Abstract: Because traditional methods have problems such as poor control stability and low control efficiency

in the process of using unmanned aerial vehicle（UAV）to check obstacles in transmission channels，a transmission

channel unmanned aerial vehicle motor auto-disturbance rejection control technology based on extreme value

search was proposed. The state variables of the unmanned aerial vehicle system was observed through the state

observer，and the operation status of the unmanned aerial vehicle system were obtained. The auto disturbance

rejection control of unmanned aerial vehicle motor in transmission channel was realized by searching for

extremum. The attitude of unmanned aerial vehicle was solved by quaternion，and high-precision attitude

information was obtained by normalizing magnetometer data and accelerometer data. On the basis of the principle

of extremum search and optimization，the inertial terms of the direction and step length was modified，and the

gradient descent method was used to modify the inertial terms to avoid possible non-convergence problems or slow

convergence problems during the search process，thereby to realize the unmanned aerial vehicle motor auto

disturbance rejection control of the transmission channel searching. The experimental results show that the

unmanned aerial vehicle under the control of the proposed method has high stability，strong anti-interference ability and high control efficiency，which is beneficial to improve the efficiency of power transmission channel survey.

      Key words: extreme value search algorithm；transmission channel；unmanned aerial vehicle（UAV）motor；

state observer；active disturbance rejection control