The Flexible Orbital Manipulator (FOM) project, initiated on 22 August 2017 and reported on 25 May 2023, produced a fully integrated robotic system designed for on‑orbit servicing (OOS) missions. The core of the system is a six‑degree‑of‑freedom arm that is fixed to the service satellite’s structure. The arm employs a PUMA‑style kinematic chain, with the last three joints intersecting at a single point, enabling efficient trajectory calculation and a wide workspace. The design targets a minimum reach of 1 500 mm and a maximum mass of 40 kg, while maintaining high stiffness and a high first natural frequency to reduce vibration during operations. Each joint offers a full 540° range of motion, is driven by brushless motors, and is coupled to a high‑ratio gearbox that is lightweight yet robust. Position feedback is provided by absolute encoders on the drive side and incremental encoders on the output side, allowing dual‑loop control for precise motion. The mechanical interface between arm and end‑effector follows an industrial standard, facilitating the attachment of various tools such as a versatile in‑space and planetary arm (VISPA) or a multi‑purpose tool (MPT) developed by Airbus.
The electrical architecture is based on a 3U SpaceVPX backplane with up to ten radiation‑hardened plug‑in cards, providing scalable redundancy. The central manipulator controller (CMC) houses a Cobham Gaisler GR740 microprocessor running the RTEMS real‑time operating system. The CMC offers 256 MB of RAM and 32 GB of mass memory, and includes a rich set of interfaces for motor drives, sensors, and the service satellite’s on‑board computer. The design allows substitution of commercial off‑the‑shelf (COTS) components without functional loss, reducing cost and development time. Software development covered trajectory generation, motion planning, command and diagnostic interfaces, and integration with the satellite’s OBC. The system achieved a functional demonstrator at Technology Readiness Level 4, with plans to advance to TRL 6 through a demonstrator cell that will be showcased at industry conferences to attract potential customers.
The project’s collaboration framework involved two German partners: Astro‑und Feinwerktechnik Adlershof GmbH and Robo‑Technology GmbH. Robo‑Technology supplied the robotics expertise, defining the manipulator’s kinematics, selecting actuators, and developing the control and software stack. Astro‑und Feinwerktechnik handled mechanical design, manufacturing of the arm and end‑effector interfaces, and integration of the system onto the service satellite. The partnership leveraged each company’s strengths to produce a modular, customizable solution that can be adapted to different mission requirements. The project was funded under the European Union’s Horizon 2020 programme, with the ESROCOS initiative providing the technical foundation for the control architecture. The timeline spanned roughly five and a half years, culminating in the 2023 final report that documents the technical achievements and outlines future steps for higher TRL qualification and industrial spin‑offs.