Nav Mesh does not work well on low poly landscape

hello everyone. im making a game that has low resolution graphics. i have a low poly landscape in which my little guys should run around. but they commonly get stuck on patchy places in the landscape. is there a way i can make the nav mesh more tolerant of the more sharp ground? please let me know. thanks in advance.

here is a link to a photo of the problem


[if the top link doesnt work try this one, still new to the forrums lol]()