Integration of ROS and RT tasks using message pipe mechanism on Xenomai for telepresence robot

A promising approach integrating non-real-time (NRT) robot operating system (ROS) packages and RT tasks is proposed to enhance the development of RT robot control applications. Since ROS alone does not provide RT properties essential for achieving precise control period in manipulating multiple devices and complicated software, Xenomai, an RT extension of Linux is adapted. However, using NRT ROS packages inside RT tasks triggers mode switching that causes inability to satisfy critical temporal constraints. To address this issue, a message pipe mechanism termed cross-domain datagram protocol (XDDP) is applied. In comparison to traditional inter-task mechanisms, XDDP provides a communication interface between RT and NRT tasks. This greatly improves robot application development utilising ROS tools and packages with RT tasks on the Xenomai domain ensuring priority-based scheduling and deterministic response in a multitasking environment. Feasibility of the proposed method was validated for practical use by realisation on the open embedded controller for a telepresence robot. Experiments were conducted to actuate the mobile base of the robot using ROS navigation packages. The results indicate that the robot accomplishes its objectives while satisfying RT constraints.