Angle Tracking Research Articles

Rack force fault tolerance estimation of steer-by-wire system under different resolver faults based on sensor flows

In the context of vehicle intelligence, steer-by-wire (SbW) has great potential for development and has become a current research hotspot. The key challenge for SbW systems is to obtain the nonlinear rack force generated by tire-road interaction, which is the source of the driver's real steering feel and the main disturbance of steering angle tracking control. Existing rack force estimators either are only suitable for non-aggressive steering or assume that the measured signals are reliable. This paper proposes a high-precision rack force estimation algorithm that is robust to primary sensor faults of a SbW system. Further, a rack force estimator based on the established high-order SbW mechanism model is designed, and a detailed stability proof and feedback gain selection guidance are given. The resolver sensor model is provided and analyzed, and a fault detection method based on discrete Fourier transform (DFT) and data fusion is developed, which has good real-time performance and high accuracy. The performance of rack force estimator was verified and compared by simulations and hardware-in-loop (HIL) experiments with various steering maneuvers and different resolver faults. The experiment results show that the proposed rack force estimation method can not only effectively improve the estimation accuracy even in aggressive steering condition and uneven road profiles, but also achieve accurate estimation of the rack force in the case of resolver faults. The proposed method obtains high-precision and high-reliability rack force estimation results while being easily embedded applied in engineering practice.

A virtual reference trajectory scheme for tracking control of wheeled mobile robots with slip disturbances

The problem of trajectory tracking control for wheeled mobile robots with slip disturbances is investigated in this paper. A virtual reference trajectory scheme is proposed based on disturbance compensations. Different from the conventional design philosophy of adding disturbance compensations to the controller, the proposed scheme integrates slip disturbance estimates into the reference trajectory. The proposed scheme consists of two parts. First, the slip disturbance estimates and the reference trajectory are fused to generate a virtual reference trajectory, where the slip disturbances are estimated using a disturbance approximation method. Second, a controller is designed to enable the wheeled mobile robot’s odometry position and yaw angle track the virtual reference trajectory, and then the actual position of the wheeled mobile robot track the position of the real reference trajectory. Comparison simulations and experiments are provided to illustrate the validity and advantages of the proposed scheme.

Adaptive Terminal Sliding Mode Trajectory Tracking Control for Autonomous Vehicles Considering Completely Unknown Parameters and Unknown Perturbation Conditions

In the actual implementation of autonomous vehicle controller and related applications, it is difficult to obtain all the actual parameters of the vehicle. Considering factors such as uneven pavement and different pavement conditions, it is difficult to accurately establish the vehicle dynamic system model. Based on the non-singular terminal sliding mode and adaptive control theory, this paper establishes a trajectory tracking control strategy for an autonomous vehicle with unknown parameters and unknown disturbances. Firstly, the complex trajectory tracking problem is decoupled from the position and heading angle tracking problem, and the preview error equation is established. Secondly, a non-singular terminal sliding mode (NTSM) controller is established to stabilize the trajectory tracking error to the origin in a finite time, and adaptive laws are proposed to estimate the unknown vehicle parameters to adapt to environmental changes. Through the CarSim–Matlab platform, typical working conditions are implemented to verify the proposed controller. Our experimental outcomes affirm that the NTSM controller effectively guarantees the autonomous vehicle’s accurate following of the reference path, ensuring smooth control inputs throughout the entire process.

Comparison of Neck Pain and Posture with Spine Angle Tracking System between Static and Dynamic Computer Monitor Use

This study investigates the effect of dynamic changes in monitor height and tilt on neck pain and posture of computer users. Using a wearable device, we aim to compare neck pain and spine angle between static and dynamic monitors. A spine angle tracking system using the Inertial Measurement Unit (IMU) was proposed, and the accuracy was validated. Eight office workers participated for five hours over two days, and each day used either a static monitor or a dynamic monitor that changed height and tilt every 30 min. The angles of C0, C7, L1, and S1 endplates were estimated using the proposed system. Changes in neck pain and spine angle with time were compared in static and dynamic monitors. The intraclass correlation coefficient confirmed a high concordance between the estimated and actual angles (p < 0.001). Rehabilitation Bioengineering Group (RBG) score increased less in the dynamic monitor compared to the static monitor (p = 0.003). Spinal curvatures are bent in the static monitor compared to the dynamic monitor. The estimated angles aligned well with X-ray measurements. A dynamic monitor that changes height and tilt at regular intervals may reduce neck pain increase and reduce bend forward posture compared to a static monitor.

