Is it Gizmo? I just did a little looking on the net and found that book. It is by a guy named Michael Dooney, and the characters are Gizmo Sprocket (the robot) and Fluffy Brockleton (the dog). They travel in Soto, their ship that resembles a trailer truck.
It was published by Chance Enterprises and later by Mirage Studios in the mid 80s.
Hope this helps.