The picture above is the vehicle with 2 steering wheels. $a_f$is the front wheel steering angle, $a_b$ is the rear wheel steering angle($a_f ≠ a_b$), $G$ is the reference point of the vehicle, L is the wheelbase and d is the wheel offset, $R_f$, $R_b$ and $R$ are the turning radius of front wheel, rear wheel and the reference point, respectively.
The questions that I cannot solve are:
1.How to get the radius of $R_f$,$R_b$ and $R$?
2.Calculate the forward kinematics form the 2 wheels' linear velocity and angular velocity to the reference linear velocity and angular velocity.That is from $v_f, w_f, v_b, w_b$ to $v, w$.
3.Calculate the reverse kinematics from the reference linear velocity and angular velocity to the 2 wheels' linear velocity and angular velocity.That is from $v, w$ to $v_f, w_f, v_b, w_b$.
If there is someone who is familiar with this, hope you can give me some clue about this. Thank you.