The following thesis is a feasibility study for the controlled deployment of robotic
scaffolding structures on randomly tumbling objects with low-magnitude gravitational field for use in space applications such as space debris removal, spacecraft
maintenance and asteroids capture and mining. The proposed solution is based on
the novel use of self-reconfigurable modular robots performing deployments on randomly tumbling objects as a task-driven reconfiguration or manipulation through
reconfiguration. The robot design focused on its control strategy which used a
decentralised modular controller with two levels. One high-level behaviour-based
component and one low-level component generating commands via a constrained
optimisation using either a linear or a non-linear model predictive control approach
and constituting a novel control method for rotating objects via angular momentum
exchanges and mass distribution changes. The controller design relied on modelling
the robot modules and the object as a rotating discretised deformable continuum
whose rigid part, the object, was an ellipsoid. All parameters were normalised when
possible and disturbances, sensors and actuator errors were modelled respectively
as biased white noises and coloured noises. The correctness of the overall control
algorithm was ensured. The main objective of the MPC controllers was to control
the deployment of a module from the tip of the spinning axis to the plane containing the object’s centre of mass while coiling around the spinning axis and ensuring
the object’s rotational state tracked a reference state. Simulations showed that the
nonlinear MPC controller should be preferred over a linear one and that, for a mass
ratio of the object’s to the module’s equal to 10000, the nonlinear MPC controller
is best suited to stability maintenance and meets the deployment requirement, suggesting that the proposed solution would be acceptable for medium-size objects such
as asteroids
