High Dynamic Motion Research Articles

Machine Tool and Technology for Manufacturing of Micro-structures by Micro Dry Electrical Discharge Milling

This paper presents a new machine tool concept for micro dry electrical discharge milling. It includes two different motion systems, EDM spindle and EDM generator, as well as the control system. The feed motion is realised with high-precision linear axes and the high-dynamic motion, needed for the gap width control, with a two axes piezo unit. A control system is based on the Open Source development platforms. It includes several microcontrollers, with each controlling individual subsystems of the machine. The hybrid EDM generator is based on the high speed GaN FET transistors, which allow to control charging and discharging phase of the capacitor without using resistance.

A Novel Biomechanical Model-Aided IMU/UWB Fusion for Magnetometer-Free Lower Body Motion Capture

The available human body inertial motion capture (MoCap) systems are aided by magnetometers to remove the drift error in yaw angle estimation, which in turn limits their application in the presence of long-lasting magnetic disturbances in indoor environments. This paper introduces a magnetometer-free algorithm for lower-body MoCap including 3-D localization and posture tracking by fusing inertial sensors with an ultrawideband (UWB) localization system and a biomechanical model of the human lower body. Using our novel Kalman filter-based fusion algorithm, the UWB localization data aided by the biomechanical model can eliminate the drift in inertial yaw angle estimation of the lower-body segments. This magnetometer-free yaw angle estimation makes the algorithm insensitive to the magnetic disturbances. The algorithm is benchmarked against the optical MoCap system for various indoor activities including walking, jogging, jumping, and stairs ascending/descending. The results show that the proposed algorithm outperforms the available magnetometer-aided algorithms in yaw angle tracking under magnetic disturbances. In a uniform magnetic field, the algorithm shows similar accuracies in localization and joint angle tracking when compared with the magnetometer-aided methods. The localization accuracy of the proposed method is better than 4.5 cm in a 3-D space and its accuracy for knee angle tracking is about 3.5° and 4.5° in low and high dynamic motions, respectively.

Human Arm Motion Tracking by Orientation-Based Fusion of Inertial Sensors and Kinect Using Unscented Kalman Filter.

Due to various applications of human motion capture techniques, developing low-cost methods that would be applicable in nonlaboratory environments is under consideration. MEMS inertial sensors and Kinect are two low-cost devices that can be utilized in home-based motion capture systems, e.g., home-based rehabilitation. In this work, an unscented Kalman filter approach was developed based on the complementary properties of Kinect and the inertial sensors to fuse the orientation data of these two devices for human arm motion tracking during both stationary shoulder joint position and human body movement. A new measurement model of the fusion algorithm was obtained that can compensate for the inertial sensors drift problem in high dynamic motions and also joints occlusion in Kinect. The efficiency of the proposed algorithm was evaluated by an optical motion tracker system. The errors were reduced by almost 50% compared to cases when either inertial sensor or Kinect measurements were utilized.

On Designing Optimal Trajectories for Servo-Actuated Mechanisms: Detailed Virtual Prototyping and Experimental Evaluation

Programmable servo-actuated mechanisms can enhance the flexibility and the reconfigurability of modern manufacturing systems. Differently from fully mechanical design solutions (such as mechanical cams) and especially in the case of high-dynamic motions, servomechanism performance depends on several interacting factors, namely electric motor and linkage dynamics, controller efficacy, and requested motion law. In particular, point-to-point (PTP) trajectories are usually designed in order to comply with technological constraints, imposed by the required interaction with the handled product, and to maximize some optimality criterion such as, for instance, energy efficiency or limited actuation torques. In this context, the present paper proposes a novel method for designing energy and peak-power optimal PTP motions. A standard optimization problem is solved by means of either cubic or quintic splines. Nonetheless, differently from previous approaches, the optimization cost functions are based on a virtual prototype of the system, which comprises behavioral models of power converter, controller, and electric motor coupled with the mechanical system. Results are then compared with experimental data obtained on a physical prototype. The comparison quantitatively shows that better-behaved PTP trajectories can be designed by including the dynamic contribution of each subsystem component.

