Inverse Kinematics Method Research Articles

Two‐handed human reach prediction models for ergonomic evaluation

AbstractAs an essential function of computerized ergonomic evaluation models based on digital human models, realistic simulation or prediction of human reach profiles is of great importance. Although several human‐modeling efforts have been made to provide the capability of reach simulation, most studies have been limited to the reach of a single extremity. A variety of activities of human operators, however, frequently involve simultaneous positioning of two or more extremities to different target positions. Such a multiple reach problem cannot be satisfactorily resolved by means of conventional single‐extremity reach models because formulation of the problem as a series of single reaches rarely yields accurate trajectory of human‐reach profiles due to interactions of multiple extremities. In this research, a two‐handed reach prediction model was developed. The human upper body was modeled as a seven‐link system with 13 degrees of freedom, being regarded as a redundant open kinematic chain with two end‐effectors. As a way of solving the two‐handed reach problem, the resolved motion method was adopted among several inverse kinematics methods as the technique is fit for real‐time redundancy control. The method is also capable of incorporating the joint range availability criterion as a cost function to minimize excessive deviations of body joints from their neutral positions. Real human‐reach profiles were compared to those obtained from the prediction model and were found to be statistically similar. The methodology is expected to be applicable to the reach simulation of both upper and lower extremities without algorithmic difficulties. © 2010 Wiley Periodicals, Inc.

ANALYSIS OF HEXAPOD ROBOT LOCOMOTION

Hexapod robot locomotion is analyzed. Trajectory forming method for one leg is introduced. Servo angles are expressed using geometric inverse kinematics method. Forming of tripod gait is described and a diagram representing it is presented. Servo control parameters are defined to ensure fluent and versatile robot control. Several servo control methods are presented. After testing robot movement using different servo control methods, gait generation is corrected and control method that meets servo control parameters is chosen.

Invariant mass spectroscopy of 19,17C and 14B using proton inelastic and charge-exchange reactions

The neutron-rich carbon isotopes 19,17C and the boron isotope 14B have been investigated, respectively, by the proton inelastic and charge-exchange reactions on a liquid hydrogen target at around 70 MeV/nucleon. The invariant mass method in inverse kinematics was employed to map the energy spectrum above the neutron decay threshold of the residual nuclei. New states on carbon isotopes are reported. An experimental capability of extracting β-decay strengths via forward angle ( p , n ) cross sections on unstable nuclei is shown.

Measurement of the inelastic branch of the stellar 14O( α,p) 17F reaction occurring in the explosive burning in Novae and X-ray bursters

The inelastic component of the key astrophysical resonance ( 1 − , E x = 6.15 MeV ) in the 14O( α,p) 17F reaction has been studied by using the resonant scattering of 17F+ p. The experiment was done at REX-ISOLDE CERN with the Miniball setup. The thick target method in inverse kinematics was utilized in the present experiment where a 44.2 MeV 17F beam bombarded a ∼ 40 μ m thick (CH 2) n target. The inelastic scattering protons in coincidence with the de-excited 495 keV γ rays have been clearly seen and they are from the inelastic branch to the first excited state in 17F following decay of the 1 − resonance in 18Ne. Some preliminary results are reported.

Modeling and Verification of an Astronaut Handling Large-mass Payload

The experiments on astronaut motions are difficult to conduct due to the limitation and high cost of constructing or simulating the microgravity environment of space. Therefore, the method of computer simulation on astronaut extravehicular activity is broadly promoted. However, validations and verifications for these simulations stated in related literatures are incomplete such as comparing with the limits of human body movements or reconstructing a three-dimensional movement for some parts of EVA video. Novel modeling and verification methods for the task of an astronaut handling large-mass payload during EVA were revealed. A simplified model of an astronaut was constructed, and the astronaut motion was conceived as a planar movement of a multi-body system which includes seven segments with six revolute joints in the human body sagittal plane. The inverse kinematics method was used to calculate joint angles, joint velocities, and joint accelerations in time domain. The solution of joint torques using the inverse recursive dynamics was achieved. Furthermore, a virtual model with the ADAMSTM software was developed and implemented to verify the results by adding the kinematical data calculated to joints in order to achieve the trace of the center of mass of the hand. Additionally, the joints kinematics and kinetics data with time in the virtual model were obtained and compared with the corresponding calculated data. This result indicates that the modeling methods proposed can be employed as a solid algorithm to conduct the simulation of astronaut’s tasks in EVA, and verification using the virtual model can be easily operated and has a good accuracy. This study provides an effective and economical way of modeling and simulation for extravehicular missions.

