Follow-up analysis of mobile robot failures

Mobile robot reliability must be guaranteed before they can be employed in hazardous domains like mine clearing or nuclear waste handling, but recent studies of robots used in urban search and rescue and military scenarios have shown a mean time between failures (MTBF) in the field of 6 to 20 hours. This paper extends previous work characterizing robot failures by including recent data and organizing failures according to a novel taxonomy , which includes human failures. Failure type and frequency data were collected from 15 robots representing three manufacturers and seven models over a period of three years, in a variety of environments. Standard manufacturing measures for product reliability were used. The results show that overall MTBF and availability have improved since the previous analysis but are still low. The MTBF across all robot types was 24 hours and availability was 54%. The control system was the most common source of failures (32%), followed by the mechanical platform. Statistical analysis shows that the time between failures, time to repair, and downtime vary widely. For this reason the means reported here are not reliable predictors for future failures, but still provide information on the overall frequency and consequences of mobile robot failures.