Hydraulic Steering Control for Agricultural Tracked Vehicles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Agricultural vehicles, particularly tracked vehicles, face challenges in maneuverability due to high turning moments, which can lead to inefficiencies in harvest yield and steering responsiveness, especially in vehicles with caterpillar chassis.
Innovation Solution
The implementation of a power steering device with hydraulic steering motors and an electric power steering controller that regulates the rotational speeds of opposing running gear wheels to optimize trajectory following, potentially dispensing with the need for an additional hydraulic pump and utilizing a series connection of hydraulic steering motors to manage turning moments effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a caterpillar chassis is used to provide stable ground contact, then stability and weight distribution are improved, but turning moments increase significantly reducing maneuverability
Solution Approach 1:
The caterpillar chassis is divided into multiple individually controllable running gear wheels (at least two opposite wheels) that can be driven at different rotational speeds. This segmentation allows independent control of each wheel's speed, enabling the vehicle to navigate turns more effectively by creating speed differentials between opposite wheels, thereby reducing the overall turning moment while maintaining the stability benefits of the tracked chassis.
Solution Approach 2:
The rotational speed parameter of the running gear wheels is dynamically adjusted during operation. By controlling the rotational speeds of opposite running gear wheels differently, the system can modulate the turning moment in real-time, allowing for improved maneuverability and reduced turning radius while the vehicle is in motion, thus resolving the contradiction between stability and ease of operation.
2Ease of operation
If rotational speeds of opposite running gear wheels are controlled differently to reduce turning moments, then maneuverability is improved, but device complexity increases due to additional steering motors and control systems
Solution Approach 1:
The existing travel drive hydraulic motors that power the running gear wheels are made multi-functional by enabling them to perform both propulsion and steering functions. By controlling the rotational speeds of opposite wheels differently through the existing hydrostatic drive system, the patent achieves steering capability without requiring separate dedicated steering motors for each wheel, thus improving maneuverability while minimizing the increase in device complexity.
Solution Approach 2:
The travel drive system serves itself by using the same hydraulic motors to perform both driving and steering functions. The system utilizes its own existing components (hydraulic motors and control system) to achieve the additional steering capability, rather than requiring entirely separate steering mechanisms. This self-service approach reduces the overall complexity increase while still achieving improved maneuverability.
3Measurement precision
If hydraulic steering motors are added to control rotational speeds of running gear wheels, then steering precision is improved, but the need for additional hydraulic pumps increases system complexity
Solution Approach 1:
The existing main drive hydraulic pump is made multi-functional by using it to power both the travel drive motors and the steering control. The same hydraulic fluid source serves dual purposes: providing power for vehicle movement and providing controlled flow for differential steering. This eliminates the need for a separate hydraulic pump dedicated solely to steering functions, thereby improving steering precision without proportionally increasing hydraulic system complexity.
4Ease of operation
If the rear wheel axle is made steerable to improve maneuverability, then steering responsiveness is improved, but the vehicle cannot effectively compensate for high turning moments generated by the caterpillar chassis
Solution Approach 1:
The steering functions of the rear wheel axle and the caterpillar chassis are merged into a coordinated control system. By combining the steerable rear axle with differential speed control of the running gear wheels, the system creates a unified steering mechanism that works together to counteract turning moments. The rear axle steering provides responsive directional control while the differential wheel speeds on the caterpillar chassis actively compensate for and reduce the high turning moments, achieving both steering responsiveness and turning moment management simultaneously.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an agricultural vehicle with a chassis comprising at least two wheels positioned opposite each other with respect to the vehicle's longitudinal axis. The chassis includes a drive system for generating propulsion along a path and a steering system for setting a desired path curve as a function of a steering angle. It is proposed that a steering assist device is provided to support the steering system, that the steering assist device comprises at least two hydraulic steering motors, and that at least two wheels positioned opposite each other with respect to the vehicle's longitudinal axis are each driven by a hydraulic steering motor. Furthermore, the steering assist device includes an electric steering assist control unit that determines target speeds for the hydraulic steering motors from the steering angle and regulates the hydraulic steering motors to these target speeds.