Robinson has been selected to run the open 400m and will be in the men's 4x400 pool, while Smalls will feature in the high jump and Mu has been selected to compete in the 800m -- though she is currently at the USA Track and Field Outdoor Championships and has a chance to make the senior USA team at Worlds in the 800m.
The trio will be among 96 athletes selected to represent Team USA in Lima and among 6,680 athletes from 41 countries.
Robinson and Mu are coming off three gold medals at the Pan American U20 Championships in San Jose, Costa Rica. Robinson showed his star power by winning the 400m in 45.04 seconds, and anchored Team USA's new World U20 record in the 4x400 in 2:59.30.
Mu won a gold medal in the 800m in 2:05.50, while Smalls scored a mark of 1.89 meters in the high jump at New Balance Nationals Outdoor, a top 15 mark all-time in the event.