2A1-A25 高次幾何モーメントを用いたモデルフリー逆運動学

In this paper, we propose the model-free inverse kinematics method based on high order moment feature and its Jacobian matrix, which can use arbitrary shape information as reference input free from the structure of targeted kinematic chains. The method is especially useful to generate the motion of humanoid systems, and we can generate the whole body pose from the set of 3D markers or the pixels 2D images, without labeling each feature point of these data with the specified link of the humanoid. The moment feature can be computed from various types of quantities, for example, from geometric points, mass density, pixel images, and the labels of some featured links, which implies general versatility and applicability of the method. We show some results of motion of a human figure generated by the label-less 3D markers and the 2D images.

Inverse Dynamic Reconstruction of Truck Cabin Ingress/Egress Motions

This paper investigates the feasibility of calculating joint forces and moments during a whole body truck cabin ingress/egress motion. For such a task, it is difficult to evaluate a future truck instep as the influences of the architecture parameters are complex over the motion and the discomfort feeling. In order to evaluate the future product at an early stage of the design process, Digital Human Models (DHMs) are interesting tools. However, most existing DHM simulation packages can only efficiently evaluate the kinematics of postures where the dynamics of the whole motion is necessary for such a task. The enhancement of DHMs towards a dynamic analysis and modeling is therefore necessary. In this study, the motions of subjects entering and exiting an adjustable truck cabin were measured by mean of an opto-electronic motion capture system and six load sensors. The joint angles were then calculated using an inverse kinematics method. And the joint loads were calculated using a classical Newton-Euler inverse dynamics method during the period when all the contact loads are measured. The comparison of the joint torques and forces at the spine L5/S1 joint calculated from the going up and going down methods show a good consistency and validate the moments and forces calculated at the other joints. In order to evaluate the joint loads when a sensor is missing, two methods are also presented, the first one making no assumption on the missing contact force, and the second one assuming that the center of pressure is known. The results show that more consistent joint loads were obtained using the method with assumption. These results validate the dynamic motion reconstruction method and open the way for a discomfort evaluation of truck cabin ingress/egress based on joint moments and forces.

Determining the three-dimensional relation between the skeletal elements of the human shoulder complex

In this paper, we present an inverse kinematics method to determining human shoulder joint motion coupling relationship based on experimental data in the literature. This work focuses on transferring Euler-angle-based coupling equations into a relationship based on the Denavit–Hartenberg (DH) method. We use analytical inverse kinematics to achieve the transferring. For a specific posture, we can choose points on clavicle, scapula, and humerus and represent the end-effector positions based on Euler angles or DH method. For both Euler and DH systems, the end-effectors have the same Cartesian positions. Solving these equations related to end-effector positions yields DH joint angles for that posture. The new joint motion coupling relationship is obtained by polynomial and cosine fitting of the DH joint angles for all different postures.

An Inverse-Kinematics Table-Based Solution of a Humanoid Robot Finger With Nonlinearly Coupled Joints

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper presents a novel approach toward the inverse kinematics solution of the humanoid robot fingers with nonlinearly coupled joints, a challenging problem existing for years. Under an assumption that the coupled joint angles of the finger are the same, we first derive an approximate closed-form solution of the finger's inverse kinematics. Then, utilizing the approximate solution as the ancillary variable, we propose to solve the finger joint angles from this approximate solution rather than the fingertip position. Through analyzing properties of the approximate solution, it can be known that the coupled joint angles in the approximate solution play the most important role in the derivation of inverse kinematics. In practical implementation, a 1-D lookup table and the linear interpolation to the approximate solution are used to calculate the accurate joint angles. Simulation and experimental results demonstrate effectiveness of the proposed inverse kinematics method. </para>