Shallow trochlear groove and narrow medial trochlear width at the proximal trochlea in patients with trochlear dysplasia: Athree-dimensional computed tomography analysis.

Although the Dejour classification is the primary classification system for evaluating trochlear dysplasia, concerns have been raised about its reliability owing to its qualitative criteria and challenges associated with obtaining accurate radiographs. This study aimed to quantify trochlear dysplasia using three-dimensional (3D) computed tomography (CT) reconstruction with novel parameters related to the transepicondylar axis (TEA). Sixty patients were enrolled, including 20 with trochlear dysplasia and 40 healthy controls. The 3D CT model was generated using the Materialise Interactive Medical Image Control System software. The following six parameters were measured in eight consecutive planes at 15° intervals (planes 0-105): the distance from the TEA to the most cortical point of the lateral condyle ('LP-TEA', where LP stands for lateral peak), medial condyle ('MP-TEA', MP for medial peak)and deepest point of the trochlea ('TG-TEA', TG for trochlear groove). The distances from the medial epicondyle (MEC) to the corresponding TEA points were measured ('LP-MEC', 'MP-MEC'and 'TG-MEC'). In the dysplasia group, TG-TEA (planes 0, 15and 30) and MP-MEC (planes 0, 15and 30) were significantly greater than those in the control group (all p < 0.05 for planes of TG-TEA and MP-MEC). For type A dysplasia, LP-MEC (plane 0) was greater than that in the control group. For type B dysplasia, the MP-MEC (planes 0 and 15) and TG-TEA (planes 0 and 15) were greater than those of the control group. For type D dysplasia, MP-MEC (planes 0, 15and 30) and TG-TEA (planes 0 and 15) were elevated. The 3D CT reconstruction analysis established a reproducible method for quantifying osseous trochlear morphology. Patients with trochlear dysplasia had a shallow TG and narrow medial trochlear width at tracking angles of 0°-30°. This finding corroborates the clinical manifestations of recurrent patellar instability that occur during early flexion. Level III.

Novel high-safety aeroengine performance predictive control method based on adaptive tracking weight

Increasing attention has been attracted to the dynamic performance and safety of advanced performance predictive control systems of the next-generation aeroengine. The latest research demonstrates that Subspace-based Improved Model Predictive Control (SIMPC) can overcome the difficulty in solving the predictive model in MPC/NMPC applications. However, applying constant design parameters cannot maintain consistent control effects in all states. Meanwhile, the designed system relies too much on sensor-measured data, and thus it is difficult to thoroughly validate the safety of the system because of its high complexity. This means that any potential hardware/software faults will endanger the engine. Therefore, this paper first presents a novel nonlinear mapping relationship to adaptively tune the tracking weight online with the change of Power Lever Angle (PLA) and real-time relative tracking error. Thus, without introducing additional design parameters, an Adaptive Tracking Weight-based SIMPC (ATW-SIMPC) controller is designed to improve the control performance in all operating states effectively. Then, a Primary/Backup Hybrid Control (PBHC) strategy with the ATW-SIMPC controller as the primary system and the traditional speed (Nf) controller as the backup system is proposed to ensure safety. The designed affiliated switching controller and the real-time monitor therein can be used to realize reasonable and smooth switching between primary/backup systems, so as to avoid bump transition. The PBHC system switches to the Nf controller when the ATW-SIMPC controller is wrong because of potential hardware/software faults; otherwise, the ATW-SIMPC controller keeps acting on the engine. The main results prove that the ATW-SIMPC controller with the optimal nonlinear mapping relationship, compared with the existing SIMPC controller, uplifts the dynamic control performance by 32% and reduces overshoots to an allowable limit, resulting in a better control effect in full state. The comparison results consistently indicate that the PBHC can guarantee engine safety in occurrence of hardware/software faults, such as sensor/onboard adaptive model faults. The approach proposed is applicable to the design of a model-based engine intelligent control system.

