Joystick Force Control for Articulated Work Vehicle Steering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Articulated work vehicles experience sudden recoil in the operator's wrist due to mechanical displacement restrictions in the pilot valve, leading to discomfort and increased burden on the operator.
Innovation Solution
The implementation of a control system that includes a joystick lever, a control valve, a force imparting component, and a controller, which gradually increases the operating force required by the operator as the joystick approaches the restricted position, mitigating the sudden recoil by adjusting the assist force or counterforce imparted by the force imparting component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pilot valve mechanically restricts the operation amount of the joystick lever to a predetermined range, then the steering angle is controlled within safe limits, but the operator's wrist is subjected to sudden recoil causing discomfort and increased burden
Solution Approach 1:
The system applies a counterforce through the force imparting component before the joystick lever reaches the restricted position. The controller detects the approach to the limit and generates a counterforce that increases progressively, preventing the sudden recoil that would occur at the mechanical restriction point. This preliminary counter-action eliminates the harmful recoil effect while maintaining the steering angle control limit.
Solution Approach 2:
The force imparting component gradually increases the counterforce as the joystick lever approaches the restricted position, preparing the operator for the upcoming limitation. This gradual increase in counterforce allows the operator to slow down the joystick operation naturally, preventing the sudden recoil at the restriction point while still enforcing the predetermined range limit.
2Stability of the object's composition
If the joystick lever operation is restricted to a predetermined range, then the steering system maintains stability, but the operation speed becomes abrupt causing sudden recoil
Solution Approach 1:
The force imparting component dynamically adjusts the counterforce based on the real-time position of the joystick lever. As the lever approaches the restricted position, the counterforce increases progressively, creating a dynamic response that guides the operator to slow down naturally. This dynamic adjustment maintains steering system stability while smoothing the operation speed transition.
Solution Approach 2:
The controller continuously monitors the position of the joystick lever and provides feedback through the force imparting component. When the lever approaches the restricted position, the controller increases the counterforce in real-time, creating a feedback loop that informs the operator of the approaching limit and guides them to reduce operation speed gradually, preventing abrupt movements.
3Ease of operation
If a force imparting component is added to mitigate recoil, then operator comfort is improved, but the device complexity increases
Solution Approach 1:
The force imparting component serves multiple functions: it provides assist force during normal operation to reduce the effort required by the operator, and it provides counterforce when the joystick approaches the restricted position to prevent sudden recoil. This multi-functionality allows a single component to address both operator comfort and control stability without proportionally increasing system complexity.
Solution Approach 2:
The patent replaces the purely mechanical restriction system with a hybrid system that uses a force imparting component controlled by a controller. This substitution allows for more sophisticated control of the counterforce, enabling gradual increase rather than abrupt mechanical restriction, thereby improving operator comfort while maintaining control limits.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Steering cylinders (21 and 22) in a wheel loader (1) are driven hydraulically and change the steering angle (θs) of a front frame (11) with respect to rear frame (12). A pilot valve (42) is linked to a joystick lever (24) and controls the flow of fluid supplied to the steering cylinders (21 and 22) according to the rotational angle (θin) of the joystick lever (24), and restricts operation of the joystick lever (24) over an angle (θ4) of a deviation angle (α). A force imparting component (27) imparts an assist force or counterforce to operation of the joystick lever (24) by the operator. A controller (28) controls the force imparting component (27) so as to decrease the assist force or increase the counterforce before the operation of the joystick lever (24) is restricted by the pilot valve (42).