Table 2 Experimental setup

Footstep angle of the steering axis

33 deg

Angular velocity of the steering axis

14.3 deg/s

Velocity of a moving wheel

0.16 m/s

Seat slider LR

0.20/− 0.20 m (moving wheel: left/right)

Seat slider FB

0.26 m

\(\theta _h\) in Fig. 7

35 deg

h in Fig. 7

0.51 m

\(l_1\) in Fig. 7

0.18 m

\(l_2\) in Fig. 7

0.23 m

\(l_3\) in Fig. 7

0.30 m

Weight of the upper part including the driver

85 kg

Weight of the lower part

72 kg

Threshold of the steering torque

50 N

Target seat rolling axis angle during step detection

4/− 4 deg (moving wheel: left/right)

Angular velocity of the steering axis during step detection

7.2 deg/s

Velocity of a moving wheel during step detection

0.21 m/s

\(\theta _1\) in Fig. 7 (due to exceeding the angle limitation of the pitch axis)

8 deg