High-precision Motion Tracking Research Articles

High-Precision Motion Detection and Tracking Based on Point Cloud Registration and Radius Search

Detecting and tracking dynamic objects in a scene using point cloud data collected by LiDAR and estimating the motion state of objects with high accuracy are challenges for autonomous driving technology. In this study, a motion detection method based on point cloud registration is investigated to detect motion through the overlapping relationship between source and target point clouds after registration and extract moving objects using clustering and scale analysis by combining the object information of interest acquired by deep learning networks. Next, object association is achieved by object motion information and geometric and texture features. Then, a point cloud registration method flow is designed to estimate the motion state of the object with high accuracy by point cloud registration. The detection, tracking and estimation of the accurate motion state of moving objects are achieved.

A human hybrid tracking and localization method for mixed reality simulation of complex system

In order to obtain stable and high-precision motion tracking in mixed reality (MR) simulation of the complex system, an optical-inertial hybrid tracking method is proposed, which combines the accuracy of optical motion capture equipment and the robustness of inertial motion capture equipment, and can reduce the occlusion problem of entity scene on the premise of ensuring the localization accuracy. The method has been applied to the ergonomic evaluation of large civil aircraft development processes, and the effectiveness and usability of the method have been verified.

Robust Hybrid Control Using Recurrent Wavelet- Neural-Network Sliding-Mode Controller for Two- Axis Motion Control System

In this paper, a robust hybrid control system (RHCS) for achieving high precision motion tracking performance of a two-axis motion control system is proposed. The proposed AHCS incorporating a recurrent wavelet-neuralnetwork controller (RWNNC) and a sliding-mode controller (SMC) to construct a RRWNNSMC. The two-axis motion control system is an x-y table of a computer numerical control machine that is driven by two field-oriented controlled permanent-magnet synchronous motors (PMSMs) servo drives. The RWNNC is used as the main motion tracking controller to mimic a perfect computed torque control law and the SMC controller is designed with adaptive bound estimation algorithm to compensate for the approximation error between the RWNNC and the ideal controller. The on-line learning algorithms of the connective weights, translations and dilations of the RWNNC are derived using Lyapunov stability analysis. A computer simulation and an experimental are developed to validate the effectiveness of the proposed RHCS. All control algorithms are implemented in a TMS320C31 DSP-based control computer. The simulation and experimental results using star and four leaves contours are provided to show the effectiveness of the RHCS. The motion tracking performance is significantly improved using the proposed RHCS and robustness to parameter variations, external disturbances, cross-coupled interference and frictional torque can be obtained as well for the two-axis motion control system.

Synchronization Control of a Dual-Cylinder Lifting Gantry of Segment Erector in Shield Tunneling Machine under Unbalance Loads

Segment assembling is one of the principle processes during tunnel construction using shield tunneling machines. The segment erector is a robotic manipulator powered by a hydraulic system to assemble prefabricated concrete segments onto the excavated tunnel surface. Nowadays, automation of the segment erector has become one of the definite developing trends to further improve the efficiency and safety during construction; thus, closed-loop motion control is an essential technology. Within the segment erector, the lifting gantry is driven by dual cylinders to lift heavy segments in the radial direction. Different from the dual-cylinder mechanism used in other machines such as forklifts, the lifting gantry usually works at an inclined angle, leading to unbalanced loads on the two sides. Although strong guide rails are applied to ensure synchronization, the gantry still occasionally suffers from chattering, “pull-and-drag”, or even being stuck in practice. Therefore, precise motion tracking control as well as high-level synchronization of the dual cylinders have become essential for the lifting gantry. In this study, a complete dynamics model of the dual-cylinder lifting gantry is constructed, considering the linear motion as well as the additional rotational motion of the crossbeam, which reveals the essence of poor synchronization. Then, a two-level synchronization control scheme is synthesized. The thrust allocation is designed to coordinate the dual cylinders and keep the rotational angle of the crossbeam within a small range. The motion tracking controller is designed based on the adaptive robust control theory to guarantee the linear motion tracking precision. The theoretical performance is analyzed with corresponding proof. Finally, comparative simulations are conducted and the results show that the proposed scheme achieves high-precision motion tracking performance and simultaneous high-level synchronization of dual cylinders under unbalanced loads.