Cortical tracking of visual rhythmic speech by 5- and 8-month-old infants: Individual differences in phase angle relate to language outcomes up to 2years.

It is known that the rhythms of speech are visible on the face, accurately mirroring changes in the vocal tract. These low-frequency visual temporal movements are tightly correlated with speech output, and both visual speech (e.g., mouth motion) and the acoustic speech amplitude envelope entrain neural oscillations. Low-frequency visual temporal information ('visual prosody') is known from behavioural studies to be perceived by infants, but oscillatory studies are currently lacking. Here we measure cortical tracking of low-frequency visual temporal information by 5- and 8-month-old infants using a rhythmic speech paradigm (repetition of the syllable 'ta' at 2Hz). Eye-tracking data were collected simultaneously with EEG, enabling computation of cortical tracking and phase angle during visual-only speech presentation. Significantly higher power at the stimulus frequency indicated that cortical tracking occurred across both ages. Further, individual differences in preferred phase to visual speech related to subsequent measures of language acquisition. The difference in phase between visual-only speech and the same speech presented as auditory-visual at 6- and 9-months was also examined. These neural data suggest that individual differences in early language acquisition may be related to the phase of entrainment to visual rhythmic input in infancy. RESEARCH HIGHLIGHTS: Infant preferred phase to visual rhythmic speech predicts language outcomes. Significant cortical tracking of visual speech is present at 5 and 8months. Phase angle to visual speech at 8months predicted greater receptive and productive vocabulary at 24months.

UAV Swarm Centroid Tracking for Edge Computing Applications Using GRU-Assisted Multi-Model Filtering

When an unmanned aerial vehicles (UAV) swarm is used for edge computing, and high-speed data transmission is required, accurate tracking of the UAV swarm’s centroid is of great significance for the acquisition and synchronization of signal demodulation. Accurate centroid tracking can also be applied to accurate communication beamforming and angle tracking, bringing about a reception gain. Group target tracking (GTT) offers a suitable framework for tracking the centroids of UAV swarms. GTT typically involves accurate modeling of target maneuvering behavior and effective state filtering. However, conventional coordinate-uncoupled maneuver models and multi-model filtering methods encounter difficulties in accurately tracking highly maneuverable UAVs. To address this, an innovative approach known as 3DCDM-based GRU-MM is introduced for tracking the maneuvering centroid of a UAV swarm. This method employs a multi-model filtering technique assisted by a gated recurrent unit (GRU) network based on a suitable 3D coordinate-coupled dynamic model. The proposed dynamic model represents the centroid’s tangential load, normal load, and roll angle as random processes, from which a nine-dimensional unscented Kalman filter is derived. A GRU is utilized to update the model weights of the multi-model filtering. Additionally, a smoothing-differencing module is presented to extract the maneuvering features from position observations affected by measurement noise. The resulting GRU-MM method achieved a classification accuracy of 99.73%, surpassing that of the traditional IMM algorithm based on the same model. Furthermore, our proposed 3DCDM-based GRU-MM method outperformed the Singer-KF and 3DCDM-based IMM-EKF in terms of the RMSE for position estimation, which provides a basis for further edge computing.

Trajectory Re-Planning and Tracking Control for a Tractor–Trailer Mobile Robot Subject to Multiple Constraints

Autonomous tractor–trailer robots possess a broad spectrum of applications but pose significant challenges in control due to their nonlinear and underactuated dynamics. Unlike the tractor, the motion of the trailer cannot be directly actuated, which often results in a deviation from the intended path. In this study, we introduce a novel method for generating and following trajectories that circumvent obstacles, tailored for a tractor–trailer robotic system constrained by multiple factors. Firstly, leveraging the state information of both the obstacles and the desired trajectory, we formulate an improved trajectory for obstacle avoidance using the nonlinear least squares method. Subsequently, we propose an innovative tracking controller that integrates a universal barrier function with a state transformation strategy. This amalgamation facilitates the accurate tracking of the prescribed trajectory. Our theoretical analysis substantiates that the proposed control methodology ensures exponential convergence of the line-of-sight (LOS) distance and angle tracking errors, while enhancing the transient performance. To validate the efficacy of our approach, we present a series of simulation results, which demonstrate the applicability of the developed control strategy in managing the complex dynamics of tractor–trailer robots.

