Table 1.

The definitions of different notations.

Notation	Parameters
$C_1$	The feature point of the left rail
$C_2$	The intersection point of the vehicle central line and the rail top surface
$C_3$	The middle point of $C_1{C}_5$
$C_4$	The vertical intersection point of $C_1{C}_5$ and the line through $C_{13}$
$C_5$	The feature point of the right rail
$C_6$	The vertical intersection point of $C_1{C}_8$ and the line through $C_2$
$C_7$	The vertical intersection point of $C_1{C}_8$ and the line through $C_5$
$C_8$	The vertical intersection point of $C_9{C}_{11}$ and the line through $C_1$
$C_9$	The left calibration center of the VCC
$C_{10}$	The middle point of $C_9{C}_{11}$
$C_{11}$	The right calibration center of the VCC
$C_{12}$	The vertical intersection point of $C_9{C}_{11}$ and the line through $C_5$
$C_{13}$	The calibration center of the MSVS
$C_{17}$	An arbitrary feature point on the surface of the railway tunnel
$C_3{C}_{16}$	The central line of the track
$C_{10}{C}_{13}$	The central line of the vehicle body
$C_1{C}_8$	The vertical ranging result of VCC for the left rail
$C_8{C}_9$	The horizontal ranging result of VCC for the left rail
$C_5{C}_{12}$	The vertical ranging result of VCC for the right rail
$C_{11}{C}_{12}$	The horizontal ranging result of VCC for the right rail
$C_{14}{C}_{17}$	The vertical ranging result of the MSVS for the railway tunnel
$C_{13}{C}_{14}$	The horizontal ranging result of the MSVS for the railway tunnel
$\mathrm{\theta }$	The vehicle rolling vibration angle