Design and prototype/demonstrate a robotic end-effector gripper that can be used to capture the Launch Adaptor Ring (LAR) of uncooperative satellites during a debris removal mission.

The d.deorbit CDF study identified the robotic gripper mechanism as a key area of technology development. The gripper, which is attached to the tip of the robotic arm, plays a important role in the satellite capture operation as it provides the mechanical and structural interface between the servicer/chaser vehicle and the target satellite during the critical capture and stabilisation operations. Due to the potentially unknown state of the target satellite, the capture operation must be able to handle both cooperative satellites (i.e. those in a known state and attitude), and tumbling uncooperative satellites. This translates to a wide range of relative motion rates between the gripper and the LAR at the start of the capture operation. The gripper design must accommodate these relative motion rates while ensuring that the capture operation is reliably completed in timely fashion and without causing the target satellite to tumble out of the capture envelope of the gripper and potentially causing damage to either or both vehicles. In order to ensure safe capture of the target satellite and reduce the possibility of pushing it out of the capture envelope the capture operation shall be done in two phases: 1. Soft capture phase where the gripper encloses the LAR, 2. Rigidization phase where the gripper securely captures LAR in a deterministic state The kinematic design of gripper contact geometry and motion profile of the contact surfaces must ensure that both phases are done in quick enough time to minimise the window of exposure to risks during the critical capture phase of the mission, while at the same time forcing the LAR into alignment with the gripper and reaching a deterministic rigidified state that will permit the interface between the LAR and the gripper to accommodate external loading events (such as manoeuvring the target, detumbling if required, and possibly de-orbit burns) In order to fulfil the requirements listed above, the gripper must also include a set of sensors that positively detect the state of the LAR and the gripper (e.g. ready for capture, soft capture, rigidized, capture failed). The reported states of the sensors shall be reported to the gripper control software, which uses the information to transition between the various capture modes. The work required for this activity includes the analysis and design of the gripper system including the capture mechanism, control electronics, and sensor package. A breadboard model of the gripper system shall also be built and used to demonstrate the successful capture of a LAR at various relative motion rates and misalignments.