Performance analysis of software architectures with real-time kernel patches for the Rescue Robot

This paper introduces software architectures of the Rescue Robot that lifts and moves wounded soldiers in battle fields or hospitals. Since the Rescue Robot interacts with humans, the robot needs a real-time operation for human safety. Moreover, it is necessary that a large number of calculations and various sensing data to move the soldiers without any damages. One of challenging problems of designing the robot software architecture is that a large number of calculations and data would disturb to decrease a response time taken until robot reacting from user's commands or emergency sensing data. The Rescue Robot uses Linux with real-time kernel patches as a real-time operating system and EtherCAT as a real-time network. We test three kinds of software architectures, Linux, Xenomai, and RTAI, for the Rescue Robots about the time taken until output commands are sent to joint motors just after the sensing data or input commands are delivered. Furthermore, we suggest a method to handle urgent commands or data quickly with a slightly modified kernel and a kernel module that reduces the time dramatically. This paper also analysis the difference of the real-time kernel patches.