This thesis describes the development of a device for the automated winding and extension of a cable used to power a robotic system. The climbing robot powered by this cable is used for non-destructive testing of vertical surfaces of load-bearing concrete structures, such as bridges. As the robotic system climbs the vertical test surfaces, it is necessary to synchronize the length of the extended cable with the robot's position, due to the risk of detachment and falling. The system can operate by supplying the cable from the ground, but if the top of the structure is accessible, the cable can be routed to the robot from above via a pulley. In this configuration, the power cable can also serve as a means of securing against a fall. To ensure the development of a satisfactory device, design requirements and a technical specification were defined. The starting point of the development was an analysis of an existing prototype, which identified functional concepts as well as areas that required improvement. The developed system consists of functional assemblies for the drum, guidance, drive, and braking, each of which was individually conceptualized and developed. The drum assembly transfers power and communication from the static part of the structure through a rotating drum to the coiled cable. The designed drum can hold 100 meters of cable, although only 30 meters were coiled during production due to availability. The guidance assembly is synchronized with the drum’s rotation and ensures even winding of the cable across the drum width. The roller-based drive assembly enables cable retraction and extension. The cable position can be tracked even in the event of slippage using an integrated encoder. For the braking function, a hybrid braking system was developed, combining dynamic braking of the drive motor for deceleration with mechanical braking to ensure complete stoppage of the system. Since braking must function in case of power loss, the drive motors are normally connected via relay to a braking resistor, ensuring rapid deceleration and safe stopping. After the physical construction of the device and the development of the control code, the system’s performance and functionality were tested. The tests confirmed the required precision in cable position and extraction speed, the maximum required extraction speed, and the functionality of the safety braking system.
Ivan Perković
2025
Master thesis
