With the acceleration of urbanization in China, the construction of urban drainage pipe network has been expanded. In recent years, urban household garbage, factory waste and construction site mud are increasing, while the traditional urban pipe network system is lack of management, leading to prominent problems of blockage of drainage pipes, sewage overflow, internal damage of chemical pipelines and other safety risks. The drainage system is figuratively compared to the lifeblood of the city, ensuring the normal operation of the drainage system is of great significance for protecting the urban environment, controlling pollution, improving people's living quality and maintaining the appearance of the city. Therefore, in order to ensure the normal operation of the drainage system, it is necessary to dredge and clean the drainage pipes regularly.

At present, the domestic commonly uses the winch dredging method and the hydraulic dredging method carries on the drainage pipeline dredging work. Winch dredging requires manual cable crossing, and the pipeline environment is bad, the marsh is full of gas, inflammable and easily poisoned, seriously affecting the life and health of workers. Hydraulic desilting method is often used for pipes with small diameter, but the high pressure water desilting has the problem of expensive equipment and high water consumption.

Thus, the pipe inspection crawler camera arises at the historic moment. Pipeline robot is a kind of machine, electricity, instrument and integrated system which can automatically walk along the inner and outer wall of pipeline, carry one or more sensors and operating machinery, and carry out a series of pipeline operations under the remote control of staff or automatic computer control.

Pipe inspection crawler camera is usually designed in modularization, with crawler, cable capstan, upper control unit, detection unit, auxiliary device, image processing software, power supply device and other modules. The walking mode is the core of the design of pipe inspection crawler camera and plays a decisive role in the overall performance of pipe inspection crawler camera. According to the walking mode of crawler, pipe inspection crawler camera can be divided into four categories: wheeled pipeline robot, tracked pipeline robot, peristaltic pipeline robot and leg-foot pipeline robot, among which wheeled pipe inspection crawler camera is the most popular.

1. Wheeled pipe inspection crawler camera

Opcr-oh, the first wheeled tube robot, was developed by the university of Florida in the early 2000s. The wheeled pipe inspection crawler camera can be divided into three types according to the mechanism: support wheel type, vehicle type and screw drive type.

According to whether the robot can change the direction of motion, it can be divided into variable type and immutable type. The vehicle-type pipe inspection crawler camera uses its own gravity to provide positive pressure and walks at the bottom of the pipeline. The wheel is directly connected with the motor, with simple structure, convenient control and smooth running. The existing wheeled pipe inspection crawler camera are mainly vehicles, and four-wheel pipe inspection crawler camera and six-wheel pipeline robots are the most common. For example, ibak-t66 four-wheel variable directional crawler (applicable to pipe diameter of 100nm or above), T86 four-wheel non-variable directional crawler (applicable to pipe diameter of 200nm or above), ge-rovver 400 six-wheel pipe inspection crawler camera (applicable to small pipe diameter), etc.

The support wheel type pipe inspection crawler camera adopts symmetrical distributed walking structure. The supporting wheel is close to the inner wall of the pipeline, which has certain pressure on the surface of the pipeline. It can walk in the drainage pipeline with a large inclination angle. In addition, it has a variable diameter structure to adapt to different pipe sizes.

The hell-driven pipe inspection crawler camera connects the wheel with the rotor and stator module, and the radial helical motion of the rotor is transformed into the axial motion of the stator through the reversing mechanism.

2. Tracked pipe inspection crawler camera

The crawler type pipeline robot includes the crawler walking part, controller, vehicle-mounted sensor and communication system. The crawler has a steering device, which has a large contact area with the pipe wall, strong adhesion and superior plane obstacle surmounting performance. However, the track drive mechanism is complicated and the size is not easy to be reduced, so it is often used in large diameter pipelines.

3. Squirming pipe inspection crawler camera

The bionic peristaltic pipe inspection crawler camera has the characteristics of simple structure, low energy consumption, large driving force, and slow walking. Among them, the serpentine pipe inspection crawler camera is more difficult to control due to its high degree of freedom, but it is more capable than other pipe inspection crawler camera in complex environments.

4. Leg-and-foot pipe inspection crawler camera

The leg-foot type pipe inspection crawler camera has high flexibility and can climb vertical and horizontal pipelines with L, T and Y nodes. However, due to its limited traction capacity, it is not suitable for long-distance cable towing operations. Gait planning and joint coordinated motion control of leg-foot type pipe inspection crawler camera have high requirements on mechanical structure design and control system algorithm, and need to combine a large number of precise sensors, so the development cost is high. At present, it is still in the development stage and has not yet entered into a wide range of practical applications.