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The series electro-hydraulic hybrid powertrain can improve the power characteristics of battery rail vehicles (BRVs) while also extending battery life and increasing vehicle mileage. A novel electric motor start-up method using the hydraulic pump/motor to reversely drive the permanent magnet synchronous motor (PMSM) to restart at a speed is proposed based on the energy reverse transfer characteristics between the electric motor and hydraulic pump/motor. PID controls the reverse driving process of the hydraulic motor. The zero vector voltage (ZVV) method is used to determine the initial speed and rotor position of the motor restart at a speed. The electric motor speed control adopts the speed sensorless space vector pulse width modulation (SVPWM) control based on the back-electromotive force (EMF) integration method. The simulation models are carried out in MATLAB/Simulink and AMESim and built a special test platform. The results show that the method for controlling electric motor restart is feasible and effective. The start-up current of the electric motor is related to its initial speed. The closer the initial speed is to its target speed, the smaller its start-up current is, the faster the electric motor reaches the stable target speed.

A band-limited magnitude-selective affine (MSA) function-based model is proposed for digital predistortion (DPD) of broadband power amplifiers (PAs) in 5G millimeter-wave frequency band. The new model is derived from the band-limited canonical piecewise linear function-based model by employing MSA functions, which can obviously reduce the number of multiplication operations and the model complexity. Experimental results show that the proposed model gives better normalized mean square error and DPD performance in comparison with some existing models when a broadband PA is excited by a 5G new radio (NR) signal of 400-MHz bandwidth at 28-GHz band.

An antipodal linearly tapered slot filtenna (ALTSFA) with diverse split-ring resonators (SRRs) is proposed. The ALTSFA is actually an antipodal linearly tapered slot antenna (ALTSA) fed by a substrate integrated waveguide (SIW) whose cut-off characteristic is utilized to obtain a lower-band suppression. A broad-coupled complementary SRR (BC-CSRR) and 11 SRRs on the ALTSA are used to achieve an upper-band suppression. Hence, filtering function with wide stopbands is achieved without enlarging its size and deteriorating the radiation performance. A prototype of the proposed ALTSFA was fabricated and measured, and a bandwidth ranging from 23.5 to 27.5 GHz, a maximum gain of 10 dBi, and a maximum out-of-band suppression of 20.55 dB are observed, validating its good performance. The proposed ALTSFA can be a promising candidate for compact 5G/B5G millimeter-wave communication system.

In this letter, a three-dimensional ground coplanar waveguide (3D-GCPW) structure is proposed as a broadband planar transition between the conventional GCPW and substrate integrated coaxial line (SICL). The proposed 3D-GCPW contains a 3-D central conductor constructed by two copper layers which are connected together by metallized blind vias and two side ground planes. Its characteristic impedance is mainly determined by the width of the 3-D central conductor and the gap to the side ground plane; thus, the requirement for machining accuracy of metallized blind vias in 3D-GCPW can be reduced during the machining process. A back-to-back structure of the 3D-GCPW transition is fabricated by a multilayer printed circuit board (PCB) process and measured to validate the good performance. The experimental results show that the proposed 3D-GCPW transition exhibits a reflection coefficient less than −10 dB and an acceptable insertion loss within dc to 42 GHz, making it promising for high-performance multiple-channel transceiver or massive integrated applications.

A high-gain dual-band resonant cavity antenna (RCA) for the fifth-generation (5G) millimeter-wave (MMW) communications is presented in this letter. The proposed antenna provides the high gain and large gain-bandwidth product over the 28 GHz band and the 38 GHz band. The heights of the second- and third-order resonant in the RCA are optimized for dual-band operation. Improvements on the gain and the bandwidth are achieved in both bands when stepped rings are added. The gain is further increased with a circular patch on a partially reflective surface, which is made by a substrate of high permittivity. Finally, a prototype is designed, simulated, and verified through measurement. Good performance is achieved: in the 26.5–28 GHz band, the bandwidth is 5.5% and the peak gain is 20.3 dBi; in the 37.5–39.4 GHz band, the bandwidth is 4.9% and the peak gain is 20.4 dBi. The proposed antenna has the features of low cost and easy fabrication as well.

