  A robot's mechanical parts routinely wear out from normal functioning and can
be lost to injury. For autonomous robots operating in isolated or hostile
environments, repair from a human operator is often not possible. Thus, much
work has sought to automate damage recovery in robots. However, every case
reported in the literature to date has accepted the damaged mechanical
structure as fixed, and focused on learning new ways to control it. Here we
show for the first time a robot that automatically recovers from unexpected
damage by deforming its resting mechanical structure without changing its
control policy. We found that, especially in the case of "deep insult", such as
removal of all four of the robot's legs, the damaged machine evolves shape
changes that not only recover the original level of function (locomotion) as
before, but can in fact surpass the original level of performance (speed). This
suggests that shape change, instead of control readaptation, may be a better
method to recover function after damage in some cases.
