Electro-mechanical Strap Stack for Robotic Arm Grounding

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Solution Overview

Problem

Robotic surgical arms face challenges in meeting the IEC601-1 standard for electrical grounding and reliability of electrical cabling due to bending and chafing around joints, which can lead to increased resistance and signal line shorting.

Innovation Solution

The implementation of a strap drive-train system with flat electrical conductors over pulleys, including a stacked configuration of ground straps and flexible signal cables, which are routed through the robotic surgical arm to maintain low resistance and prevent bending stresses, using a combination of metal and beryllium copper straps to ensure reliable grounding and signal routing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrical cabling is routed through joints of motion in robotic surgical arm, then connectivity is maintained, but bending and chafing occur leading to increased resistance and signal line shorting

Engineering Contradiction:

Improveelectrical cabling reliabilityVSAvoidbending and chafing stresses

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The electrical cabling system is segmented into multiple independent flat conductors that are stacked and routed separately through the joints, rather than as a single bundled cable. This segmentation allows each conductor to follow its own path with controlled bending, reducing chafing and maintaining reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from traditional three-dimensional cable bundling to a two-dimensional stacked arrangement of flat conductors. This dimensional change allows the conductors to be layered in a compact configuration that minimizes bending stresses and facilitates controlled routing through joint areas.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If traditional grounding methods are used in robotic surgical arm, then grounding is provided, but resistance to ground exceeds the IEC601-1 standard requirement of 200 milli-ohms

Engineering Contradiction:

Improvegrounding complianceVSAvoidground resistance

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

Multiple grounding conductors are merged into a stacked configuration where several flat ground straps are layered together and routed through the same path. This merging of multiple grounding paths reduces overall ground resistance by providing parallel conduction paths, ensuring compliance with the IEC601-1 standard.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The grounding system uses composite construction with multiple layers of conductive materials (metal and beryllium copper straps) stacked together. This composite structure provides redundant conduction paths and maintains low resistance even when individual layers experience bending or stress.

Inventive Principle:

Principle #40Composite materials

3Ease of operation

If electrical conductors are routed through moving joints, then connectivity is maintained, but bending stresses lead to chafing and signal line failures

Engineering Contradiction:

Improvecable routing flexibilityVSAvoidsignal line integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent employs thin, flexible flat conductor films that can bend and flex as the robotic arm moves through its range of motion. These thin-film conductors are more resistant to chafing and fatigue compared to traditional rigid or thick cables, maintaining signal integrity while accommodating joint movement.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The conductors are pre-routed and pre-positioned in stacked configurations before the robotic arm operates. This preliminary routing ensures that bending radii are optimized and stress points are minimized from the outset, preventing chafing and maintaining reliability during operation.

Inventive Principle:

Principle #10Preliminary action

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 solution effectively reduces chassis ground resistance to meet the IEC601-1 standard, enhances the reliability of electrical cabling by minimizing bending stresses, and maintains signal integrity through controlled routing and stacking of conductors, thereby ensuring safe and efficient operation of robotic surgical systems.

Implementation Method 1

flat electrical conductors over pulleys in a strap drive-train

Methodology Applied

Scientific EffectPulley: Pulley

Data Source

PatentUS10646292B2Electro-mechanical strap stack in robotic arms

Publication Date: 2020.05.12 INTUITIVE SURGICAL OPERATIONS INC

AI summary

In one embodiment of the invention, a strap drive-train for use in a robotic arm to enable movement of a linkage assembly of the robotic arm is provided. The linkage assembly includes a plurality of links pivotally coupled in series together at a plurality of joints, respectively, for movement of the robotic arm about a pitch axis. The strap drive-train includes a first driver pulley rigidly coupled to a link of the plurality of links and a second driver pulley rigidly coupled to another link of the plurality of links. The electro-mechanical strap stack includes at least one of a ground strap and an electrical cable strap in a stacked configuration with a drive strap, wherein the electro-mechanical strap stack is connected between the first driver pulley and the second driver pulley through a middle link.