Safety

Because the PR2 is designed as a development platform, it has to work well even when the code running on it is buggy. Robots under development can hit both objects and people in their world, and breaking the robot, the table, or the grad student isn't a good option.

The PR2 avoids the high forces, velocities, and inertia associated with traditional industrial arms through the use of a novel drive-train. The same design that can prevent it from breaking a person's arm prevents the mechanism from needing repair if it hits a table or a doorway, which is a major advantage when developing code directly on the real hardware.

The system works by using a spring counterbalance and very efficient drive-trains to get high performance from motors without big gear heads on them. This means that when the robot hits an obstacle it can just stop, minimizing the effect of the inertia of the motor from continuing to push it forward.

The safe use of a robot in close proximity to people is a considerable challenge, and is an active area of development in the robotics community. A robot like the PR2 can hurt a user in many ways. By developing a robot that is safe enough to physically interact with, we aim to support and advance research development in the area of true robot safety.