Target Rotation Angle Research Articles

Seismic Performance Evaluation of Moment Resistance Connection by Load Velocity.

AbstractThe seismic performance of beam‐column connections is typically evaluated using a loading protocol specified by codes such as AISC. This protocol involves applying incremental and repeated loads at a specified speed to reach a target rotation angle, with a low load velocity of about 0.5 mm/s to 1.0 mm/s. However, testing at such a low load velocities may not fully account for brittleness breakdown due to factors such as a reduction in material toughness and a decrease in maximum deformation rate caused by stress concentration in vulnerable areas at high load velocities.Therefore, it is important to verify the seismic performance of connections, including their plastic deformation ability, under the influence of dynamic loads with high velocities, such as those experienced during an earthquake. We conducted a static and dynamic experiment on welded connections and extended end plate connections to analyze the effect of load velocity on connections behavior.Our results showed that increasing the load velocity reduced the strength of the connection, its plastic deformation capacity, and energy absorption capacity. These findings confirm that load velocity can significantly affect the seismic performance of connections and suggest that the current loading protocol may not fully capture the connection behavior under dynamic loads.

Investigation of the Dependence of the Yield of Neutrons and Protons of the DD Reaction from Ti and CVD Diamond on the Target Rotation Angle

Investigation of the Dependence of the Yield of Neutrons and Protons of the DD Reaction from Ti and CVD Diamond on the Target Rotation Angle

Investigation of the Dependence of the Yield of Neutrons and Protons of the DD Reaction from Ti and CVD Diamond on the Target Rotation Angle

Investigation of the Dependence of the Yield of Neutrons and Protons of the DD Reaction from Ti and CVD Diamond on the Target Rotation Angle

Deep Deterministic Policy Gradient and Active Disturbance Rejection Controller based coordinated control for gearshift manipulator of driving robot

In order to improve the shift precision of the gearshift manipulator, a coordinated control method for the gearshift manipulator based on the Deep Deterministic Policy Gradient (DDPG) and Active Disturbance Rejection Controller (ADRC) is proposed. Firstly, the kinematic model and dynamics model of the gearshift manipulator are established. Secondly, a coordinated control strategy is proposed to solve the target rotation angle of the servo motor, so as to deal with the nonlinear trajectory problem caused by the mechanical decoupling strategy. Then, an ADRC-based controller and a DDPG-based parameter adjuster are proposed. A DDPG model is established to adaptively adjust the control parameters of ADRC through the target rotation angle, actual rotation angle and rotation angle error. Finally, the theoretical stability proof and experimental verification of the proposed method are conducted. The test results show that the mean absolute error of the proposed method is 34% and 18% lower than that of ADRC and fuzzy PID methods. It shows the effectiveness of the method.

Bionic Perception Method of Navel Orange Plucking Position Based on Fmincon and PD Angle Control

In this paper, a bionic perception method of navel orange plucking position based on Fmincon and Proportional Differential (PD) angle control is proposed to solve the problems of wind disturbance and green branches in dynamic unstructured environment. Different from these algorithms that limited to two-dimensional images, this method realizes picking position perception in three-dimensional. Meanwhile, the perception method and the picking robot control algorithm are achieved simultaneously. Firstly, an optimal solution model of the global target rotation angle of the control system based on Fmincon is established to solve the angle optimization problem of robot target approach motion. Secondly, a bionic perception system of plucking position based on PD angle control is constructed to solve specific perception problems. Finally, a joint simulation platform for picking robots based on Solidworks, Adams, and Simulink is given; the validity and accuracy of the algorithm were verified. The experimental results show that the picking accuracy rate is 95%, the angle error of each mechanism and the displacement error are less than 0.5 degrees and 10mm, respectively. The total time from the optimized angle calculation to the system's stability is only about 0.33s. This method is suitable for the rapid perception of plucking position and active angle control of picking robots under dynamic unstructured environment.

