Tow Bar Force Control for Self-Propelled Trailer Stability
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Solution Overview
Problem
Existing tow bar arrangements for manually or semi-manually propelled vehicles struggle to safely and efficiently manage heavy or powerful trailers, especially under varying conditions such as uphill or downhill terrain, without requiring excessive user effort or compromising safety.
Innovation Solution
A tow bar arrangement with a control device that includes a force sensor, a digital low-pass filter, and a PI or PID regulator to manage the electric motor of the trailer, ensuring the trailer counteracts the measured force, using a FIR filter with a cut-off frequency between 25% and 75% of the system's horizontal resonance frequency, and a time shift of at least 50% of the truncation length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional tow bar arrangement is used, then the structure is simple, but the control of the self-propelled trailer is poor and unsafe
Solution Approach 1:
The tow bar arrangement transitions from a static rigid connection to a dynamic system with movable components. The second tow bar is movable relative to the first tow bar, allowing the system to adapt to different towing conditions and improve control safety while maintaining structural simplicity through controlled motion rather than complex mechanisms.
Solution Approach 2:
The tow bar system is divided into multiple segments - a first rigid tow bar and a second movable tow bar - that can move independently relative to each other. This segmentation allows each component to perform specific functions (rigid connection for stability, movable connection for control) thereby improving overall control safety without requiring a completely complex new structure.
2Ease of operation
If a rigid tow bar connection is used, then the structure is stable, but the ability to control the self-propelled trailer is limited
Solution Approach 1:
The system employs a dynamic tow bar connection where the second tow bar can move relative to the first tow bar. This dynamic capability enables the operator to control the self-propelled trailer more effectively by adjusting the angle and position of the second tow bar, while the overall connection remains stable through the guided motion paths of the movable components.
3Adaptability or versatility
If the tow bar allows angular movement, then the control flexibility is improved, but the risk of unintended angular acceleration is increased
Solution Approach 1:
The system incorporates feedback mechanisms through the interaction between the movable second tow bar and the vehicle body. The geometric constraints and mechanical connections provide natural feedback that limits unintended angular acceleration while allowing controlled angle adjustments. The movable tow bar's motion is constrained by the vehicle body structure, creating a self-regulating system that adapts to towing conditions without requiring active control intervention.
Data Source
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AI summary
Tow bar arrangement (100) for interconnection of a pulling vehicle (10) and a pulled trailer (20).The arrangement (100) comprises a control device (110) with a force sensor (111) arranged to sense an instantaneous relative force between vehicle (10) and trailer (20).The control device (110) is arranged to produce a control signal for an electric motor (21) arranged to propel the trailer (20) so that a motor force counter-acts said measured force.The invention is characterised in that the control device (110) is arranged to a first time series of force measurements, in that the control device (110) comprises a low-pass filter (112) producing a second low-pass filtered time series, and in that a regulator (113) is ar-ranged to regulate said second time series to produce said control signal.