  We study self propelled stokesian robots composed of assemblies of balls, in
dimensions 2 and 3, and prove that they are able to control their position and
orientation. This is a result of controllability, and its proof relies on
applying Chow's theorem in an analytic framework, similarly to what has been
done in [3] for an axisymmetric system swimming along the axis of symmetry.
However, we simplify drastically the analyticity result given in [3] and apply
it to a situation where more complex swimmers move either in a plane or in
three-dimensional space, hence experiencing also rotations. We then focus our
attention on energetically optimal strokes, which we are able to compute
numerically. Some examples of computed optimal strokes are discussed in detail.
