Resource: LEGO® Robots

When the Mars rover Opportunity trundled into a foot-high sand dune and became bogged down for weeks on the Red Planet early in 2005, someone on the crew of the Mars Exploration Rover Mission must have thought, "If we could just pick it up and move it, this nightmare would be over." Of course, the distance between Earth and Mars — more than 50 million kilometers (31 million miles) at any given time — made such an easy fix impossible. Instead, Opportunity's Earth-bound operators drove the rover to safety over five painstaking weeks.

Clearly, programming a robot to travel on the surface of another planet is infinitely more complex and risky than programming one to navigate an obstacle course in a LEGO® competition. Nevertheless, the two processes have much in common. In fact, although Earth-based operators can direct Opportunity and its twin rover Spirit at any time, the rovers often operate autonomously. The Mars rovers, like the LEGO® robots in this video segment, rely essentially on prior computer programming to navigate their respective landscapes.

Even before the rovers touched down on the Martian surface, they relied on computer programming and a vast array of cameras and sensors to guide them to a safe landing. Radar and visual cameras monitored the descent of each rover and, in the case of Spirit, automatically triggered a rocket that slowed the horizontal movement and ensured the rover's relatively soft touchdown.

Once on the surface of Mars, Spirit and Opportunity have operated autonomously for more than one-third of the total distance they have traveled. In this mode, operators give each rover a destination, and the rover determines the best way to get there. Using images from stereo cameras, the rover creates a 3-D representation of the surrounding terrain and analyzes it for hazards, such as large rocks, rough terrain, and steep slopes. Using this information, the rover plots the safest and shortest route between its current location and its assigned destination.

Although the Mars rovers' autonomous navigation system is far more complex than the one in the LEGO® robots, engineers who designed the Mars system used a similar process to develop it. Before the rovers were launched, engineers considered each potential challenge and used the design process to develop a solution. They researched and brainstormed ideas for solutions, created designs from those ideas, tested their designs, evaluated their designs' performance, and refined the designs based on the evaluation. In much the same way, the ZOOM team worked together to find a solution for each challenge on the LEGO® course. However, just as the Mars crew overlooked the hazard of the Martian sand dune, the ZOOM team could not have predicted a runaway rover that would thwart their mission in the LEGO® tournament.

To learn more about the Mars rovers, Spirit and Opportunity, check out Mars Dead or Alive: A Hostile Environment and Anatomy of a Rover.

To learn more about robots that are designed to operate autonomously, check out Kismet and Robot Race.