Hydraulic Steering Control Switching for Drift and Dead Band
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Solution Overview
Problem
Existing steering systems suffer from mechanical play, hydraulic dead band, and drift issues, leading to an imperfect relationship between steering input and vehicle behavior.
Innovation Solution
A hydraulic steering system incorporating both open loop and closed loop controls, with cross-over transition means that dynamically switch between these modes based on vehicle parameters and steering conditions, ensuring smooth transitions and improved precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop control is used in the hydraulic steering system, then the system structure is simple, but the steering precision and responsiveness are insufficient due to mechanical play and hydraulic dead band
Solution Approach 1:
The control system dynamically switches between open-loop and closed-loop modes based on operating conditions. The cross-over transition means enable the system to operate in open-loop mode during normal conditions for simplicity, and automatically transition to closed-loop mode when precision requirements increase, thus adapting the complexity level to actual needs
Solution Approach 2:
Cross-over transition means are introduced as intermediary components between the open-loop and closed-loop control paths. These transition means include switching valves and control circuits that smoothly transfer control authority between the two modes, eliminating abrupt transitions and ensuring continuous steering control
2Measurement precision
If closed loop control is used to improve steering precision, then the steering responsiveness and precision are improved, but the system complexity increases
Solution Approach 1:
The system employs dynamic control mode selection where closed-loop control is activated only when needed based on steering conditions, vehicle speed, and precision requirements. This dynamic approach allows the system to maintain high precision when necessary while avoiding unnecessary complexity during normal operations
Solution Approach 2:
The closed-loop control path incorporates feedback from wheel angle sensors and steering sensors to continuously monitor and adjust steering position. The feedback mechanism enables automatic correction of mechanical play and hydraulic dead band effects, improving precision without requiring permanent complex structure
3Ease of manufacture
If mechanical steering components are used, then the system is simple to manufacture, but mechanical play and drift occur affecting steering accuracy
Solution Approach 1:
The patent replaces purely mechanical steering transmission with an electro-hydraulic control system. Electric motors and hydraulic actuators substitute for mechanical linkages, eliminating mechanical play and backlash. The system maintains manufacturing feasibility by using standardized electro-hydraulic components rather than custom mechanical assemblies
Solution Approach 2:
Hydraulic fluid serves as an intermediary medium between the electric motor and the steering mechanism. The hydraulic system transmits force without rigid mechanical connections, eliminating mechanical dead band and play while maintaining smooth power transmission
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 achieves a better alignment of steering input with vehicle behavior by mitigating mechanical play and drift, enhancing steering responsiveness and precision.
Implementation Method 1
a pressure source P and control means controlling a fluid supply from the pressure source to the steering motor
Data Source
Figure 1
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AI summary
A hydraulic steering system (1) is described, the system (1) comprising a steering command device (2) having a steering sensor (3), a steering motor (6), a wheel sensor (9), a pressure source (P), and control means (12) controlling a fluid supply from the pressure source (P) to the steering motor (6), wherein the control means (12) comprise an open loop control (19). Such a steering system should have a good relationship between steering input from the operator and steering behaviour of the vehicle to be steered. To this end the control means (12) comprise in addition to the open loop control (19) a closed loop control (20), wherein cross-over transition means (21) are provided which are connected to the open loop control (19) and to the closed loop control (20) and control a transition between the open loop control (19) and the closed loop control (20).