under hard braking, you will feel a pulsating brake pedal
what causes it is, when a wheel is about to start skidding, the ABS sensor for that wheel slightly relieves the pressure on just that wheel & skidding is avoided
This can be a weird feeling if you are not accustomed to it
One of my jobs when i worked for the State of California, was to help with testing vehicle operation in conjunction with the California Highway Patrol & automotive manufacturers.
It was very interesting to say the least, we had 3 days of testing with the ABS systems
at a later time, we did about a month of testing with driver less vehicles
I drove several different size trucks that were obstacles, i didn't have gear that the cars had, just normal trucks, mostly 10 wheelers