Table 2 Parameters used in the overrun analysis process and their meanings.

L₁

Perpendicular distance between the center of the flexible articulation and the center of the wheel of the adjacent drive module along the axis of the recessed bushing (mm)

L₂

Perpendicular distance between the center of the flexible articulation and the center of the wheel of the adjacent drive module along the axis of the taper bar (mm)

L₃

Perpendicular distance between the center of the wheel and the axis of the taper bar (mm)

L₄

Distance between the contact point of the obstacle and the swing leg and the center of the wheel (mm)

L₅

Distance between the contact point of the ground and the swinging leg and the center of the wheel in the first stage of obstacle crossing (mm)

L_G1

Distance between the first center of articulation and the center of mass of the first drive module in the horizontal direction (mm)

L_G2

Distance between the second center of articulation and the center of mass of the second drive module in the horizontal direction (mm)

L_G3

Distance between the second center of articulation and the center of mass of the third drive module in the horizontal direction (mm)

r

Wheel radius when the swing leg is not deployed (mm)

h

Height of obstacle (mm)

ϕ_i (i = 1, 2, …, 10), ϕ'₃

The acute angle between the bars or the line connecting two points and the horizontal at each stage of crossing the obstacle (deg)

f_ni (i = 1, 2, …, 9)

Pressure at each point of contact between the robot and the ground or obstacle at each stage of crossing the obstacle (N)

f_si (i = 1, 2, …, 9)

Friction at each point of contact between the robot and the ground or obstacle at each stage of crossing the obstacle (N)

G_i (i = 1, 2, 3)

Gravity of drive modules in each section (N)

T_ei (i = 1, 2, 3), T'_e1

Torque due to bending of the spring at each articulation at each stage of crossing the obstacle (N·m)