| The all-terrain wheeled mobile robot is widely used in outdoor environments because of its simple structure,flexible movement and easy control.As the complexity of the outdoor environment increases,the performance requirements for all-terrain mobile robots also increase.The instability of the body during the steering process has been widely discussed by scholars.The solutions to this problem are mainly manifested in two aspects.One is to focus on the innovative design of the suspension vibration reduction system,and the second is to design a steering control system to improve system stability by controlling wheel speed or torque.To improve system stability by controlling wheel speed and torque.This thesis combines the two methods to design an all-terrain mobile robot that combines a suspension vibration reduction system and a steering control strategy.By establishing a road vibration model and a dynamic model under steering conditions,its dynamic characteristics are analyzed,and a fuzzy PID controller based on the vibration reduction system model is designed to realize steering control.Finally,an experimental prototype was developed to verify the rationality of the all-terrain mobile robot suspension damping mechanism and steering control strategy for outdoor experiments under different terrains.The thesis consists of the following four parts:(1)The vibration reduction system is designed for the use of all-terrain mobile robots.Because all-terrain mobile robots are applied in complex environments,the functional requirements of all-terrain mobile robots can be analyzed and the main design parameters can be determined.The maximum power and maximum torque are determined by calculating the driving mechanism under the limit working conditions.Through the calculation of the important parameters of the suspension,the stiffness coefficient and damping coefficient of the suspension are preliminarily determined.,and the three-dimensional model of the all-terrain mobile robot is constructed by the application of the SolidWorks software finally.(2)The vibration reduction system of the all-terrain mobile robot is modeled in mathematics.The vibration model of the suspension damping mechanism is established,so as to obtain the transfer function of the system.And the stability of the system is determined by observing the Bode diagram;By establishing the dynamic model under steering conditions,the dynamic characteristic parameters are determined and analyzed which provides theoretical basis for the subsequent research on steering control strategy.(3)Steering control strategy is under researched.Since the fuzzy PID control strategy has good robustness,a fuzzy PID control strategy based on the vibration reduction model is designed.By designing the fuzzy PID controller and establishing the fuzzy rules,the PID parameters are tuned by a large number of practical experiments,and finally the task of controlling the whole terrain mobile robot to steer stable is completed.(4)Experimental research.The simulation experiment research and outdoor experiment research was completed.Through the development of simulation experiment,the vibration experiment scheme of the different terrain of the all-terrain mobile robot and the rotation experiment scheme at different speeds were designed.The vibration conditions of the beams before and after were analyzed and optimized,and the fuzzy PID control algorithm is compared and verified;Through carrying out outdoor experiments,the experiment plan of the body vibration of the all-terrain mobile robot under different outdoor roads is designed and the gyroscope is used to reflect the vibration of the body on different roads,and the stability of the body is analyzed before and after optimization.Therefore,it is verified that the combination of the independent suspension vibration reduction mechanism and the steering control strategy greatly improves the stability of the all-terrain mobile robot when turning,and provides a guarantee for a variety of operations in complex environments. |
PDF Full Text Request