  We show how to construct an arbitrary robust one-qubit unitary operation with
a control Hamiltonian of $A_x(t) \sigma_x + A_y(t) \sigma_y$, where $\sigma_i$
is a Pauli matrix and $A_i(t)$ is piecewise constant. Our method, based on
planar geometry, admits a simple and intuitive interpretation. Furthermore, the
total execution time and the number of elementary gates of the obtained
sequence are comparable to those of the shortest known concatenated composite
pulses.
