Phase-Modulated Pulse Signal for Lawn Mower Positioning
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Solution Overview
Problem
Existing automatic lawn mowers face challenges in efficiently determining their position relative to the cutting area and adjusting movements with high energy consumption and complex electronic circuits, and require expensive and complicated circuitry for signal processing.
Innovation Solution
The apparatus uses a phase-modulated electric signal with pulses separated by intervals, allowing the lawn mower to determine its position through filtering and phase displacement analysis, enabling reliable positioning and movement adjustments with a simple and cost-effective electronic structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-frequency sine wave signal is propagated continuously in the perimetral cable, then the lawn mower can reliably determine its position by comparing the detected signal with a stored reference, but the energy consumption of the system becomes non-negligible
Solution Approach 1:
The patent applies periodic action by transmitting the identification signal in periodic pulses instead of continuous waves. The signal is sent in discrete time intervals with specific pulse durations and separation times, allowing the lawn mower to detect position information periodically rather than continuously, thereby significantly reducing energy consumption while maintaining positioning reliability.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that during each active pulse period, the signal transmission is continuous and uninterrupted. The pulse waveform maintains consistent amplitude and frequency characteristics throughout its duration, ensuring reliable detection while minimizing total transmission time compared to continuous wave approaches.
2Reliability
If a current signal with at least two different harmonic components is used, then the lawn mower can determine its position by separating and analyzing the harmonics, but the technique becomes complex requiring complicated and expensive circuits on board the lawn mower
Solution Approach 1:
The patent applies parameter changes by using a single-frequency signal with variable amplitude modulation instead of multi-frequency harmonic signals. The identification information is encoded in the amplitude variations of the pulse signal, allowing the lawn mower to determine position through simple amplitude comparison rather than complex harmonic separation, thus reducing circuit complexity while maintaining positioning accuracy.
Solution Approach 2:
The patent substitutes complex signal processing mechanics with simpler detection mechanics. Instead of requiring the lawn mower to perform complex harmonic analysis with sophisticated circuits, the system uses amplitude-modulated pulses that can be detected through simpler comparison circuits, replacing complex mechanical/electronic processing with simpler detection based on signal presence and amplitude characteristics.
3Reliability
If the electric signal is propagated substantially continuously in the perimetral cable, then the lawn mower can maintain constant positioning information, but a non-negligible energy consumption is generated
Solution Approach 1:
The patent implements periodic action by transmitting the positioning signal in discrete pulses with specific intervals rather than continuously. The signal transmission occurs during defined pulse periods and remains inactive during separation periods, creating a periodic pattern that maintains positioning information availability while dramatically reducing overall energy consumption compared to continuous transmission.
Solution Approach 2:
The patent applies self-service by designing the pulse signal characteristics to inherently provide positioning information without requiring constant transmission. The amplitude-modulated pulse structure contains sufficient identification data within each pulse period, allowing the lawn mower to determine position during pulse intervals and remain in a low-power state during separation intervals, making the system self-sufficient in maintaining positioning continuity.
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 allows the lawn mower to accurately determine its position and adjust operations efficiently while reducing energy consumption and electronic complexity, ensuring reliable operation with a straightforward and affordable electronic setup.
Implementation Method 1
Each pulse is formed with a substantially periodical carrier signal at a main frequency f, which is phase-modulated with phase displacements equal to k*180°
Implementation Method 2
The electric signal is propagated in cable 2
Data Source
Figure 1
Figure 2~3
Figure 4a~5
AI summary
An apparatus for cutting grass, comprising: a lawn mower provided with actuating means for movement of the lawn mower, one or more blades for grass cutting in a cutting area (S); an electric cable confining said cutting area; a management device associated with the cable and configured for outputting an electric signal comprising a plurality of pulses separated from each other, each pulse being formed with a portion of a substantially periodic carrier signal at a main frequency, which is phase-modulated with phase displacements equal to 0° or 180°. The management device is connected to the cable to make said electric signal propagate in said cable. The lawn mower is further provided with: sensor means for detecting the electric signal; an operating module configured for filtering in the electric signal, at least one first pulse in a main frequency band defining a neighbourhood of the main frequency, thus obtaining a corresponding first filtered pulse and identifying data D1 in the first filtered pulse as a function of the phase displacements; a memory in which main reference data (Ref) are contained; a main comparison module for comparing the data identified in the first filtered pulse and said main reference data, and generating a corresponding notification signal representative of the fact that said lawn mower is positioned inside or outside the cutting area; a connected control unit for operating the actuating means as a function of the notification signal.