Design and analysis of a 2-DOF synchronous planar drive for machine tools

This paper presents a synchronous planar motor prototype with a cross winding system for high dynamic motion in two feed axes. The approach uses a synchronous permanent magnet planar motor, where the magnets are located in the stationary part and the coils are mounted on one moving yoke. A cross winding technology with concentrated windings is implemented to realize a compact feed drive for machine tools. An experimental setup was used to obtain the characteristic behavior of the inductance and disturbance- and feed-force deviation of the drive. Disturbance-forces like cogging- and detent-forces occur due to parasitic effects between the permanent magnets and the iron based yoke. It is theoretically and experimentally shown, that both winding layers marginally interact. Based on the identified characteristics, two independent cascade control systems are developed. The disturbance-force is compensated by a feedforward control. The performance of this first prototype is finally shown in a circular milling setup.

3D Tube Forming and Applications of a New Bending Machine with Hydraulic Parallel Kinematics

This research presents a new versatile bending machine and its practical applications. The proposed machine uses a new method. When tubes are fed into the fixed and mobile dies, they are bent by shifting the relative position of the mobile die. The bending radius is controlled by the relative distance and orientation between the mobile die and the tube. The bending angle is controlled by the length of the fed tube. This forming process has a big advantage. A change in the expected bending shape will need no change in the tooling system but only a new definition of the motion of the active die and the length of the fed tube. Active die movements are controlled by a 6-DOF Parallel KinematicsMechanism (PKM) with a hydraulic servo drive. Making use of the hydraulic PKM serves not only to achieve a complete motion along six axes but also to obtain the high dynamic motion of the bending machine. Application examples show that the bending machine can be applied to a designer’s furniture and universal designed products. Until now, these processes have been difficult to achieve using a conventional bending machine.

Visual-Inertial-Aided Navigation for High-Dynamic Motion in Built Environments Without Initial Conditions

In this paper, we present a novel method to fuse observations from an inertial measurement unit (IMU) and visual sensors, such that initial conditions of the inertial integration, including gravity estimation, can be recovered quickly and in a linear manner, thus removing any need for special initialization procedures. The algorithm is implemented using a graphical simultaneous localization and mapping like approach that guarantees constant time output. This paper discusses the technical aspects of the work, including observability and the ability for the system to estimate scale in real time. Results are presented of the system, estimating the platforms position, velocity, and attitude, as well as gravity vector and sensor alignment and calibration on-line in a built environment. This paper discusses the system setup, describing the real-time integration of the IMU data with either stereo or monocular vision data. We focus on human motion for the purposes of emulating high-dynamic motion, as well as to provide a localization system for future human-robot interaction.

Theoretical analysis of errors in correction algorithms for periodic nonlinearity in displacement measuring interferometers

► Periodic error correction is dependent on absolute phase (absolute position). ► More than 1.25 fringes of displacement is needed for effective correction. ► Algorithms are not as effective under high dynamic stage motions. Two different measure-and-correct algorithms, the Chu–Ray algorithm and the Eom algorithm, were simulated to estimate their effectiveness for correcting periodic nonlinearity applied a simulated wafer positioning system. Both algorithms, which demonstrated no periodic nonlinearity in some example constant velocity and constant acceleration datasets, and their specific implementations are described in detail. The algorithms were tested for both slit and scan directions using estimated wafer stage trajectories for ramping up to a constant scanning velocity with no velocity in the slit direction. Three different heterodyne frequencies and three different sampling frequencies were simulated to estimate the optical system and data acquisition parameters. The initial phase offset was also considered in the simulations and had a significant effect on both the scan and slit offset errors. The offset error appears to increase for certain initial phase values which manifests from compensating the periodic errors combined with the high stage dynamics. High noise levels and displacement jumps were observed when high velocity changes during a correction period suggesting increasing the minimum velocity threshold and limiting the maximum acceleration can improve the effectiveness of these algorithms.

