UC Berkeley

The single greatest difference between biological organisms and human technologies today is perhaps robustness. Robustness is broadly defined as a system's ability to maintain performance despite disturbances. Qualitatively, a complex system may be called robust if it exhibits some or all of the following properties - multi-functionality, fault tolerance, damage resistance, modularity and redundancy. However, even the best engineering approaches that have attempted to consider some of these aspects find themselves 'fragile', slow and computationally intensive. On the other hand, I contend that biological systems are truly robust and capable of a plethora of complex activities such as locomotion, reproduction, respiration etc. In addition, animals constantly overcome challenges of growth and perform self-repair and learning, still a challenge for even the best engineered systems today. Using the cockroach as my model organism, I have investigated the role of exoskeletons in enabling robust high-speed locomotor behavior in cockroaches. Specifically, I have discovered that the cockroach exoskeleton

(1) is effective at dealing with external loads/impulses through body reconfiguration,

(2) facilitates (or enhances) rapid horizontal to vertical transitions during high-speed running, and

(3) compensates for damage (loss of appendages (or its parts)) undergoing a limited decrement in high-speed running performance.

Based on the impressive locomotion performance by cockroaches despite perturbations, internal and external to the animals, we propose that robustness is a crucial measure of the effectiveness of a system's performance.