For those who operate a robotic forklift around a factory, manipulate a mechanical arm on an assembly line or guide a remote-controlled laser scalpel inside a patient, the ability to pinpoint exactly where their instrument is in three-dimensional (3D) space is critical.

To make that measurement more reliable, a public-private team led by the National Institute of Standards and Technology (NIST) has created a new standard test method to evaluate how well an optical tracking system can define an object’s position and orientation—known as its “pose”—with six degrees of freedom: up/down, right/left, forward/backward, pitch, yaw and roll.

The ability to pinpoint precisely where the tip of a robotic arm is in three-dimensional space is critical in such arenas as remote-controlled surgery. Image credit: U.S. Army/ Robert T. Shields. Optical tracking systems work on a principle similar to the stereoscopic vision of a human: a person’s two eyes work together to simultaneously take in their surroundings and tell the brain exactly where all of the people and objects within that space are located. In an optical tracking system, the “eyes” consist of two or more cameras that record the room and are partnered with beam emitters that bounce a signal—infrared, laser or LIDAR—off objects in the area. With both data sources feeding into a computer, the room and its contents can be virtually recreated.

Determining the pose of an object is relatively easy if it doesn’t move, and previous performance tests for optical tracking systems relied solely on static measurements. However, for systems such as those used to pilot automated guided vehicle forklifts, that isn’t good enough. Their “vision” must be 20/20 for both stationary and moving objects to ensure they work efficiently and safely.

To address this need, a recently approved ASTM International standard (ASTM E3064-16) now provides a standard test method for evaluating the performance of optical tracking systems that measure pose in six degrees of freedom for static—and for the first time, dynamic—objects. According to NIST electronics engineer Roger Bostelman, the new standard can evaluate the ability of an optical tracking system to locate things in 3D space with unprecedented accuracy: the margin of error is 0.02 millimeters for assessing static performance and 0.2 millimeters for dynamic performance.