A Study on Information Fusion of AHRS Based on DSP

For the angular velocity gyro drift and noise and the inertial navigation solution of the integral nature, the navigation error of the attitude will accumulate over time. With the increase of navigation time, the system may fail. In high dynamic motion the accelerometer / magnetometer attitude measurement navigation system will not work properly. Therefore, the accelerometer / magnetometer attitude determination system, haven’t no drift, but poor dynamic performance. This article will realize a low-cost, precision Attitude Calculation System with more effective integration of the two.

Presentation of Membrane-Anchored Glycosphingolipids Determined from Molecular Dynamics Simulations and NMR Paramagnetic Relaxation Rate Enhancement

Challenges for structural characterization of membrane-bound glycosphingolipids include their high internal dynamic motions and their physical proximity to membrane surfaces. Here we demonstrate that NMR paramagnetic relaxation enhancement can be used, alongside independent molecular dynamics simulations and an outer-sphere relaxation model, to quantitatively characterize the presentation (insertion depth and orientation relative to a membrane surface) of ganglioside GM1 in biologically relevant membrane environments. Longitudinal and transverse paramagnetic relaxation enhancement effects were measured for GM1, anchored to phospholipid bicelles, using both water-soluble and membrane-anchored paramagnetic probes, respectively. A method was developed to rapidly calculate paramagnetic relaxation enhancement effects from thousands of structures taken from a simulation of GM1 in a phospholipid bilayer. The combined computational and experimental approach yielded experimentally verified atomic-resolution 3D models of a highly plastic membrane-bound biomolecule.

Effects of Clustered Epitopes in Multivalent Ligand−Receptor Interactions

Many biological ligands are composed of clustered binding epitopes. However, the effects of clustered epitopes on the affinity of ligand-receptor interactions in many cases are not well understood. Clustered carbohydrate epitopes are present in naturally occurring multivalent carbohydrates and glycoproteins, which are receptors on the surface of cells. Recent studies have provided evidence that the enhanced affinities of lectins, which are carbohydrate binding proteins, for multivalent carbohydrates and glycoproteins are due to internal diffusion of lectin molecules from epitope to epitope in these multivalent ligands before dissociation. Indeed, binding of lectins to mucins, which are large linear glycoproteins, appears to be similar to the internal diffusion mechanism(s) of protein ligands binding to DNA, which have been termed the "bind and slide" or "bind and hop" mechanisms. The observed increasing negative cooperativity and gradient of decreasing microaffinity constants of a lectin binding to multivalent carbohydrates and glycoproteins result in an initial fraction of lectin molecules that bind with very high affinity and dynamic motion. These findings have important implications for the mechanisms of binding of lectins to mucins, and for other ligand-biopolymer interactions and clustered ligand-receptor systems in general.

Long Range Communication in the Envelope Protein Domain III and Its Effect on the Resistance of West Nile Virus to Antibody-mediated Neutralization

The envelope protein domain III (ED3) of West Nile virus is the major virus-specific neutralization domain and harbors most of the critical mutations that induce resistance against antibody-mediated neutralization. We investigated the molecular mechanisms of neutralization resistance by studying the biophysical perturbations of monoclonal antibody (mAb)-resistant mutations on ED3 wild type. Our results showed that although the solution structure between ED3 wild type and mutants was preserved, the mutations that confer the highest degree of resistance to mAbs showed low protein stability and high local dynamic motions. Interestingly, the latter was observed in regions outside the mutation sites, indicating long range communications within ED3. Thus, we hypothesized that the mechanisms involved in resistance to mAb neutralization may include, in addition to mutations in the epitope, long range effects among distant structural elements. This hypothesis is consistent with reported mutations in other flaviviruses whose surfaces are not exposed for the interaction with other macromolecules, yet they confer mAb neutralization resistance.

