Precision machining fields often require worktables with different stroke sizes. To address the need for scalability and facilitate manufacturing, this study proposes a novel infinite expansion magnetically levitated planar motor (MLPM) based on PCB stator coils. Different from existing magnetic levitation systems that use PCB coils, the design presented in this paper utilizes smaller coil units, with each coil being independent of one another. The coils are structured in a spiral pattern on a 16-layer PCB, comprising 15 layers of coils, while the last layer is dedicated to wiring and other circuits. Magnetic field modeling is conducted for both the stator coil and the 2D Halbach array structure employed in the system. A simple table lookup method is employed to accurately account for the prevalent end effects observed during system motion. Additionally, the decoupling effect of magnetic force and torque is evaluated by solving for the current vector at different points along a specific trajectory. To verify the accuracy of the proposed system’s modeling, a prototype is developed and tested. Experimental results demonstrate that compared to traditional harmonic model methods, the proposed approach improves the calculation accuracy of magnetic force by 50.31% and torque by 70.65%. This study presents a new MLPM system with vast potential applications in precision manufacturing and robotics. The innovative design and improved performance characteristics make it a promising technology for enhancing the capabilities of worktables in precision machining fields.

This paper develops a prototype of magnetic suspension balance (MSB) for mass measurement, in which the mass of the sealed sample is transferred to the measuring unit via the magnetically suspended method. Considering that the excitation current decides the magnetic force while the magnetic force balances the gravity of the detected object, a type of compact MSB can be obtained by combining the force sensor unit and the magnetic suspension coupling unit (MSCU). Many efforts are undertaken to improve the performance of the compact MSB. The design parameters of the MSCU are optimized to decrease the sensitivity of the magnetic force to the variation of the suspension height; the magnetic suspension system is regulated by an active disturbance rejection control method to decrease the current fluctuation in the stator coil; the calibration method founded on the least-squares method is employed to suppress the data drifts existed in the measuring process. The testing results show that both the resolution and repeatability of the MSB reach 500 μg, and the measuring uncertainty is less than 1 mg for the weights up to 1 g.

Magnetic suspension coupling can enable isolation of the balance itself from the physical environment of the sample, which makes non-contact weighing possible. In this paper, a novel triple-actuator magnetic suspension balance (MSB) system is developed by moving away from the traditional single-actuator MSB design scheme. An accurate triple-actuator rigid body motion decoupling model and a magnetic coupling model are proposed, and a self-tuning of the parameters of the control algorithm is achieved with a lightweight network structure to achieve fast and stable control of the actuator. The realization results show that the triple-actuator structure design improves the load capacity as well as measurement range of the MSB and overcomes the actuator spin problem in single degree of freedom measurements, with the root mean square error of the measurements of milligram samples being less than 0.47 mg, and that of 100 g being below 2.6 mg, representing is an improvement of 35.5% compared with single-actuator MSB. Thanks to the adaptive control algorithm, the measurement time under differentiated loads is stabilized at 6.5 s, which is 35% higher than the MSB with a single actuator.

Metal detectors detect hidden metal objects through electromagnetic induction. Significant research has focused on improving the detector sensitivity by redesigning the structure of differential receiving coils. Higher sensitivity allows the detector to identify smaller metal objects or detect objects at greater depths. This is significant in applications such as security screening and industrial quality control, where precision is essential. This paper introduces a novel receiving PCB coil prototype for a high-sensitivity metal detector and presents a numerical modeling method to optimize the coil size. The strip coils distributed around the emitting coil are employed in the differential receiving coils, thereby strengthening the induced voltages caused by the electromagnetic field excited from the detected metal objects. The balance state of the differential receiving coils is analyzed using a numerical model based on the Biot-Savart law, solving the total magnetic flux from the emitting windings. An optimization problem is constructed from the numerical model, and the optimal design parameters of the receiving coil are determined via a heuristic algorithm. Experimental results indicate that the newly designed prototype exhibits superior sensitivity compared to commercial differential detectors of comparable size. Specifically, the sensitivity of the novel detector is twice that of the advanced commercial counterpart.

The concept of magnetic suspension balance (MSB) represents a novel approach to the non-contact sensing of trace sample mass. Nevertheless, the actual processing and assembly are challenging to guarantee that the centreline of the magnetically coupled structure is entirely coaxial with gravity. This results in periodic rotation and jittering of the kinematic levitation body, and the mass measurement exhibits a similar pattern of error. This paper presents a cascade MSB (CMSB) system designed based on Hall sensors and electronic analytical balances. The system employs the magnetic coupling force as the internal force, thereby mitigating the adverse effects of rotation instability on measurement results. The parameters of the coils and permanent magnets in the magnetic coupling unit are optimised to ensure that the magnetic coefficients are not sensitive to height. Furthermore, the optimal arrangement strategy of the Hall sensors is obtained based on this optimised structure in combination with electromagnetic simulation. The present CMSB system is capable of isolated measurement of sample mass while retaining the high measurement performance of the electronic analytical balance. The experiments show that the proposed CMSB has a mean absolute error of 1.03 mg and a root mean square error of 0.37 mg in the measurement of milligram samples compared to the pre-optimisation period, which is a 10.3% improvement in accuracy and a 27.3% improvement in stability.