Gait synthesis for hexapod robots with a locked joint failure

Robotica ◽  
2005 ◽  
Vol 23 (6) ◽  
pp. 701-708 ◽  
Author(s):  
Jung-Min Yang
Keyword(s):  
Fault Tolerant ◽  
Static Stability ◽  
Walking Robots ◽  
Robot Kinematics ◽  
Hexapod Robot ◽  
Joint Failure ◽  
Straight Line ◽  
Gait Synthesis ◽  
Gait Study

This paper presents a strategy for generating fault-tolerant gaits of hexapod walking robots. A multi-legged robot is considered to be fault-tolerant with respect to a given failure if it is capable of continuing its walking after the occurrence of a failure, maintaining its static stability. The failure concerned in this paper is a locked joint failure for which a joint in a leg cannot move and is locked in place. The kinematic condition for the existence of fault-tolerant gaits is derived for straight-line walking of a hexapod robot on even terrain. An algorithm for generating fault-tolerant gaits is described and, especially, periodic gaits are presented for forward walking of a hexapod robot with a locked joint failure. The leg sequence and the stride length formula are analytically driven based on gait study and robot kinematics. A case study on post-failure walking of a hexapod robot with the wave gait is shown to demonstrate the applicability of the proposed method.

Fault-tolerant crab gaits and turning gaits for a hexapod robot

Robotica ◽  
2005 ◽  
Vol 24 (2) ◽  
pp. 269-270 ◽  
Author(s):  
Jung-Min Yang
Keyword(s):  
Stride Length ◽  
Fault Tolerant ◽  
Stability Margin ◽  
Hexapod Robot ◽  
Joint Failure ◽  
Gait Planning

This paper studies crab gaits and turning gaits of a hexapod robot with a locked joint failure. Due to the reduced workspace of a failed leg, fault-tolerant gaits have limitations in their mobility. Based on the principles of fault-tolerant gait planning, periodic crab gaits and turning gaits are proposed in which a hexapod robot carries out tripod walking after a locked joint failure, having a reasonable stride length and stability margin.

Fault Tolerant Gaits for a Six-Legged Robot With One Locked or Uncontrollable Failure

2014 ◽  
Author(s):  
Hui Du ◽  
Feng Gao ◽  
Yang Pan
Keyword(s):  
High Speed ◽  
Stride Length ◽  
Fault Tolerant ◽  
Legged Robots ◽  
Robot Kinematics ◽  
Legged Robot ◽  
Long Distance ◽  
Gait Study

Multi-legged robots need fault tolerant gaits if one or more legs are broken down and cannot have maintenance when in long-distance operations or hash environments. There are two common faults of robot actuations: locked and uncontrollable failure. In this paper, a novel parallel-parallel six-legged robot as our prototype has good fault tolerant capability to continue walking with a locked or uncontrollable leg. The leg sequence and the formula of the leg/body stride length are driven based on gait study and robot kinematics. Then, a continuous fault tolerant gait is proposed which enables the robot maintain high speed and stability.

RT-ZooKeeper: Taming the Recovery Latency of a Coordination Service

2021 ◽  
Vol 20 (5s) ◽  
pp. 1-22
Author(s):  
Haoran Li ◽  
Chenyang Lu ◽  
Christopher D. Gill
Keyword(s):  
Fault Tolerant ◽  
Empirical Evaluation ◽  
Distributed Applications ◽  
Edge Computing ◽  
Challenges And Opportunities ◽  
Cloud Environments ◽  
Hand Coordination ◽  
Recovery Protocols ◽  
Recovery Latency

Fault-tolerant coordination services have been widely used in distributed applications in cloud environments. Recent years have witnessed the emergence of time-sensitive applications deployed in edge computing environments, which introduces both challenges and opportunities for coordination services. On one hand, coordination services must recover from failures in a timely manner. On the other hand, edge computing employs local networked platforms that can be exploited to achieve timely recovery. In this work, we first identify the limitations of the leader election and recovery protocols underlying Apache ZooKeeper, the prevailing open-source coordination service. To reduce recovery latency from leader failures, we then design RT-Zookeeper with a set of novel features including a fast-convergence election protocol, a quorum channel notification mechanism, and a distributed epoch persistence protocol. We have implemented RT-Zookeeper based on ZooKeeper version 3.5.8. Empirical evaluation shows that RT-ZooKeeper achieves 91% reduction in maximum recovery latency in comparison to ZooKeeper. Furthermore, a case study demonstrates that fast failure recovery in RT-ZooKeeper can benefit a common messaging service like Kafka in terms of message latency.

