Johannes Sebald

Structured and symmetric ima architecture optimization: Use case ARIANE launcher

The current European space launcher ARIANE 5 has an avionics system designed in the 90s. Possible benefits of introducing Integrated Modular Avionics (IMA) to it have been investigated with a model-based optimization approach. From this investigation two novel features for avionics architecture optimization are presented, first, a method for logically structured allocation and, second, a method symmetric function allocation. IMA are state-of-the art in large aircraft. The high degree of freedom in software allocation sizing and placement makes an optimal manual planning, however, hardly possible. Optimization algorithms achieve objectively better results, but their results often lack non-functional requirements which are inherently incorporated in manual designs. For an existing avionics architecture optimization framework extensions are presented, which improve the convenience, quality, and subjective attractiveness of automatically derived architectures. All features are demonstrated for an IMA-based avionics architecture optimization for the ARIANE 5 and future launchers. The solution quality, optimization time, and subjective impressions are analyzed. It is shown how the extended optimization methods help to improve fragmentation and sensor distances by 14% and 24% respectively without degrading the primary design objective.

Microsecond-precision time stamping in a deterministic distributed sensor network utilizing openPOWERLINK

Utilizing open source protocols and commercial off-the-shelf components for space flight promises to reduce costs and risks. A major challenge to achieve this are the demanding performance criteria. In this research project a distributed sensor network was built by employing a commercially available System-on-Chip development platform and combining it with the open source deterministic openPOWERLINK protocol. A high precision timer module implemented in the Programmable Logic allows the locally time stamped data to have a clock resolution of 20 nanoseconds. This is combined with a network wide clock correction mechanism to ensure a global time stamp precision of less than 10 microseconds relative to all other time stamps on the network.

Low power ASIC design for infrared sensor network inside ARIANE 5 vehicle equipment bay

In this work the design of low power infrared transceiver ASIC with AMS350nm technology is presented. There are two different types of transceiver designs that have been developed. The first design is based on IrDA 9600 baud serial infrared (SIR) standard physical signal layer that uses split-phase Manchester coding technique and the second design is using uni-polar return zero coding (RZ) technique. The prototypes of the circuit are built and tested on a Field Programmable Gate Arrays (FPGA) Spartan-3E board provided by Digilent. After finishing the prototype, the ASIC synthesized, manufactured and tested. The infrared transceiver ASIC is intended for infrared sensor communication inside ARIANE launcher. Instead of using commercial infrared transceiver ICs, the ASIC design in this work is used as a blue print for radiation hardened ASIC design that can be qualified for the space environments. Other aspects such as Electromagnetic Compatibility (EMC) with launcher electrical equipment are also considered in the frame of the ASIC development.

Bit-Error-Rate measurement of infrared physical channel using reflection via Multi Layer Insulation inside in ARIANE 5 Vehicle Equipment Bay for wireless sensor network communication

In this work we investigate the Bit-Error-Rate (BER) of the Infrared (Ir) Communication inside the Vehicle Equipment Bay (VEB) of the ARIANE 5. Measurements were performed to find the impact of the reflection of the infrared signal via Multi Layer Insulation (MLI) on the infrared wireless sensor network (Ir WSN) communication in the VEB. The main focus is to find the relationship between the BER and the transmitting/receiving angle depending on variation of the Ir transmitter power. A further experiment was done by varying the transmission current with a constant angle for BER estimation without adding extra special signals (e.g. Additive white Gaussian noise (AWGN)) to the transmitter. Ambient white light from LEDs and 50 Hz fluorescent AC light was superimposed in the measurement to introduce additional noise for the infrared receiver into the physical channel.