Winch Boom Steering for Ski Slope Tracked Vehicle Yaw Control
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Solution Overview
Problem
Tracked vehicles used for preparing ski slopes experience deviations in trajectory due to yaw torque and differential track slippage, particularly on very steep slopes, which are exacerbated by the use of a winch, leading to loss of grip and ineffective correction methods.
Innovation Solution
A control device for a tracked vehicle with a boom that pivots about a pivot axis, controlled by an intuitive user interface with switches to rotate the boom in specific directions, using sensors to detect vehicle direction and adjust the boom's rotation accordingly, mitigating the effects of yaw torque and track slippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pivot axis of the boom is positioned far from the center of gravity to improve cable anchoring capability, then the winch can be more effectively used on steep slopes, but a yaw torque is generated that causes the vehicle trajectory to deviate from the desired path
Solution Approach 1:
The control system applies a counteracting steering command to the tracks before the yaw torque can significantly deviate the vehicle. When the boom is rotated to anchor the cable, the control unit preemptively adjusts track speeds to compensate for the expected yaw moment, preventing trajectory deviation rather than correcting it after occurrence.
Solution Approach 2:
The system continuously monitors the boom rotation angle and cable tension, and this information is fed back to the control unit which adjusts the track speeds in real-time. This closed-loop control ensures that any yaw torque generated by boom rotation is immediately compensated, maintaining accurate trajectory control despite the offset pivot axis position.
2Ease of operation
If differential track speeds are used to correct trajectory deviation, then the vehicle direction can be adjusted, but the correction is ineffective when one track has lost grip due to winch cable force
Solution Approach 1:
The boom acts as an intermediary element to generate corrective moments. Instead of relying on differential track speeds which fail when one track loses grip, the system rotates the boom to create a counteracting yaw torque that realigns the vehicle trajectory, providing an alternative correction mechanism that works even when track grip is compromised.
Data Source
AI summary
A tracked vehicle for preparing ski slopes has a chassis extending along a longitudinal axis; a winch mounted on the chassis; a boom pivoting about a pivot axis to guide and orientate the cable of the winch between the chassis and the cable anchor point; an actuation system for rotating the boom about the pivot axis relative to the chassis in a first and second direction; and a user interface comprising a first and a second switch arranged in front of an operator and to the right and left of each other and configured to rotate the boom so as to steer the tracked vehicle to the right and to the left respectively when the cable is anchored to the cable anchor point.