A Robust and High-Precision Three-Dimensional Motion Tracking Algorithm for Gymnasts

A Robust and High-Precision Three-Dimensional Motion Tracking Algorithm for Gymnasts

Adaptive Fuzzy Sliding Mode Control for High-Precision Motion Tracking of a Multi-DOF Micro/Nano Manipulator

This letter introduces a robust adaptive control methodology for piezo-actuated flexure-based micro/nano manipulation mechanisms. This special control approach is established for tracking of the desired complex motion trajectories with system uncertainties. Further, the control methodology is formulated to accommodate not only the system uncertainties but also nonlinearities including the hysteresis effect and external disturbances in the motion of a 3-degrees-of-freedom (3-DOF) XYZ micro/nano manipulator. Adaptive fuzzy sliding mode control (AFSMC) is developed for the formulation of the control methodology. The fuzzy logic component and adaptation law employed in the controller are used to approximate the system uncertainties and compensate for the effect of nonlinear terms in the system. The resulting control strategy is devised using a sliding mode control scheme. The asymptotic tracking ability of the designed controller is proved by using Lyapunov-based stability analysis. Furthermore, an experimental study is performed on the 3-DOF compliant monolithic parallel micro/nano manipulator and the results confirm that the designed control approach produces high-precision motion tracking and smaller tracking errors compared to a model-free control technique, i.e. Proportional-Integral-Derivative (PID) controller.

Image-based tracking technique assessment and application to a fluid–structure interaction experiment

This work analyses the accuracy and capabilities of two image-based tracking techniques related to digital image correlation and the Lucas–Kanade optical flow method, with the subsequent quantification of body motion in a fluid–structure interaction experiment. A computer-controlled shaker was used as a benchmark case to create a one-dimensional oscillatory target motion. Three target frequencies were recorded. The measurements obtained with a low-cost digital camera were compared to a high-precision motion tracking system. The comparison was performed under changes in image resolution, target motion and sampling frequency. The results show that, with a correct selection of the processing parameters, both tracking techniques were able to track the main motion and frequency of the target even after a reduction of four and five times the sampling frequency and image resolution, respectively. Within this good agreement, the Lucas–Kanade technique shows better accuracy under tested conditions, achieving up to 15.6% of lower tracking error. Nevertheless, the achievement of this higher accuracy is highly dependent on the position of the selected initial target point. These considerations are addressed to satisfactorily track the response of a wall-mounted cylinder subjected to a range of turbulent flows using a single camera as the measuring device.

Design, Manufacturing and Test of a High-Precision MEMS Inclination Sensor for Navigation Systems in Robot-Assisted Surgery

Robot supported minimally invasive interventions are state of the art in operating theatres. To increase the accuracy of surgical instrument positioning, high-precision motion tracking systems are required. The miniaturization of microelectromechanical systems (MEMS) facilitates the placing of orientation detection sensors close to the mounting of the surgical instrument to enhance positioning accuracy. A high resolution inclination sensor was developed using the innovative approach of laser-micro-welding. Trench sizes down to 800 nm are fabricated with more than 6-fold increase in aspect ratios (structure depth to electrode gap) compared to sensors without gap reduction. Electrical and physical tests as well as finite-element-simulations were performed. An increased sensitivity from 7.2 fF/° up to 60 fF/° was verified for the sensor with reduced electrode gap and a customized ASIC.

Prospective motion correction with NMR markers using only native sequence elements.

