Industrial Truck Drawbar Speed Control via Steering Angle
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Solution Overview
Problem
Industrial trucks with tiller-steered systems experience unsafe operating conditions due to abrupt speed changes during steering, especially at high speeds and large steering angles, leading to jerky braking and acceleration, which can be hazardous, especially in confined spaces.
Innovation Solution
A transitional area is introduced between the maximum and reduced speed ranges of the tiller's pivoting angles, where the maximum driving speed is continuously adjusted based on the tiller's swivel position, ensuring no sudden acceleration or deceleration by reducing speed in proportion to the steering angle, thereby enhancing operational safety and ergonomics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maximum driving speed is reduced to a fixed value when a specific steering angle is exceeded, then operational safety is improved, but abrupt braking and acceleration occur during speed transitions, leading to annoying operating behavior and dangerous conditions
Solution Approach 1:
The patent applies dynamics by making the maximum driving speed variable rather than fixed. The control device continuously adjusts the maximum driving speed based on the current steering angle, creating a dynamic speed profile that adapts to the operator's steering inputs. This eliminates abrupt speed transitions while maintaining safety limits, as the speed changes smoothly in proportion to the steering angle changes.
Solution Approach 2:
The patent implements parameter changes by modifying the maximum driving speed parameter as a function of the steering angle parameter. When the steering angle increases beyond a threshold, the control device proportionally reduces the maximum driving speed parameter, creating a continuous relationship between steering input and speed limit. This prevents sudden braking or acceleration while maintaining operational safety.
2Reliability
If the maximum driving speed is reduced to a fixed value at large steering angles, then cornering behavior and operational safety are improved, but sudden deceleration occurs during steering, causing jerky braking
Solution Approach 1:
The patent applies dynamics by implementing a dynamic speed adjustment mechanism that responds continuously to steering angle changes. Rather than applying a fixed speed reduction at a threshold angle, the system dynamically calculates and applies speed reductions proportional to the rate and magnitude of steering angle changes, ensuring smooth deceleration without jerky braking.
Solution Approach 2:
The patent applies preliminary action by anticipating speed adjustments before abrupt steering movements complete. The control device monitors steering angle in real-time and begins reducing maximum driving speed progressively as the steering angle approaches critical thresholds, preventing sudden deceleration by preparing the speed transition in advance.
3Reliability
If the maximum driving speed is reduced to a fixed value when the tiller is deflected, then safety is improved, but sudden acceleration occurs when the tiller returns to straight-ahead position, creating dangerous operating conditions
Solution Approach 1:
The patent applies dynamics by implementing bidirectional speed control that responds to both steering angle increases and decreases. As the tiller returns toward the straight-ahead position, the control device dynamically increases the maximum driving speed parameter proportionally, preventing sudden acceleration while maintaining safety. This creates a smooth, continuous speed profile throughout the entire steering cycle.
Data Source
Figure 1
Figure 2
AI summary
The truck (1) has a drawbar (8), where maximum driving speed (Vmax) of truck is controllable depending on a pivoting angle (alpha) of drawbar around a vertical axis (7). The truck is drivable with the maximum driving speed and a reduced limit speed (V1) in respective pivot regions (S1, S2). A transition region (S3) is formed between the pivot regions, where the maximum driving speed is continuously changeable with the pivoting angle of the drawbar in the transition region. The limit speed in the one of the pivot regions (S2) is 0.33 times of the maximum driving speed in the other pivot region.