Graduation Year


Document Type




Degree Granting Department

Computer Science

Major Professor

Robin Murphy, Ph.D.

Committee Member

Kimon Valavanis, Ph.D.

Committee Member

Dewey Rundus, Ph.D.


fault tolerance, robotics, reliability analysis, meta-study, field work


The considerable risk to human life associated with modern military operations in urban terrain (MOUT) and urban search and rescue (USAR) has led professionals in these domains to explore the use of robots to improve safety. Recent studies on mobile robot use in the field have shown a noticeable lack of reliability in real field conditions. Improving mobile robot reliability for applications such as USAR and MOUT requires an understanding of how mobile robots fail in field environments.

This paper provides a detailed investigation of how ground-based mobile robots fail in the field. Forty-four representative examples of failures from 13 studies of mobile robot reliability in the USAR and MOUT domains are gathered, examined, and classified. A novel taxonomy sufficient to cover any failure a ground-based mobile robot may encounter in the field is presented. This classification scheme draws from established standards in the dependability computing [30] and human-computer interaction [40] communities, as well as recent work [6] in the robotics domain. Both physical failures (failures within the robotic system) and human failures are considered.

Overall robot reliability in field environments is low with between 6 and 20 hours mean time between failures (MTBF), depending on the criteria used to determine if a failure has occurred. Common issues with existing platforms appear to be the following: unstable control systems, chassis and effectors designed and tested for a narrow range of environmental conditions, limited wireless communication range in urban environments, and insufficient wireless bandwidth. Effectors and the control system are the most common sources of physical failures. Of the human failures examined, slips are more common than mistakes. Two-thirds of the failures examined in [6] and [7] could be repaired in the field. Failures which resulted in the suspension of the robot's task until the repair was completed are also more common with 94% of the failures reported in [13].