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.

A complete analytical solution to the inverse kinematics of the Pioneer 2 robotic arm

Robotica ◽  
2005 ◽  
Vol 23 (1) ◽  
pp. 123-129 ◽  
Author(s):  
John Q. Gan ◽  
Eimei Oyama ◽  
Eric M. Rosales ◽  
Huosheng Hu
Keyword(s):  
Analytical Solution ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Robotic Manipulators ◽  
Robotic Arm ◽  
Effective Solution ◽  
Robotic Arms ◽  
Unstructured Environment ◽  
Inverse Kinematics Problem

For robotic manipulators that are redundant or with high degrees of freedom (dof), an analytical solution to the inverse kinematics is very difficult or impossible. Pioneer 2 robotic arm (P2Arm) is a recently developed and widely used 5-dof manipulator. There is no effective solution to its inverse kinematics to date. This paper presents a first complete analytical solution to the inverse kinematics of the P2Arm, which makes it possible to control the arm to any reachable position in an unstructured environment. The strategies developed in this paper could also be useful for solving the inverse kinematics problem of other types of robotic arms.

scholarly journals Study of a Computer-Based Control System with Fault-Tolerant and Fail-Safe Behavior

2015 ◽  
Vol 13 (3-4) ◽  
pp. 34-45
Author(s):  
Mariya Hristova
Keyword(s):  
Probabilistic Models ◽  
Fault Tolerant ◽  
General Scheme ◽  
Base System ◽  
Critical Systems ◽  
Critical Technology ◽  
Previous Edition ◽  
System 2 ◽  
Software And Hardware ◽  
Fail Safe

Abstract The software and hardware of Safety Critical Systems - SCS, which control special critical technology process or operation, are subject of enhanced requirements for reliability and inadmissibility of any incorrect controlling influences (safety) after failures. This paper suggests and investigates a hybrid computerbased fail-safe/fault-tolerance FST-structure with single reservation, which has the qualities to meet these requirements. The base system 2 ∨ 2, based on which it is built, is studied in the previous edition of Information Technjlogies and Control. For derivation of probabilistic models through which to establish the efficiency of the strutucral redundancy in a fault-tolerant structure, in this paper are used the published results. Formulas are derived for the probability of failure-free operation (availability coefficient), for safe failure and for unidentified (dangerous) failure. Models are found for calculation of the enhancement of reliability and the variation of safety relative to the base system 2 ∨ 2. Subject of analysis are type software and hardware modifications of the proposed general scheme used in the practice of different companies, which manufacture and operate SCSs. It is proven that at the expense of acceptable hardware redundancy and insignificant increase of dangerous failures the probability of interruption of the operation of the FST- system and its down-time due to failure may decrease by tenths of thousands of times.

scholarly journals SOFTWARE IMPLEMENTED HARDWARE-TRANSIENT FAULTS DETECTION

2014 ◽  
pp. 26-30
Author(s):  
Goutam Kumar Saha
Keyword(s):  
Error Correction ◽  
Fault Tolerant ◽  
Low Cost ◽  
Transient Faults ◽  
Fault Tolerant System ◽  
Cost Approach ◽  
Run Time ◽  
Commodity Systems ◽  
Fail Safe ◽  
Register Error

This paper examines a software implemented self-checking technique that is capable of detecting processorregisters' hardware-transient faults. The proposed approach is intended to detect run-time transient bit-errors in memory and processor status register. Error correction is not considered here. However, this low-cost approach is intended to be adopted in commodity systems that use ordinary off-the-shelf microprocessors, for the purpose of operational faults detection towards gaining fail-safe kind of fault tolerant system.

scholarly journals Engineering the quantum-classical interface of solid-state qubits

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
David J Reilly
Keyword(s):  
Quantum Information ◽  
Solid State ◽  
Degrees Of Freedom ◽  
Technology Development ◽  
Fault Tolerant ◽  
Building Blocks ◽  
Experimental Physicist ◽  
And Mathematics ◽  
Classical Control ◽  
And Control

AbstractSpanning a range of hardware platforms, the building-blocks of quantum processors are today sufficiently advanced to begin work on scaling-up these systems into complex quantum machines. A key subsystem of all quantum machinery is the interface between the isolated qubits that encode quantum information and the classical control and readout technology needed to operate them. As few-qubit devices are combined to construct larger, fault-tolerant quantum systems in the near future, the quantum-classical interface will pose new challenges that increasingly require approaches from the engineering disciplines in combination with continued fundamental advances in physics, materials and mathematics. This review describes the subsystems comprising the quantum-classical interface from the viewpoint of an engineer, experimental physicist or student wanting to enter the field of solid-state quantum information technology. The fundamental signalling operations of readout and control are reviewed for a variety of qubit platforms, including spin systems, superconducting implementations and future devices based on topological degrees-of-freedom. New engineering opportunities for technology development at the boundary between qubits and their control hardware are identified, transversing electronics to cryogenics.

