What Is LiDAR? How Robots Use Lasers to Measure Distance.

What Is LiDAR?

LiDAR, short for Light Detection and Ranging, is a sensing technology that uses light to measure distances to objects and surfaces.

Many LiDAR systems emit laser light and measure characteristics of the returned reflections to calculate distance.

Robots use LiDAR to detect obstacles, map environments, and estimate their position.

For example, an autonomous mobile robot may use LiDAR to identify warehouse walls, shelving, and other obstacles while navigating.

Key Takeaways

• LiDAR measures distance using emitted light and detected reflections.
• It can produce two-dimensional scans or three-dimensional collections of spatial measurements.
• LiDAR is useful for navigation and mapping, but performance depends on sensor design, range, surfaces, and environmental conditions.

How Does LiDAR Work?

Imagine a mobile robot equipped with a rotating laser scanner.

The sensor emits light in different directions.

When the light reaches an object, some of it reflects back toward the sensor.

A time-of-flight LiDAR system measures the delay between transmission and reception.

Because light travels at a known speed, the sensor can estimate the distance to the object.

The robot combines many distance measurements to construct a representation of its surroundings.

Other LiDAR technologies use different measurement techniques, including phase-based or frequency-modulated approaches.

What Is a Point Cloud?

A point cloud is a collection of measured points representing locations in space.

A three-dimensional LiDAR sensor can produce points with X, Y, and Z coordinates.

For example, a point cloud from a warehouse may contain measurements corresponding to floors, walls, shelves, and equipment.

Software can use this information to identify obstacles or construct maps.

However, the point cloud does not automatically identify what each object is.

Additional perception algorithms may be needed to distinguish a worker from a storage rack.

2D LiDAR vs. 3D LiDAR

2D LiDAR commonly measures distances across one scanning plane.

It is widely used in indoor mobile robotics for navigation and obstacle sensing.

3D LiDAR measures points across a wider vertical and horizontal region, producing a three-dimensional representation.

It is useful in autonomous vehicles, surveying, and applications requiring more detailed spatial information.

The appropriate sensor depends on the environment, required coverage, and cost.

LiDAR vs. Camera

Cameras capture visual information such as color, texture, and appearance.

LiDAR measures spatial distances.

A camera may be useful for recognizing a cardboard box.

LiDAR can provide information about where surfaces are located.

Combining the two can give a robot complementary information about its surroundings.

However, neither sensor works perfectly under every condition.

What Are LiDAR's Limitations?

Reflective, transparent, dark, or otherwise difficult surfaces can affect measurements, depending on sensor technology.

Weather, dust, sunlight, and other environmental conditions can also influence performance.

LiDAR systems have specified ranges, resolutions, and fields of view.

These characteristics must be evaluated for the application.

Frequently Asked Questions

Can LiDAR work in complete darkness?

Many active LiDAR sensors can measure distance without visible environmental lighting because they emit their own light.

Does LiDAR use artificial intelligence?

The basic distance-measurement process does not require AI. AI may be used to interpret LiDAR data.

The Bottom Line

LiDAR provides robots with spatial information about nearby objects and surfaces. It is an important sensor for mapping, localization, and obstacle detection.