Self-steering performance of a new bogie with four independently rotating wheels using caster angle

An idea is proposed to recover the self-steering ability of the bogie composed of independently rotating wheels using caster angles. The stability of the dynamic system is analysed via eigenvalues. The guiding performance of the new bogie is studied on straight and curved tracks. A scale testing is carried out to validate the hunting phenomenon. The results show that the dynamic system of the new bogie is asymptotically stable. The new bogie with caster angles can dynamically correct the direction and automatically go back to the track centerline. The exponentially damped hunting motion is observed for the new bogie with four independent wheels. The bogie possesses the self-centring ability on straight tracks. The angle of attack of the left front wheel obviously decreases with the decreasing anti-yaw stiffness on circular curves. Finally, the hunting phenomenon of the new bogie is verified by the scaled prototype test.