Floating bumper in autonomous cleaning robot

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Solution Overview

Problem

Autonomous cleaning robots lack obstacle detection when reversing, leading to increased mission failure due to wedging under furniture or other objects, as traditional bumpers do not provide comprehensive perimeter sensing.

Innovation Solution

A full-perimeter bumper system with a spring module that secures the bumper to the outer shell, allowing it to detect horizontal bumps while resisting movement due to inertial forces, using Hall Effect sensors to differentiate between bumps and noise, and a breakaway mechanism to only register forces above a threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional front bumper is used for obstacle detection, then the robot can detect obstacles in the front direction, but the robot cannot sense obstacles encountered while backing up or along the sides

Engineering Contradiction:

Improveobstacle detection capabilityVSAvoiddetection coverage direction

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The bumper is divided into multiple independent segments (front bumper, rear bumper, side bumpers) that can be positioned at different locations around the robot. Each segment independently detects obstacles in its specific direction, collectively providing full perimeter coverage without requiring a single complex sensing system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bumper system transitions from a single-direction (front-only) detection approach to a multi-dimensional perimeter detection system. By placing bumpers at front, rear, and side positions, the system achieves 360-degree spatial coverage, adding dimensional completeness to the detection capability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If a full perimeter bumper is used to provide comprehensive obstacle detection, then the robot can detect obstacles in all directions including rear and sides, but the bumper may move due to inertial forces during acceleration creating false positive detections

Engineering Contradiction:

Improveobstacle detection accuracyVSAvoidfalse positive detections from inertial movement

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Spring modules are installed to counterbalance the inertial forces acting on the bumper during robot acceleration and deceleration. The spring force opposes the inertial movement, keeping the bumper in its neutral position and preventing false trigger activations while maintaining the bumper's ability to detect actual obstacles.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The spring modules provide pre-configured cushioning force that absorbs and compensates for inertial shocks before they can cause the bumper to move into a trigger position. This beforehand cushioning prevents false detections by neutralizing the effect of acceleration-induced inertial forces.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the bumper is secured rigidly to the outer shell to prevent movement, then inertial forces cannot cause false positives, but the bumper cannot detect vertical bumps that cause wedging under furniture

Engineering Contradiction:

Improvedetection sensitivity to vertical bumpsVSAvoidfalse positive detections

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The bumper system transitions from a rigid fixed connection to a dynamic spring-supported connection. The spring modules allow the bumper to move vertically in response to bump forces while maintaining horizontal position stability through spring restraint, enabling selective detection of vertical obstacles during backing operations.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The connection between bumper and outer shell changes from rigid (zero compliance) to spring-supported (controlled compliance). This parameter change in connection stiffness allows the bumper to respond to vertical bump forces while the spring force maintains horizontal position, filtering out false positives from inertial movement.

Inventive Principle:

Principle #35Parameter changes

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

Enhances obstacle detection during reverse operations, reducing wedging incidents and improving navigation by accurately identifying bumps and preventing false positives, thus increasing mission completion rates.

Implementation Method 1

a spring module connected to the outer shell and to the bumper, the spring module comprising: a bumper mount connected to the bumper; a cap connected to the outer shell; a spring connected to the cap and the bumper mount

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

using Hall Effect sensors to differentiate between bumps and noise

Methodology Applied

Scientific EffectHall Effect: Hall Effect

Data Source

PatentUS11213181B2Floating bumper in autonomous cleaning robot

Publication Date: 2022.01.04 IROBOT CORP

AI summary

An autonomous mobile cleaning robot can include a robot body, a bumper, and a coupling. The robot body can include a displacement sensor. The bumper can be moveably coupled to the body. The coupling can include a displacement limiter associated with the displacement sensor. The displacement limiter can inhibit or limit sensing by the displacement sensor of displacement of the bumper from the robot body caused by forces below a threshold horizontal force value.