The variety of applications where Jep is employed never fail to
amaze us. We recently interviewed Stefan Windt from the Technical
University in Braunschweig, Germany on how the Lions
Racing Team is using Jep in their race car telemetry system.
The team participates in the annual international engineering contest
Formula Student. Last
year, they won the Most Innovative use of Electronics award at the
Formula Student Germany event. And with their new car, the LR07,
they are determined to keep up the pace with a sophisticated telemetry
system which processes and reports vehicle sensor data to a set
of remote devices.
What does the telemetry system do?
"The telemetry system consists of three parts. The server
component in the car transmits the acquired sensor data to a central
base station at the edge of the race track. This base station
is the interface between the clients and the race car. It handles
the data synchronization and communication with the car, data
distribution to the clients and also holds all configuration information
used by the clients."
What role does Jep play in your software?
"From the beginning, we wanted to build a highly flexible
system that covers all possible cases that may occur. Even if
somebody has a new requirement regarding data analysis, it should
be possible to realize this by configuration - not by coding.
The easiest way to be most flexible seemed to be using formulas
that any user can define on their on. Even at runtime. We are
now able to calculate complex sensor data and map the relations
between sensors and data sources without having hard-coded any
Why are you using Java rather than another language?
"One goal of the team was, to provide access to archived
data for later analysis over the Internet. Because the Internet
root servers are mostly Linux based systems, we decided to choose
Java. So we can use the base software to run in race and Internet
mode. This saved us from developing a second server program.
Other reasons were a possible client port to mobile devices,
the easy communication between the base and clients using object
streams, and last but not least: the many established libraries
and tools that saved us a lot of work."
Why are you using Jep rather than some other software?
"During the planning and design phase, we encountered, that
the use of simple equations is not sufficient. We needed something
that can also handle variables, strings and customized functions
within formulas. Another criteria was an effective evaluation
to view live data with low latency and have a low CPU load for
longer battery life time of our laptops while testing the car."
Which Jep features are you using?
default functions, predefined constants and Boolean operators
were already a very good basis. But we needed to define several
additional functions for accessing raw data, sensors, characteristic
maps, car statics and so on. Therefore it sometimes was necessary
to process a varying number of arguments or have not only numeric
values as a result of the equation. Jep made it possible! It was
very easy to integrate and customize Jep to match our requirements."
We say "Toi toi toi!" - good luck - to the German team
in this year's events and for the years ahead!