Fault tolerance criteria and walking capability analysis of a novel parallel-parallel hexapod break walking robot

Robotica ◽  
2014 ◽  
Vol 34 (3) ◽  
pp. 619-633 ◽  
Author(s):  
Yang Pan ◽  
Feng Gao ◽  
Hui Du
Keyword(s):  
Fault Tolerance ◽  
Parallel Mechanism ◽  
Fault Tolerant ◽  
Legged Robots ◽  
Harsh Environments ◽  
Walking Robot ◽  
Passive Joint ◽  
Actuation System ◽  
Capability Analysis ◽  
Simulation Results

SUMMARYFault tolerance is a very important issue for legged robots, especially in some harsh environments. One of the most fragile parts is the actuation system. There are two common faults of robot actuators: (1) the motor is locked and could not move anymore; (2) the motor is uncontrollable and can be treated as a passive joint. In this paper, we first discuss all fault combinations of a single leg of a hexapod walking robot with parallel-parallel mechanism topology. Then, the leg tolerable criterion is brought out, which defines whether a leg is fault tolerant. After that, the fault tolerance of the whole robot is researched, and we found that the robot can walk with one tolerable leg or two opposite tolerable legs. Finally, relative simulation results are given, which show the robot walk with one or two broken legs.

scholarly journals System Control In Fault And Normal Conditions Case Study - Quanser SRV-02

2015 ◽  
Vol 67 (1) ◽  
pp. 133-138
Author(s):  
Ionut Cristian Resceanu ◽  
Cristina Floriana Resceanu
Keyword(s):  
Fault Tolerance ◽  
Theoretical Analysis ◽  
Control Method ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Control Law ◽  
System Control ◽  
Sensor Fault ◽  
Simulation Results

Abstract A fault tolerant control method is proposed for Quanser SRV-02 System in order to maintain the required performance in the presence of sensor failures. The proposed approach integrates control law and a sensor fault tolerance schema. Theoretical analysis and simulation results have confirmed the effectiveness of the proposed method.

scholarly journals A Methodology to Analyze the Fault Tolerance of Demosaicking Methods against Memory Single Event Functional Interrupts (SEFIs)

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1619
Author(s):  
Luis Alberto Aranda ◽  
Alfonso Sánchez-Macián ◽  
Juan Antonio Maestro
Keyword(s):  
Fault Tolerance ◽  
Fault Tolerant ◽  
Soft Errors ◽  
Normal Operation ◽  
Harsh Environments ◽  
Single Event ◽  
Electronic Circuits ◽  
Memory Chip ◽  
Interpolation Algorithms ◽  
Rgb Images

Electronic circuits in harsh environments, such as space, are affected by soft errors produced by radiation. A single event functional interrupt (SEFI) can affect the behavior of a memory chip, with one or more rows, columns or even the whole device producing a wrong value when reading a set of stored bits. This problem may affect raw Bayer images stored in satellites and other spacecraft. In this paper, we present a methodology to analyze how different interpolation algorithms behave when they try to reconstruct the affected Bayer images into standard red, green and blue (RGB) images. This methodology can be used to compare and develop new fault-tolerant algorithms. The proposed methodology has been illustrated by studying a subset of interpolation algorithms. The results obtained from this example show that the interpolation algorithms that traditionally offer better results in a normal operation (in the absence of errors) are not always the best when SEFI errors are present in the Bayer images.

Fault tolerance properties and motion planning of a six-legged robot with multiple faults

Robotica ◽  
2016 ◽  
Vol 35 (6) ◽  
pp. 1397-1414 ◽  
Author(s):  
Hui Du ◽  
Feng Gao
Keyword(s):  
Fault Tolerance ◽  
Motion Planning ◽  
Full Advantage ◽  
Screw Theory ◽  
Fault Tolerant ◽  
Legged Robots ◽  
Legged Robot ◽  
Multiple Faults ◽  
Real Effects ◽  
Nuclear Disaster

SUMMARYThe six-legged robot Octopus is designed for nuclear disaster relief missions. When the robot suffers from failures, its performance can be significantly affected. Thus, fault tolerance is essential for walking and operating in environments inaccessible to humans. The current fault-tolerant gaits for legged robots usually either initially lock the entire broken leg or just abandon the broken leg, but then fail to take full advantage of the normal actuators on the broken leg and add extra constraints. As the number of broken legs increases, the robot will no longer be able to walk using the existing fault-tolerant gaits. To solve this problem, screw theory is used for analyzing the remaining mobility after failure. Based on the analysis, a method of motion planning through fault-tolerant Jacobian matrices, which are linear, is presented. This method can enable the robot to accomplish desired movement using broken legs along with other certain concomitant motions as compensation. Finally, experiments and simulations of multiple faults demonstrate the real effects on the Octopus robot.

scholarly journals Schéma DHT hiérarchique pour la tolérance aux pannes dans les réseaux P2P-SIP

