Marco Straubel

Deployable Composite Booms for Various Gossamer Space Structures

Deployable structures are required to either enable orbit transfer of very large structure or to make the orbit transfer of medium and small size structures more affordable. Hereby, deployable booms are basic building blocks of such deployable structures. DLR is providing a concept for deployable booms that utilize very thin CFRP material and which can be stowed by coiling. The given paper introduces the concept of the CFRP booms and discusses the problems of their self deployment tendency. Furthermore, different mechanisms are presented that are able to control the deployment. Tests under artificial zero-g environment have been conducted to verify the applicability of the control concepts. Hence, the paper also gives insight in objectives, setup and the results of the experiment as well as a final evaluation of the concepts. Finally, an outlook on current and future projects that use the introduced booms or equivalent systems is given.

Testing of the Deorbitsail drag sail subsystem

Deorbitsail is a 3U Cubesat project that will launch, deploy, and support a large drag sail deorbiting payload. The flight payload sail system will deploy to 5 by 5 meters, increasing the frontal area of the spacecraft dramatically. A series of 4-by-4-meter sail deployments has been performed with a prototype of the proposed system. The prototype system tests included partial deployments in environmental chambers and full-scale deployment at ambient lab conditions. Design changes arising from testing of the sail system prototype are described in this paper. Engineering model construction is underway and the Deorbitsail launch will be in 2014. Deorbitsail is a European Commission 7th Framework Programme project with nine partner organizations.

Smart-Structures Technology for Parallel Robots

Industrial robots play an important role in automation technology. A further increase of productivity is desired, especially in the field of handling and assembly, the domain of industrial robots. Parallel robots demonstrated their potential in applications with needs for high-dynamic trajectories in the recent years. Within the scope of the Collaborative Research Center (SFB 562)—‘Robotic Systems for Handling and Assembly’ the German Aerospace Center (DLR) and the Technical University of Braunschweig investigate smart-structures technology for parallel robots. In this paper the results of the main topics new active components, Finite-Element based elastic position dependent modeling and vibration control are summarized. The latest parallel robot called is equipped with new active rods. The design as well as the dimensioning of the rod with surface mounted piezo patch actuators is described. For trajectory based robot control, rigid body models are required. In parallel robots with vibration reduction a coupled approach is necessary in which elastic and rigid body equations are combined. The derivation of the equations for parallel robot is presented. Finally, the implemented vibration control is explained. In a position-dependent approach several robust controllers are switched to gain optimal control performance. A stability proof for the switching process is derived.

The Design and Test of the GOSSAMER-1 Boom Deployment Mechanisms Engineering Model

The main focus of this paper is the detailed introduction of the oom deployment concept implemented for the German eployable membrane technology demonstrator Gossamer-1. The technology aims for solar sailing, thin-film photovoltaic and drag augmentation as possible use cases. Therefore, the main functional and geometrical requirements for the mechanisms are derived from the mission design and the global sail deployment concept which are both introduced in detail. The regarding mechanism design is explained on concept level and illustrated with evaluating tests of the engineering model. Finally, an outlook on the future of the project, including the current design status of the engineering qualification model, is given.

Design and Sizing of the GOSSAMER Boom Deployment Concept

Since 2011 DLR is preparing 3 orbit demonstrations of deployment and operation of a solar sail. For this mission bundle a new deployment control mechanism for DLR’s tubular CFRP shell booms has been developed that is applicable to all 3 evolution steps of the GOSSAMER—Road Map. According to the mission goal of GOSSAMER-1 and its addressed deployed sail size of 5 × 5 m2, a down scaled configuration of the booms and an adapted deployment mechanism are currently under development. The paper introduces the boom and its deployment mechanism concepts and describes and concludes tests and simulations that have been performed to proof the mechanical performance of the deployed booms.

Boom Concept for Gossamer Deployable Space Structures

Deployable structures are necessary to realize large but weight-efficient space systems. DLR provides a deployable mast that can be used either at once to realize e.g. long dipole antennas of some ten meters or to setup structures that use this mast as basic building block structure. This section shall, therefore, enable a basic insight on the concept and of the resulting challenges. Moreover, a deployment test series under weightlessness is presented and evaluated to show possible concepts of deployment control and demonstrate the potentials.

A New Deployable Truss for Gossamer Space Structures

A new deployable mast for realization of large, deployable space structures such as antennas of high arperture, long instrument booms, large solar arrays or solar sails has been developed at the DLR. The triangular truss is based on the use of longerons of composite tapes and shows a signicant increase in mass eciency compared to existing deployable mast concepts. The longerons of thin carbon bre tapes enable realization of large cross-sectional dimensions which leads to a strong insensitivity of critical compression load towards element length. Thereby, in comparison to trusses with longerons of solid rods - the most commonly used type of longerons - higher truss bay length and radius can be achieved for a lower amount of structural mass. This directly contributes to bending stiness and strength. The folding mechanism makes use of the high deformation capability of longerons of tapes in attened state. It is based on a two path folding pattern where the truss is attened rst in cross-direction and reeled up afterwards. This is enabled by the combined use of exible longerons and hinges added to one batten row and ensures high volume eciency. This is especially true for very long masts as the stowage volume mainly depends on the intial reeling radius.