How we can measure the impact of a wheels on ground..so called RUT made by the four wheel robot instantly........how can measure the rut made by the robot .?
If you only need to pick up the impact, use a piezo sensor, or weight sensor from an electronic balance. You can calibrate it so the output is proportional to impact force.
A microphone can be used to "hear" the sound of impact. Again, by calibration of the output one can estimate impact force.