translate English to French: Stage 1 — developing a viable concept; Stage 2 — the prototype; Stage 3 — commercial implementation; and Stage 4 — the continuous innovation cycle.
Étape 1 - élaborer un concept viable; Étape 2 - le prototype; Étape 3 - la mise en oeuvre commerciale; et Étape 4 - le cycle de l'innovation continue.