Digital PLL Signal Detection for Autonomous Lawnmower Boundaries

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Solution Overview

Problem

Existing autonomous lawn mowers face challenges in accurately detecting digital received signals from charging stations to determine their workspace boundaries, leading to reduced signal quality and sensitivity.

Innovation Solution

The implementation of a signal processing apparatus with a digital phase locking loop that adjusts detection time based on signal edge times, shifting it towards the bit center of the digital received signal, and verifies the signal through correlation with a pattern signal, ensuring high signal quality and sensitivity with a single signal acquisition per bit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If digital received signal detection is performed without phase coupling, then device complexity is reduced, but signal quality and detection sensitivity deteriorate

Engineering Contradiction:
Improvesignal qualityVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex analog phase-locked loop circuits with a digital implementation. The digital phase-locked loop uses digital signal processing techniques to achieve phase coupling between the pattern signal and digital received signal, thereby improving signal quality while avoiding the complexity of analog circuit implementations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters of the signal detection system by introducing phase coupling through the digital phase-locked loop. This parameter change (phase alignment) improves the correlation between the pattern signal and received signal, enhancing detection sensitivity and signal quality without requiring additional hardware complexity.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If multiple signal captures per bit are performed, then signal quality improves, but detection time and processing complexity increase

Engineering Contradiction:
Improvesignal qualityVSAvoiddetection time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary phase coupling using the digital phase-locked loop before the actual signal capture. By pre-aligning the phase of the pattern signal with the digital received signal, the system ensures that a single capture per bit yields optimal signal quality, eliminating the need for multiple captures and subsequent averaging operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The digital phase-locked loop implements a feedback mechanism that continuously monitors the phase relationship between the pattern signal and digital received signal. This feedback enables real-time phase adjustment, ensuring that each signal capture occurs at the optimal moment, thereby achieving high signal quality with minimal captures.

Inventive Principle:
Principle #23Feedback

3Productivity

If signal capture is performed without phase alignment, then processing speed increases, but detection sensitivity decreases

Engineering Contradiction:
Improveprocessing speedVSAvoiddetection sensitivity
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent substitutes complex analog phase alignment mechanisms with a digital implementation. The digital phase-locked loop achieves phase coupling through digital signal processing, maintaining processing speed while significantly improving detection sensitivity through accurate phase alignment between the pattern signal and received signal.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2960742B1Signal processing device for an autonomous service robot
Publication Date: 2021.10.06 ROBERT BOSCH GMBH
  • EP2960742B1 patent drawingFigure 1~2
  • EP2960742B1 patent drawingFigure 3~4

AI summary

The invention relates to a signal processing device for an autonomous service robot (10), in particular for an autonomous lawnmower, comprising at least one signal acquisition unit (12) for acquiring at least one digital received signal (14), and at least one processing unit (16) for processing the at least one digital received signal (14). It is proposed that the at least one processing unit (16) comprises at least one digital phase-locked loop (18) for phase-coupling at least one pattern signal (20) to the at least one digital received signal (14).