2011 ◽  
Vol Volume 14 - 2011 - Special... ◽  
Author(s):  
Ibrahima Diané ◽  
Ibrahima Niang
Keyword(s):  
Fault Tolerance ◽  
Fault Tolerant ◽  
Multimedia Applications ◽  
High Volatility ◽  
International Audience ◽  
Physical Defects ◽  
Simulation Results ◽  
P2p Overlay

International audience This paper focuses on fault tolerance of super-nodes in P2P-SIP systems. These systems are characterized by high volatility of super-nodes. Most fault-tolerant proposed solutions are only for physical defects. They do not take into consideration the timing faults that are very important for multimedia applications such as telephony. This paper proposes a timing and physical fault tolerant mechanism based on P2P overlay with two levels for P2P-SIP systems. The simulation results show that our proposition reduces mostly the nodes location latency and increases the probability to find the called nodes. Cet article met l'accent sur la tolérance aux pannes de super-noeuds dans les systèmes P2P-SIP. Ces systèmes sont caractérisés par une forte volatilité des super-noeuds. La plupart des solutions tolérant aux pannes proposées traitent des défaillances physiques et ne prennent pas en compte les défaillances temporelles qui sont aussi importantes pour des applications multimédia telle que la téléphonie. Cet article propose un mécanisme de tolérance aux pannes physiques et temporelles basé sur un réseau de recouvrement P2P à deux niveaux pour les systèmes P2P-SIP. Les résultats de simulation ont montré que notre proposition diminue considérablement la latence de localisation des noeuds ordinaires et augmente la probabilité de les retrouver.

Fault Tolerant Guidance of Under-Actuated Satellite Formation Flying Using Inter-Vehicle Coulomb Force

2019 ◽  
Vol 2 (1) ◽  
pp. 43-52
Author(s):  
Alireza Alikhani ◽  
Safa Dehghan M ◽  
Iman Shafieenejad
Keyword(s):  
Fault Tolerance ◽  
Formation Flying ◽  
Fault Tolerant ◽  
Coulomb Force ◽  
Control Law ◽  
Triangular Form ◽  
Satellite Formation Flying ◽  
Satellite Formation ◽  
Guidance Law ◽  
Tolerance Approach

In this study, satellite formation flying guidance in the presence of under actuation using inter-vehicle Coulomb force is investigated. The Coulomb forces are used to stabilize the formation flying mission. For this purpose, the charge of satellites is determined to create appropriate attraction and repulsion and also, to maintain the distance between satellites. Static Coulomb formation of satellites equations including three satellites in triangular form was developed. Furthermore, the charge value of the Coulomb propulsion system required for such formation was obtained. Considering Under actuation of one of the formation satellites, the fault-tolerance approach is proposed for achieving mission goals. Following this approach, in the first step fault-tolerant guidance law is designed. Accordingly, the obtained results show stationary formation. In the next step, tomaintain the formation shape and dimension, a fault-tolerant control law is designed.

Fault Tolerant Reliable Protocol (FTRP) Performance Evaluation in Wireless Sensor Networks: An Extensitive Study

2019 ◽  
pp. 1-36
Keyword(s):  
Wireless Sensor Networks ◽  
Fault Tolerance ◽  
Sensor Networks ◽  
Fault Tolerant ◽  
Cluster Head ◽  
Biological Data ◽  
Wireless Sensor ◽  
Delivery Ratio ◽  
Good Performer ◽  
Wide Range

Fault Tolerant Reliable Protocol (FTRP) is proposed as a novel routing protocol designed for Wireless Sensor Networks (WSNs). FTRP offers fault tolerance reliability for packet exchange and support for dynamic network changes. The key concept used is the use of node logical clustering. The protocol delegates the routing ownership to the cluster heads where fault tolerance functionality is implemented. FTRP utilizes cluster head nodes along with cluster head groups to store packets in transient. In addition, FTRP utilizes broadcast, which reduces the message overhead as compared to classical flooding mechanisms. FTRP manipulates Time to Live values for the various routing messages to control message broadcast. FTRP utilizes jitter in messages transmission to reduce the effect of synchronized node states, which in turn reduces collisions. FTRP performance has been extensively through simulations against Ad-hoc On-demand Distance Vector (AODV) and Optimized Link State (OLSR) routing protocols. Packet Delivery Ratio (PDR), Aggregate Throughput and End-to-End delay (E-2-E) had been used as performance metrics. In terms of PDR and aggregate throughput, it is found that FTRP is an excellent performer in all mobility scenarios whether the network is sparse or dense. In stationary scenarios, FTRP performed well in sparse network; however, in dense network FTRP’s performance had degraded yet in an acceptable range. This degradation is attributed to synchronized nodes states. Reliably delivering a message comes to a cost, as in terms of E-2-E. results show that FTRP is considered a good performer in all mobility scenarios where the network is sparse. In sparse stationary scenario, FTRP is considered good performer, however in dense stationary scenarios FTRP’s E-2-E is not acceptable. There are times when receiving a network message is more important than other costs such as energy or delay. That makes FTRP suitable for wide range of WSNs applications, such as military applications by monitoring soldiers’ biological data and supplies while in battlefield and battle damage assessment. FTRP can also be used in health applications in addition to wide range of geo-fencing, environmental monitoring, resource monitoring, production lines monitoring, agriculture and animals tracking. FTRP should be avoided in dense stationary deployments such as, but not limited to, scenarios where high application response is critical and life endangering such as biohazards detection or within intensive care units.

