Why use voice commands at all? Even the best voice recog tech is only about 98% effective. It would seem to me that a reomote control would be more reliable and easier to use. If you are giving the service robot to a new user, there is no reason to retain the verbal command system.
This is a good move to augment the ‘manpower’ in care homes for disabled people. However, robots should not and never replace service dogs. A dog provides warmth and care to the disabled person on top of fetching medication. A dog provides entertainment, while a robot cannot. It may be new or a novelty for care homes, but should not replace dogs.