Research On The Design And Control Of Bionic Chicken’s Neck System And Quasi-zero Stiffness Low-frequency Vibration Isolation System

The stable operation of mobile structural health monitoring devices such as cameras,3D laser scanners,and ultrasonic detectors is challenged by complex narrow engineering structures,significant shaking,and low-frequency vibration environments.While existing load-bearing equipment/systems for mobile structural health monitoring devices have played a significant role in the field of civil engineering,there are still a series of issues that urgently need to be addressed.These include low flexibility,limited functionality,and poor adaptability to multiple working conditions,resulting in limited capability to cope with complex engineering structures and harsh monitoring environments.Therefore,it is necessary to develop equipment/systems that are more flexible in motion and can maintain end stability,and to study isolation systems for low-frequency vibration to ensure the stable operation of detection devices.It is worth noting that birds,such as chickens,achieving absolute stability of their heads through the flexibility of their neck,which may offer new research ideas.Additionally,the synergistic mechanism of chicken’s neck support and isolation inspires the equivalent principle for quasi-zero stiffness systems with high static load stiffness and low dynamic isolation stiffness.The traditional classic quasi-zero stiffness system exhibits excellent low-frequency isolation characteristics,but further research is needed to meet the isolation requirements for large low-frequency vibrations and load-bearing capacity in the field of civil engineering.Therefore,focusing on the stable detection requirements of mobile structural health monitoring devices in complex narrow engineering structures,significant shaking,and low-frequency vibration environments,this study conducts research on bionic chicken’s neck systems and quasi-zero stiffness low-frequency isolation systems from the perspectives of system design and control.On one hand,two bionic chicken’s neck systems are proposed,which have excellent motion flexibility and spatial accessibility,and can achieve absolute spatial stability of end-mounted device through motion compensation control,meeting the stable operation requirements of detection devices in complex narrow engineering structures and significant shaking environments.On the other hand,for the low-frequency vibration isolation of mobile structural health monitoring devices,a quasi-zero stiffness low-frequency isolation system with six oblique springs and its semi-active control is proposed.The main research contents are as follows:(1)The two structural design methods with excellent flexibility for the bionic chicken’s neck system,including the multi-level series connection of bionic vertebral units and the multi-level series connection of origami modular segments,are proposed.Kinematic analyses are conducted for each design.By conducting observational experiments on chicken movements,scanning the structure of cervical vertebrae,and analyzing muscle tissue,the biological mechanisms behind the flexible movements of chicken’s neck are summarized.On this basis,the bionic hyper-redundant system and the bionic origami continuous system are proposed.Among them,the backbone of the bionic hyper-redundant is composed of twelve bionic vertebral units connected in series and evenly divided into four cervical segments.These segments are driven by steel wires independently led out from the base,providing excellent spatial motion flexibility.The main structure of the bionic origami continuous system consists of three origami modular segments connected in series,also driven by steel wires independently led out from the base,which have lightweight,internal interconnection space,high scalability,and flexibility in motion.Furthermore,detailed exploration is conducted on the folding patterns,degrees of freedom,and stiffness programmability of the Miura-derived origami tubes within the bionic origami continuous system.Meanwhile,prototypes of the two bionic chicken’s neck systems are respectively produced.Based on geometric analysis,homogeneous coordinate transformations,the standard Denavit-Hartenberg(D-H)method,and the pseudoinverse Jacobian matrix method,kinematic analysis of the forward and inverse motions are conducted for the three spaces of the bionic hyper-redundant system,and the kinematic coupling relationship of the driving space between multiple cervical vertebrae segments are explored in detail.Based on the constant curvature assumption,homogeneous coordinate transformations,and the Newton-Raphson method,the kinematic of the bionic origami continuous system is explored in detail,with decoupling of the relationships between the driving spaces of multiple segments.(2)A motion compensation control algorithm of the bionic chicken’s neck system is developed,achieving spatial absolute stability of the system’s end under significant shaking.This has the potential to address the problem of poor detection accuracy of mobile structural health monitoring devices in the field of civil engineering.Firstly,two kinematic simulation models of the bionic chicken’s neck systems are constructed separately.The kinematic simulation results are compared and verified with kinematic theory and experiments.The correctness of the kinematic simulation models,inverse kinematics solution from task space to joint space,as well as the decoupling analysis of the driving space of multiple joint segments,are confirmed.Based on this,exploration of the reachable task space at the end of the two bionic chicken’s neck systems are conducted.Next,a motion compensation control algorithm for the end of the bionic chicken’s neck systems is proposed and simulated.The results indicate that the proposed systems can achieve the biomimetic objective of maintaining absolute spatial stability at the end under significant shaking of the base.Finally,prototype kinematic verification,motion flexibility,and application demonstration experiments are conducted,fully demonstrating the flexibility of the proposed bionic chicken’s neck systems’ structural design,the correctness of the kinematic analysis,and the potential applications in the field of mobile structural health monitoring.(3)A quasi-zero stiffness low-frequency vibration isolation system with six oblique springs and its semi-active control are proposed,addressing the narrow zero-stiffness displacement range issue of traditional quasi-zero stiffness systems.This system can effectively isolate vibrations for mobile structural health monitoring devices under large-amplitude low-frequency disturbances in engineering structures.Firstly,a quasi-zero stiffness low-frequency isolation system is achieved by combining a mechanism with six oblique springs and a coil spring,which provide negative stiffness and positive stiffness,respectively.The force-displacement and stiffness-displacement characteristics of both the six oblique spring negative stiffness mechanism and the overall system are analyzed separately.Additionally,the effects of structural parameters on the quasi-zero stiffness characteristics and the static load-carrying capacity of the system are explored.At the same time,the static experiments of the prototype have demonstrated that the proposed system possesses quasi-zero stiffness characteristics.Secondly,the force transmission characteristics and displacement transmission characteristics of the proposed system are investigated.Comparison with traditional vibration isolation systems shows that the proposed system demonstrates excellent low-frequency isolation performance.To further enlarge the effective displacement range of quasi-zero stiffness vibration isolation system,a semi-active control strategy based on displacement feedback is utilized to actively adjust the inclination angles of oblique springs and realize the alteration of the stiffness of the proposed system.A virtual prototype simulation model is constructed.The results indicate that the proposed control strategy expands the zero-stiffness displacement range of the system,enhancing its ability to meet large-amplitude low-frequency vibration excitation in the field of structural engineering.