The Design and Dynamic Control of a Unified Power Flow Controller with a Novel Algorithm for Obtaining the Least Harmonic Distortion

This study investigates the control and dynamic operation of the Unified Power Flow Controller made of shunt and series converters, a Static Synchronous Compensator, and a Static Synchronous Series Compensator, respectively, connected back-to-back through a common DC-link capacitor. The model of a 48-pulse Voltage Source Converter is constructed from a three-level Neutral Point Clamped converter, which allows the total harmonic distortion to be reduced. An optimal conduction angle tracking system of the three-level inverter is designed to minimize distortion by detecting proper harmonic component elimination. Starting from the six-step modulation strategy, the dq decoupled control schemes of both compensators in open and closed loops are presented. Finally, the MATLAB-Simulink model of the power flow controller is implemented and analyzed. The results show that the controller can track the power changes and apply a suitable voltage to the power system so that the power flow can be controlled. This way, the power flow controller dynamically improves the voltage and power quality across the power network while simultaneously improving the transient stability of the system. It can eliminate all system disturbances resulting from oscillations and harmonics in voltage and current within a very short time. The procedural approach used to model and simulate the Unified Power Flow Controller, as well as the new algorithm used to obtain the harmonic number that minimizes the total harmonic distortion, can be applied to any AC power system.

Research on anti-swing control strategies for three-dimensional overhead cranes with non-stationary enhanced swing angle suppression

In this paper, a non-stationary enhanced swing angle suppression control strategy is proposed to address the issue of excessive swinging angles during the transportation process of a three-dimensional overhead crane. Firstly, in response to the substantial non-stationary initial swing angle resulting from the abrupt increase in driving force during the startup of the overhead crane, we have devised a time-varying damping resistance model. This model is specifically designed to curtail the rapid force surge, subsequently diminishing the swing angle of the payload. Secondly, during the transport phase of the overhead crane, we have established an augmented coupling signal between the displacement tracking error and the payload swing angle tracking error. Drawing upon the principles of energy dissipation, we have devised a nonlinear sway controller. Next, the closed-loop stability of the control system is validated through the use of Lyapunov’s method and the LaSalle invariance principle. Finally, the proposed control strategy’s effectiveness has been substantiated through simulation analysis and physical experiments. This approach not only proves capable of effectively suppressing excessive payload swing angles during the transportation process of the overhead crane but also facilitates the rapid and precise positioning of the payload. This significantly enhances the efficiency of the overhead crane’s transport operations.

Beam Tracking Based on a New State Model for mmWave V2I Communication on 3D Roads

&lt;p&gt;The expansion of 5G and Internet of Things has laid a good foundation for the in-depth research of Internet of vehicles. Low frequency resources are scarce, and Internet of vehicles communication requires extremely high communication rate. Millimeter wave can meet the above two requirements, but its characteristics and the complicated communication conditions of Internet of vehicles make it difficult to combine the two. Overcoming these problems and making beam tracking accurate and steady is a major challenge at present. In this paper, a new extended Kalman filter tracking algorithm is proposed for mmWave V2I scenarios. On the basis of the original algorithm, a threshold prediction update mechanism is added. A new scheme is adopted, which takes position and velocity as tracking variables, and the tracking model is derived for the first time in MIMO 3D scenarios based on this scheme. The model considers the three-dimensional road conditions, including the vehicle deflection motion and the millimeter wave link blocked by large vehicles, which is more suitable for practical application scenarios. The simulation results reveal that the position and velocity tracking scheme is superior to the angle and gain tracking scheme, and the tracking error of the proposed algorithm is lower than that of the algorithms using similar state models. Based on the three-dimensional scene, it considers more realistic situations, and is more consistent with the kinematic characteristics of the vehicle and has more practical significance.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Energy response of a mono-axis tracked solar thermal collector with vacuum tubes