To develop a method of tracking active NMR markers that requires no alterations of common imaging sequences and can be used for prospective motion correction (PMC) in brain MRI. Localization of NMR markers is achieved by acquiring short signal snippets in rapid succession and evaluating them jointly. To spatially encode the markers, snippets are timed such that signal phase is accrued during sequence intervals with suitably diverse gradient actuation. For motion tracking and PMC in brain imaging, the markers are mounted on a lightweight headset. PMC is then demonstrated with high-resolution T2 *- and T1 -weighted imaging sequences in the presence of instructed as well as residual unintentional head motion. With both unaltered sequences, motion tracking was achieved with precisions on the order of 10 µm and 0.01° and temporal resolution of 48 and 39 ms, respectively. On this basis, PMC improved image quality significantly throughout. The proposed approach permits high-precision motion tracking and PMC with standard imaging sequences. It does so without altering sequence design and thus overcomes a key hindrance to routine motion tracking with NMR markers. Magn Reson Med 79:2046-2057, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Experimental Investigation of Robust Motion Tracking Control for a 2-DOF Flexure-Based Mechanism

The design, parameter identification and robust motion tracking control of a two degree of freedom (2-DOF) flexure-based micro/nanomechanism are presented in this paper. In the presented compliant mechanism, the cross-axis coupling ratio is below 1% indicating excellent decoupling performance. Despite this, during motion tracking the cross coupling effect cannot be ignored. To enhance the accuracy of micro/nanomanipulation, a laser interferometry-based sensing and measurement system is established. Nonlinearities such as creep/drift and hysteresis are present in this system, which are compensated with closed-loop control. Open-loop tracking results for a 1-DOF trajectory, with and without cross-axis coupling compensation are also presented. Robust motion tracking control is extended to support 2-DOF motion trajectories. This controller is implemented to track the desired trajectories over one and two axes of motion. Robust motion control demonstrates high precision and accurate motion tracking of the 2-DOF flexure-based mechanism. The cross-axis coupling is treated as a known disturbance and the performance of tracking 1-DOF trajectory, with and without cross-axis coupling compensation, is presented. Circular motion trajectories with radii of 10 μm, 1 μm, and 250 nm are also tracked. The experimental results presented in this paper demonstrate effective compensation of the cross-axis coupling with high precision motion tracking. The resultant 2-DOF closed-loop position tracking error in the X and Y axes are within ±20 nm during dynamic motion, and ±8 nm in the steady state.

Brownian motion of arbitrarily shaped particles in two dimensions.

We implement microfabricated boomerang particles with unequal arm lengths as a model for nonsymmetric particles and study their Brownian motion in a quasi-two-dimensional geometry by using high-precision single-particle motion tracking. We show that because of the coupling between translation and rotation, the mean squared displacements of a single asymmetric boomerang particle exhibit a nonlinear crossover from short-time faster to long-time slower diffusion, and the mean displacements for fixed initial orientation are nonzero and saturate out at long times. The measured anisotropic diffusion coefficients versus the tracking point position indicate that there exists one unique point, i.e., the center of hydrodynamic stress (CoH), at which all coupled diffusion coefficients vanish. This implies that in contrast to motion in three dimensions where the CoH exists only for high-symmetry particles, the CoH always exists for Brownian motion in two dimensions. We develop an analytical model based on Langevin theory to explain the experimental results and show that among the six anisotropic diffusion coefficients only five are independent because the translation-translation coupling originates from the translation-rotation coupling. Finally, we classify the behavior of two-dimensional Brownian motion of arbitrarily shaped particles into four groups based on the particle shape symmetry group and discussed potential applications of the CoH in simplifying understanding of the circular motions of microswimmers.

High-Precision Motion Control for a Linear Permanent Magnet Iron Core Synchronous Motor Drive in Position Platform

The high precision motion tracking controller consisting of a linear permanent magnet iron core synchronous motor (LPMICSM) operating on a positioning platform is proposed. First, we address important issues related to the construction and driving theorem of the LPMICSM. Next the general system dynamic model is derived and analyzed. Then, because of the uncertainties and unknown parameters of the underlying system, a discrete adaptive sliding-mode (DASM) controller is proposed to guarantee system stability for both regulation and tracking tasks. Finally, according to the reported experimental results, the satisfactory performances including step regulation and tracking sinusoid, has been achieved. Therefore, the proposed control method is feasible and effective in high-precision motion control of LPMICSM.

