Agricultural Train Braking Control for Cornering Overrun Stability
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Solution Overview
Problem
Existing agricultural tractors with trailers face safety issues during downhill driving and cornering due to over-braking and jackknifing, which can lead to axle slip and potential damage to the drive motor, as existing control systems only account for longitudinal forces and not transverse forces at the coupling point.
Innovation Solution
A control device in the tractor adjusts the braking systems of both the tractor and trailer based on detected steering angles and operating parameters, calculating a correction factor to account for both longitudinal and transverse forces at the coupling point, thereby preventing critical driving situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the driving speed is reduced by adjusting engine speed and transmission ratio, then the deceleration is achieved, but the entire mass is decelerated by the tractor's drive axle causing over-braking and increased slip
Solution Approach 1:
The braking function is segmented between the tractor's drive axle and the trailer's braking system. The control device activates the trailer's braking system independently to share the deceleration load, preventing over-braking of the tractor's drive axle and reducing slip risk.
2Speed
If deceleration is generated solely by the drag torque of the drive motor, then speed control is achieved, but the drive motor over-revves and may be damaged
Solution Approach 1:
The trailer's braking system acts as an intermediary to share the deceleration burden. By activating the trailer brakes during overrun operation, the mechanical load on the drive motor is reduced, preventing over-revving and potential damage while maintaining speed control.
3Measurement precision
If the coupling force is determined solely from transmission and drive motor parameters, then the longitudinal force component is detected, but the trailer's braking system is controlled using incomplete parameters
Solution Approach 1:
The force detection is extended from one dimension (longitudinal) to two dimensions by incorporating steering angle data. The control device calculates both longitudinal and transverse force components at the coupling point using the steering angle, enabling accurate determination of the total coupling force magnitude for proper braking control.
4Stability of the object's composition
If the tractor corners with a jackknifed train, then the forces at the coupling point are distributed, but the existing control system cannot detect the actual coupling force
Solution Approach 1:
The control device uses steering angle feedback to continuously calculate and update the coupling force magnitude during cornering operations. This feedback mechanism allows the system to adapt the braking control in real-time based on the actual jackknifed configuration, ensuring accurate force compensation even when the train is cornering.
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3
AI summary
The present invention relates to an agricultural train (10) comprising a tractor (12) as a towing vehicle, which is driven by a drive motor (22) cooperating with a continuously variable transmission (24) and has a first braking system (32), and at least one trailer (14) coupled to the tractor (12) at a coupling point (72), which has a second braking system (34), wherein the tractor (12) has a control device (42) for controlling at least one braking system (32, 34) of the agricultural train (10), which is designed and configured for actuating at least one of the braking systems (32, 34) of the train (10) depending on a determined overrun operation of the train (10) and/or towing vehicle (12), wherein the control device (42) is configured to determine the presence of an overrun operation depending on at least one operating parameter of the transmission (24) and/or the drive motor (22), characterized in thatthat the control device (42) is configured to calculate a correction factor (K) as a function of a steering angle (αsteering) detected during a push-pull operation in order to correct a coupling force (Fcoupling,x) determined from the at least one operating parameter at the coupling point (72) taking into account the steering angle (αsteering).