. Looking towards a sustainable future, Transilvania University of Brasov develops many projects on diverse renewable energy conversion systems; this paper presents a solar tracked solar thermal collector (STC) system, designed for a future implementation on Transilvania University campus. The specific requirement is that the STC system has to be configured to keep a zero energy response during the summer holydays (when the energy consumption is null). The proposed solution describes a mono-axial solar tracking system designed to perform an annual step wise tracking program to capture the most of the available solar energy using a solar thermal collector (STC) with vacuum tubes. The tracking program represents an optimised step tracking law developed in dependence with the diurnal movement of the sun. Numerical simulations are done for one year interval, for Brasov Romania geographic site, to evaluate the daily variations of: the pseudo-equatorial solar angles (γ, β); the pseudo-equatorial tracking angles (γ*, β*); the incidence angle; the available beam solar radiation (B) and the beam received solar radiation by the STC system (B*). The energy response of the tracked STC, for Brasov, Romania, is evaluated considering both clear sky and cloudy sky conditions, while neglecting the diffuse radiation effect.

Robust adaptive control of underwater glider for bottom sitting-oriented soft landing

This paper deals with the formalization, design, theorization, and implementation of a robust adaptive nonlinear control scheme to solve the bottom sitting-oriented soft landing control problem for an underwater glider under model uncertainties, actuator dynamics, and external disturbances. First, uniformized motion equations are derived based on Lie derivatives for describing pitch angle and vertical velocity tracking control. Then, the robust adaptive control framework is enhanced by containing an anti-windup auxiliary system and a disturbance observer. The stability of the closed-loop control system based on Lyapunov theory is proven to guarantee the boundedness of the entire internal signals. Finally, multifarious experimental results are also conducted by a self-developed underwater glider to demonstrate the effectiveness of the proposed controller.

Double-loop frame-based adaptive neural sliding-mode control of single-input 3-DOF flexible-joint manipulator

Flexible-joint manipulators (FJMs) have been attracting much attention in recent decades. However, position control and vibration suppression of single-input (SI) multi-degrees-of-freedom (multi( ⩾ 3 )-DOF) FJM is still a high mountain to climb due to the characteristic that some states of such FJMs cannot be directly controlled by the SI. This paper aims to carry out this challenging research. We present a double-loop frame-based adaptive neural sliding-mode control method for an uncertain horizontal SI 3-DOF FJM, i.e. a two-link FJM with only one actuator at the first joint. Since only the actuator angle can be directly controlled, in the inner loop, we design a torque controller so that the actuator angle tracks a time-varying reference actuator angle, designed in real-time by the outer loop. In the outer loop, we consider the reference actuator angle as a virtual control signal and design it based on the dynamic coupling relationships, aiming to indirectly control the first link to its target position and suppress the vibration of both links. Furthermore, to enhance the transient system performance, we plan the input signal of the outer loop (i.e. the target angle) as a smooth reference-trajectory signal. The validity and superiority of this method are demonstrated in simulations.

Structural Flexibility Effect on Spaceborne Solar Observation System’s Micro-Vibration Response

The spaceborne solar observation system is crucial for the study of space phenomena such as solar flares, which requires high tracking accuracy. This study presents a coupling model that integrates mechanical, electrical, and control models to investigate the structural flexibility effect on the micro-vibration response. We established a rigid–flexible model using mechanical parts. We considered the influence of flexible features while studying the dynamic responses in its operation. The state-space equations of the system showed that modal frequency, damping, and modal participation factors played significant roles. We derived transfer functions using the Laplace transform of the coupling models to better understand this mechanism, and Simulink models were thereby established. We simulated the acceleration responses of the rigid–flexible and rigid models under angle tracking modes, and the results showed significant differences. We also simulated the acceleration responses of the models under various control frequencies, and the optimal control frequency was thus obtained. Finally, we performed experiments, and the results indicated that the rigid–flexible model could better predict the motion and acceleration responses for the spaceborne solar observation system. This study provides valuable information for understanding the role of flexible features in space performance high-tracking accuracy instruments and for micro-vibration suppression research.

