Extending the life of legacy robots: MDS-Ach, a real-time, process based, networked, secure middleware based on the x-Ach methodology

Abstract

This work shows how to add modern tools to legacy robots while retaining the original tools and original calibration procedures/utilities through the use of a lightweight middleware connected to the communications level of the robot. MDS-Ach is a middleware made for the Xitome Mobile Dexterous Social (MDS) Robot originally released in 2008. The robot is being actively used at multiple locations including the U.S. Naval Research Laboratory's Laboratory for Autonomous Systems Research (NRL-LASR). The MDS-Ach middleware gives the MDS Robot the software capabilities of modern robot systems using the x- Ach real-time processes based architecture. It controls the MDS Robot directly over the controller area network (CAN) bus via a dedicated real-time daemon. Each process communicates with the others over a network capable shared memory. The shared memory is a "first-in-last-out" (i.e. reads the newest data first) non-head-of-line blocking ring buffer which ensures readability of latest data first while retaining the ability to retrieve the older data. When running over a network, UDP or TCP protocol can be utilized depending on the timing and reliability requirements. SSH tunneling is used when secure connections between networked controllers are required. The MDS-Ach middleware is designed to allow for simple and easy development with modern robotic tools while adding accessibility and usability to our non-hardware-focused partners. Real-time collision avoidance and a robust inverse kinematics solution are implemented within the MDS-Ach system. Examples of collision avoidance, inverse kinematics implementation, and the software architecture are given.