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Chapter 6
Summary and Future Work
6.1 Summary
Service robots with their numerous actuators and sensors on board, where each defines an own coordinate
frame, need a way to easily do coordinate transformations. Therefor robotic frameworks have to
provide methods to efficiently distribute TF Data between components and to provide a quality measurement
for a transformation. This quality measurement enables the system integrator to parametrize
the system to get the needed accuracy for a specific application.
In this work an abstract representation of component-based robotic systems and the data flow
between components which is related to transformations was introduced. This representation allows
to judge the design of existing systems and also helps to design new systems. Further, together with the
tf tree it is possible to see which component is responsible for which transformation. The examples
and the simulation in Chapter 5 showed that the proposed representation is suited to describe any
system in relation to transformations.
The quality measurement based on a 3D Gaussian normal distribution allows to describe the position
uncertainty at a point in time of a frame relative to another frame. It was shown that it is
possible to calculate the quality of one transformation but also of a transformation chain. Further the
measurement allows the system integrator to see which transformation in a chain introduces the most
uncertainty. With this knowledge counter-measures like the one presented in Section 4.4.4 can be
taken to increase the quality.
Finally the values for the Communication Object which contains the TF Data for one transformation
was presented. The CommObject ensures a clear separation of components and thus allows
reusability of them in different applications.
This work has introduced an abstract representation of component-based systems in relation to
transformations. Further it showed the benefit of using a quality measurement for transformations
which was not used in robotics until now. It puts the system integrator in a position to better understand
the system and to configure it in a way to reach the needed accuracy for an application.
6.2 Future Work
This thesis provides the fundamentals for managing coordinate frame transformations in a distributed,
component-based robot system. It showed the value of an abstract system representation and a quality
measurement for transformations.
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