Subcarrier‐based tomographic imaging for single‐frequency network passive radar with orthogonal frequency‐division multiplexing waveform

Most of modern digital television and broadcast systems adopt two key techniques, namely, orthogonal frequency-division multiplex (OFDM) technology and single-frequency network (SFN) technology. The multicarrier structure of the OFDM modulation enables us to perform tomographic imaging for each subcarrier independently. No narrowband approximations are needed in this process. Furthermore, all transmitters in SFN operate at the same frequency band but situated in different locations. SFN constitutes a multistatic passive radar system naturally even with just one receiver. The spatially separated transmitters provide spatial diversity and can be exploited to improve image resolution. In this study, the authors first derive the exact formulation of subcarrier based tomographic imaging. Then, point spread function is used to study the imaging performance of the novel processing technique in terms of resolution. Finally, for several scenarios, numerical simulations are conducted and their results are compared, which indicated that the proposed method can obtain decent results even under the conditions of very limited transmitters and small target rotation angle.

Design of a laser receiver used for farmland laser location

To develop a small agricultural machine location system for small paddy fields in the south of China, we have designed a laser receiver for farmland laser three point location system. The laser receiver adjusts its receiving target rotation angle in real time through the servo mechanism, to ensure that it can effectively receive the signal transmitted from the laser emission source. Meanwhile, in order to accurately identify the laser spot center of the target, we have studied, the laser spot preprocessing algorithms based on the arithmetic mean filter algorithm, median filter algorithm andα-β filter algorithm. The laser receiver was fixed on the transplanter and tested dynamically. The result shows that the laser receiver can receive and recognize the laser signal accurately when the transplanter moves at different speeds such as 5,12,20 cm/s in the distance of 100 m, in the meantime, it can reflect the moving state of the transplanter in real time.

Method for measuring target rotation angle by theodolites

To overcome the disadvantage of the current measurement methods using theodolites in an environment with shock and long working hours and so on, this paper proposes a new method for 3D coordinate measurement that is based on an immovable measuring coordinate system. According to the measuring principle, the mathematics model is established and the measurement uncertainty is analysed. The measurement uncertainty of the new method is a function of the theodolite observation angles and their uncertainty, and can be reduced by optimizing the theodolites’ placement. Compared to other methods, this method allows the theodolite positions to be changed in the measuring process, and mutual collimation between the theodolites is not required. The experimental results show that the measurement model and the optimal placement principle are correct, and the measurement error is less than 0.01° after optimizing the theodolites’ placement.

Multistatic and MIMO Distributed ISAR for Enhanced Cross-Range Resolution of Rotating Targets

In this paper, we present a new technique to exploit the data acquired simultaneously by multiple radar sensors carried by multiple air platforms to increase the cross-range resolution of inverse synthetic aperture radar (ISAR) images of rotating targets. This distributed ISAR technique is devised for two different cases: 1) multiple-input-multiple-output (MIMO) case with each platform carrying an active radar that transmits and receives RF waveforms and 2) multistatic case with a single platform carrying an active radar (transmitting and receiving) and the remaining platforms equipped with passive sensors (namely, receiving only). The processing chain proposed for the distributed ISAR is shown, together with the results obtained against simulated ISAR data for both the MIMO and the multistatic cases. The performance analysis shows that the proposed technique is able to provide an increase of the cross-range resolution up to the number of platforms in the multistatic case and even higher in the MIMO case, if the platforms are properly located. This is of great benefit in applications where the target rotation angle is insufficient to guarantee the desired resolution. A typical case is the imaging of ship targets with rotation induced by the sea swell structure under low sea state conditions. To make the results appealing for practical application, the performance degradation is also analyzed arising from errors in the knowledge of both the target rotation motion and the acquisition geometry. Experimental data collected by a ground-based radar operating together with a rotating platform are processed by following the presented distributed ISAR technique to validate the proposed approach.

