Mower Steering Sensor Assembly With Rotary Displacement Amplifier
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Solution Overview
Problem
Conventional mowers transitioning from hydraulic to electric drive systems face challenges in accurately detecting small movements of steering control levers due to high hysteresis and low resolution in existing rotary motion sensors, which are costly and unsuitable for the turf market.
Innovation Solution
A sensor assembly with a rotary displacement amplifier and rotary sensor is used to amplify small movements of the lap bar, utilizing a planetary gear set to increase resolution and reduce hysteresis, enabling precise control of electric motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional rotary motion sensors are used to detect lap bar movements, then the system is simpler and cheaper, but the measurement precision is insufficient due to high hysteresis and low resolution
Solution Approach 1:
A rotary displacement amplifier is introduced as an intermediary component between the lap bar and the rotary sensor. The amplifier includes a planetary gear set that mechanically amplifies small lap bar movements before they reach the sensor, enabling precise detection without requiring an overly complex high-resolution sensor
Solution Approach 2:
The patent replaces direct mechanical coupling with a mechanical amplification system. Instead of relying solely on the sensor to detect minute movements, the mechanical amplifier converts small movements into larger, more easily measurable rotations, substituting pure sensor complexity with mechanical advantage
2Measurement precision
If high-resolution rotary sensors are used to detect small movements, then measurement precision improves, but the cost increases making it unsuitable for the turf market
Solution Approach 1:
The rotary displacement amplifier serves as a cost-effective intermediary that performs the difficult work of amplification mechanically. This allows the use of a standard, lower-cost rotary sensor rather than requiring an expensive high-resolution sensor, making the system suitable for cost-sensitive turf market applications
Solution Approach 2:
The system changes the parameter being measured by amplifying the displacement before measurement. Instead of measuring small movements directly with an expensive sensor, the amplifier transforms the measurement parameter into a larger, more easily and economically measured quantity
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
The sensor assembly effectively detects and amplifies small movements of the lap bar, allowing for precise control of the mower's movement, reducing hysteresis and enhancing operational accuracy without increasing costs.
Implementation Method 1
A sensor assembly with a rotary displacement amplifier and rotary sensor is used to amplify small movements of the lap bar, utilizing a planetary gear set to increase resolution and reduce hysteresis
Data Source
AI summary
An example sensor assembly includes: a rotary displacement amplifier configured to be coupled to a lap bar of a mower and configured to amplify movement of the lap bar; and a rotary sensor comprising a sensor shaft coupled to, and rotatable by, the rotary displacement amplifier, wherein the rotary displacement amplifier is configured to transmit an amplified movement of the lap bar to the sensor shaft, and wherein the rotary sensor is configured to provide a signal indicative of a rotary position of the sensor shaft to a drive motor controller of the mower to drive an electric motor based on the signal.