Comparison of under-actuated and fully-actuated serial robotic arms: a case study

2021 ◽  
pp. 1-13
Author(s):  
Matteo Bottin ◽  
Giulio Rosati
Keyword(s):  
Degrees Of Freedom ◽  
Simple Point ◽  
Controllable System ◽  
Robotic Arms ◽  
Passive Joint ◽  
Final Configuration ◽  
Vibration Behavior ◽  
Rotational Joint ◽  
Point To Point

Abstract Under-actuated robots are very interesting in terms of cost and weight since they can result in a state-controllable system with a number of actuators lower than the number of joints. In this paper, a comparison between an under-actuated planar 3 degrees of freedom (DOF) robot and a comparable fully-actuated 2 degrees of freedom robot is presented, mainly focusing on the performances in terms of trajectories, actuator torques, and vibrations. The under-actuated system is composed of 2 active rotational joints followed by a passive rotational joint equipped with a torsional spring. The fully-actuated robot is inertial equivalent to the under-actuated manipulator: the last link is equal to the sum of the last two links of the under-actuated system. Due to the conditions on the inertia distribution and spring placement, in a simple point-to-point movement the last passive joint starts and ends in a zero-value configuration, so the 3 DOF robot is equivalent, in terms of initial and final configuration, to the 2 DOF fully-actuated robot, thus they can be compared. Results show how while the fully actuated robot is better in terms of reliable trajectory and actuator torques, the under-actuated robot wins in flexibility and vibration behavior.

A Robotic Cell for Embedding Prefabricated Components in Extrusion-Based Additive Manufacturing

2020 ◽  
Author(s):  
Yeo Jung Yoon ◽  
Oswin G. Almeida ◽  
Aniruddha V. Shembekar ◽  
Satyandra K. Gupta
Keyword(s):  
Additive Manufacturing ◽  
Degrees Of Freedom ◽  
Robotic Manipulators ◽  
The Other ◽  
Robotic Arm ◽  
Robotic Cell ◽  
Material Extrusion ◽  
Surface Polishing ◽  
Pick And Place ◽  
6 Degrees Of Freedom

Abstract By attaching a material extrusion system to a robotic arm, we can deposit materials onto complex surfaces. Robotic manipulators can also maximize the task utility by performing other tasks such as assembly or surface polishing when they are not in use for the AM process. We present a robotic cell for embedding prefabricated components in extrusion-based AM. The robotic cell consists of two 6 degrees of freedom (DOF) robots, an extrusion system, and a gripper. One robot is used for printing a part, and the other robot takes a support role to pick and place the prefabricated component and embed it into the part being printed. After the component is embedded, AM process resumes, and the material is deposited onto the prefabricated components and previously printed layers. We illustrate the capabilities of the system by fabricating three objects.

Shape Optimization of Robotic Manipulators for Maximum Stiffness and Load Carrying Capacity

1989 ◽  
Author(s):  
S. Lamancusa ◽  
D. A. Saravanos ◽  
H. J. Sommer
Keyword(s):  
Carrying Capacity ◽  
Robotic Manipulators ◽  
Performance Criteria ◽  
Geometrical Shape ◽  
Load Carrying Capacity ◽  
Robotic Arms ◽  
Specific Strength ◽  
Specific Stiffness ◽  
Maximum Stiffness ◽  
Load Carrying

Abstract Structural optimization can result in robotic arms with significantly improved stiffness and load carrying capacity. The geometrical shape of the manipulator links can be optimized for maximum stiffness-to-weight and strength-to-weight ratios. The problem of stiffening and strengthening a manipulator is solved by optimal redistribution of the available material without increasing the total mass of the manipulator. Since manipulators are programmed to move through a range of postures, thereby creating different loading conditions on the links, a multi-posture design criteria is implemented to provide a more uniform stiffness and strength over the range of possible postures. Finite element based performance criteria are developed which facilitate the simultaneous maximization of specific stiffness and strength. Three application examples on a SCARA class arm illustrate the dramatic potential for simultaneous improvements in specific stiffness and specific strength. The significance of multiple postures on the optimal design, the merits of tapered versus straight link shapes, and the relation of maximum stiffness to maximum strength, are also examined.

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