| Motion control is the basis for realizing autonomous movement of indoor mobile robots.Trajectory tracking and obstacle avoidance are the two most basic motion functions of mobile robots,which are affected by positioning methods and positioning accuracy.Ultra-Wideband(UWB)is an emerging positioning technology.Compared with other positioning technologies,it has been the research hotspots of the indoor mobile robot due to the advantages of low cost,high anti-interference ability,light weight,low consumption,high precision,etc.There are still many problems in achieving autonomous movement of mobile robots based on UWB positioning technology: UWB measurement has deviations and noise,which affects the positioning accuracy of mobile robots;on the other hand,there are some obstacles existing in indoor environment.Aiming at this kind of trajectory tracking problem,it is difficult to design a stable trajectory tracking algorithm with obstacle avoidance.Based on this,this thesis studies the control of indoor mobile robots based on Ultra-Wideband positioning.The main research contents are organized as follows:(1)Aiming at the positioning and control of indoor mobile robot.An UWB indoor positioning system was built based on the trilateration,the kinematic model of the mobile robot was established and its general control problems were analyzed.(2)Using the UWB system with double tags,the Least Square(LS)method was used to calculate the location of the tags,and the two-dimensional location was solved by the fusion of the two tags.Through the experiment,the reasons of the location error and the attitude difficult to estimate in the process of solving the mobile robot with double tags were analyzed.(3)An Extended Kalman Filter(EKF)algorithm model based on double-tag UWB positioning technology was established.The EKF algorithm with deviation estimation was proposed to reduce the position deviation and noise in the positioning process,and a position and attitude positioning system based on UWB was constructed by combining odometer.(4)Aiming at the problem of trajectory tracking in an unknown environment,a nonlinear trajectory tracking controller is designed based on error feedback adjustment.There is a problem that a single trajectory tracking algorithm can't deal with the complex environment well.To solve this problem,an obstacle avoidance algorithm was proposed based on the geometric relation between the mobile robot and an obstacle.(5)Aiming at the proposed trajectory tracking and obstacle avoidance algorithms,this thesis proposed a switching strategy,that is,the mobile robot's trajectory tracking and obstacle avoidance algorithms are switched via the switching strategy to solve the trajectory tracking and obstacle avoidance in a multi-controller control system,respectively,which realizes the design control rate of block design and simplify the difficulty in control design.Finally,experiments were carried out based on the simulation based on the proposed UWB positioning algorithm.The experimental results showed that the mobile robot can meet the positioning requirements of the mobile robot utilizing UWB positioning,and achieve trajectory tracking and obstacle avoidance.Based on UWB positioning technology,this thesis solves the problem of trajectory tracking in an environment filled with obstacles,providing a reference for the research of autonomous mobile robots. |
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