6 research outputs found
RobotKube: Orchestrating Large-Scale Cooperative Multi-Robot Systems with Kubernetes and ROS
Modern cyber-physical systems (CPS) such as Cooperative Intelligent Transport
Systems (C-ITS) are increasingly defined by the software which operates these
systems. In practice, microservice architectures can be employed, which may
consist of containerized microservices running in a cluster comprised of robots
and supporting infrastructure. These microservices need to be orchestrated
dynamically according to ever changing requirements posed at the system.
Additionally, these systems are embedded in DevOps processes aiming at
continually updating and upgrading both the capabilities of CPS components and
of the system as a whole. In this paper, we present RobotKube, an approach to
orchestrating containerized microservices for large-scale cooperative
multi-robot CPS based on Kubernetes. We describe how to automate the
orchestration of software across a CPS, and include the possibility to monitor
and selectively store relevant accruing data. In this context, we present two
main components of such a system: an event detector capable of, e.g.,
requesting the deployment of additional applications, and an application
manager capable of automatically configuring the required changes in the
Kubernetes cluster. By combining the widely adopted Kubernetes platform with
the Robot Operating System (ROS), we enable the use of standard tools and
practices for developing, deploying, scaling, and monitoring microservices in
C-ITS. We demonstrate and evaluate RobotKube in an exemplary and reproducible
use case that we make publicly available at
https://github.com/ika-rwth-aachen/robotkube .Comment: 7 pages, 2 figures, 2 tables; Accepted to be published as part of the
26th IEEE International Conference on Intelligent Transportation Systems
(ITSC), Bilbao, Spain, September 24-28, 202
How Thioredoxin Dissociates Its Mixed Disulfide
The dissociation mechanism of the thioredoxin (Trx) mixed disulfide complexes is unknown and has been debated for more than twenty years. Specifically, opposing arguments for the activation of the nucleophilic cysteine as a thiolate during the dissociation of the complex have been put forward. As a key model, the complex between Trx and its endogenous substrate, arsenate reductase (ArsC), was used. In this structure, a Cys29Trx-Cys89ArsC intermediate disulfide is formed by the nucleophilic attack of Cys29Trx on the exposed Cys82ArsC-Cys89ArsC in oxidized ArsC. With theoretical reactivity analysis, molecular dynamics simulations, and biochemical complex formation experiments with Cys-mutants, Trx mixed disulfide dissociation was studied. We observed that the conformational changes around the intermediate disulfide bring Cys32Trx in contact with Cys29Trx. Cys32Trx is activated for its nucleophilic attack by hydrogen bonds, and Cys32Trx is found to be more reactive than Cys82ArsC. Additionally, Cys32Trx directs its nucleophilic attack on the more susceptible Cys29Trx and not on Cys89ArsC. This multidisciplinary approach provides fresh insights into a universal thiol/disulfide exchange reaction mechanism that results in reduced substrate and oxidized Trx