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OGD precision distance sensor

Technology overview

ifm’s laser distance sensors leverage the advantages of pmd time-of-flight technology for accurate and long range distance measurement.

Light waves propagate from the laser light source. When the light bounces off the target, the phase pattern shifts and the shift is directly proportional to the distance.

Diagram of sensor using time of flight technology

This proprietary technology provides:

  • Robust detection of small reflective targets
  • Quick installation due to color and angle independence
  • Measured distance information via IO-Link

Applications

Assembly automation error proofing

What if your optical sensor could see whether a small part was missing, upside down or misaligned before it moved to the next assembly step?

The OGD Precision sensor is ideal for error proofing. The 1 mm diameter laser light spot easily detects the slightest change in part orientation.

Accurate position monitoring

What happens when the quality of your part does not meet specification? What if you could also collect the data from your machines to prove correct quality?

The OGD Precision sensor locates a miniature plastic lug to verify it is correctly positioned on the carrier before the workpiece is transferred to the next assembly station. If the lug is not positioned correctly, the distance will be off by a few millimeters. The sensor detects and signals this deviation.

Unlock sensor potential with IO-Link

Via IO-Link, the OGD family can provide:

  • Current distance to target
  • Target reflectivity
  • Device status
  • Remote parameterization

FAQs

Q. Why is error proofing important in manufacturing?

A. Error proofing ensures the quality of products leaving a manufacturing plant. The sooner defects are found, the less expensive it is to fix. The image below is a representation of the escalating cost of defects the further they go into the assembly process.

Q. How is error proofing accomplished?

A. There are three general methods for error proofing:

  1. Single point solutions – high accuracy lasers, background suppression sensors, distance measurement
  2. 2D vision systems – most expensive and highest cost
  3. Manual checks – least effective due to labor costs and inconsistency

Manual checks are decreasing over time and the single point solutions increasing over time.

Q. How does PMD time-of-flight technology compare to other single point solutions for distance measurement?

A. Standard background suppression sensors are lower-cost alternatives, but they can rapidly lose accuracy as sensing distance increases. Ultrasonic sensors are also lower-cost, but they can be negatively affected by background noise, ambient temperature and target size. Traditional time-of-flight sensors can be more accurate, but that accuracy comes at a higher cost and typically in a larger housing.

Q. Why can I only set the set point in the programming menu and not the reset point?

A. The difference between the set and reset points is known as hysteresis. It keeps the output stable if the measured value varies around the set point. The OGD sensors have a fixed hysteresis that depends on the reflectivity of the background and it is shown on the datasheet. For black backgrounds, the hysteresis is approximately 5 mm and for white backgrounds, it is approximately 3 mm.