Joystick Steering Unit Positioning Without Large Counterforce Motors
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Solution Overview
Problem
In steer-by-wire systems using a joystick lever, achieving sufficient counterforce torque is challenging due to increased operational counterforce with higher speed reduction ratios, leading to larger motor sizes that complicate user-specific positioning of the operation unit.
Innovation Solution
A work vehicle design incorporating a hydraulic actuator, actual steering angle detection, an operating unit with a support and biasing mechanism, and a position adjustment control system to manage the steering operation, reducing the size of the operation unit by eliminating the need for large motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the speed reduction ratio is increased to produce sufficient counterforce torque, then the counterforce becomes too large when operating the joystick lever, but the counterforce is necessary for operational feel
Solution Approach 1:
The patent replaces the traditional mechanical speed reducer with a motor-driven system. The motor generates the necessary counterforce torque through electromagnetic forces, eliminating the need for mechanical gear reduction. This allows precise control of counterforce while avoiding the excessive friction and cogging torque inherent in mechanical speed reducers.
Solution Approach 2:
The patent changes the operational parameters of the motor to dynamically adjust the counterforce. By controlling motor current and torque output, the system can provide appropriate counterforce during normal operation while minimizing resistance when the operator intends to move the joystick. This parameter control resolves the contradiction between needing counterforce for operational feel and avoiding excessive counterforce for ease of operation.
2Power
If a large-scale motor is used to provide sufficient torque without speed reducer, then the operation unit increases in size, but the operation unit size needs to be reduced for better positioning adaptability
Solution Approach 1:
The patent eliminates the mechanical speed reducer and uses a motor with direct drive capability. The motor's electromagnetic torque provides the necessary force without requiring mechanical multiplication, allowing for a more compact operation unit design that can be positioned adaptively for different users.
Solution Approach 2:
The motor serves multiple functions: it provides the necessary torque for steering control, generates operational counterforce for feedback, and enables compact sizing of the operation unit. This multi-functionality allows the system to achieve high power output without increasing the physical size of the operation unit, improving adaptability to different user body types.
3Ease of operation
If the speed reduction ratio is reduced to lower operational counterforce, then a large-scale motor is required, but large motors increase operation unit size and reduce positioning flexibility
Solution Approach 1:
The patent dynamically controls motor parameters (current, voltage, torque) to provide the exact amount of force needed for each operating condition. This parameter control allows the motor to deliver high torque when necessary while maintaining low operational counterforce during normal joystick manipulation, eliminating the need for either high speed reduction ratios or large motor sizes.
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 system effectively reduces the size of the operation unit while maintaining operational feel through a biasing mechanism, allowing for precise positioning and efficient steering control without the need for large motors, thus enhancing user experience and operational efficiency.
Implementation Method 1
a hydraulic actuator that changes an actual steering angle
Implementation Method 2
a biasing part that biases the operating part to a predetermined position with respect to the rotating part
Data Source
AI summary
A work vehicle includes a hydraulic actuator that changes an actual steering angle, an actual steering angle detecting part, an operating unit that performs a steering operation, a position adjusting control part that controls the position adjusting part based on the actual steering angle, and a steering control part that controls the hydraulic actuator. The operating unit includes a support part, a rotating part supported rotatably by the support part, an operating part supported rotatably by the support part or the rotating part, a biasing part that biases the operating part to a predetermined position with respect to the rotating part, a position adjusting part that adjusts a rotation angle of the rotating part with respect to the support part, and a rotation angle detecting part configured to detect the rotation angle of the operating part with respect to the support part or the rotating part.