APPLICATIONS WITH A NEW 6-DOF BENDING MACHINE IN TUBE FORMING PROCESSES

This research presents a new flexible bending machine and its practical applications. The proposed machine uses a new method. When tubes are fed into the fixed and mobile dies, they are bent by shifting the relative position of the mobile die. The bending radius is controlled by the relative distance and orientation between the mobile die and the tube. The bending angle is controlled by the length of the fed tube. This forming process has a big advantage. A change of the expected bending shape will need no change in the tooling system but only a new definition of the motion of the active die and the length of the fed tube. The active die movements are controlled by a 6-DOF parallel kinematics mechanism (PKM) with hydraulic servo drive. Making use of the PKM serves not only to achieve a complete motion along six axes but also to obtain a high dynamic motion of the bending machine. Application examples show that the bending machine can be applied to designer's interiors, universal designed products, and automotive parts. Until now these processes have been difficult to achieve using a conventional bending machine.

Synthesis of high dynamic range motion blur free image from multiple captures

Advances in CMOS image sensors enable high-speed image readout, which makes it possible to capture multiple images within a normal exposure time. Earlier work has demonstrated the use of this capability to enhance sensor dynamic range. This paper presents an algorithm for synthesizing a high dynamic range, motion blur free, still image from multiple captures. The algorithm consists of two main procedures, photocurrent estimation and saturation and motion detection. Estimation is used to reduce read noise, and, thus, to enhance dynamic range at the low illumination end. Saturation detection is used to enhance dynamic range at the high illumination end as previously proposed, while motion blur detection ensures that the estimation is not corrupted by motion. Motion blur detection also makes it possible to extend exposure time and to capture more images, which can be used to further enhance dynamic range at the low illumination end. Our algorithm operates completely locally; each pixel's final value is computed using only its captured values, and recursively, requiring the storage of only a constant number of values per pixel independent of the number of images captured. Simulation and experimental results demonstrate the enhanced signal-to-noise ratio (SNR), dynamic range, and the motion blur prevention achieved using the algorithm.

The Application of GPS to the H-II Orbiting Plane

This paper describes the application of GPS to the H-II orbiting plane (HOPE). The HOPE is a Japanese space transportation vehicle that will be launched at the end of the 1990s. It will be launched by the H-II rocket, a Japanese next-generation main launcher, and will return to the earth autonomously after various orbital operations. GPS is a key component in guiding the HOPE safely during the on-orbit, rendezvous, de-orbit, and approach phases. This paper presents the analytical results of GPS receiver design and orbit determination. Specifically, it addresses expected pseudorange and delta range variations, tolerance to high dynamic motion, time to first fix (TTFF), antenna location, and navigation performance. Receiver design is to be verified beforehand by installing the GPS receiver on the orbital re-entry experimental (OREX) vehicle. The OREX vehicle will be launched in 1993 by the first H-II rocket. The main purpose of GPS experiments in the OREX is to evaluate the functions and performance of the GPS navigation system during the on-orbit and re-entry phases.

Response of an edge‐supported, circular, foil electret earphone with radially‐varying parameters

In edge‐supported, circular, foil electret earphones sound pressures are generated in the ear canal by volumetric changes produced by motion of the foil. For a given driving voltage the dynamic foil motion and sound pressure level increase as the static deflection of the foil center increases within limits. Beyond a critical central deflection the foil electret collapses onto the back electrode thereby reducing the earphone response. If the earphone parameters are uniform, the static ?nd dynamic foil amplitudes are parabolic functions of radial location. With the introduction of radially varying earphone parameters it is possible to broaden the region of the foil electret which experiences high amplitude static and dynamic motion, thus increasing the sound pressure level generated at a given driving voltage. Theoretical arguments limit the increase in earphone sensitivity which may be obtained in this manner to 6 dB. Numerical studies of the effect of a radially varying charge distribution or radially var...