NuBot:A Magnetic Adhesion Robot with Passive Suspension to Inspect the Steel Lining

The steel lining of huge facilities is a significant structure,which experiences extreme environments and needs to be inspected periodically after manufacture.However,due to the complexity(crisscross welds,curved surface,etc.)of their inside environments,high demands for stable adhesion and curvature adaptability are put forward.This paper presents a novel wheeled magnetic adhesion robot with passive suspension applied in nuclear power containment called NuBot,and mainly focuses on the following aspects:(1)proposing the wheeled locomotion suspension to adapt the robot to the uneven surface;(2)implementing the parameter optimization of NuBot.A comprehensive optimization model is established,and global optimal dimensions are properly chosen from performance atlases;(3)determining the normalization factor and actual dimensional parameters by constraints of the steel lining environment;(4)structure design of the overall robot and the magnetic wheels are completed.Experiments show that the robot can achieve precise locomotion on both strong and weak magnetic walls with various inclination angles,and can stably cross the 5 mm weld seam.Besides,its maximum payload capacity reaches 3.6 kg.Results show that the NuBot designed by the proposed systematic method has good comprehensive capabilities of surface-adaptability,adhesion stability,and payload.Besides,the robot can be applied in more ferromagnetic environments and the design method offers guidance for similar wheeled robots with passive suspension.

VIBRATION OPTIMIZATION OF A PASSIVE SUSPENSION SYSTEM VIA GENETIC ALGORITHM

In this paper,we have formulated mathematical models to optimize the bouncing transmissibility of the sprung mass of the half car system with passengers’seat suspensions considering different road conditions.The corresponding problem has been solved with the help of advanced real coded Genetic Algorithm(GA).The nonlinearity of suspension spring and damper,which are the most important characteristics of the suspension,has been taken into account in order to validate the model to real applications.The nonlinear cubic polynomial has been used to describe the spring characteristic and a quadratic polynomial has been used to describe the damper characteristic.The coefficients of each polynomial represent the design parameters of the suspension system and are to be determined.To find these parameters we have formulated a nonlinear optimization problem in which the bouncing transmissibility of the sprung mass at the center of mass has been minimized with respect to technological constraints and the constraints which satisfy the performance as per ISO 2631 standards.The advanced real coded GA has been used to solve this problem in time domain and the results obtained have been compared to those obtained using the existing design parameters.The objective function and the constraints have been evaluated by simulating the vehicle model over two roads with multiple bumps at uniform velocity.