Boundary Cable Signal Prefiltering for Robotic Mower CDMA Reception
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Solution Overview
Problem
Robotic lawnmowers face challenges in correctly receiving CDMA signals due to the attenuating effect of the boundary cable, which acts as a low-pass filter, making it difficult to compensate for varying R and L components in different work areas, leading to incomplete signal reception.
Innovation Solution
A robotic lawnmower system with a charging station and signal generator that transmits prefiltered signals through a current generator, using a current generator instead of a voltage generator and prefiltering the signal according to a model of the work area's RL-circuit to ensure correct reception of CDMA signals without increasing overall field strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage generator is used to transmit signals through the boundary cable, then the signal can be transmitted, but the higher frequency components are attenuated by the RL-circuit of the work area
Solution Approach 1:
The patent changes the fundamental parameter of signal transmission from voltage-based to current-based. By using a current generator instead of a voltage generator, the signal is transmitted as current through the boundary cable. This approach compensates for the attenuating effect of the RL-circuit because current transmission is less susceptible to the frequency-dependent impedance variations caused by the boundary cable and work area characteristics, thereby improving high frequency component reception.
2Reliability
If the R- and L-components of the work area are compensated for, then signal reception improves, but substantial signal processing is required
Solution Approach 1:
The patent applies preliminary action by pre-filtering the signal before transmission through the boundary cable. The signal is shaped in advance to account for the expected attenuation characteristics of the RL-circuit. This pre-processing approach simplifies the receiver's task, as the signal arrives already optimized for the specific work area characteristics, eliminating the need for complex real-time compensation processing at the receiver end.
3Force
If the current level of the signal is increased, then the magnetic field strength increases, but the electric power consumption of the boundary line increases
Solution Approach 1:
The patent changes the transmission parameter from voltage to current, which fundamentally alters the power consumption characteristics. By transmitting as current rather than voltage, the system achieves stronger magnetic field generation (since magnetic field strength is directly proportional to current) without the quadratic power loss associated with voltage transmission through resistive cables. This results in more efficient power utilization.
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 approach enables improved reception of CDMA signals by adapting the signal transmission to the work area's characteristics, reducing interference and ensuring robust communication between the lawnmower and charging station, even in areas with overlapping or stacked work zones.
Implementation Method 1
a boundary line demarcating a work area of the automatic work system and transmitting the preset boundary signal while generating a electromagnet field
Data Source
Figure 1A~2
Figure 3~4
Figure 5A~5C
AI summary
A robotic lawnmower system comprising a charging station (210) and a robotic work tool (100), the charging station comprising a signal generator (240) to which a boundary cable (250) is to be connected, the signal generator (240) being configured to transmit a signal (245) through the boundary cable (250), and the robotic working tool (100) comprising a sensor (170) configured to pick up magnetic fields generated by the signal (245) in the boundary cable (250) thereby receiving the signal (245) being transmitted and a controller (110) configured to analyse the picked up signal, wherein the signal generator (240) is further configured to: prefilter the signal through an filter model; and transmit the prefiltered signal to through the boundary cable (250) by means of a current generator.