Reconfiguration Commands Research Articles

A Reconfigurable Modular Vehicle Control Strategy Based on an Improved Artificial Potential Field

The reconfigurable modular vehicle group can transform into different configurations according to different requirements to be competent for various tasks and scenarios and to facilitate the utilization of robots in unstructured scenarios. Efficient and effective reconfiguration strategies and path planning are essential for improving the performance of modular vehicle groups. First, a multi-sensing four-wheel-drive Mecanum vehicle was built, which was equipped with UWB positioning (based on wireless carrier communication technology), communication based on ESP8266 modules, ultrasonic ranging and a magnetic structure. Second, concerning the indoor storage environment, a UWB two-way bilateral ranging and positioning system was designed, and the experimental accuracy for positioning could reach ±0.1 m. Third, a path planning strategy based on the improved artificial potential field method was adopted. According to the target configuration as well as the obstacle avoidance requirements, the motion space was converted into a gravitational field and a repulsive force field, and the vector superposition of the gradients was used for the path planning of each vehicle in turn. Depending on the reconfiguration command and the connection matrix, the magnetic structure would strengthen or disconnect the vehicle group configuration. Finally, the vehicle reconfiguration from the stochastic dispersion state to the target configuration and the transition between different configurations were accomplished using the proposed strategy in both simulations and experiments.

RSCM technology for developing runtime-reconfigurable telecommunication applications

Runtime reconfiguration is a fundamental requirement of many telecommunication applications which also has been addressed by management standards like CMIP, 3GPP TS 32.602, and NETCONF. Two basic commands considered by these standards are CREATE and DELETE which operate on managed objects inside an application. The available configuration management technologies, like JMX, OSGi, and Fractal, do not support the CREATE and DELETE reconfiguration commands of the telecommunication standards. In this paper, we introduce a novel technology, called RSCM, for development of runtime reconfigurable applications complying with the telecommunication standards. The RSCM subagent takes the responsibility of loading the application from the configuration file, executing the runtime reconfiguration commands (including CREATE and DELETE), enforcing validity of the configuration state, and updating the configuration file according to the latest reconfiguration commands. We exploit the modular and object oriented features of the XML technology for storing the configuration state of a program in a configuration file. The software development process is tailored such that the design of XML schemas of managed classes is performed parallel to the design of software classes. In addition, a novel programming approach based on indirect referencing is proposed which allows safe and almost immediate deletion of managed objects at runtime. This indirect referencing mechanism affects the implementation of associations in class diagrams and prevents methods of a class to use the “this” pointer freely. The RSCM technology has been successfully used in several commercial telecommunication applications; including an SMS service center, an SMS gateway, and an SMS hub.

Two-stage time-optimal formation reconfiguration strategy

A time-optimal reconfiguration strategy for formation flying of autonomous acceleration-controlled agents is presented. In the proposed strategy, the agents are moved to a special designated formation in the time interval between the completion of the mission in the current formation and the issuance of the next reconfiguration command. It is shown that the problem of finding the special designated formation which minimizes the expected value of the reconfiguration time is nonconvex. This optimization problem is treated for two cases of constrained acceleration, and constrained acceleration and velocity. It is shown that in both cases, the search space for finding the special designated formation can be reduced to a convex compact set. An alternative search algorithm is presented for the second case, which consists of searching a vicinity of possible formations, and solving a convex nondifferentiable optimization problem. This search algorithm is typically much faster than the one concerning the acceleration constraint only. The effectiveness of the proposed strategy is illustrated by simulation.

Two-dimensional magnetic micro-module reconfigurations based on inter-modular interactions

We present a scheme of two-dimensional module reconfiguration based on interactions between microscale magnetic modules with potential applications in micro-robotics, particularly in automatic micro-fabrication, non-invasive diagnoses, micro-surgery, and drug delivery at unreachable sites. The approach taken is a mixture of a top-down engineering approach and a bottom-up self-assembly approach, where reconfiguration commands are delivered from outside the workspace in the form of a magnetic field, which directs configuration changes in the set of modules by changing the strengths of individual magnetic moments. The magnetic modules in the study, 750μm in size, are constrained to a liquid surface, providing a simplified two degrees of freedom translational motion environment, where the laterally interacting inter-module magnetic force determines the assembly configuration. In this way, the relative distance of the magnets simply reflects the strength of the interactions, and thus easily enables the design of the system’s reconfiguration scenario. Reconfiguration occurs when the magnetic attractive forces are changed. To direct the assembly morphology in a controlled manner, the modules are addressed magnetically by incorporating a different magnetic material into each module type, each with different magnetic hysteresis characteristics. For addressing different modules’ magnetizations, we incorporate three different magnetic materials that feature different magnetic coercivities. This allows for the independent control of the magnetization of each material using applied external fields of varying strength, leading to arbitrary configuration change in a three-module set and limited control over a four-module set. General cases with more than five modules are further discussed.

