a first detecting module, arranged on a side of the speed measuring module near where the vehicle enters, which is configured to detect incoming of the vehicle, generate an incoming vehicle signal in response to that the incoming of the vehicle is detected, and transmit the incoming vehicle signal to the speed measuring module to trigger the speed measuring module to measure the speed of the vehicle.

Optionally, the device further includes:

a second detecting module, arranged on a side of the line scan camera near where the vehicle leaves, which is configured to detect leaving of the vehicle, generate an outgoing signal in response to that the leaving of the vehicle is detected, and transmit the outgoing signal to the control module to trigger the control module to control the line scan camera to stop the image capturing on the chassis of the vehicle.

Optionally, the device further includes:

a metal protection cylinder;

wherein the line scan camera is arranged in the metal protection cylinder; and wherein

a transparent cover for a lens of the line scan camera is arranged on the metal protection cylinder, a damage-proof protection member is arranged over the transparent cover, and a light incident hole is formed on the damage-proof protection member.

Optionally, the metal protection cylinder includes an outer cylinder and an inner cylinder sleeved in the outer cylinder, wherein

the line scan camera is arranged inside the inner cylinder;

the transparent cover is supported over the inner cylinder, and the damage-proof protection member is supported over the outer cylinder.