Axon’ Cable is in charge of developing the connection between the PPU (Power Processing Unit) and the RIT2X thruster. The wire harness to be developed has to withstand very severe constraints that may seem difficult to combine. Here, we are talking about high voltage, high frequencies, high temperature and radiation. Developing the connection also means designing the components of the wire harness, i.e. the cables and connectors.
Axon’ Cable’s core business is designing new connectivity solutions, i.e. solutions tailored to the customer’s specific requirements, usually in very harsh environments. A close collaboration, or more specifically, co-engineering, is required with the customer in order to have a comprehensive understanding of the needs. Axon’ Cable has based its process of product design on open innovation. Cross-over from aerospace or medical technologies towards those of space or automotive enables the company to offer innovations to customers within a rapid time scale. It means that a technology developed for one market can be used or adapted for another.
Open innovation is based on a close cooperation with the customer but starts with the sharing of knowledge inside the Axon’ group. Internal seminars and meetings are regularly held inside the group between the technical teams, each of which focuses on a specific area of expertise such as electricity, mechanics or insulating materials.
Working on development projects is in Axon’s DNA”, explains Gilles Rouchaud, Aerospace & Space Development & Manufacturing Manager. « We have a close collaboration with space agencies and develop interconnect solutions for both traditional space and “New Space” companies. We develop customized solutions for connectors, harnesses or complete satellite cabling. All these challenging projects broaden our knowledge and strengthen our ability to adapt. Having multi-skilled teams and an agile organisation is a real advantage. We can rely on our electrical, mechanical or material experts as well as project leaders, planning or quality support.”
Gilles Rouchaud, Axon’ Aerospace & Space Development & Manufacturing Manager
Cable design: first results
When practice meets theory, the result is close collaboration between academia and industry. In order to design the very best solution for the DEEP PPU harness, Axon’ Cable and the Polytechnic University of Madrid (UPM) have joined forces. UPM has carried out simulations based on theoretical solutions, balanced with Axon’s practical manufacturing capabilities and expertise in cable design. Both companies have agreed on two realistic solutions: the first is based on a flat cable assembly and the second on a round cable. Both solutions deliver good electrical performances but each has its drawbacks. The flat configuration requires several layers of insulating materials including overbraiding which makes the cable too rigid. This solution has proved to be incompatible with the integration into a space system because of its lack of flexibility. The second solution would have been to integrate very small wires into a round cable, but so small that their size makes cabling impossible. The time needed to improve this option is not in line with the project schedule.
Axon’ Cable has been manufacturing flat flexible cables (FFC) for over 30 years for consumer electronics and automotive applications. By combining multiple areas of expertise, Axon’ Cable is able to study and develop flat interconnects for space applications.
The solution, however, may come from another project with the French Space Agency, CNES, which is working on the validation of a copper-free cable designed by Axon’ Cable. Several types of cable constructions have been tested. One of them is a perfect combination of the two solutions recommended by Axon’ and UPM. Hence the idea to adapt this cable into a flat configuration and test it for the DEEP PPU harness.
Connectors: a wealth of expertise in miniature solutions
Not only is Axon’ an expert in cable manufacturing but also in the design and manufacture of miniature connectors. They are engineered to meet a huge range of electrical, mechanical and environmental challenges, which can include high frequency, high voltage, high data rates, or resistance to vibration and shock or to cosmic radiation. Highly vertically integrated, the company is able to manufacture all the different components of the connector in-house including contacts, inserts, connector shells, elastomeric seals and backshells. This expertise enables the company to design the optimal interconnect solution for the specific project requirements.
The proof is in the pudding
Once the collaborative design is complete, Axon’ has in-house manufacturing and test capabilities for every single process in cable, connector and harness manufacture. Axon’ has a team of experts dedicated to test and qualify interconnect solutions for the most severe markets including space or nuclear. As far as samples for the DEEP PPU project are concerned, several parameters have been considered including the tensile strength, partial discharges at high voltage and shielding effectiveness to characterise the electromagnetic compatibility of the interconnect. These tests have all helped to rapidly assess and validate solutions.
With regard to thermal cycling and mechanical shock and vibration, these tests still have to be defined within the consortium. Once the development tests are passed, the first products will be integrated into the equipment. The real operating system testing will be performed by Airbus in Toulouse.