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Photodetectors are devices capable of recognizing photons at frequencies ranging from the far-infrared end of the electromagnetic spectrum to the gamma-ray end. These devices are quite ubiquitous and can be found in everything from supermarket doors to TV remote controls and smartphone cameras.
Photodetectors also allow for a wide range of possibilities in the field of robotics. The following is a short list of ways that photodetectors are being used in this arena.
Photodetectors for Security Monitoring
For years, stationary photodetectors have been used for security monitoring, with the most common application being infrared motion detectors for indoor security systems.
With the dawn of mobile security drones and robots, photodetectors have opened up a whole new world of data collection for security purposes. For now, security robots aren’t able to adequately replace a human security guard. They simply supplement what human security officers are capable of doing.
The fundamental function of these robots is advanced surveillance; collecting information like license plate images and facial recognition scans. With IR vision abilities and substantial processing power, these robots offer a type of constant, low-level and highly detailed surveillance that a human just cannot perform.
Using Photodetectors for Process Control
There are numerous ways photodetectors in a machine vision system can be used to control mechanical production processes. A standard camera can be used to identify parts lying stationary on a surface or moving on a conveyor for a robotic system that picks or moves these items. Or, photodetectors can be used to conduct a 3D scan of a surface in search of parts.
In many situations, robotic process control systems only require something as basic as position sensors to verify that an item is in the right place or to supply some kind of feedback on a process. However, some systems need a precise comparison of radiation at multiple different wavelengths. In recycling facilities, for instance, the differing fluorescence of plastics can be used to sort robotically, while other spectroscopic systems can make a distinction among various kinds of glass.
Increasingly, machine vision systems are being included in highly flexible production robots. Pick and Place applications require a robot to be capable of identifying an item based on its appearance and pick it up. Some robotic conveyor systems require a machine vision system to identify when and where a target item has arrived at a predetermined location.
IR Photodetectors in the Defense Industry
Without a doubt, the greatest drivers of robotic innovation have been potential defense applications. For decades, militaries have used IR photodetectors in heat-seeking missiles. The development of decoys like magnesium flares has then led to the creation of more advanced detection systems that can differentiate between decoys and real targets. Militaries have also used IR cameras for night vision and more recently to detect land mines.
In 2017, the US Department of Defense launched Project Maven, an initiative to leverage artificial intelligence to classify and analyze massive amounts of surveillance video. The project has been working on AI software that can flag people, vehicles, and objects of interest.
How are Photodetectors used in Self-Driving Cars?
While autonomous car systems are still largely in the testing phase, they will not be possible without photodetectors. A self-driving car has to be able to navigate traffic, identify traffic signs and identify pedestrians. All of this requires a sophisticated photodetection system and a massive amount of computing power.
As part of the development process, autonomous cars must be “trained” through countless hours of driving; so that they can recognize key navigation indicators and potential collision hazards to a level of consistency that makes them safe for operation on our roads.
References and Further Reading
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