Abstract. In order to meet the requirements of large-blade fatigue testing, a horizontal dual-point linear exciter loading program is developed. In this paper, Lagrange's equation and FEM method are used to simulate the dual-point excitation theory model. The horizontal dual-point excitation characteristics of the blade are validated by the experimental method. The relationship among the dual-point exciting force, cycle time and bending moment during blade fatigue test in flap wise direction is studied. The advantages of horizontal dual-point excitation in blade fatigue test are analysed. Compared with vertical single-point excitation when the equal bending moment is reached, the exciting force and energy consumption required for dual-point excitation are reduced by 60.0% and 96.8%. Resonant frequency of the test system is improved by reducing the dead weight because of dual-point horizontal excitation. The entire blade fatigue test time is shortened by 7.4%. The use of horizontal dual-point excitation could save energy and shorten the entire fatigue test time.
For humanoid robots, maintaining a dynamic balance against uncertain disturbance is crucial, and this function can be achieved by coordinating the whole body to perform multiple tasks simultaneously. Researchers generally accept hierarchical whole-body control (WBC) to address this function. Although experts can build feasible hierarchies using prior knowledge, real-time WBC is still challenging because it often requires a quadratic program with multiple inequality constraints. In addition, the torque tracking performance of the WBC algorithm will be affected by uncertain factors such as joint friction for a large transmission ratio proprioceptive-actuated robot. Therefore, the balance control of physical robots requires a systematic solution. In this study, a robot control system with high computing power and real-time communication ability, UBTMaster, is implemented to achieve a reduced WBC in real time. Based on these, a whole-body control scheme based on task priority for the dynamic balance of humanoid robots is implemented. After realizing the joint friction model identification, finally, a variety of balancing scenarios are tested on the Walker3 humanoid robot driven by the proprioceptive actuators to verify the effectiveness of the proposed scheme. The Walker3 robot exhibits excellent balance when multiple external disturbances occur simultaneously. For example, the two feet of the robot are subjected to tilt and displacement perturbations, respectively, while the torso is subjected to external shocks simultaneously. The experimental results show that the dynamic balance of the robot under multiple external disturbances can be achieved by using strictly hierarchical real-time WBC with a systematic design.
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