A TTP-Based Measuring System
The objective of the project A TTP-Based Measuring System is to
demonstrate the suitability of a time-triggered architecture as a basis for
a closed loop measuring system that serves as a test environment for
Electronic Control Units (ECUs). The main task of the project is to build a
prototype of the measuring system based on TTP.
The proposed system, besides providing all the features that are available
with currently used test equipment, adds numerous benefits that can only be
provided by a time-triggered architecture, in which the bus access scheme
(the message schedule) is planned beforehand.
The main benefits are:
-
Composability:
-
A measuring system is composed of a number of "instruments" that consist of
a node computer and peripherals like sensors in our system. In a
time-triggered architecture each of these instruments can be designed and
tested autonomously. The integration of a set of instruments on one
communication channel does not lead to any side-effects, because the
temporal sequence of the bus access is determined and validated a
priori.
-
Globally Timestamped Measurement Values:
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TTP provides a globally synchronized timebase to all members of the system.
Thus it is possible to timestamp measured values, which enables
chronological ordering of values or determination of phase relations among
values.
-
Data Transmission with Bounded Latency:
-
Considering the deterministic bus access scheme the latency that measured data
experiences from the point in time it is sampled to the point in time it
is available at the receiver is bounded. A given maximum latency constraint
is taken into account by the configuration software.
In comparison to a centralized measuring system a distributed solution
offers a scalable amount of computation power. The processors of the
remote nodes that basically control the measuring equipment can be used to
pre- or postprocess data as well. Thus the amount of data that has to be
transferred on the bus can be reduced significantly and the computer
controlling the measurement process can be relieved of these data
preparations.
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