Motion autonomy for humanoids: experiments on HRP‐2 No. 14

AbstractThis paper deals with whole‐body motion planning and dynamic control for humanoid from two aspects: locomotion including manipulation and reaching. In the first part, we address a problem of simultaneous locomotion and manipulation planning that combines a geometric and kinematic motion planner with a dynamic humanoid motion generator. The second part deals with whole‐body reaching tasks by using a generalized inverse kinematics (IK) method to fully exploit the high redundancy of the humanoid robot. Through experiments using humanoid platform HRP‐2 No. 14 installed at LAAS‐CNRS, we first verify the validity of each method. An integrated experiment is then presented that unifies the both results via visual perception to execute an object‐fetching task. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Cross sections for nuclide production in aFe56target irradiated by 300, 500, 750, 1000, 1500, and 2600 MeV protons compared with data on a hydrogen target irradiated by 300, 500, 750, 1000, and 1500 MeV/nucleonFe56ions

This work presents the cross sections for radioactive nuclide production in $^{56}\mathrm{Fe}$($p,x$) reactions determined in six experiments using 300, 500, 750, 1000, 1500, and 2600 MeV protons of the external beam from the ITEP U-10 proton accelerator. In total, 221 independent and cumulative yields of radioactive residuals of half-lives from 6.6 min to 312 d have been obtained. The radioactive product nuclide yields were determined by direct $\ensuremath{\gamma}$-spectrometry. The measured data have been compared with the experimental data obtained elsewhere by the direct and inverse kinematics methods and with calculation results of 15 different codes that simulated hadron-nucleus interactions: MCNPX (INCL, CEM2K, BERTINI, ISABEL), LAHET (BERTINI, ISABEL), CEM03 (.01, .G1, .S1), LAQGSM03 (.01, .G1, .S1), CASCADE-2004, LAHETO, and BRIEFF. Most of the data obtained here are in a good agreement with the inverse kinematics results and disprove the results of some earlier activation measurements that were quite different from the inverse kinematics measurements. The most significant calculation-to-experiment differences are observed in the yields of the $A&lt;30$ light nuclei, indicating that further improvements in nuclear reaction models are needed, and pointing out as well to a necessity of more complete experimental measurements of such reaction products.

Analytical inverse kinematics with body posture control

This paper presents a novel whole-body analytical inverse kinematics (IK) method integrating collision avoidance and customizable body control for animating reaching tasks in real-time. Whole-body ...

Full-body performance animation with Sequential Inverse Kinematics

In this paper, we present an analytic-iterative Inverse Kinematics (IK) method, called Sequential IK (SIK), that reconstructs 3D human full-body movements in real time. The input data for the reconstruction is the least possible (i.e., the positions of wrists, ankles, head and pelvis) in order to be usable within a low-cost human motion capture system that would track only these six features. The performance of our approach is compared to other well-known IK methods in reconstruction quality and computation time obtaining satisfactory results for both. The paper first describes how we handle the spine and the clavicles before offering a simple joint limit model for ball-and-socket joints and a method to avoid self-collisions induced by the elbow. The second part focuses on the algorithms comparison study.

Unbound excited states in 19,17C

The neutron-rich carbon isotopes 19,17C have been investigated via proton inelastic scattering on a liquid hydrogen target at 70 MeV/nucleon. The invariant mass method in inverse kinematics was employed to reconstruct the energy spectrum, in which fast neutrons and charged fragments were detected in coincidence using a neutron hodoscope and a dipole magnet system. A peak has been observed with an excitation energy of 1.46(10) MeV in 19C, while three peaks with energies of 2.20(3), 3.05(3), and 6.13(9) MeV have been observed in 17C. Deduced cross sections are compared with microscopic DWBA calculations based on p-sd shell model wave functions and modern nucleon–nucleus optical potentials. Jπ assignments are made for the four observed states as well as the ground states of both nuclei.

