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The insulated bearing may be damaged when operating under the action of current. Firstly, a novel dynamic model of insulated bearing-steel pedestal system with shaft current damage is proposed, and the model is solved based on the Runge-Kutta algorithm. Then, the model is verified by the experimental results. Based on the solution results of the dynamic model, the influence of mass and damage on the vibration signal is analyzed, the effect of damage on the stability of the insulated bearing-steel pedestal system is studied, and the influence of radial clearance on the vibration characteristics of the insulated bearing-steel pedestal system is discussed. The results indicate that, the vibration acceleration signal of the pedestal shows a positive correlation with the mass mi and the mass mo. As the length of damage increases, a few points begin to leave the quasi-periodic ring, and the quasi-periodic ring in Poincaré map gradually breaks. The coupling effect of shaft current damage and radial clearance makes the insulated bearing-steel pedestal system easier to enter an unstable motion state. [ABSTRACT FROM AUTHOR]

Dynamic models that consider multiple nonlinear factors including the two-dimensional deformation and higher-order modes are too computationally complex to be suitable for real-time control of the rotating Euler-Bernoulli beam. This article proposes a new dynamic modeling method according to the assumed mode method. The new modeling method not only has high modeling accuracy but also has a brief mathematical expression. In addition, based on the new modeling method, a neural network sliding mode control strategy using the saturation function is designed to improve the rotational accuracy of the Euler-Bernoulli beam. In the control law design, the saturation function is proposed instead of the unit step function to reduce the chattering phenomenon. Simulation and control experiments describe that the new dynamic modeling method has higher modeling accuracy than the modeling method based on the one-dimensional deformation; the proposed strategy can effectively decrease the rotation angle tracking error of the rotating Euler-Bernoulli beam and improve the control accuracy. [ABSTRACT FROM AUTHOR]

The raceway damage of the bearing restricts the operation stability of the system. Therefore, in the case of damage, simulating vibration response and predicting the performance of the shaft-cylindrical roller-bearing-pedestal system have high research value. According to the structural characteristics and the force transfer relationship, a dynamic model of the shaft-cylindrical roller-bearing-pedestal system is established in this paper. Then, the vibration response of the system is simulated by Runge–Kutta algorithm and measured by experiment. Finally, the effects of load and speed, damage size, and radial clearance on the dynamic performance are investigated. The simulation and measurement results indicate that the load F and the speed N can promote the enhancement of the vibration acceleration signal. As the damage length continues to increase, the ring in the Poincaré map begins to break, and the system transits from quasi-periodic to chaotic motion. The vibration signal is more affected by the damage size than by the damage location. When the radial clearance increases from 5 × 10−6 m to 15 × 10−6 m, the PTP value increases from 23.83 m·s−2 to 61.36 m·s−2. [ABSTRACT FROM AUTHOR]

Based on the structure of damaged bearing, a nonlinear dynamic model is proposed. The nonlinear vibration response is obtained by solving the dynamic equation of the bearing system. Firstly, the influence of radial load and rotational speed on the nonlinear vibration response of the bearing system is analyzed. Then, the different vibration characteristics of the system when the inner and outer raceways of the bearing are damaged are discussed. Finally, the influence of the degree of shaft current damage on the nonlinear characteristics of the bearing system is studied. The results indicate that the bearing system presents bifurcation, jump, and chaos with the change of radial load. With the increase of the rotational speed, the path of the bearing system from chaos to quasi-periodic changes. With the increase of the degree of shaft current damage, the system gradually transitions from a stable state to a chaotic state. [ABSTRACT FROM AUTHOR]

Many factors lead to fluctuations of output speed in the motor side during the movement processes in a flexible manipulator with an axially translating arm. These factors include the time‐varying characteristics of manipulator parameters, external disturbance, and flexibility in the manipulator. The vibration of flexible manipulators is strengthened by fluctuations of output speed, which seriously affects the motion accuracy. Therefore, a variable parameters proportional–integral (PI) control strategy based on disturbance observer is adopted to reduce fluctuations of output speed in a dual flexible servo system. First, the dynamic model of the dual flexible servo system is established by the assumed mode method. Then, the variable parameters PI control strategy is applied to the servo system, and the controller parameters in different conditions are selected by pole placement strategies. Finally, numerical simulations and control experiments of the servo system are carried out. The results show that the control strategy using the variable parameters and disturbance observer could reduce fluctuations of output speed and improve the motion accuracy of flexible manipulators. [ABSTRACT FROM AUTHOR]

A power line inspection robot has to overcome many kinds of obstacles in inspection processes. The strain clamp is the obstacles difficult for inspection robots to overcome. The inspection robot needs to have a particular climbing ability to overcome the strain clamp. Therefore, the ability to climb power lines is the key point of the inspection robot's design. An inspection robot with retractable double serial manipulators is proposed to improve the climbing and obstacle-crossing ability. Besides, this paper shows that the inspection robot is more suitable for climbing from static analysis and dynamic evaluation index. Firstly, the obstacle-crossing processes and structures of the inspection robot are introduced. Next, the static analysis is carried out when inspection robot climbs the power lines. The static analysis shows that the new inspection robot has a smaller driving torque. What's more, the dynamic model of the inspection robot is established by Lagrange's dynamical equations. By constructing the dynamic evaluation indexes, the inspection robot with retractable arms performs better dynamic characteristics. Finally, a prototype robot is carried out to cross obstacles and climb up power lines. The results show that the inspection robot can overcome different obstacles and has a good climbing performance. [ABSTRACT FROM AUTHOR]