Signal Generation

As an important part of the HERMESS team, we are responsible for the signal generation and the installation of the measurement sensors in the ring and to guarantee the fulfilment of the order. For this we work closely with the signal processing team, enabling us to install the components.

The main task here is to install the measuring sensors on the module wall in a manner appropriate to the species. For this purpose, 6 measuring positions were evenly distributed on the ring, each of which is equipped with a measuring unit (STAMP: Strain and Temperature Amplified Measurement Point).
The division of the 6 measuring units is shown in fig. 1.

Fig. 1: Arrangement of the measuring units - short STAMP - in the module.

At each position 2 strain gauge rosettes and a temperature sensor are combined to form a STAMP. The detailed orientations are shown in fig. 2. While the strain gauge rosette with a sensor aligned parallel to the longitudinal axis of the rocket detects axial and tangential deformations, the second strain gauge rosette rotated 45° detects the shear components. Placing the temperature sensor close between the two rosettes ensures that the local temperature is measured across both rosettes.

Each STAMP is connected to a nearby fuselage-mounted connector board to form the half-bridge for two strain gages each and relieve the sensitive sensors of the strains that occur during start-up. These in turn are connected to the signal processing units (SPU), which use the four-wire technique for the PT-100 and the V-wire technique for the strain gage rosette half bridges. The techniques used eliminate the influence of wire resistances between SPU and STAMP on the measured values. The cables, plugs and wiring techniques used must be resistant to electromagnetic interference and are currently being tested.

STAMP_internal_configurationV1-1.jpgFig. 2: Arrangement of a STAMP.

In addition to the concept of the correct arrangement of the STAMPs, it is the task of the signal generation to realize them and to fix them in the module in a flight-proof way. For this purpose, a gluing method standardized for strain gauges is used which leads to a stable mounting by correct hardening.

This procedure is to be used in the next step to position all STAMPs successfully and thus enable the first test procedures on the module.
In addition, a concept is currently being developed to connect the connections of the sensors to the printed circuit boards in a way that is appropriate to the type of sensor, which will also be glued to the module wall around the sensor arrangement.