Abstract: In order to realize the high-precision trajectory tracking control of four-wheel skid-steering mobile

robot（SSMR），under slip and external disturbance，an auto-disturbance tracking controller based on double closedloop rail structure was designed，and its stability was proved. First of all，in order to solve the influence of the fourwheel SSMR rotation sub-motion on the control performance，the concept of virtual wheel spacing was proposed，and the dimensionless parameters were introduced to reflect the uncertain influence of the rotation sub-motion through the virtual wheel spacing，which optimized the mathematical model of the traditional robot. Then，considering the influence of external disturbance in the working environment of the robot，an auto-disturbance rejection trajectory tracking controller with double closed-loop structure was designed. The controller has the characteristics of simple structure，few control parameters and easy application. Finally，the physical simulation test was further built on the basis of software simulation，and compared with the traditional PID method. The results show that the trajectory tracking accuracy of the control method is higher，and the anti-disturbance performance is more than doubled.

    Key words: mobile robot；four-wheel skid-steering；trajectory tracking；double closed-loop