HYDAC at hand to ensure mobile machinery toes the line.
Oftentimes mobile machinery needs to operate around high voltage power lines or near structures that can be dangerous such as buildings or log stacks if they’re knocked over, as examples.
This is according to HYDAC Automation and Control Engineer Christopher Michaels.
This has often seen the imposition of limitations on mobile equipment such as excavators and diggers.
“These impositions include a height limiting system or a rotation limiting system to limit yaw,” Mr Michaels says.
He points out that often HYDAC’s customers provide an aftermarket solution for end-users who want to instal limited movement on mobile machines.
“What’ll they do,” Mr Michaels queries.
“First, they’ll have an inclinometer such as our HIT 1500 to measure angle and calculate height, and that is one of HYDAC’s supply points.
“Some customers may use rotary encoders and equipment on the turret for these purposes – equipment which HYDAC doesn’t supply.
HYDAC does stock rotary encoders – the HAT series – that are best suited to OEMs that can design a rotary encoder into their system.
“But for the height side, HYDAC supplies the inclinometer that, depending on the angle of the inclinometer, provides a signal reading to the controller,” Mr Michaels says.
“And now just recently, we've also started supplying a controller and screen for ease of integration with the already supplied inclinometers.”
Inclinometer modus operandi
Mr Michaels explains that usually the inclinometer is mounted on the excavator or digger’s boom.
“This means that as the boom begins to incline, the signal out of the inclinometer will start to increase relative to the angle of the boom, which will be seen by the controller,” he says.
“In the controller there is usually a program that defines the height limitations and compares that to the signal of the inclinometer.
“Other factors are also taken into consideration such as temperature, oil and flow, but for the purposes of the article simplification is called for to avoid unnecessary complication.”
Controller halts movement for safety
Mr Michaels says the controller looks at the inclination signal and compares it to a limit: if the angle is 20° and the limit set in the PLC is 25°, the height limiting system will not intrude and the machine remains free to move.
“But as the angle of the boom is increased – imagine the operator pulling the joystick and the boom starting to rise – it begins to reach the limit defined in the controller, at which point the controller cuts out movement.
“At that point, the controller will no longer allow the movement of the boom in that direction, to which the only other direction is down and away.”
Red flag alerts when need be
Mr Michaels highlights that, generally, some warning signals will come to the fore such as a buzzer that goes off or a light that flashes.
“The new 5” screen being supplied in this instance is being used to display warning graphics, similar to what you may see with parking sensors in your car,” he says.
“It’s a basic but effective system: the inclinator alerts the controller, which is the brain. It looks at the sensor signal and decides whether the operator is still within operating tolerance, and from there decides if it needs to limit the machine’s movement.
“While all the decision making is happening inside the controller, the screen is there to visually display information to the operator.”
Other information can usually be displayed on the screen such as basic machine operating speed, ground speed, temperature, and engine revolutions per minute.
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