Displacement Estimation Error in Laser Scanning Monitoring of Retaining Structures Considering Roughness

Point clouds were obtained after laser scanning of the concrete panel, SMW, and sheet pile which is most widely used in retaining structures. The surface condition of the point cloud affects the displacement calculation, and hence both local roughness and global curvature of each point cloud were analyzed using the different sizes of the kernel. The curvature of the three retaining structures was also analyzed by the azimuth angle. In this paper, artificial displacements are generated for the point clouds of 100%, 80%, 60%, 40%, and 20% of the retaining structures, and displacement and analysis errors were calculated using the C2C, C2M, and M3C2 methods. C2C method is affected by the resolution of the point cloud, and the C2M method underestimates the displacement by the location of the points in the curvature of the retaining structures. M3C2 method had the lowest error, and the optimized M3C2 parameters for analyzing the displacement were presented.

Displacement Sensing of an Active String Actuator by an Optical Fiber

We have fabricated a string-shaped actuator called “Active string” that has high contractile displacement/force by accumulating thin pneumatic artificial muscles using the string production process. However, displacement control of the active string is challenging because general bulky and rigid displacement sensors are not suitable for the sensor element of the active string. Therefore, in this report, a flexible optical fiber sensor is combined with the active string to enable sensing of its displacement. As the active string contracts, the radius of curvature of the optical fiber decreases, and light intensity propagating in the optical fiber decreases due to bending loss. The experimental results showed that the optical fiber sensor value changed with corresponding to the displacement of the active string. It shows the possibility that it is possible to make a displacement estimation of the displacement of the active string using an optical fiber sensor.

Digitalization of Cross-Country Skiing Training Based on Multisensor Combination

The status and role of science and technology in the field of modern competitive sports have become increasingly prominent. The construction of a scientific training command system is of great significance for improving the scientific level of the training process and deepening the digital cognition of ski training. This paper is based on the multisensor combination to conduct a digital research on cross-country skiing training, aiming to conduct in-depth research on the realization of human motion capture and the theory of motion inertial sensing. To build a scientific, formal, and malleable ski training program, the requirements for data acquisition, recording, and analysis are quite strict. For this, it is necessary to use scientific and reasonable tools combined with multiple algorithms to process information and data. During the experiment, accelerometers, gyroscopes, and magnetometers are selected as sensors to receive motion information, and recognition algorithms for identifying weightlessness, hybrid filtering algorithm, displacement estimation algorithm, and kinematic principles are adapted to process multisensor data using information integration technology. A human body motion model was established based on kinematic principles, and a cross-country skiing motion measurement program was designed. The experimental results show that, according to the combination of multisensing and video platform, the athlete’s posture prediction is adjusted, and the action on the track is more consistent, which can accelerate the athlete’s skiing speed and the size of the inclination angle to a large extent. It can affect the direction of the athlete’s borrowing force and the adjustment of gravity during the exercise. The tilt angle is expanded from 135° to 170°, and it can maintain good continuity during the exercise.