Lifetime measurement of candidate chiral doublet bands in the Rh103,104 isotopes with the recoil-distance Doppler-shift method in inverse kinematics

Lifetime measurement of candidate chiral doublet bands in the Rh103,104 isotopes with the recoil-distance Doppler-shift method in inverse kinematics

C24 STEPを用いた工作機械の構造・形状統合モデルの提案とその5軸加工への応用(第2報) : モデリングシステムの構築と統一的逆運動学計算手法の提案(OS-4 生産システムとCAD/CAM(1))

In machining process, especially multiaxis NC machining, it is necessary to simulate the motion for confirmation of NC data. However, in such case, there are three problems; 1) It is no common integrated model of kinematics and shape for machine tools. 2) It is no modeling system of integrated machine tool model. 3) It is no unified solving method of inverse kinematics. To solve these problems, an integrated model of kinematic model and shape model for machine tools based on STEP(ISO10303) is proposed. A modeling system to generate an integrated model to associate kinematic model with shape model is developed and the integrated model for 5-axis machining is generated as an example. A motion simulation system including a unified solving method of inverse kinematics using Groebner Basis is also developed.

Mathematical simulation of combined trajectory paths of a seven link biped robot

The following article focuses on biped robot simulation and control over combined trajectory paths with the aid of mathematical modeling methods focusing on the effects of hip height over torso’s modified motion. The mathematical simulation has been exploited to interpolate the combined trajectory of the robot path with the given breakpoints using inverse kinematic and dynamic methods to determine ZMP and stability treatments. After the robot’s combined path determination, a third-order spline is utilized because of its high precision and ability to calculate the kinematic, dynamic and control parameters. With the aid of this software, common parameters such as joint angles and inertial forces for the given specifications and nominal conditions are calculated and simulated.

Inverse kinematics resonance scattering on thick target with EXCYT beams

The resonance scattering method in inverse kinematics on infinite target has been applied to two systems, 18O + α and 9Be + α, in order to test and to optimize an experimental apparatus in view of a set of resonance scattering experiments to be performed with 8Li and 9Li radioactive ion beams delivered by the facility EXCYT. The scattering excitation functions, deduced for the two systems, were compared with previous results reported in literature. Results show that reliable stopping power data are essential for the application of this technique.

Low-lying resonant states inF16using aO15radioactive ion beam

A 120 MeV $^{15}\mathrm{O}$ radioactive ion beam with an intensity on target of $4.5\ifmmode\times\else\texttimes\fi{}{10}^{4}$ pps has been developed at the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. This beam has been used to study the level structure of $^{16}\mathrm{F}$ at low energies via the $p$($^{15}\mathrm{O}$, $p$) reaction using the thick target inverse kinematics method on a polyethylene target. The experimental excitation function was analyzed using $R$-matrix calculations. Significantly improved values for the level widths of the four low-lying states in $^{16}\mathrm{F}$ are reported. Good agreement with the theoretical spectroscopic factors is also obtained.

Single and double proton emissions from theO14+He4interaction

We observed single and double proton emissions in the $^{14}\mathrm{O}+^{4}\mathrm{He}$ interaction by the thick target inverse kinematic (TTIK) method at initial energy for $^{14}\mathrm{O}$ at 32.7 MeV. We found that the protons mainly originate from the resonance excitation of states in $^{18}\mathrm{Ne}$. The observed states in $^{18}\mathrm{Ne}$ decay by protons mainly to proton unstable states in $^{17}\mathrm{F}$. It was found that the decay of a state in $^{18}\mathrm{Ne}$ at ${E}_{\mathrm{ex}}=8.45$ MeV demonstrates the features of a decay by a correlated proton pair. The observed properties of the $^{14}\mathrm{O}+^{4}\mathrm{He}$ interaction make a previous interpretation for the rate of $^{14}\mathrm{O}$($^{4}\mathrm{He}$, $p$)$^{17}\mathrm{F}$ at astrophysical energies suspect. We show how the TTIK method should be modified to obtain the data of astrophysical interest.