Flexible Low-Level Control Software Framework for Achieving Critical Real-Time Deadlines

Abstract

In this work, a low-level software framework is proposed to simplify software development for Hardware Abstract Layered (HAL) control systems, identify networking methods for accurate real-time communication between devices, and verify task completion. The framework is implemented on a distributed microcontroller system composed of Texas Instruments TM4C123GXL Tivas for a multi-joint robot. The robot’s high-level controller executes dynamic motion control algorithms, with low-level controllers responsible for each individual joint. All microcontroller software is unified into one program and uses initialization files from the high-level controller to configure each individual Tiva depending on its location on the robot. The EtherCAT communication protocol is utilized to avoid unnecessary overhead from traditional networking protocols. A real-time operating system, TI-RTOS, enforces crucial deadlines and provides powerful diagnostic tools for the designer to optimize task completion. Overall, our proposed framework overcomes the major challenges of writing low-level control software so that development is less time-consuming, simpler to manage, and easier to validate. Further, this work can be used for many kinds of robotic systems and applications that use microcontrollers within a multi-layered control architecture.