Fig. 4From: Service robot planning via solving constraint satisfaction problemCase 1: Simple object fetch for human. Step 1 is the starting point. The robot proceeds to master bedroom door(N6) and opened it in Step 2. It then goes to the cupboard (N11), opens it, and gets a book, and closed the cupboard in Step 3. Finally, in Step 4, it goes into the master bedroom and passes the book to the humanBack to article page