Now showing 1 - 10 of 147
  • Publication
    Metadata only
    Design and Development of a Roaming Wireless Safety Emergency Stop
    Modern manufacturing is characterized by a high degree of automation, with autonomous systems also frequently being used. In such environments human intervention in the event of malfunctions or maintenance becomes a rare but also necessary task. When human workers are no longer an integral part of the production process, but only intervene when necessary, e.g., in the case of unexpected machine behavior, appropriate safety solutions will become even more important. This work describes a wireless communication system enabling a flexible and safe emergency stop function for multiple automation cells. A portable emergency stop switch allows seamless transition between different wireless cells, ensuring functional safety. The communication protocol combines IO-Link Wireless features with the safety requirements already implemented in IO-Link Safety. Security requirements are fulfilled through encryption and authentication. The IO-Link Wireless roaming functionality is used to extend the system across several manufacturing cells. An experimental setup confirms the suitability of the system for various applications. The results demonstrate the effectiveness of the handover mechanism and evaluate the potential of the system to improve flexibility, availability and security in dynamic production environments. Future extensions could include the use of AI based evaluation of the radio signals for an intelligent cell handover.
  • Publication
    Open Access
  • Publication
    Open Access
    Contribution to IO-Link Wireless Safety – Architecture and System Extensions
    (Universitätsbibliothek der HSU / UniBwH, 2024-02) ; ;
    Helmut-Schmidt-Universität / Universität der Bundeswehr Hamburg
    ;
    Schiller, Frank
    Functional safety systems protect humans and equipment from hazards while machines or humans perform automation processes. Therefore, the systematic and safe design of functional safety protocols and systems together with appropriate safety management and maintenance concepts is critical and must follow quality standards. In the field of production automation, IO-Link Wireless (IOLW) offers energy-efficient and cost-effective solutions for wireless sensors/actuator communication close to the machines on the industrial shop-floor. In case of safety applications within IO-Link (IOL), currently only a wired extension of a functional safety protocol, called IO-Link Safety (IOLS), exists. Thus, the applied safety features in IOLS are not sufficient for a safety extension of IOLW. Therefore, a safety concept proposal to enhance IOLW with safety features is suggested. This proposal is realized for safety critical communication in industrial environments with performance characteristics of demanding safety integrity level (SIL) 3 requirements. As also data security is of paramount importance, security-for-safety mechanisms are adopted for IOLW Safety, especially to meet the necessary criteria within the safety requirement specification (SRS) to ensure a one-to-one connection between an IOLW Master and an IOLW Device. Potential cryptographic algorithms are evaluated with respect to energy consumption and timing. Reliable and energy-efficient characteristics are crucial for a fast and secure wireless communication solution, especially for mobile safety applications. Therefore, the current consumption should not significantly increase due to implemented cryptographic algorithms. A current measurement method is designed to evaluate the current consumption for different crypto-algorithms together with an uncertainty estimation. Furthermore, a SRS is elaborated together with an authorized certification organization with a profound focus on standards (mainly IEC 61508 and IEC 61784-3) regulating the probability of dangerous failure on demand (PFD) addressed within SRSs. Also, relevant security standards (e.g., IEC 62443) involving security-for-safety for IO-Link Wireless Safety (IOLWS) are considered. The PFD is determined using probabilistic models to verify the regulations stated in the standards. Taking performance parameters into account, which are crucial for industrial manufacturing processes, a safety process data unit (SPDU) is designed and certified by the authorized safety organization for different payload lengths and cycle times. This is necessary, because for various applications safety devices require different payload lengths. Therefore, measurements for different payload lengths to enable various safety devices are performed to analyze cycle and processing times of the communication channels and devices. The protocol architecture, including a safety and security communication layer, is introduced including services to provide features to the application layer. A prototype implementation assures that the concept is applicable in real world with existing hardware to meet the stated requirements within the SRS. The measurements demonstrate feasibility of the concept and its assumptions.
