Modern robotics is heavily invested in computer vision systems that aim to let automatons understand the world around them. A project from MIT researchers eschews all that with the Cheetah 3, a robot that has no visual sensors whatsoever. In spite of that, it can maneuver around obstacles, jump on tables, and walk up stairs. The team believes this approach could be less expensive and more effective than complex visual analysis systems that can be easily fooled.
As the name implies, the quadrupedal Cheetah 3 is an improved version of an older robot called Cheetah 2. In addition to having more refined software algorithms, the new robot is more flexible with a greater range of motion. As a result, it can do some impressive things like running at high speed across varying terrain. You’ve probably seen several robots do that in the past, but the difference is Cheetah 3 can’t see what it’s doing — it can only feel what it’s doing.
Cheetah 3 blindly gropes around the world using two algorithms developed by MIT engineers. There’s a contact detection algorithm that helps the robot determine the best time for each of its four legs to commit to a step. For example, if the robot steps on something flexible that can interfere with its balance, it might choose to pull back. A solid surface that seems safe will trigger Cheetah 3 to place its weight on that foot and carry on.
Once the robot commits to take a step with the contact detection algorithm, it’s up to the second “model-predictive control algorithm” to decide how much force the leg should apply. If the leg doesn’t apply the right amount of force, the body won’t move correctly in the desired direction. That can cause the robot can slip or fall over. The model-predictive control algorithm calculates multiple positions for the robot’s legs and body half a second in the future, and chooses the right amount of force to keep the robot moving correctly.
All of this enables the Cheetah 3 to do advanced, life-like things. You probably remember all those videos of Boston Dynamics engineers shoving robots around. Well, Cheetah 3 can withstand the same kind of harassment. It can also walk up stairs that are strewn with small blocks that would trip up lesser robots. It does all this without seeing anything ahead of time.
The team plans to present the Cheetah 3 at a robotics conference later this year. They believe this approach to building robotic locomotion will work in more situations and environments where visual sensors may not work. Nothing precludes future versions of the Cheetah from having cameras, but they won’t be necessary for basic features like coping with obstacles in its path.