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A X-wing flapping-wing mechanism with wings flapping symmetrically is designed. The crank slider mechanism is adopted to convert the circular motion of the crank into the linear reciprocating motion of the straight shaft, and the straight shaft drives the wings on both sides through the rocker to realize the symmetric flapping of the wings. A prototype of the flapping-wing mechanism is made, and the motion test of the flapping-wing mechanism is carried out using an optical motion capture system and a wind tunnel. The reliability of the flapping-wing mechanism is analyzed from the flapping angle amplitude, the flapping frequency, the lift generated, and the operating condition of the motor. Through comparative experiments, a set of suitable flapping angle amplitudes and wing surface areas are determined, so that the flapping-wing mechanism could generate 12.9 g of lift, and it is verified that the clap-fling mechanism could effectively improve the lift of the flapping-wing mechanism.

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The inertial measurement unit is popularly used as a wearable and flexible tool for human motion tracking. Sensor-to-body alignment, or anatomical calibration (AC), is fundamental to improve accuracy and reliability. Current AC methods either require extra movements or are limited to specific joints. In this research, the authors propose a novel method to achieve AC from standard motion tests (such as walking, or sit-to-stand), and compare the results with the AC obtained from specially designed movements. The proposed method uses the limited acceleration range on medial-lateral direction, and applies principal component analysis to estimate the sagittal plane, while the vertical direction is estimated from acceleration during quiet stance. The results show a good correlation between the two sets of IMUs placed on frontal/back and lateral sides of head, trunk and lower limbs. Moreover, repeatability and convergence were verified. The AC obtained from sit-to-stand and walking achieved similar results as the movements specifically designed for upper and lower body AC, respectively, except for the feet. Therefore, the experiments without AC performed can be recovered through post-processing on the walking and sit-to-stand data. Moreover, extra movements for AC can be avoided during the experiment and instead achieved through the proposed method. [ABSTRACT FROM AUTHOR]