When hard realtime matters: Software for complex mechatronic systems

Abstract

Abstract-A still growing number of software concepts and framworks have been proposed to meet the challenges in the development of more and more complex robotic systems, like humanoids or networked robotics. The issue of hard realtime, however, has not been the main focus of such concepts, but is essential for building and controlling mechatronic systems. Here we discuss the specific demands of complex mechatronic systems and present a software concept, the "agile Robot Development" (aRD) concept, we developed at our institute. We show that the performance of current computing and communication hardware allows for a flexible component based concept with distributed execution even in hard realtime with rates in the kHz range.

EMG-based teleoperation and manipulation with the DLR LWR-III

“…The low-level robot controller runs on a VxWorks realtime machine at a rate of 1kHz. Communication between the two layers is realised via the ARDNet Interface [17]. The core component of the Robot Control kernel is the Cartesian Impedance Controller (CIC) which receives a desired Cartesian frame as input and calculates the desired joint torques (further details on this control scheme can be found in [12]).…”

Catching flying balls and preparing coffee: Humanoid Rollin'Justin performs dynamic and sensitive tasks

“…The head joints are controlled to keep the balls in the cameras' field of view. All software components communicate in hard realtime by means of the institute's aRD (agile Robot Development) software framework [9]. this scheme also for highly dynamic tasks 1 , in addition the software has to thoroughly keep track of all timings in the sub-millisecond range.…”

Kinematically optimal catching a flying ball with a hand-arm-system

“…4) has to provide distributed computational resources while meeting hard realtime constraints for the parallel planning as well as the robot controllers. For the communication between the software components running on the diverse computers we use the aRD (agile robot development) software concept [12], which we especially developed for applications with complex mechatronic components with high computational demands under hard realtime constraints. By using Gigabit Ethernet connections a worst case delay of < 1ms even for transmitting the largest data packets in the system (the arm movement path for the 7 joint angles) with a size of 64KByte could be achieved.…”