A method in a self-propelled robotic tool and a self-propelled robotic tool
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Solution Overview
Problem
Existing collision detection methods in self-propelled robotic tools are unreliable and inefficient, particularly when the primary collision detection sensor becomes non-functional or irrelevant due to environmental factors such as obstruction or darkness.
Innovation Solution
A method that switches between two modes: a first mode using the collision detection sensor and a second mode utilizing motor current measurements and, optionally, IMU data to ensure reliable collision detection even when the primary sensor is non-functional.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If collision detection is carried out using a collision detection sensor, then collision detection reliability is improved under normal conditions, but the system becomes vulnerable to sensor failures or environmental obstructions that render the sensor non-functional
Solution Approach 1:
The system changes the detection parameter from optical sensor data to motor current characteristics. When the optical sensor becomes non-functional, the system transitions to monitoring motor current parameters, which continue to provide collision detection capability through a different physical measurement approach
Solution Approach 2:
The motor current measurement acts as an intermediary detection method. Instead of directly relying on the optical sensor, the system uses motor current as an intermediate indicator that indirectly reflects collision events, providing a backup detection pathway when the primary sensor fails
2Adaptability or versatility
If the robotic tool switches to a second mode using motor current measurements when the sensor is non-functional, then collision detection adaptability is improved, but the measurement precision may be reduced compared to direct sensor detection
Solution Approach 1:
The system performs preliminary recording of motor current baselines during normal operation. This preliminary data collection enables the system to establish reference values that improve the precision of subsequent collision detection through comparison, reducing the precision loss that would otherwise occur with indirect detection
Solution Approach 2:
The system uses feedback from motor current measurements compared against recorded baselines to detect collisions. This feedback mechanism allows the system to maintain measurement precision by continuously comparing actual current draw against expected values, identifying deviations that indicate collision events
3Reliability
If motor current baseline is recorded with IMU data and elevation data, then collision detection reliability under varying conditions is improved, but the device complexity increases
Solution Approach 1:
The motor current measurement system serves multiple functions: it provides both collision detection and serves as a baseline for compensating environmental variations. By recording baselines under different conditions (flat terrain, uphill, downhill), the single motor current parameter becomes a multi-functional indicator that adapts to various operating scenarios without requiring separate detection systems
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
Ensures reliable collision detection by adapting to sensor failures, maintaining functionality in various circumstances, including when the primary sensor is obstructed or inoperative.
Implementation Method 1
collision detection is instead carried out based on a motor current measurement in relation to the recorded motor current baseline
Data Source
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AI summary
The present disclosure relates to a self-propelled robotic work tool 1 and a method for collision detection in such a self-propelled robotic tool. The robotic tool comprises at least one driving wheel 9 driven by an electric motor 35, and at least one collision detection sensor 15)for detecting a collision with another object 7. In the method the robotic tool operates in a first mode 55 where the collision detection sensor is functional, and when determining 57 a condition where the collision detection sensor 15 is non-functional or irrelevant, it enters a second mode 59. In the first mode 55, collision detection is carried out based on the collision detection sensor 15, and a motor current baseline in a non-collision state is recorded. In the second mode 57, collision detection is instead carried out based on a motor current measurement in relation to the recorded motor current baseline. This allows reliable and efficient collision detection under different circumstance.