scholarly journals Fault Analysis and Non-Redundant Fault Tolerance in 3-Level Double Conversion UPS Systems Using Finite-Control-Set Model Predictive Control

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2210
Author(s):  
Luís Caseiro ◽  
André Mendes
Keyword(s):  
Fault Tolerance ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Fault Tolerant ◽  
Finite Control ◽  
Control Set ◽  
Corrective Actions ◽  
Uninterruptible Power ◽  
Hardware Reconfiguration ◽  
Redundant Fault

Fault-tolerance is critical in power electronics, especially in Uninterruptible Power Supplies, given their role in protecting critical loads. Hence, it is crucial to develop fault-tolerant techniques to improve the resilience of these systems. This paper proposes a non-redundant fault-tolerant double conversion uninterruptible power supply based on 3-level converters. The proposed solution can correct open-circuit faults in all semiconductors (IGBTs and diodes) of all converters of the system (including the DC-DC converter), ensuring full-rated post-fault operation. This technique leverages the versatility of Finite-Control-Set Model Predictive Control to implement highly specific fault correction. This type of control enables a conditional exclusion of the switching states affected by each fault, allowing the converter to avoid these states when the fault compromises their output but still use them in all other conditions. Three main types of corrective actions are used: predictive controller adaptations, hardware reconfiguration, and DC bus voltage adjustment. However, highly differentiated corrective actions are taken depending on the fault type and location, maximizing post-fault performance in each case. Faults can be corrected simultaneously in all converters, as well as some combinations of multiple faults in the same converter. Experimental results are presented demonstrating the performance of the proposed solution.

scholarly journals An FTC Design via Multiple SOGIs with Suppression of Harmonic Disturbances for Five-Phase PMSG-Based Tidal Current Applications

2021 ◽  
Vol 9 (6) ◽  
pp. 574
Author(s):  
Zhuo Liu ◽  
Tianhao Tang ◽  
Azeddine Houari ◽  
Mohamed Machmoum ◽  
Mohamed Fouad Benkhoris
Keyword(s):  
Fault Tolerance ◽  
Energy Conversion ◽  
Tidal Current ◽  
Fault Tolerant ◽  
Tidal Current Energy ◽  
Electromagnetic Forces ◽  
Model Free ◽  
Energy Conversion Systems ◽  
Power Scale ◽  
Current Energy

This paper firstly adopts a fault accommodation structure, a five-phase permanent magnet synchronous generator (PMSG) with trapezoidal back-electromagnetic forces, in order to enhance the fault tolerance of tidal current energy conversion systems. Meanwhile, a fault-tolerant control (FTC) method is proposed using multiple second-order generalized integrators (multiple SOGIs) to further improve the systematic fault tolerance. Then, additional harmonic disturbances from phase current or back-electromagnetic forces in original and Park’s frames are characterized under a single-phase open condition. Relying on a classical field-oriented vector control scheme, fault-tolerant composite controllers are then reconfigured using multiple SOGIs by compensating q-axis control commands. Finally, a real power-scale simulation setup with a gearless back-to-back tidal current energy conversion chain and a small power-scale laboratory prototype in machine side are established to comprehensively validate feasibility and fault tolerance of the proposed method. Simulation results show that the proposed method is able to suppress the main harmonic disturbances and maintain a satisfactory fault tolerance when third harmonic flux varies. Experimental results reveal that the proposed model-free fault-tolerant design is simple to implement, which contributes to better fault-tolerant behaviors, higher power quality and lower copper losses. The main advantage of the multiple SOGIs lies in convenient online implementation and efficient multi-harmonic extractions, without considering system’s model parameters. The proposed FTC design provides a model-free fault-tolerant solution to the energy harvested process of actual tidal current energy conversion systems under different working conditions.

Inverse Kinematic Solution and Dynamic Model to 3PTT Parallel Mechanism

2014 ◽  
Vol 945-949 ◽  
pp. 1421-1425
Author(s):  
Xiu Qing Hao
Keyword(s):  
Dynamic Model ◽  
Dynamic Simulation ◽  
Parallel Mechanism ◽  
Inverse Kinematic ◽  
Euler Method ◽  
Research Subject ◽  
Adams Software ◽  
Inverse Kinematic Analysis ◽  
Simulation Results ◽  
Kinematic Solution

Take typical parallel mechanism 3PTT as research subject, its inverse kinematic analysis solution was gotten. Dynamic model of the mechanism was established by Newton-Euler method, and the force and torque equations were derived. Dynamic simulation of 3PTT parallel mechanism was done by using ADAMS software, and simulation results have verified the correctness of the theoretical conclusions.

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