Variable Deadzone Steering Control for Mobile Machines
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Solution Overview
Problem
Existing steering systems for mobile machines, such as wheel loaders and haul trucks, lack the ability to selectively implement positional and velocity-based steering strategies with the same steering input device and do not account for travel speed in modifying steering gain and deadzone, leading to limitations in operator control and stability.
Innovation Solution
A steering system that includes a steering actuator, a travel speed sensor, an operator input device with a variable deadzone, and a controller that adjusts the steering actuator's operation based on the operator input and travel speed, allowing for position or speed-based control strategies and varying the deadzone in response to machine speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed steering gain and deadzone are used regardless of travel speed, then the steering system is simple to control, but the operator control precision and stability deteriorate at different speeds
Solution Approach 1:
The patent implements dynamic adjustment of steering gain and deadzone based on machine travel speed. The controller continuously monitors travel speed and automatically modifies steering parameters in real-time, transitioning from fixed parameters to dynamically adaptive parameters. This resolves the contradiction by making the steering system responsive to operating conditions while maintaining operator control precision across different speed ranges.
Solution Approach 2:
The patent changes the parameters of steering gain and deadzone based on travel speed conditions. At low speeds, higher gain and smaller deadzone are applied for precise control, while at high speeds, lower gain and larger deadzone are applied for stability. This parameter adaptation resolves the contradiction between control precision and system complexity by using speed-based parameter switching.
2Ease of operation
If a small deadzone is used for responsive steering, then steering responsiveness is improved, but unintended steering maneuvers increase at high speeds
Solution Approach 1:
The patent dynamically changes the deadzone parameter based on travel speed. At low speeds, a small deadzone is maintained to preserve steering responsiveness and ease of operation. At high speeds, the deadzone is automatically increased to filter out minor input variations and prevent unintended steering maneuvers, thereby maintaining reliability and stability.
Solution Approach 2:
The deadzone is implemented as a dynamic parameter rather than a fixed value. The controller continuously adjusts the deadzone size according to the measured travel speed, creating a adaptive steering system that automatically optimizes the balance between responsiveness and stability for current operating conditions.
3Measurement precision
If a large steering gain is used for responsive steering, then steering precision is improved, but overcorrections and instability increase at high speeds
Solution Approach 1:
The patent implements speed-dependent steering gain adjustment. At low travel speeds, a large steering gain is applied to provide precise steering control and responsive machine behavior. At high travel speeds, the gain is automatically reduced to prevent overcorrections and maintain steering stability, resolving the contradiction between precision and stability.
Solution Approach 2:
The steering gain is implemented as a dynamic parameter that continuously adapts to travel speed conditions. The controller monitors speed and automatically modifies the gain factor, creating a smoothly transitioning steering system that maintains optimal precision-stability balance across the entire operating speed range.
4Adaptability or versatility
If separate steering systems are used for positional and velocity control, then control strategies are optimized, but device complexity increases
Solution Approach 1:
The patent implements a single unified steering control system that can operate with different control strategies (positional control, velocity control, or combinations) depending on the operating conditions. The controller selectively applies different control algorithms based on travel speed and operator input characteristics, providing strategic flexibility without requiring separate physical steering systems.
Solution Approach 2:
The control strategy itself is made dynamic, allowing the system to switch between positional control dominance at low speeds and velocity control dominance at high speeds. This dynamic strategy selection within a single system provides the adaptability of multiple systems while maintaining the simplicity of one integrated control architecture.
Data Source
AI summary
A steering system for a machine having at least one steerable traction device is disclosed. The steering system may have a steering actuator operatively connected to the at least one steerable traction device, and a travel speed sensor configured to generate a signal indicative of a travel speed of the machine. The steering mechanism may also have an operator input device having a deadzone. The deadzone may vary in response to the signal. The steering system may also have a controller in communication with the steering actuator, the operator input device, and the travel speed sensor. The controller may be configured to affect operation of the steering actuator in response to operation of the operator input device only when the operation of the operator input device deviates from the deadzone.