Sept 15 (Reuters) - Self-driving startup Argo AI, automaker Ford Motor Co (F.N) and Walmart Inc (WMT.N) will together launch an autonomous vehicle delivery service in Miami, Austin, and Washington, D.C, the companies said on Wednesday. Initial integration testing is expected to begin later this year, the companies added. The move comes as consumer expectations shift to next-day or same-day delivery, particularly in urban areas with a higher concentration of deliveries. The multi-city service will allow Walmart customers to place online orders of groceries and other popular items for autonomous delivery to their homes. Argo"s cloud-based system will integrate with Walmart"s online ordering platform to route orders and schedule package deliveries. Ford"s self-driving test vehicles with Argo"s self-driving system will then deliver the orders to customers. "This collaboration will further our mission to get products to the homes of our customers with unparalleled speed," said Tom Ward, senior vice president of last mile delivery at Walmart in the United States. Walmart had previously partnered with General Motor"s (GM.N) Cruise on a self-driving delivery pilot and with self-driving vehicle startups Gatik and Nuro to explore delivery through autonomous vehicles.