West Michigan is now 8-8 on the season.
Anthony Pereira started the scoring when he singled home Cole Baumi in the second inning to give West Michigan a 1-0 lead.
Lake County responded with two runs in the third to take a 2-1 lead.
Robson scored in the home half of the third on a Blaise Salter sacrifice fly to tie the game 2-2. The game then remained tied until Robson’s walk-off single.
Whitecaps reliever Bryan Garcia picked up his first win on the season, while starter Anthony Castro got a no-decision. Castro pitched five innings, allowing no earned runs on three hits.
The Whitecaps will finish off their series with Lake County at home on Sunday at 1 p.m.