Experimental Analysis of Laser Interferometry-Based Robust Motion Tracking Control of a Flexure-Based Mechanism

This paper presents experimental analysis of laser interferometry-based closed-loop robust motion tracking control for flexure-based four-bar micro/nano manipulator. To enhance the accuracy of micro/nano manipulation, laser interferometry realized robust motion tracking control is established with the experimental facility. This paper contains brief discussions about the error sources associated with the laser interferometry-based sensing and measurement technique, along with detailed error analysis and estimation. Comparative error analysis of capacitive position sensor-based system and laser interferometry-based system is also presented. Robust control demonstrates high precision and accurate motion tracking of the four-bar flexure-based mechanism. The experimental results demonstrate precise motion tracking, where resultant closed-loop position tracking error is of the order of $\pm$ 20 nm, and a steady-state error of about $\pm$ 10 nm. With the experimental study and error analysis, we offer evidence that the laser interferometry-based closed-loop robust motion tracking control can minimize positioning and tracking errors during dynamic motion.

Experimental Study of Laser Interferometry Based Motion Tracking of a Flexure-Based Mechanism

This paper presents an experimental study of laser interferometry-based closed-loop motion tracking for flexure-based four-bar micro/nano manipulator. To enhance the accuracy of micro/nano manipulation, laser interferometry-based motion tracking control is established with experimental facility. The authors present and discuss open-loop control, model-based closed-loop control, and robust motion tracking closed-loop control for flexure-based mechanism. A comparative error analysis for closed-loop control with capacitive position sensor and laser interferometry feedback is discussed and presented. Model-based closed-loop control shows improvement in position and motion tracking over open-loop control. Robust control demonstrates high precise and accurate motion tracking of flexure-based mechanism compared to the model-based control. With this experimental study, this paper offers evidence that the laser interferometry-based closed-loop control can minimize positioning and tracking errors during dynamic motion, hence realizing high precision motion tracking and accurate position control.

Robust Adaptive Constrained Motion Tracking Control of Piezo-Actuated Flexure-Based Mechanisms for Micro/Nano Manipulation

This paper presents a robust adaptive constrained motion tracking control methodology for piezo-actuated flexure-based micro/nano manipulation mechanisms. This unique control approach is established for the tracking of desired motion trajectories in a constrained environment exhibiting some degree of uncertain stiffness. The control methodology is also formulated to accommodate not only the parametric uncertainties and unknown force conversion function, but also nonlinearities including the hysteresis effect and external disturbances in the motion systems. In this paper, the equations for the dynamic modeling of a flexure-hinged four-bar micro/nano manipulation mechanism operating in a constrained environment are established. A lumped parameter dynamic model that combines the piezoelectric actuator and the micro/nano manipulation mechanism is developed for the formulation of the control methodology. Stability analysis of the proposed closed-loop system is conducted and the convergence of the motion tracking errors is proven theoretically. Furthermore, precise motion tracking ability in following a desired motion trajectory is demonstrated in the experimental study. An important advantage of this control approach is that it does not require the exact values for the system parameters and the force conversion function in the physical realization. This proposed constrained motion tracking control methodology is very useful for applications demanding high-precision motion tracking with force sensing and feedback.

