Adaptive Bike Brake

A kid in the neighborhood had a disabled hands that prevent him from squeezing the brake on his adaptive tricycle e bike. Other than that he can ride the bike fine but without brake control he cannot safely ride the bike. I would like to build an electronically controlled bike brake that connects to a custom made lever that he can control with his disabled hands. I would also like a backup remote that his mom can have so she can also trigger the brake.

I have a decent concept of how I can do this project using high quality RC car/plane servos and controller but I was curious if anyone has come across a product that already exists. Like an add on brake system. As much as I like tinkering Id rather just purchase something that's already been designed and tested. I see there are companies that make custom adaptive bikes but they are crazy expensive.