Design a User-defined robot of your choice (or you can use the URDF file) and enable the LIDAR Scanner so that any obstacle placed on the path of the light scan will cut the light rays. Visualize the robot in the Gazebo workspace, and also show the demonstration in RViz. (NB: Gain knowledge on wiring URDF file and .launch file for enabling any user-defined robot to get launched in the gazebo platform.) SLAM : One of the most popular applications of ROS is SLAM(Simultaneous Localization and Mapping). The objective of the SLAM in mobile robotics is to construct and update the map of an unexplored environment with the help of the available sensors attached to the robot which will be used for exploring. URDF: Unified Robotics Description Format, URDF, is an XML specification used in academia and industry to model multibody systems such as robotic manipulator arms for manufacturing assembly lines and animatronic robots for amusement parks. URDF is especially popular with users of the Robo
Fault Tolerance Techniques
- Introduction
- Hardware Faults – Occurs due to a physical defect of a system like a broken wire or a logic struck at 0 in a gate.
- Software faults – occurs due to a bug introduced in a system so the software misbehaves for a given set of inputs
- Error – the manifestation of a fault is the error (Fault may occur anytime, but only the error manifests that fault)
- Fault Latency – the time between the onset of fault and its manifestation as an error is the fault latency
- Error Recovery
- Forward Error Recovery – the error is masked without any computations having to be redone.
- Backward Error Recovery - the system is rolled back to a moment in time before the error is believed to have occurred.
What Causes Failures?
There are three main causes of failures:
- Errors in the specification or design
- Mistakes in the specification and Design are very difficult to guard.
- Many hardware failures and all software failures occur due to such mistakes.
- It is difficult to ensure that the specification is completely right.
- Defects in the components
- Hardware components can develop defects.
- Wear and tear of components
- Environmental effects
- Devices can be subjected to whole array of stresses, depending on the application.
- High ambient temperatures can melt components or otherwise damage them.
Fault Types
Faults are classified according to temporal and output behavior
- Temporal behavior classification
A(t) B(t)
C(t) D(t)
- Permanent faults
- Does not die away with time, remains until it is repaired
- Ex. Broken wires
- From the above Diagram: A(t)>0; B(t) =C(t) = D(t)=0
- Intermittent Fault
- It cycles between the fault active and fault benign states.
- Eg. Caused by loose wires
- From the above Diagram: A(T)>0; B(t)>0; D(t)>0; C(t)=0
- Transient Fault
- Dies away after some time
- Ex: environmental effects
- From the above Diagram: A(t)>0; C(t)>0; B(t)=D(t)=0
- Output behavior classification
- Malicious
- Non malicious
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