Cost-Effective and Fault Tolerant Vehicle Control Architecture for X-by-Wire Systems (Part 2: Implementation Design)

Author(s):  
Kohei Sakurai ◽  
Yuichiro Morita ◽  
Kentaro Yoshimura ◽  
Nobuyasu Kanekawa ◽  
Kotaro Shimamura ◽  
...  
Author(s):  
Umakanta Mahanta ◽  
Bhabesh Chandra Mohanta ◽  
Anup Kumar Panda ◽  
Bibhu Prasad Panigrahi

Torque ripple reduction is one of the major challenges in switching table-based direct torque control (DTC) while operating for open phase faults of an induction motor, as the switching vectors are unevenly distributed. This can be minimized by increasing the level of the inverter and with the use of multi-phase motors. Fuzzy logic-based DTC is another solution to the above problem. In this paper, a comparative analysis is done between switching table-based DTC (ST-DTC) and fuzzy logic-based DTC for increasing the performance during open phase faults of a five-phase induction motor. The result shows that in fuzzy logic-based DTC with a two-level inverter, the torque ripple is reduced by 5.164% as compared with ST-DTC with a three-level inverter. The fuzzy logic-based DTC with the three-level inverter also gives better performance as compared with fuzzy logic-based DTC with the two-level inverter. The current ripple also reduced by 9.605% with respect to ST-DTC. Thus, fuzzy logic-based DTC is more suitable and cost effective for open phase fault-tolerant drives.


2021 ◽  
Author(s):  
James Gaston

The work area of a team of small robots is limited by their inability to traverse a very common obstacle: stairs. We present a complete integrated control architecture and communication strategy for a system of reconfigurable robots that can climb stairs. A modular robot design is presented which allows the robots to dynamically reconfigure to traverse certain obstacles. This thesis investigates the implementation of a system of autonomous robots which can cooperatively reconfigure themselves to collectively travers obstacle such as stairs. We present a complete behaviorand communication system which facilitates this autonomous reconfiguration. The layered behavior-based control system is fault-tolerant and extends the capabilities of a control architecture known as ALLIANCE. Behavior classes are introduced as mechanism for managing ordering dependencies and monitoring a robot's progress through a particular task. The communication system compliments the behavioral control and iimplementsinherent robot failure detection without the need for a base station or external monitor. The behavior and communication systems are validated by implementing them ona mobile robot platform synthesized specifically for this research. Experimental trials showed that the implementation of the behavior control systems was successful. The control system provided robust, fault-tolerant performance even when robots failed to perform docking tasks while recongifuring. Once the robots reconfigure to form a chain, a different control scheme based on gait control tables coordinates the individual movements of the robots. Several successful stair climbing trials were accomplished. Improvements to the mechanical design are proposed.


Author(s):  
Nidhal Mahmud

The use of robotics systems is increasingly widespread and spans a variety of application areas. From healthcare, to manufacturing, to space missions, these systems are typically conceived to perform dangerous or critical tasks. The nature of such tasks (e.g., surgery operations or radioactive waste clean-up) places high demands on the dependability of robotics systems. Fault tree analysis is among the most often used dependability assessment techniques in various domains of robotics. However, fault tree analysis of cost-effective fault tolerant robotics systems requires compositional synthesis of fault trees extended with the expressive power to allow analyzing the sequential dependencies among the components. Thereafter, a relevant experience from the automotive domain is presented. This consists mainly of a suitable synthesis approach that computes expressions of global failure conditions from the dysfunctional behavior local to the components. The benefits of the approach to dependability analysis of robotics architectures are highlighted by using a fault-tolerant example system.


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