Effect of Direct Vibration on the Activity of Deep Trunk Muscles of Patients with Non-specific Chronic Low Back Pain

Background: We used two methods, direct and indirect, to study the application of vibration training. This pilot study aimed to investigate the short-term effect of direct vibration and spinal stabilization exercises on the deep trunk muscles of patients with non-specific chronic low back pain (CLBP). Methods: Sixty-two participants with non-specific CLBP were randomly placed into two groups, one with direct vibration to the trunk muscles, VSE (vibration-plus stabilization exercise) group, and one without, CSE (conventional stabilization exercise) group. The groups underwent twelve sessions of an exercise program for spinal stability. We measured the thickness and activity of the following trunk muscles using ultrasonography and surface electromyography (sEMG): transversus abdominis (TrA), external oblique (EO), internal oblique (IO), rectus abdominis (RA), lumbar multifidus (LM), and lumbar erector spinae (LES). Results: The ultrasonographic examination revealed that the ratio of muscle thickness to muscle contraction and relaxation was increased after training in the TrA and LM muscles of patients in the CSE group, and in the TrA, LM, and IO muscles in the VSE group. We also found that the LM/LES ratio in the CSE group and the IO/RA, TrA/RA, and LM/LES ratios in the VSE group were significantly increased. Using multiple regression analysis, we showed that the improvement of the symptoms was related to increased activity of the deep trunk muscles in the VSE group (p<0.05).Conclusion: The findings suggest that direct vibration on the trunk muscles may increase the activity of contracting deep muscles and be used in addition to the effective enhancement of stabilization exercise in patients with non-specific CLBP.Trial registration: KCT0003858. Registered 26 April 2019.

A gantry robot system for cutting single Y-shaped welding grooves on plane workpieces

To guarantee the strength and precision of the final welding assemblies, it is necessary to cut welding grooves before welding thick workpieces. General methods to cut welding grooves on plane workpieces need much manual assistance, and some even need manual operation purely. Therefore, this paper proposed a robot system for cutting Y-shaped welding grooves with full automation. Flame cutting technology has been adopted, requiring no jig to fix workpieces, which also causes no direct vibration to robot structure. Vision-based sub-system firstly captures the edges to be cut, which are composed of continuous points, and a laser range finder (LRF) starts to obtain the thickness of the edges precisely. To convert these edges into the trajectory of flamer, Least Square Method and Hermite Interpolation are respectively utilized to fit lines and curves. Robot system subsequently computes the motion-related parameters according to the position of the edges and geometric parameters of the desired welding grooves. The inverse kinematics of this robot is solved by geometry methods, which decreases computation burden and saves much time compared with traditional algebra method. Another core novelty is that a velocity planning method combining optimization algorithm has been put forward, which, we think, is not only useful in this gantry robot but also benefits other motion axes with heavy load. This further reduces vibration. Finally, the simulation and experimental results both prove the feasibility of this system. To date, no available robots or machines tool can finish this process with full automation (to the best of our knowledge).

Development of Direct-Vibration Actuator for Bezel-Less Display Panels on Mobile Phones

With the development of technology, multimedia devices such as smartphones, tablets, and wearable devices have become necessities in our lives, and many new products are introduced every year. Companies are expanding smartphone displays and are developing bezel-less display panel designs. The enlarged display limits the space available for a speaker, and a new actuator must therefore be developed. Indirect-vibration actuators were developed for full-wide display designs. Using the same sound-generation principle as that of the indirect-vibration actuator, the mechanism and design of the direct-vibrating actuator is proposed in this paper. Using 3D finite element method (FEM), the force factor is obtained and used for design optimization. A sample is produced, and an experiment is conducted for sound pressure level (SPL) comparison. The experiment results show that the newly designed direct-vibration actuator can replace the dynamic receiver in mobile devices and enable the application of the bezel-less display design.

Bone Conduction Implants for Hearing Rehabilitation in Skull Base Tumor Patients

Bone conduction implants transfer sound to the inner ear through direct vibration of the skull. In patients with skull base tumors and infections, these devices can bypass a dysfunctional ear canal and/or middle ear. Though not all skull base surgery patients opt for bone conduction hearing rehabilitation, a variety of these devices have been developed and marketed over time. This article reviews the evolution and existing state of bone conduction technology.