Provided is a computer-assisted method for ascertaining a movement of an apparatus, which has a tool that is movable by way of translational and/or rotational axes of movement of the apparatus, includes the following method steps: a first movement trajectory of the tool is ascertained in a first configuration space. A predetermined parameter of a movement of the tool is optimized when ascertaining the first movement trajectory. A check is carried out as to whether the first movement trajectory satisfies at least one predetermined first boundary condition. A second movement trajectory of the tool in a second configuration space is ascertained by transforming the first movement trajectory into the second configuration space if the first movement trajectory satisfies the predetermined first boundary condition. A check is carried out as to whether the second movement trajectory satisfies at least one predetermined second boundary condition.