  We study the depinning transition of a driven chain-like system in the
presence of frustration and quenched disorder. The analysis is motivated by
recent transport experiments on artificial vortex-flow channels in
superconducting thin films. We start with a London description of the vortices
and then map the problem onto a generalized Frenkel-Kontorova model and its
continuous equivalent, the sine-Gordon model. In the absence of disorder,
frustration reduces the depinning threshold in the commensurate phase, which
nearly vanishes in the incommensurate regime. Depinning of the driven
frustrated chain occurs via unstable configurations that are localized at the
boundaries of the sample and evolve into topological defects which move freely
through the entire sample. In the presence of disorder, topological defects can
also be generated in the bulk. Further, disorder leads to pinning of
topological defects. We find that weak disorder effectively reduces the
depinning threshold in the commensurate phase, but increases the threshold in
the incommensurate phase.
