Onboard Computing

Multiplex Twinstar in autonomous flight



ROCS - Design and Characteristics

To demonstrate new algorithms in actual flight, an onboard computing system for small UAVs is required. As most commercial or hobby-grade systems have drawbacks in terms of size, power requirements, level of access and crucially computing power, the Research Onboard Computing System (ROCS) has been developed at iFR.

ROCS with OCMv2

It currently consists of an ARM A8 microprocessor and a Xilinx Spartan 6 field-programmable gate array (FPGA). The latter can be used as a coprocessor for computationally intensive applications, especially if parallelization is possible. The whole system consists of several modules to ease modifications and upgrades. One of these modules is a Hardware-in-the-Loop Testbed, which allows running the final implementation of an algorithm on the actual hardware in a Matlab/Simulink-based simulation.



ROCS - History of Development

ROCS with OCMv1

  • OCMv1

    The first Onboard Computer Module to be developed at the Institute of Flight Mechanics and Control.

    The first generation of the onboard computer used only a Spartan 3 FPGA with a Microblaze embedded into the fabric. An additional microcontroller took care of datalogging and telemetry. This version is no longer in use but served as a basis for the development of version two.

  • OCMv2

    The second version of the Research Onboard Computer Module; this version is currently used not only by iFR scientists, but also by several german research facilities.

    In this version the Microblaze “softcore” was replaced by a separate Gumstix Overo, which is based on an ARM Cortex A8 running at 720MHz. It runs an embedded Linux, making development and usage much simpler. In addition the FPGA was upgraded to a bigger Spartan 6 to have more resources for complex algorithms.

  • OCMv3

    The next version is currently under development and will be based on the Xilinx Zynq, which contains a dual-core ARM processor and an FPGA in the same package. This greatly simplifies and speeds up the communication between the two units.



iFR Groundstation

iFR Groundstation

For our missions, we make use of an in-house developed groundstation running on a Personal Computer. The groundstation is used for both monitoring mission data and modifying parameters whilst operating the vehicle.

The iFR Groundstation is especially tailored for specific research applications. The software is continually extended to meet requirements of upcoming research projects. As for example, the latest version of the iFR Groundstation is capable of displaying the onboard controller modes as a finite automaton. This gives the operator information about both the current mode and the state transitions possible.


@2015 iFR - Flight Mechanics and Controls Lab


Flight Mechanics and Controls Lab
Pfaffenwaldring 27
70569 Stuttgart


Phone:   +49 711 685-67061

Fax:        +49 711 685-66670

Mail:       ifr@ifr.uni-stuttgart.de