Leddar, short for LED Detection and Ranging, is a new type of detection and ranging sensor that uses LEDs to detect objects and determine their distance. While the Leddar is low resolution, it is also low cost, and it may find new applications in vehicles, traffic management, robotics and safety. Read on for our hands-on review.

Developed by Canadian firm LeddarTech, Leddar is very similar to a Lidar, or Laser Radar. Lidar uses a laser beam to measure distances by determining the amount of time that it takes a laser dot to bounce off a target. Since measuring a point is of limited value, most Lidars sweep the laser around in a circle by bouncing it off a spinning mirror. More advanced Lidars, like the Velodyne 64, use multiple laser beams and a spinning head to measure in three dimensions.

The Leddar uses diffused light from several LEDs to illuminate a scene in short pulses. The LEDs illuminate a whole area at once, instead of a spot, with multiple detectors sampling this light from various angles, all simultaneously. The sensor we were sent for evaluation had 16 detectors in an array, and covered a 90-degree area. This makes the LeddarTech sensor a type of “flash lidar."

Among the key features of this technology are:

  • Low Cost: The LeddarTech sensor evaluation kits sell for US$299, which compares favorably with sweeping laser sensors that range from several thousands up to $70,000 in price.
  • High Update Rate: The sensor samples its entire field of view 100 times a second.
  • Immune to Motion: Many Lidar sensors are subject to “motion blur” due to the sweeping nature of their lasers. The nanoseconds long pulse of the Leddar freezes all but the fastest of motions.
  • Simple Operation: The data from the Leddar sensor is designed to be easy to interpret and work with.
  • The LeddarTech was very simple to set up – driver software and an application (Windows 7 or later) that could visualize the results were included.

    In short, we found that the system works exactly as advertised. During our tests, the sensor returned accurate and stable readings from walls, doors and metal objects. Though it does have its limitations – it generally failed to see objects much below six inches (15 cm) in size at the distances I was testing (10-20 feet or 3-6 meters). Occasionally I would get dual returns (two detections from a single sensor) depending on object distance and width.

    Potential applications for the Leddar vary from an adaptive cruise control system for cars that detects the distance to cars in front and adjusts speed accordingly; safety zone monitoring for industrial machinery; a simple obstacle detection systems for ground robots – say a robot that is cutting your lawn; traffic monitoring for intelligent traffic lights; and as a perimeter fence for security.

    Given the low cost and high-update rate object detection of this sensor, I would certainly consider using it in my robotics applications for collision avoidance. More generally it also heralds the start of a trend towards lower cost detection and ranging units, and solid-state flash units in particular, that will be beneficial to emerging areas such as self-driving cars.

    The Leddar comes in a variety of packages and sizes, such as a special ruggedized model for industrial use, and a outdoor model designed for traffic monitoring.

    The LeddarTech video below provides a brief overview of the system.

    Source: LeddarTech

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