Key requirements are a selection of the requirements which have determined the design and development. These are the most important performance requirements which put a major constraint on the design as well as other requirements. The following table gives a summary of the key requirements. Note that the actual requirement text is more detailed than in this brief overview.
Key technical requirements/targets
|Thermo-elastic distortion||<0.015°||To be achieved by minimizing thermal gradients (MLI, materials with high conductivity) and the application of low-CTE material.|
|Repeatability||<0.008°||Between successive deployments;|
|Stiffness||<0.015° @ 0.0075 m/s²||Depointing due to linear S/C accelerations|
|Deployed frequency||>0.7 Hz||Target for 1.8 m arm length and a reflector mass of 30 kg.|
|Mass||<23kg||Target for 1.8 m arm length, to be minimized within constraints of stiffness and cost.|
|Integration accuracy||Alignment of hinges for successful stowage, alignment reproducibility of S/C and reflector interfaces|
Challenges for the project were:
The A-ADS has a modular design which allows a wide range of mission configurations by tuning only a few design parameters. . This approach in combination with the use of standard building blocks minimizes the non-recurring design effort for a specific application and allows any desired configuration. A special kinematic model is available to assess the design parameters of the A-ADS based on customer inputs (stowed and deployed reflector position & orientation and S/C interface location). These parameters are transferred to 3D-CAD for verification and to quickly establish the A-ADS design for the specified antenna configuration and accommodation. Some examples are given below:
Key parameters for ADS are:
Assembly, Integration and Test features
The A-ADS system has two main functions:
The antenna configuration differs from mission to mission (different focal lengths, reflector diameters, stowed configuration). The A-ADS will be designed such that a wide range of mission configurations can be covered with a standard, configurable design. This is to minimize the non-recurring effort in a project.
The EM design is shown in Figure 4.1. The shown configuration has an arm length of approximately 3meter.
The A-ADS has spring driven hinges at the joints. All hinges have an opening angle of 180° except for the root hinge which has a customized opening angle depending on the configuration. When fully opened the hinges are locked and a stiff support structure for the reflector is obtained. At the end of the arm a gimbal is located which is able to point the reflector around two axes with a resolution of 0.0025°. The gimbal or pointing actuator is an off-the-shelf unit with flight heritage (ADTM Mk2 by Airbus DS UK). A synchronization system ensures a synchronous deployment of the hinges and the deployment speed is controlled by an actuator. The deployment actuator restrains the motorization springs and actually works as a break rather than as an actuator. Once deployed and latched, the ADTM Mk2 is used for trimming and continuous pointing of the reflector.
In summary the project covered the following steps:
All activities in the ARTES 5.2 project are completed ready to progress to formal qualification under an ARTES 3-4 project.