Analysis of Braking Performance of Distributed Drive Vehicle Under Two-Wheel Hub Motor Failure

For distributed hub-driven vehicles, under braking conditions, when the hub motor fails, it will seriously threaten the safety of the vehicle, and there will be dangerous conditions such as braking distance increase and braking deviation, while the failure of the two-wheel hub motor has a more complex impact on the braking performance of the vehicle. Based on this, this paper selected a distributed hub motor drive vehicle as the research object and simulated the braking performance of the vehicle under the failure of the ipsilateral-side two-wheel hub motor system, coaxial two-wheel hub motor system, and diagonal two-wheel hub motor system. Combined with the vehicle’s driving track, yaw speed, and centroid side deflection Angle, the influence degree of the vehicle’s braking and stability was analyzed. The results show that the failure of the outer two-wheel hub motor has the greatest effect on vehicle braking stability than that of the diagonal wheel failure and the coaxial wheel failure. The effect of two-wheel hub motor failure on vehicle braking is greater than that of diagonal wheel failure and ipsilateral-side wheel failure. With the increase in vehicle braking speed and the decrease in road adhesion coefficient, vehicle instability, and braking performance become worse and worse.

Online Iterative Optimization for Angle Tracking of Electromagnetic Scanning Micro-Mirror With Unmatched Interference and Hysteresis

Online Iterative Optimization for Angle Tracking of Electromagnetic Scanning Micro-Mirror With Unmatched Interference and Hysteresis

Mechanism design and dynamic switching modal control of the wheel-legged separation quadruped robot

AbstractCurrently, most wheel-legged robots need to complete the switching of the wheel-and-leg modal in a stationary state, and the existing algorithms of statically switching the wheel-leg modal cannot meet the control requirements of multimodal switching dynamically for robots. In this paper, to achieve efficient switching of the wheel-and-leg modal for a quadruped robot, the novel transformable mechanism is designed. Then, a multimodal coordination operation control framework based on multiple algorithms is presented, incorporating the minimum foot force distribution method (algorithm No.1), the minimum joint torque distribution method (algorithm No.2), and the method of combining the single rigid body dynamic model with quadratic programming (algorithm No.3). In the process of switching wheel-leg modal dynamically, the existing algorithm No.3 is prone to produce the wrong optimal force due to the change of the whole-body rotational inertia. Therefore, an improved algorithm No.1 and algorithm No.2 are proposed, which do not consider the change in the body’s inertia. The control effects of the three algorithms are compared and analyzed by simulation. The results show that algorithm No.3 can maintain a small error in attitude angle and speed tracking regardless of whether the robot is under multilegged support or omnidirectional walking compared to the other two algorithms. However, proposed algorithms No.1 and No.2 can more accurately track the target speed when the robot is walking with wheels raising and falling. Finally, a multi-algorithm combination control scheme formulated based on the above control effects has been demonstrated to be effective for the dynamic switching of the wheel-and-leg modal.

Impact of backtracking strategies on techno-economics of horizontal single-axis tracking solar photovoltaic power plants

Optimisation of horizontal single-axis tracking solar photovoltaic power plants is important for its optimal application. Commonly, standard backtracking has been applied to avoid mutual shading and improve the full load hours and levelised cost of electricity; however, this approach is not always the best solution for state-of-the-art modules with half cell technology. Backtracking has not yet been studied for different test sites with different solar and climatic conditions. This study aims to improve the knowledge on the techno-economic performance of horizontal single-axis tracking systems with half cell modules applying different backtracking strategies in full hourly resolution for nine test sites globally and varying row spacing. In addition to the standard backtracking algorithm, an advanced backtracking algorithm that varies the tracking angle only if the irradiance can be improved, and an advanced sophisticated backtracking algorithm simulating the irradiance for all possible tracking angles, are studied. The results confirm that standard backtracking is only superior for specific conditions. Compared to no backtracking, standard backtracking shows up to ca. 9% higher levelised cost of electricity due to lower full load hours. Advanced backtracking can lower the levelised cost of electricity by up to 9% and advanced sophisticated backtracking by up to 12%, due to improved full load hours. In general, results are similar and comparable for all test sites studied. This study highlights the importance of backtracking for optimised future horizontal single-axis tracking system planning.