Due to its own structural characteristics, permanent magnet synchronous linear motors (PMSLMs) have unstable motor parameters during operation due to the end effect and the inherent magnetic circuit instability. At the same time, linear motors have the characteristics of reciprocating switching motion and high-speed positioning motion in industrial applications, thus placing high demands on the controller. In order to improve the performance of the PMSLM, this paper firstly studies the linear motor structure, the distribution characteristics of its air gap magnetic field are obtained, and the simulation analysis for the back electromotive force (EMF) of PMSLM of its running process is carried out. Then, a state observer based on the sliding mode state observer (SMO) is built to replace the traditional speed sensor and a super-twisting sliding mode controller is designed. The double-closed loop control of the speed and the use of high-order sliding mode control features effectively reduce the chattering of the system and reduce the impact of the observation error brought by the observer on the system. The adaptive sliding mode control strategy is used to effectively suppress the influence of the boundaryless uncertainty interference on the system and reduce the influence of the observation error brought by the observer on the system. This paper also combines the linear motor experimental platform to further verify the control scheme based on the super-twisting sliding mode non-sensing linear motor. The simulation and experimental results show that SMO has accurate speed and position tracking performance, the system's chattering is significantly reduced, the control precision is excellent, and the introduction of adaptive sliding mode controller enhances the robustness of the system.

Background The treatment of diabetic foot ulcers in this case is complex and multidisciplinary, and an interdisciplinary team is extremely beneficial. Case presentation We performed the intervention on an old type 2 diabetes patient with poor health, whose left toes were severely necrotic. Surgery, including debridement and patella truncation, had positive effects on lower extremity circulation, infection control, cavity treatment, bone destruction, surgical debridement, recovery of foot function, and nursing. After 5 months, the patient’s foot ulcer had healed, and walking function was preserved. Conclusions Scheduling interventional surgery and debridement are the key point in a complicated diabetic foot ulcers case, and multidisciplinary collaboration in treatment of diabetic foot is significantly important.

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Considering the influence of fluid structure interaction and cavitation on the actual deformation of hydrodynamic spherical bearing, the fluid-solid coupling analysis and multiphase flow simulation of spherical bearing for multi-degree-of-freedom motors are realized in this paper. The finite element simulation analysis of the model is carried out by using multi-physical field coupling software. In the study of bearings with and without effects of cavitation, the analysis shows that the peak value of oil film pressure and elastic deformation of spherical bearing decrease when cavitation effect is considered. The oil film pressure increases with the increase of eccentricity, rotation speed, viscosity and the decrease of the clearance between stator and rotor, which improves the bearing capacity of the bearing, but also intensifies the cavitation in the oil film divergence area and increases the gas volume fraction. And the oil film pressure test platform with different rotational speeds of the spherical rotor is set up, the measured experimental data are in good agreement with the numerical results. In the practical application of the motor, appropriate parameters should be selected, which is helpful to improve the working condition of spherical bearings, ensure the stable operation of bearings and prolong the service life.