In the on-orbit assembly process of space robots, the relationship between their "hands" and "eyes" cannot be effectively calibrated, and the inertial parameters of the robot and the object being operated are variable, which may lead to assembly failure. To solve this problem, we design a depth estimator based on the traditional uncalibrated visual servo. It can estimate the depth value of the target feature online using the measurement data of the robot and the image motion. A sliding mode controller is designed in the space robot joint control ring to control the robot joint motion in real time, and the system error is corrected according to the feedback image information to complete alignment and tracking. Finally, the effectiveness of the method is verified by simulation. The uncalibrated visual servo alignment method proposed in this paper can free the space robot from the complicated calibration program, thereby overcoming the influence of uncertain inertial parameters on the assembly accuracy and improving the robustness of "hand-eye coordination" to ensure successful completion of on-orbit assembly tasks of the space robot in complex space environments.
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