Joystick Neutral Region Control for Smooth Hydraulic Actuator Stops
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Solution Overview
Problem
Existing control systems for work vehicles, such as compact wheel loaders, using open centre directional solenoid valves result in unpredictable movement rates of booms and implements due to motor rotational speed, leading to rough stops and material loss when the joystick is quickly released, causing operator discomfort and vibrations.
Innovation Solution
A control method that applies a predetermined first-order filter to the driving current of open centre directional solenoid valves based on joystick position information to achieve a smooth stop when the joystick is released to the neutral region, ensuring a controlled and continuous reduction of the driving current to zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open centre directional solenoid valves are used to control hydraulic actuators, then device complexity is reduced and cost is lowered, but the flow rate becomes dependent on pump inlet flow and motor rotational speed, causing unpredictable movement rates
Solution Approach 1:
The control system continuously monitors the actual movement rate of the boom and implement through sensors and feedback signals, comparing it with the desired rate, and dynamically adjusts the solenoid valve opening degree to compensate for variations caused by motor speed changes, thereby maintaining predictable and controllable movement rates
Solution Approach 2:
The system dynamically changes the opening degree parameter of the solenoid valve based on real-time operating conditions, particularly motor rotational speed, to maintain consistent flow rate characteristics and predictable actuator movement rates across varying operational states
2Productivity
If the joystick is quickly released to the neutral region, then the operator can rapidly change control commands, but the boom and implement experience rough stops causing material loss and operator discomfort
Solution Approach 1:
The control system detects when the joystick is being released toward the neutral region and preemptively activates damping control, gradually reducing the solenoid valve opening degree to cushion the impending stop, thereby preventing rough halts and associated vibrations while maintaining rapid responsiveness to operator intent
Solution Approach 2:
The control system dynamically adjusts the solenoid valve opening degree in real-time based on joystick position and movement rate, transitioning from full opening during active movement to gradual closure during release, thereby adapting the hydraulic flow characteristics to prevent rough stops while maintaining operational responsiveness
3Object-affected harmful factors
If a predetermined first-order filter is applied to the driving current of solenoid valves, then the stop smoothness is improved and vibrations are reduced, but the response time of the system increases
Solution Approach 1:
The control system dynamically adapts the filter characteristics based on operational context, applying stronger filtering during release phases to prevent rough stops while maintaining more responsive behavior during active control phases, thereby balancing smoothness and response time according to real-time needs
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 method enhances the controllability and comfort of the operator by ensuring a smooth operation of the boom and implement, reducing the risk of material loss and vibrations during joystick release, thereby improving user experience and operational efficiency.
Implementation Method 1
applying a predetermined first order filter to a driving current of the open centre directional valve so as to control the driving current to reach zero with a derivative over time reaching with continuity a zero value
Data Source
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AI summary
A control method for actuating a soft stop movement of at least one of a boom and an implement connected to the boom in a work vehicle is disclosed. Actuating the boom and the implement occurs by means of a joystick controlled by a user, a movement of the joystick in a predetermined control area according to a first preset direction causing the actuation of the boom by a first hydraulic actuator and a movement of the joystick in the control area according to a second preset direction causing the actuation of the implement by a second hydraulic actuator. Each hydraulic actuator includes a respective open centre directional solenoid valve whose opening degree is controlled by means of a driving current as a function of a the position of the joystick. The control method comprises detecting a travel of the joystick from a driving region to a predetermined neutral region, measuring a neutral time in which the joystick position is continuously inside the neutral region, and if the neutral time is greater than a predetermined threshold of time, controlling the driving current so that it reaches zero with a derivative over time reaching with continuity a value which is lower than a predetermined rate threshold value.