna for the capacitive sensor circuit.