In this article, novel millimeter-wave (mmWave) filtennas (filtering antennas) are proposed to realize compact size and low insertion loss for 5G applications. It is achieved by employing eighth-mode substrate-integrated waveguide (EMSIW) cavities fully shielded by metallized vias and cover as resonators, which are named as fully shielded EMSIW (FSD-EMSIW) cavities. Interdigital coupling between cavities is introduced in order to obtain higher coupling strength for wideband operation. The proposed single-polarized antenna consists of a feeding stripline, two FSD-EMSIW cavities, and two stacked square patches, generating the four-order filtering antenna response. Furthermore, this design has been extended to realize a dual-polarized filtenna by employing double sets of feeding network. For demonstration, single-/dual-polarized filtenna prototypes were fabricated and measured, the measured results show that the 5G mmWave band (24.25–29.5 GHz) can be covered with average gains of 4.5 dBi. Good bandpass filtering response is also observed. Finally, to validate the proposed idea in array applications, a 16-element filtenna array is designed and measured with good performance.

In this paper, to address the problem of automatic positioning and grasping of bolster spring with complex geometric features and cluttered background, a novel image-based visual servoing (IBVS) control method based on the corner points features of YOLOv3 object detection bounding box is proposed and applied to the robotic grasping system of bolster spring. The YOLOv3 object detection model is used to detect and position the bolster spring and then based on the corner points features of the bolster spring bounding box, the IBVS controller is designed to drive the end effector of the robot to the desired pose. This method adopts the approach-align-grasp control strategy to achieve the grasping of the bolster spring, which is very robust to the calibration parameter errors of the camera and the robot model. With the help of Robotics and Machine Vision Toolboxes in Matlab, IBVS simulation analysis based on feature points is carried out. The results show that it is reasonable to use the corner points of the object detection bounding box as image features under the initial pose where the image plane is parallel to the object plane. The positioning and grasping experiments are conducted on the robotic grasping platform of bolster spring. The results show that this method is effective for automatic positioning and grasping of bolster spring with complex geometric features and cluttered background, and it has strong robustness to the change of illumination.

In recent years, human motion recognition, as an important application of the intelligent perception of the Internet of Things, has received extensive attention. Many applications benefit from motion recognition, such as motion monitoring, elderly fall detection, and somatosensory games. Several existing RF-based motion recognition systems are susceptible to multipath effects in complex environments, resulting in lower recognition accuracy and difficulty in extending to other scenarios. To address this challenge, we propose RF-Motion, a device-free commercial off-the-shelf (COTS) RFID-based human motion recognition system that can detect human motion in complex multipath environments such as indoor environments. And when the environment changes, RF-Motion still has high recognition accuracy, even without retraining. In addition, we use data slicing to solve the problem of discontinuity in the time domain of RFID communication and then use the synthetic aperture (SAR) algorithm to obtain the fingerprint feature matrix corresponding to each motion. Finally, the dynamic time warping (DTW) algorithm is used to match the prior motion fingerprint database to complete the motion recognition. Experiments show that RF-Motion can achieve up to 90% accuracy for human motion recognition in an indoor environment, and when the environment changes, it can still reach a minimum accuracy of 87%.

This letter reports a strategy of full-digital arrays with nonreciprocal transmitting (Tx) and receiving (Rx) beam patterns, for the first time, for 5G/6G wireless communications. The proposed full-digital array contains a smaller number of Rx channels than that of the Tx channels. The unequal number of Tx and Rx channels makes the transmitting and receiving patterns asymmetrical, which would not only release the burden of data processing but also reduce the hardware cost and power consumption of the entire system. Importantly, as compared with conventional large-scale beamforming arrays, the proposed strategy will not deteriorate the range of coverage at an instantaneous time. A 64-element full-digital beamforming array prototype was designed, fabricated, and characterized for a proof-of-concept demonstration.

A novel wideband magnetoelectric (ME) dipole antenna with dual circular polarization and unidirectional radiation is proposed in this letter. The proposed antenna is based on two perpendicular sub-ME dipoles realized by four V-shaped patches and four V-section columns, and each of them is composed of an electric dipole and a magnetic dipole in parallel. Fed by two simple Γ-shaped feeds, 90° phase difference between the electric dipole and the magnetic dipole in each of the sub-ME dipoles is achieved, hence the dual-circularly polarized radiation is generated. Wide impedance bandwidth is obtained in virtue of the two kinds of dipoles being excited simultaneously. The 3 dB axial-ratio (AR) bandwidth is enlarged by optimizing the V-section columns and a circular cavity. Besides, the port isolation is apparently enhanced by adding slits on the patches and elaborating different spacings between each feed and its two-sided columns. Measured results show that the proposed antenna has many appealing properties, such as a unidirectional radiation pattern, an impedance bandwidth (reflection coefficients ≤–10 dB and port isolation ≥ 10 dB) of 51.1% and a 3 dB AR bandwidth of 41.9%.