An Intelligent Winch for Vertical Profiling
An intelligent winch can be used to precisely position sensors and to continuously pass along their real-time data stream. Designed to be a component of a complete vertical profiling system, the winch will provide an interface to its internal computer that will accept commands instructing the system to move the instrument to a particular position and at what speed. Position can be specified by number of winch drum revolutions from a known home position (in very small increments). Additionally, if external position feedback is provided to the system (for example depth in water from an external transducer) position can be specified in the units of the external feedback. The system can be protected from malfunction by monitoring the cable tension via additional optional inputs.
The system consists of a winch drum whose diameter, length, and side flange height are determined by the turning radius and amount of electrical/lifting cable to be spooled. The drum is mounted on a frame via bearings and a hollow axle that can be turned by an electric motor from one side and has a slip ring installed on the other. The motor is sized for the expected load, geared for the desired maximum rotational speed, and has an integral position encoder. The electrical/lifting cable is specified considering the expected mechanical load as well as the number and gauge of conductors that will be required to provide power and communications to the attached instrumentation. A weather-tight box mounted to the frame includes a computer and motor controller, as well as connectors for the cable/slip ring contacts, an Ethernet connector for the internal computer interface and digital I/O ports for the high/low limit/tension inputs and manual up/down controls.
The software interface provides a simple command set to control winch movement. In the absence of optional position feedback, commands would be for up and down by a number of winch revolutions at a specified speed. Given external position feedback additional commands become available to move to a specific position or to move a specific distance. Commands are also available to provide a motor current limit and to stop the system. The system will provide feedback about position, moving speed (or stopped), motor current draw, and fault conditions including over-current, over-temperature, and high and low limit inputs.