Capstan Winch Torque Control for Cable Slippage
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Solution Overview
Problem
Capstan winches experience cable slippage due to wear and adverse conditions, leading to reduced traction efficiency and motor wear, and existing solutions complicate the system with additional devices and permanent torque regulation.
Innovation Solution
A method where the storage drum motor operates at a constant minimum torque, with an encoder measuring the storage drum's rotations to determine the cable's unwinding length, comparing it to the theoretical length, and activating mechanical brakes if a threshold is exceeded, ensuring orderly winding and safety without additional mechanical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cable speed measurement device is added to the winch input to control cable slippage, then cable grip on the capstan is improved, but device complexity increases and cable wear accelerates
Solution Approach 1:
The invention removes the cable speed measurement device from the winch input and relocates the measurement function to the storage drum end. By extracting the measurement function from the problematic location and implementing it where the storage drum rotates, the patent eliminates the need for additional components at the winch input while maintaining slippage detection capability.
Solution Approach 2:
The invention replaces the mechanical cable speed measurement device with an electronic encoder system mounted on the storage drum. This substitution eliminates mechanical wear at the winch input by using non-contact optical or magnetic sensing to measure storage drum rotation, thereby reducing cable wear while maintaining measurement functionality.
2Reliability
If continuous torque regulation is implemented on the storage drum motor, then cable slippage is controlled, but motor wear increases and reliability decreases
Solution Approach 1:
The invention replaces continuous torque regulation with periodic or intermittent control. The storage drum motor operates at constant torque during normal operation, and only activates additional torque when slippage is detected by the encoder system. This periodic intervention maintains cable grip while minimizing unnecessary motor operation and wear.
Solution Approach 2:
The invention implements feedback control through the encoder system that monitors storage drum rotation and compares it with capstan rotation. When slippage is detected through this feedback loop, the system adjusts storage drum motor torque accordingly. This closed-loop feedback replaces continuous open-loop torque regulation, reducing motor wear while maintaining slippage control.
3Reliability
If the storage drum motor operates at high torque to prevent cable slippage, then cable grip is improved, but electrical consumption increases
Solution Approach 1:
The invention applies partial action by operating the storage drum motor at constant nominal torque rather than excessive high torque. The motor provides just enough torque to maintain cable tension and prevent slippage, without over-engineering the output. This partial action approach reduces electrical consumption while maintaining adequate cable grip.
Solution Approach 2:
The invention changes the torque parameter from variable high torque to constant nominal torque. By stabilizing the torque output at an optimal level and using feedback control to intervene only when necessary, the system maintains cable grip while minimizing energy consumption. This parameter optimization reduces electrical usage compared to continuous high-torque operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the winch operation, maintains orderly winding, and enhances safety by preventing cable slippage, while minimizing electrical consumption and wear on the storage drum motor, even under hostile conditions.
Implementation Method 1
an encoder measuring the storage drum's rotations to determine the cable's unwinding length
Implementation Method 2
activating mechanical brakes if a threshold is exceeded
Data Source
Figure 1
AI summary
This method is intended to control the operation of a capstan winch. This winch comprises: ▪ a storage drum (2) for a lifting or hauling cable (6), driven by a first electric motor (3), one end of said cable being fixed to the drum (2); ▪ a capstan (4), consisting of at least one drum around which said cable from the storage drum is wound in a plurality of turns distributed in a single layer, the other end of the cable being intended to lift or haul a load (7), said capstan drum being rotated by means of a second electric motor (5). The method consists of fixing the torque of the electric motor (3) of the storage drum (2) to a minimum and constant nominal value.