... from www.positek.com
Modern forestry logging machines are complex and sophisticated
pieces of equipment able to fell and manoeuvre trees andtrunks
efficiently. To help control the hydraulic controls on the machines,
sensors are fitted inside the hydraulic cylinders. The sensors
provide feedback on the position of the rams to the main control
system. The hydraulic cylinders are a compact design and have
very little room to house the sensor and any associated electronics.
In this application it was necessary to design the sensor with
a small space envelope in the cylinder and to use an external
electronic interface. The Positek P106 inductive position sensor
was chosen for this application because of its small size and
the compact electronic interface. Usually the P106 sensor interface
is mounted onto the body of the hydraulic ram. However, in this
particular application the main system control electronics was
mounted close to the cylinder. This meant that the Positek interface
could be installed directly into the main module.The Positek
interface is only 32mm diameter and is available as a double-sided
surface mount PCB assembly. With integral pins and a specially
moulded support ring it can be mounted directly onto the main
control circuit. This assembly is very easy to assembly and
eliminates the need for separate electronics enclosures and
the associated wiring and connectors.
In the logging industry much of the work is carried out in
the winter when temperatures can vary from -40° up to 40°C
during the working day. This is a harsh temperature cycling
routine and introduces special needs for the protection of electronics
against condensation forming during the thermal cycling.
The P106 sensor incorporates technology developed by Positek
and used in its other displacement sensor products. This PIPS®
technology is based on inductive coils and uses a unique custom
integrated circuit to produce an accurate analogue output signal.