Research On Self-adaptive Technology Of Multi-functional In-pipe Robot

As a highly efficient and reliable automatic equipment,pipeline robot can replace the manual completion in pipeline detecting and cleaning.It is widely used in the fields of oil and gas,chemical industry and urban water supply and drainage.Because of the change of pipe diameter and various obstacles in the pipeline,the adaptability of the pipeline robot has gradually become an important factor to measure the performance of itself.In order to improve the passability,flexibility and adaptability of the pipeline robot,this paper puts forward an active self-adaptive design scheme based on force feedback control.According to the design plan,the three-dimensional structure is carried out.The scheme selection,size characteristic analysis and mechanical characteristics analysis are carried out for the active diameter adjusting mechanism.The analysis results provide the rules for the serial design of the robot body.The wheel drive strategy is determined,and DC motor+worm gear is selected as the power combination.The designed adaptive pipe robot has 6 driving wheels,which can individually adjust the radial expansion and driven separately,with higher flexibility and adaptability.The force and posture of the robot during the operation in straight pipe and elbow are analyzed.Then,the relationship between the working attitude angle and the positive pressure of the driving wheel is obtained.By combining the robot traction force model with the attitude analysis,the relation formulas between the positive pressure N_i of the driving wheels and the attitude angle?,the inclination angle of the pipe?,the gravity G,the adhesion coefficient?,and the traction P_a in the horizontal,inclined and vertical pipeline are obtained.It provides programming basement for active adaptive control system.The traction force of driving wheel mechanics model and the attitude analysis are combined to get the force formula of the driving wheel and the variable diameter mechanism when the pipe robot operates in the horizontal,inclined and vertical pipeline.The position and attitude model and the over bending model of the robot in the elbow are studied.The formula of position and attitude and the difference velocity model are obtained,they provides a theoretical basis for the control of over bending.Positive pressure control scheme and diameter adjusting mechanism displacement control scheme is designed,which is based on a closed loop control algorithm.The operation posture of the robot in the straight pipe was analyzed,and the attitude control strategy was formulated.Using the characteristics of active self-adaptive pipeline robots with 6 driving wheels,a non-differential speed test method is proposed when running in an elbow pipe.For example,the motion of pipeline robot in horizontal elbow pipe is analyzed.The relationship between the extended displacement of each diameter adjusting mechanism and the pipe parameters is established.The radius of curvature can be obtained through solving the equation set,which provides data for the over bending differential model.based on the diameter adaptation range 250mm-450mm,the adaptive pipe robot prototype has been designed and make.The basic performance parameters,variable diameters and driving parameters of the prototype are introduced.Also,the robot control system is programmed.6 different experiments were carried out in horizontal pipes,inclined pipes and vertical pipes.By comparing the pre-tightening force with traction force measured under different attitude angles,different adhesion forces and different pipe inclination angles,the experimental data obtained are within 10%relative to the theoretical values.The experimental results verify the correctness of the force calculation model,the rationality of the structural design and active self-adaption control system.