Monthly Archives: April 2019

MAMA, it’s only a tool, (but then again a very special one)

We are happy to announce that the Mechanical Automated Membrane Aligner or MAMA tool has been commissioned with good results.

This tool (which in actual fact is a dedicated Sunsensor assembly robot) has demonstrated the capability to assemble Sunsensors with a unprecedented precision.

In essence the tools functioning is very simple:

    – The operator loads a semi-assembled Sunsensor and a membrane.
    – The operator connects the Semi-assembled sensor to the readout electronics.
    – After closing the door, the tool picks up the membrane and suspends it above the semi-assembled sensor.
    – The A high stability Sun simulator is turned on and illuminates the semi assembled sensor.
    – The tool actively aligns the membrane with respect to the semi-assembled sensor and tag adheres the membrane into position.
    – the assembled sensor can be removed for further processing without the risk of shifting the membrane to photodiode alignment.

Although the principle of operation is simple, the actual implementation has not been without it’s issues.

Perseverance and creativity were required to ensure the final assembly accuracy was in the micrometer range. This type of accuracy also requires a careful mechanical design that ensures a very stable mechanical setup.

Although a special (dedicated) stable table is still under development, first assembly tests and associated calibrations have shown that the tool will allow us to reduce the non-calibrated accuracy of our sensors from 3.5° to 2° or even less.

As we will only change the specification if we have proven the improved accuracy, we will have to calibrate a statistically significant number of sensors before we will formally reduce the specification. Nevertheless, based on tests performed so far we are fairly confident that the final specification will be somewhere between 2° and 1.5°.

This means that the vast majority of missions will be able to fly our sensors without uploading any calibration data and without preforming any compensation calculations. As a result only a couple of simple formulas used on the currents measured will directly translate into the Sun attitude with respect to the mounting plane of the sensors. Because this significantly simplifies the use of the sensors, as no memory to upload calibration tables is needed, no code to perform the interpolation algorithms is needed and no configuration control to check if the correct correction tables are uploaded is needed. Consequently we are sure the MAMA tool directly contributes to our customers satisfaction.

We would like to acknowledge the Netherlands Space Office (NSO) and the European Space Agency (ESA) for supporting this development in frame of the GSTP program.

In addition (and on a personal note) I would like to thank our own Stefan Schmidt in particular for persevering and leading this sub-project into success. Although it wouldn’t have been possible without the mechanical engineering performed at Lencon Engineering and the software assistance of Frank Bulk and many other contributors, Stefan has been the driving force behind transforming the setup from only a tool into the MAMA tool. A tool with a beating hart, allowing Lens R&D to beat all known competition on non-calibrated accuracy and reproducibility.