scholarly journals Stability-based motion planning for a modular morphing wing

2021 ◽  
Author(s):  
Michael C. F. Kwong
Keyword(s):  
Selection Process ◽  
Static Stability ◽  
Path Selection ◽  
Critical Parameters ◽  
Morphing Wing ◽  
Wing Geometry ◽  
Variable Geometry Truss ◽  
Different Levels ◽  
Longitudinal Static Stability

Aircraft wing geometry morphing is a technology that has seen recent interest due to demand for aircraft to improve aerodynamic performance for fuel saving. One proposed idea to alter wing geometry is by a modular morphing wing designed through a discretization method and constructed using variable geometry truss mechanisms (VGTM). For each morphing maneuver, there are sixteen possible actuation paths for each VGTM module, and thus offering a three module morphing wing to have a total of 16(to the power of 3) permutations of actuation paths for one morphing maneuver. Focused on longitudinal static stability, critical parameters and aircraft stability theory, this thesis proposes a method to find an optimal actuation path for a designated maneuver iteratively. A case study of a three module morphing wing demonstrated the actuation path selection process. Numerically, different actuation paths had different levels of longitudinal static stability; these paths were drawn in CATIA and were visually verified.

scholarly journals Planning Fail-Safe Trajectories for Space Robotic Arms

2021 ◽  
Vol 8 ◽  
Author(s):  
Oliver Porges ◽  
Daniel Leidner ◽  
Máximo A. Roa
Keyword(s):  
Degrees Of Freedom ◽  
Fault Tolerant ◽  
Robotic Manipulators ◽  
Task Completion ◽  
Joint Failure ◽  
Space Applications ◽  
Robotic Arms ◽  
Hazardous Environments ◽  
Potential Risks ◽  
Fail Safe

A frequent concern for robot manipulators deployed in dangerous and hazardous environments for humans is the reliability of task executions in the event of a joint failure. A redundant robotic manipulator can be used to mitigate the risk and guarantee a post-failure task completion, which is critical for instance for space applications. This paper describes methods to analyze potential risks due to a joint failure, and introduces tools for fault-tolerant task design and path planning for robotic manipulators. The presented methods are based on off-line precomputed workspace models. The methods are general enough to cope with robots with any type of joint (revolute or prismatic) and any number of degrees of freedom, and might include arbitrarily shaped obstacles in the process, without resorting to simplified models. Application examples illustrate the potential of the approach.

Reconfigurable Fault Tolerant PID Networked Control for Magnetic Levitation Case Study

2007 ◽  
pp. 1085-1090
Author(s):  
P Quiñones-Reyes ◽  
H Benítez-Pérez ◽  
E Mendez-Monroy ◽  
F Cárdenas-Flores ◽  
F García-Nocetti
Keyword(s):  
Magnetic Levitation ◽  
Fault Tolerant ◽  
Networked Control

Improving Dependability of Robotics Systems, Experience from Application of Fault Tree Synthesis to Analysis of Transport Systems

2015 ◽  
Vol 3 (2) ◽  
pp. 38-62 ◽  
Author(s):  
Nidhal Mahmud
Keyword(s):  
Electric Vehicles ◽  
Fault Tolerant ◽  
Fault Tree ◽  
Fault Tree Analysis ◽  
Transport Systems ◽  
Sequential Dependencies ◽  
Novel Approach ◽  
Assessment Techniques ◽  
Tree Synthesis

The use of robotics systems is increasingly widespread and spans a variety of application areas. From manufacturing, to surgeries, to chemical, these systems can be required to perform difficult, dangerous and critical tasks. The nature of such tasks 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, there is still a lack of adjustment methods that can efficiently cope with the sequential dependencies among the components of such systems. In this paper, the authors first introduce some relevant techniques to analyze the dependability of robotics systems. Thereafter, an experience from research projects such as MAENAD (European automotive project investigating development of dependable Fully Electric Vehicles) is presented; emphasis is put on a novel approach to synthesizing fault trees from the components and that is suitable for modern high-technology robotics. Finally, the benefits of the approach are highlighted by using a fault-tolerant case study.

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