Refined Wave-Based Control Applied to Nonlinear, Bending, and Slewing Flexible Systems

The problem of controlling the position and vibration of open-chain flexible structures undergoing fast maneuvers is of wide interest. In this work, the general flexible structure is actuated by a single actuator at one end, which, depending on the case of interest, is capable of rotating, translating, or simultaneously translating and rotating the root of the flexible system. The goal is to control the motion of the entire flexible system from rest to rest. This needs a simultaneous synthesis of position control and active vibration damping. A new strategy is presented based on further developments of wave-based control. As before it views the actuator motion as simultaneously launching and absorbing mechanical waves into and out of the system. But a new simple method of resolving the actuator motion into two waves is presented. By measuring the elastic forces exchanged at the interface between the actuator and the rest of the system, a returning displacement wave can be resolved. This is then added to a set, launch wave to determine the actuator motion. Typically the launch wave is set to reach half the target displacement, and the addition of the return wave absorbs the vibration while simultaneously moving the system the second half of the target displacement, neatly achieving the two goals in one controlled motion. To date wave-based control has been applied to lumped, second-order, longitudinally vibrating systems. The refined method avoids a difficulty that previously arose in some contexts, thereby making wave-based control even more generic. It can easily control nonlinear elastic systems, laterally bending systems (in the sense of Euler–Bernoulli beams), and slewing systems where lateral translation and system rotation are strongly coupled. Numerical simulation results are presented for controlled, rest-to-rest maneuvers of representative flexible structures, all controlled using the same (linear) algorithm. The first case is control of a string of rigid bodies interconnected by nonlinear springs. The second problem is the rotational control of a very flexible one-link planar manipulator. Finally, in an extension of the previous system, the actuator both translates and rotates, slewing the flexible system to a target lateral displacement and a target rotation angle simultaneously. The strategy is found to be remarkably effective with many advantages. It seamlessly integrates position and vibration control. It is rapid, robust, energy efficient, and computationally light. It requires little sensing, little knowledge of the flexible system dynamics, and copes well with nonideal actuator behavior. It is generic and easily handles a wide variety of flexible systems. It can get the entire system to stop dead exactly at target with little vibration in transit.

Analysis of Polarization Orientation Angle Shifts by Artificial Structures

In this paper, the polarization orientation angle shifts induced by artificial structures were analyzed and attempted to combine target orientation information which characterizes an urban area with the polarization orientation angle information extracted by the circular-polarization method. In order to illustrate the characteristic of the polarization orientation angle shifts represented in an urban area, the X-band polarimetric synthetic aperture radar (SAR) datasets of Sendai City acquired by Pi-SAR were used. This paper is based on Kimura's idea that the variation of the polarization orientation angle shifts depends on the artificial structures, particularly for the target rotation angle. We found that the polarization orientation angle shift is also affected by the relative relationship between the target rotation angle and the flight direction. From these results, it is possible to estimate the target rotation angle via computation of the polarization orientation angle shift from polarimetric SAR data.

A high-performance/low-latency vector rotational CORDIC architecture based on extended elementary angle set and trellis-based searching schemes

The coordinate rotational digital computer (CORDIC) algorithm is a well-known iterative method for the computation of vector rotation. For applications that require forward rotation (or vector rotation) only, the angle recoding (AR) technique provides a relaxed approach to speed up the operation of the CORDIC algorithm. In this paper, we further apply the concept of AR technique to extend the elementary angle set in the microrotation phase. This technique is called the extended elementary-angle set (EEAS) scheme. The proposed EEAS scheme provides a more flexible way of decomposing the target rotation angle in CORDIC operation, and its quantization error performance is better than the AR technique. Meanwhile, to solve the optimization problem encountered in the EEAS scheme, we also proposed a novel search algorithm, called the trellis-based searching (TBS) algorithm. Compared with the greedy algorithm used in the conventional AR technique, the proposed TBS algorithm yields apparent signal-to-quantization-noise ratio (SQNR) improvement. Moreover, in the scaling phase of the EEAS-based CORDIC algorithm, we suggest a novel scaling operation, called Extended Type-II (ET-II) scaling operation. The ET-II scaling operation applies the same design concepts as the EEAS scheme. It results in much smaller quantization error than conventional Type-I scaling operation in the numerical approximation of scaling factor. By combining the aforementioned new schemes, the proposed EEAS-based CORDIC algorithm can improve the overall SQNR performance by up to 25 dB compared with previous works. Also, given the same target SQNR performance, we require only about 66% iteration number in the iterative CORDIC structure, or use 66% hardware complexity in the parallel CORDIC structure compared with conventional AR technique. Hence, high-performance/low-latency CORDIC very large-scale integration architectures can be achieved without degrading the SQNR performance.