  • Publication
    Open Access
  • Publication
    Metadata only
    Ab initio potential energy surfaces for the O₂-O₂ system and derived thermophysical properties
    (AIP Publishing, 2023-09-14)
    New intermolecular potential energy surfaces (PESs) for the quintet, triplet, and singlet states of two rigid oxygen (O₂) molecules in their triplet ground electronic states were developed. Quintet interaction energies were obtained for 896 O₂-O₂ configurations by supermolecular coupled cluster (CC) calculations at levels up to CC with single, double, triple, and perturbative quadruple excitations [CCSDT(Q)] with unrestricted Hartree-Fock (UHF) reference wave functions. Corrections for scalar relativistic effects were calculated as well. Triplet interaction energies were obtained by combining the quintet interaction energies with accurate estimates for the differences between the quintet and triplet energies obtained at the UHF-CCSD(T) level of theory. Here, we exploited the fact that the triplet state is almost identical to the readily accessible "broken-symmetry" state, as shown by Valentin-Rodríguez et al. [J. Chem. Phys. 152, 184304 (2020)]. The singlet interaction energies were estimated from the quintet and triplet interaction energies by employing the Heisenberg Hamiltonian description of the spin splittings. The three PESs are represented analytically by site-site models with five sites per molecule and anisotropic site-site interactions. To validate the PESs, we calculated at temperatures from 55 to 2000 K the second virial coefficient using statistical thermodynamics and the shear viscosity, thermal conductivity, and self-diffusion coefficient in the dilute gas phase using the kinetic theory of molecular gases. The calculated property values are in excellent agreement with the most accurate experimental data from the literature. Therefore, we also propose new reference correlations for the investigated properties based solely on the calculated values.
  • Publication
    Metadata only
    An Analysis of Rolling Horizon Multi-Agent Path Finding in Robotic Sorting Systems
    (IEEE, 2023-09)
    Hein, Benedikt
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    ;
    Kirchheim, Alice
    The growth of parcel shipments for end-customer delivery led to the emergence of robotic sorting systems, which offer improved flexibility and cost-effectiveness compared to conveyor-based sorting systems. Controlling large fleets of mobile robots for sorting tasks remains a challenge, as it requires solving a complex multi-agent path finding problem. One possible solution is the recently introduced rolling horizon collision resolution framework, which is actively discussed in the literature. However, its configuration to suit robotic sorting systems concerning real-time capabilities and throughput is still the object of ongoing investigation. To address this research gap, this study investigates the application of the rolling horizon collision resolution framework on two types of robotic sorting systems and a parameter study is conducted to assess its potential in terms of real-time capability and sorting performance.
  • Publication
    Open Access
    Newsletter hpc.bw 02/2023
    (UB HSU, 2023-06-30) ; ;
    Preuß, Hauke
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    ; ;
    Bechelaoui, Imane
    ;
    Kolling, Alexander
  • Publication
    Metadata only
    Cross Second Virial Coefficients of the H₂O-H₂ and H₂S-H₂ Systems from First-Principles
    (2023-01-01)
    The cross second virial coefficien B₁₂ for the interactions of water (H₂O) with molecular hydrogen (H₂) and of hydrogen sulfide (H₂S) with H₂ were obtained at temperatures in the range from 150 to 2000 K from new intermolecular potential energy surfaces (PESs) for the respective molecule pairs. The PESs are based on interaction energies determined for about 12 000 configurations of each molecule pair employing different high-level quantum-chemical ab initio methods up to coupled cluster with single, double, triple, and perturbative quadruple excitations [CCSDT(Q)]. Furthermore, the interaction energies were corrected for scalar relativistic effects. Both classical and semiclassical values for B₁₂ were extracted from the PESs using the Mayer-sampling Monte Carlo approach. While our results for the H₂O-H₂ system validate the older first-principles results of Hodges et al. [J. Chem. Phys. 2004, 120, 710-720], B₁₂ for the H₂S-H₂ system was, to the best of our knowledge, hitherto neither measured experimentally nor predicted from first principles.
  • Publication
    Open Access
    Newsletter hpc.bw 01/2023
    (UB HSU, 2023-01) ;
    Mayr, Matthias
    ;
    Wangelin, Klaus
    ;
    Leinen, Willi
  • Publication
    Open Access
    Auf dem Weg zur Digitalität in Schule
    (Helmut-Schmidt-Universität / Universität der Bundeswehr Hamburg, Forschungscluster OPAL, 2023) ; ; ; ;
    Czarnojan, Izabela
    ;