SONARANGE Ultrasonic Sensors - An Overview
 

Ultrasonic sensors are mainly used in machine manufacturing and process control for distance measurement, as proximity switch or for room supervision. They work on the principle of time of flight measurement of sound. The time of flight in air (back and forth) is approx. 6ms per meter. Compared to other measuring principles ultrasound is very robust. It passes dirty environment as well, and it is reflected by almost all surfaces. Thus it is independent of material, colour and surface structure of the target to be detected.

 
 

Sonic beam at 100kHz
  Why ultrasound?

  • Independent of material, surface, colour, size

  • Works under dust, dirt, fog, bright light

  • Detects transparent and shining objects

  • Wide measuring ranges from few mm up to >6m

 
 

SNT Sensortechnik AG is a pioneer in the field of ultrasonic sensors for distance measurement. The SONARANGE ultrasonic transducers are developed and manufactured in house. They differ from other products especially through their high emitted sound power. This also enables them to detect small and moving objects.

 
 

          

Sonic beam at 200kHz
  Why SNT ultrasonic sensors?
     

  • SNT sensors have a measurably higher sound power thanks to SONARANGE transducer design and high transmitter voltage.

  • This makes the sensors more sensitive and thus they can also detect moving and small targets.

  • SNT offers a wide product range

  • SNT offers customized solutions, too

  • SNT develops ultrasonic transmitters with help of FEM simulations

 
 

 

FEM model
  Limits of ultrasonic sensors
   

  • Relatively slow (switching speed approx. 1...25Hz)

  • Exception: Ultrasonic barrier (200Hz)

  • Resolution approx. 1...2mm (due to wave length of sound)

  • Works only in air

  • Have problems with very hot or very cold targets

 
 

      

  Sonic beam at 300kHz
 

 

Some Applications
    Level measurement:

  • Level measurement in tanks and containers and in processes

  • Waste water gauge measurement

  • Monitoring liquid levels in bottling plants

  • Checking for tailbacks on conveyor belts

  • Monitoring contents of granulate hoppers on injection moulding machines

  • Distance monitoring on combine harvesters, beet lifters etc.

  • Monitoring ground clearance and distance on agriculture and construction vehicles
    Process control:
   

  • Controlling belt tension or sag

  • Sensing and signalling valve positions

  • Measuring roll diameter on reeling machines

  • Monitoring the height of stacks (charges, storehouse, assembling machines)

  • Detecting material feed

  • Detecting the feed of strip stock to blanking machines and presses

  • Detecting on plastic blow-moulding machines
    Counting / Detection:
   

  • Counting persons at sales displays or show cases

  • Access supervision at rotating doors, counters etc.

  • Door automation

  • Detecting transparent objects, foils, flat glass, bottles etc.

  • Sensing objects in robot grippers

  • Recognising full or empty pallets

  • Count and detect objects with 'difficult' surface

  • Detect wrong parts on conveyors

  • Collision protection on vehicles
    Scanning of dimensions:
   

  • Determining the dimensions of packages

  • Sensing the height of plants in automated green houses

  • Measuring the volume of tree-trunks

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