Wheel Loader Joystick Counterforce Control With Variable Base Plate Angle
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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 when the speed reduction ratio is increased, leading to a larger motor size that complicates user-specific positioning adjustments.
Innovation Solution
A work vehicle with a hydraulic actuator, actual steering angle detecting part, operating unit, relative angle detecting part, steering control part, and position adjustment control part, where the operating unit includes a biasing part to adjust the rotation angle based on the relative rotation angle, allowing for reduced size and improved operational feel without the need for a large motor.
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 operational feel is improved
Solution Approach 1:
The patent applies dynamics by making the speed reduction ratio variable rather than fixed. The operating unit includes a rotating part that can change its rotation angle relative to the support part, and the position adjustment control part dynamically adjusts the speed reduction ratio based on the relative rotation angle. This allows the system to provide high counterforce torque when needed (at certain rotation angles) while maintaining ease of operation at other angles, resolving the contradiction between sufficient counterforce and operational ease.
2Ease of operation
If the speed reduction ratio is decreased to reduce operational counterforce, then the motor size must be increased to maintain sufficient torque, but the operation unit size is reduced
Solution Approach 1:
The patent uses a variable speed reduction mechanism where the effective speed reduction ratio changes with the rotation angle of the operating part. The position adjustment control part modifies the rotation angle of the rotating part based on the relative rotation angle between the operating part and rotating part, thereby dynamically adjusting the speed reduction ratio. This allows the system to use a smaller motor while still providing sufficient torque when needed, as the variable ratio amplifies motor torque only during specific phases of operation rather than requiring constant high torque capability.
3Power
If a large-scale motor is used to maintain sufficient torque with lower speed reduction ratio, then the motor torque is sufficient, but the operation unit becomes difficult to position for different users
Solution Approach 1:
The patent replaces a fixed-size large-scale motor with a variable speed reduction mechanism controlled by the position adjustment control part. This controller adjusts the rotation angle of the rotating part based on the relative rotation angle between the operating part and rotating part, effectively creating a variable transmission ratio system. This allows the use of a smaller motor while maintaining sufficient torque output, and the system becomes more adaptable as the variable ratio can be adjusted to suit different user needs and positions.
Solution Approach 2:
The patent changes the parameter of speed reduction ratio from a fixed value to a variable parameter that can be adjusted based on operating conditions. The position adjustment control part modifies the rotation angle of the rotating part, thereby changing the effective speed reduction ratio. This parameter change allows the system to optimize between torque output and operational ease dynamically, and enables better adaptability for different users without requiring a large-scale motor.
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 solution enables a compact operation unit with adjustable counterforce, enhancing user experience by providing the necessary operational feel without the size and positioning issues associated with large motors.
Implementation Method 1
a hydraulic actuator which changes the actual steering angle
Implementation Method 2
a biasing part which biases the operating part to a predetermined position with respect to the rotating part
Data Source
Figure 1
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AI summary
An operating unit (25) in a wheel loader (1) includes a joystick lever (51), a support part (42), a base plate (71), a biasing part (44), and a position adjusting part (45). The biasing part (44) biases the joystick lever (51) to a predetermined position with respect to the base plate (71). The position adjusting part (45) adjusts the rotation angle of the base plate (71) with respect to the support part (42). A lever absolute angle sensor (26), a base plate angle sensor (101), and a second computing part (114) detect a detection value θd_detect of a lever relative angle of the joystick lever (51) with respect to the base plate (71). A motor drive control part (110) sets a torque based on the detection value θd_detect of the lever relative angle and uses the torque to control the position adjusting part 45 based on the detection value θs_detect of the vehicle body frame angle.