Two-stage energy-optimal formation reconfiguration strategy

In this paper, the concept of two-stage energy-optimal reconfiguration strategy for formation flying of autonomous agents is presented. It is desired to move the agents to a special designated formation in the idle time (the time between the completion of the current formation mission and the issuance of the next reconfiguration command), in order to minimize the expected value of the reconfiguration energy consumption. The position of each agent in the special designated formation is obtained as a function of the agent’s current position and the weighted center of gravity of the set of possible positions for that agent. It is shown that this strategy can reduce energy consumption considerably compared to conventional strategies. In the case of constrained acceleration, it is shown that the results remain the same as the unconstrained case if the reconfiguration time is sufficiently longer than its minimum possible value. The effectiveness of the proposed strategy is illustrated by simulation.

Coexistence of Dynamic Spectrum Access Based Heterogeneous Networks

This paper addresses the coexistence issue of distributed heterogeneous networks where the network nodes are cognitive radio terminals. These nodes, operating as secondary users (SUs), might interfere with primary users (PUs) who are licensed to use a given frequency band. Further, due to the lack of coordination and the dissimilarity of the radio access technologies (RATs) among these wireless nodes, they might interfere with each other. To solve this coexistence problem, we propose an architecture that enables coordination among the distributed nodes. The architecture provides coexistence solutions and sends reconfiguration commands to SU networks. As an example, time sharing is considered as a solution. Further, the time slot allocation ratios and transmit powers are parameters encapsulated in the reconfiguration commands. The performance of the proposed scheme is evaluated in terms of the coexistence between PUs and SUs, as well as the coexistence among SUs. The former addresses the interference from SUs to PUs, whereas the latter addresses the sharing of an identified spectrum opportunity among heterogeneous SU networks for achieving an efficient spectrum usage. In this study, we first introduce a new parameter named as quality of coexistence (QoC), which is defined as the ratio between the quality of SU transmissions and the negative interference to PUs. In this study we assume that the SUs have multiple antennas and employ fixed transmit power control (fixed-TPC). By using the approximation to the distribution of a weighted sum of chi-square random variables (RVs), we develop an analytical model for the time slot allocation among SU networks. Using this analytical model, we obtain the optimal time slot allocation ratios as well as transmit powers of the SU networks by maximizing the QoC. This leads to an efficient spectrum usage among SUs and a minimized negative influence to the PUs. Results show that in a particular scenario the QoC can be increased by 30%.

RecDEVS: A Comprehensive Model of Computation for Dynamically Reconfigurable Hardware Systems

This paper introduces a novel formal model of computation denoted as RecDEVS. It is targeted to the development of dynamically reconfigurable hardware systems, a domain that still misses a formal design methodology. RecDEVS supports the description of hardware reconfiguration as a native part of a system model and thus can be used as a foundation of new design methodologies. Reconfiguration is addressed by means of a small set of reconfiguration commands and a dedicated executive component. Special care has been taken to support the flexible communication network of dynamically changeable hardware structures. We describe how RecDEVS benefits from the Dynamic Structure Discrete Event Specified Systems (DSDEVS) model that has been generalized. To illustrate the feasibility of the proposed approach the implementation of RecDEVS inside on top of SystemC based simulation engine is demonstrated.

Multimodal User Input to Supervisory Control Systems: Voice-Augmented Keyboard

The use of a voice-augmented keyboard input modality is evaluated in a supervisory control application. An implementation of voice recognition technology in supervisory control is proposed: voice is used to request display pages, while the keyboard is used to input system reconfiguration commands. Twenty participants controlled GT-MSOCC, a highfidelity simulation of the operator interface to a NASA ground control system, via a workstation equipped with either a single keyboard or a voice-augmented keyboard. Experimental results showed that in all cases where significant performance differences occurred, performance with the voice-augmented keyboard modality was inferior to and had greater variance than the keyboard-only modality. These results suggest that, current moderately priced voice recognition systems are an inappropriate human-computer interaction technology in supervisory control systems.

GT-MSOCC: A Domain for Research on Human - Computer Interaction and Decision Aiding in Supervisory Control Systems

Modeling and aiding operators in supervisory control environments are necessary prerequisites to the effective use of automation in complex dynamic systems. A research program is described that explores these issues within the context of the Georgia Tech-Multisatellite Operations Control Center (GT-MSOCC). GT-MSOCC is a real-time interactive simulation of the operator interface to a NASA ground control system for unmanned Earth-orbiting satellites. GT-MSOCC is a high fidelity domain in which a range of modeling, decision aiding, and workstation design issues addressing human-computer interaction may be explored. GT-MSOCC is described in detail. The use of high-fidelity domains as research tools is also discussed, and the validity and generalizability of such results to other domains are examined. In addition to a description of GT-MSOCC, several other related parts are included. A GT-MSOCC operator function model (OFM) is presented. The GT-MSOCC model illustrates an enhancement to the general operator function modeling methodology that extends the model's utility for design applications. The proposed methodology represents operator actions as the lowest level discrete control network nodes. Actions may be cognitive or manual; operator action nodes are linked to information needs or system reconfiguration commands. Thus augmented, the operator function model provides a formal representation of operator interaction with the controlled system and serves as the foundation for subsequent theoretical and empirical research. A brief overview of experimental and methodological studies using GT-MSOCC is also given.