Constrained Motion Tracking Control of Piezo-Actuated Flexure-Based Four-Bar Mechanisms for Micro/Nano Manipulation

This paper presents a robust methodology for constrained motion tracking control of piezo-actuated flexure-based four-bar micro/nano manipulation mechanisms. This unique control approach is established for the tracking of desired motion trajectories in a constrained environment exhibiting some degree of uncertain stiffness. The control methodology is also formulated to accommodate not only the parametric uncertainties and unknown force conversion function, but also nonlinearities including the hysteresis effect and external disturbances in the motion systems. In this paper, the equations for the dynamic modelling of a flexure-hinged four-bar micro/nano manipulation mechanism operating in a constrained environment are established. A lumped parameter dynamic model that combines the piezoelectric actuator and the micro/nano manipulation mechanism is developed for the formulation of the control methodology. Stability analysis of the proposed closed-loop system is conducted, and the convergence of the motion tracking errors is proven theoretically. Furthermore, precise motion tracking ability in following a desired motion trajectory is demonstrated in the experimental study. This robust constrained motion tracking control methodology is very useful for the development of high performance flexure-based micro/nano manipulation applications demanding high-precision motion tracking with force sensing and feedback.

Adaptive feedforward compensation of force ripples in linear motors

In this paper, an adaptive control scheme is proposed to reduce force ripple effects impeding motion accuracy in Permanent Magnet Linear Motors (PMLMs). The displacement periodicity of the force ripple is first obtained by using a Fast Fourier Transform (FFT) analysis. The control method is based on recursive least squares (RLS) identification of a nonlinear PMLM model which includes a model of the force ripple. Based on this model, the control algorithm can be commissioned which consists of a PID feedback control component, an adaptive feedforward component for compensation of the force ripple and another adaptive feedforward component based on the inverse dominant linear model which will serve to expedite motion tracking response. Simulation and experimental results are presented to verify the effectiveness of the proposed control scheme for high precision motion tracking applications.

High-precision control of linear actuators incorporating acceleration sensing

This paper presents the application of the acceleration sensor in the enhancement of the performance of high-precision motion tracking linear actuators which are based on permanent magnet linear motors (PMLM). A feedforward–feedback control structure is developed which harness effectively the acceleration measurements made available. It utilises a linear full-state feedback controller and an iterative learning feedforward controller (ILC). Experimental results show the acceleration feedback can improve the tracking performance and learning convergence of the control system.

Optical high-precision three-dimensional position measurement system suitable for head motion tracking in frameless stereotactic radiosurgery.

Head motion is a significant source of therapy-effect degradation in frameless stereotactic radiosurgery (SRS). In this study, a three-dimensional (3-D) optical head motion measurement system and a coordinate transformation algorithm were used to track patient head motion. With this system, head motion in frameless SRS was carefully investigated with a precision of < 0.1 mm. Head motions without any restraint (three cases) and with a Laitinen adapter (four cases) were measured with a data sampling rate of once per second for 30 min. Positions of IR light emission diode markers attached to the head were analyzed by two statistical methods. From these data, mathematically simulated head motions were obtained in each of the three coordinate directions for nonrestraint and Laitinen-adapter SRS. The results show that segmenting a frameless SRS procedure into a sequence of short intervals and repeating registration of the target position for each interval is a good strategy for better therapy precision. This optical 3-D position measurement system is suitable for high-precision head motion tracking in frameless SRS.

Optical High-Precision Three-Dimensional Position Measurement System Suitable for Head Motion Tracking in Frameless Stereotactic Radiosurgery

Head motion is a significant source of therapy-effect degradation in frameless stereotactic radiosurgery (SRS). in this study, a three-dimensional (3-D) optical head motion measurement system and a coordinate transformation algorithm were used to track patient head motion. With this system, head motion in frameless SRS was carefully investigated with a precision of <0.1 mm. Head motions without any restraint (three cases) and with a Laitinen adapter (four cases) were measured with a data sampling rate of on ce per second for 30 min. Positions of IR light emission diode markers attached to the head were analyzed by two statistical methods. From these data, mathematically simulated head motions were obtained in each of the three coordinate directions for nonrestraint and Laitinen-adapter SRS. The results show that segmenting a frameless SRS procedure into a sequence of short intervals and repeating registration of the target position for each interval is a good strategy for better therapy precision. This optical 3-D position measurement system is suitable for high-precision head motion tracking in frameless SRS.