Synchronization redundancy

The relative scheduling formulation provides a theoretical basis for analyzing redundancy in the synchronization of a given operation. Using synchronization redundancy can reduce the size of the corresponding control circuit, and algorithms are presented to remove all redundancies in a schedule. 

The chapter is organized as follows. We describe the criterion that will drive the control optimization in Section 9.1. We then present the concept of synchronization redundancy in Section 9.2, and show how they can be used to reduce the control cost Finally, we present in Section 9.3 a technique called control synchronization that introduces redundancies by lengthening and serializing the constraint graph hardware model. 

From the previous section, we see that synchronization redundancies can be used to reduce the conffol cost Since redundant anchors do not affect the start... 

A recent development uses the quadratic synchronous transit approach to get close to a transition state, and then a Newton or eigenvector-following algorithm to complete the optimization. It performs optimizations in redundant internal coordinates. The key reference is due to Peng, Ayala and Schlegel. 

In order to increase availability redundant subsystems may be deployed. The redundant controllers may work in l-out-of-Z principle (or dual cross wired) comprise two subsystems of identical design. They could be kept electrically isolated from one another, and are synchronized over fiber-optic cables. In the event of a fault, there should be a bumpless transfer from the active subsystem to the backup subsystem. Though it is possible to keep two subsystems but in the same rack, or spatially it is better to keep them apart so that in case of fire both systems may not be lost. 

Triple redundant system In a triple redundant system, there will be three processors operating synchronously. In addition to error detection and... 

Moreover, clock synchronization algorithms are typically master-slave such as Chrony [12], frequently without master redundancy, which makes them sensitive to single point failures. Conversely, Adaptive TDMA is fully distributed and thus resilient by nature to the failure of any of its nodes. 

Removing redundant anchors - It is often the case that not all anchors in the anchor set are needed to compute the start time of an operation. This is due to the cascading effect of anchors that make some redundant in computing the start time. For a well-posed graph, we identify and remove the redundant anchors. Through redundancy removal, it is possible to obtain a smaller and faster control implementation because the start time depends on fewer offsets, and hence fewer synchronizations. 

The part of first group the management of commucation serial line protocol is. Standardized communication protocol is a precondition for a stable and resilient communication between devices. Communication between BluesenseAD and the computer is executed on a arrhythmic seridl line in the both directions, that means duplex. Type of transmission is commonly referred as asynchronous but the correct name is arrhythmical because between the facilities there is some synchronization in the form of special marks at the beginning and end of the frame. [6] For the detection of communication errors cyclic redundancy sum CRC (Cyclic Redundancy Check) is used which even allows, in some cases, to correct transmission error [7]. 

Another option might have been the implementation of a triple modular redundant [4] (TMR, fault masking structural redundancy) system with robust majority voting schemes at the actuators. Such systems can be built either with synchronously running processor units and distributed local code/data memories, or asynchronously running processor units with local access to code and shared access to triple redundant data memories. The complexity and hardware demand of such a system architecture is so high, however, that this idea had to be rejected for technical reasons (mass, volume, harness, power consumption, etc.). 

In relative scheduling, the start time of an operation is defined as time offsets with respect to the completion of anchors. Constraints are feasible or well-posed depending on whether they can be satisfied under restricted or general input conditions, respectively. Redundancy of anchors was introduced to simplify the start time of operations by removing redundant anchor dependencies. This can lead to a more efficient control implementation because operations need to be synchronized to a fewer number of signals. Analysis of these properties was presented in this chapter. 

The irredundant anchor set IR v) of a vmex v is the minimum set of synchronizing points affecting the activation of v. In Figure 9.1(b) the irredundant anchor sets are IR v) = 6 and IR b) = a. The proof stating the equivalence of start times computed with and without the redundant anchors is given in Chapter 6. 

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