Control Handle Capacitive Sensing for Reliable Hand Presence Detection
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Solution Overview
Problem
Existing control input devices in teleoperated systems face safety risks due to unintentional motion, such as slippage or incidental contact, which can lead to unintended manipulation of medical instruments, and current hand presence detection methods are prone to errors, including 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 precise detection of hand presence through capacitance sensing, enabling safe activation of the controlling mode only when a user's hand is correctly positioned.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical beam-break sensors are used to detect hand presence, then hand detection capability is provided, but false negatives occur when the handle occludes the user's hand or false positives occur due to dust and scratches on sensor surface
Solution Approach 1:
The patent replaces optical sensors with a capacitive sensing system that uses electrical fields to detect hand presence. The control input device includes a capacitive sensor that detects changes in capacitance when a user's hand approaches or contacts the device, eliminating the need for optical beam-break sensors and their associated alignment and contamination issues.
2Object-affected harmful factors
If the control input device is electrically grounded, then electrical safety is improved, but capacitive sensing of hand presence cannot be performed
Solution Approach 1:
The patent divides the control input device into electrically isolated segments. The handle or grip portion is electrically isolated from the main device body using insulating materials, allowing the isolated portion to function as a capacitive sensor while the main body remains grounded for safety. This segmentation enables both capacitive sensing and electrical safety to coexist.
Solution Approach 2:
The patent introduces electrical insulation as an intermediary between the capacitive sensing element and the grounded chassis. This insulation layer allows the sensing portion to maintain a floating electrical potential necessary for capacitive detection, while the grounded chassis provides safety, with the insulation acting as a mediator between these conflicting requirements.
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 unintended motion and enhances safety by accurately detecting hand presence, minimizing false detections and ensuring reliable activation of the controlling mode in teleoperated systems.
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.