Collective motion of interacting simple robots

Linear vibration of thin-walled beams of equal angle-section

The purpose of this study was to validate the accuracy of our novel 3D speckle tracking method by using numerical data, and to demonstrate the rapid processing of this method by using data obtained from human subjects. In order to create a method that can rapidly assess cardiac function in regional heart wall segments, a 3D speckle tracking algorithm was created that focuses on data quality and performance. Prototype application software based on this algorithm was written to evaluate cardiac wall motion and to calculate indices such as strain. Time series 3D image data were generated for artificial numerical models that simulate the shape of the left ventricle and exhibit various types of motion. We compared observed values returned by the algorithm with expected values yielded by the models. This software was also applied to volume data of the human heart acquired by a 3D ultrasound system. Measurement of the indices was evaluated by using an error ratio that was a residual between an expected value and estimated one divided by the expected value. The average error ratio of the time series volumes was less than 5% for all indices, and no individual error ratio was more than 10% for numerical models. The process was complete within 0.5s per frame for human heart volumes. This application software can provide good estimates of various wall motion indices. The results are similar to data from numerical models, and are provided quickly enough for routine clinical usage.

To describe the brake creep-groan phenomenon and several types of stick-slip motions, we propose both analytical and experimental investigations for an automatic transmission equipped vehicle. A lumped torsional model is employed to approximate the dynamics of the real mechanical system. This model assigns inertia to the drive, brake rotor, brake caliper and tire/vehicle, and by appropriate algorithms the simulation time histories include the effects of the friction non-linearity coupling brake and rotor. We consider how to force this particular system, from what physical state, and finding appropriate parameters and solutions. Important computational issues, as related to the stick-slip or slip-stick transitions, are addressed with the algorithms. Driving forces are assigned with two functions, one appropriate for comparison with the test and the other to study stick-slip orbits, which have been found to have various types of motion depending on the controlling brake actuation parameters. Since the groan features a discontinuous friction force and finite-repeating motions some comparisons are made in the frequency and time-frequency domains. These demonstrate the expected stick-slip frequency and multiple orders.

Modelling how proteins bind to one another is a challenging task, in part due to the conformational changes that can occur upon complex formation. We here describe the various types of motion that occur upon protein binding and discuss their treatment in computational protein-protein docking methods to predict the structure of the bound complex. Considered are five different categories of structural change, that cover timescales from picoseconds to milliseconds and amplitudes extending to tens of angstroms. First small-scale motion, which includes bond stretching, bond angle bending and dihedral rotation is addressed. This is followed by larger motions of the protein main-chain, the loops and entire protein domains. Finally, we consider the class of intrinsically disordered proteins including protein segments that refold upon binding. For each category, the capabilities and limitations of current docking procedures are discussed by means of an illustrative example.

This paper presents the development of the animation of robots in virtual reality environments, whose mechanisms can be coupled -the movement relies on mechanical principles-; and uncoupled mechanisms, i.e., the degrees of freedom are controlled independently via a control unit. Additionally, the present phases to transfer the design of a robot developed in a CAD tool to a virtual simulation environment without being lost the physical characteristics of the original design are showed, for which it is considered the various types of motions that the robot can perform depending on the design. Finally, shows the results obtained from the simulation of motion of a robot hexapod 18DOF and Theo Jansen mechanism.

Generation of natural human motion is one of key techniques for multimodal dialogue systems with a human-like avatar. In particular, natural and expressive lip motion synthesis is necessary to make conversation between a user and an avatar richer. However, such expressive lip motion is often difficult to be generated automatically because it can be changed depending on phonemic context and prosody. To address this difficulty, we introduce a novel motion generation method on the basis of the modulation of a set of dynamic models learned from neutral motion data. As a suitable model for lip motion generation, we adopt a hybrid dynamical system, which consists of linear dynamical systems for each motion unit and a symbolic automaton for switching between these units. We show that, from the viewpoint of control theory, it is possible to modulate linear dynamical systems for various types of motion. Early results demonstrate the applicability of the proposed method using lip motion synthesis for simple phoneme sequences.

The nonlinear damping effect on response of coupled three degree-of-freedom autoparametric vibration system with elastic pendulum attached to the main mass is investigated numerically. It was assumed that the main body is suspended by an element characterized by non-linear elasticity and non-linear damping force and is excited harmonically in the vertical direction. The elastic pendulum characterized also by -linear elasticity and non-linear damping. Solutions for the system response are presented for specific values of the uncoupled normal frequency ratios and the energy transfer between modes of vibrations is observed. Curves of internal resonances for free vibrations and external resonances for exciting force are shown. In this type system one mode of vibration may excite or damp another one, and except different kinds of periodic vibration there may also appear chaotic vibration. Various techniques, including chaos techniques such as bifurcation diagrams and: time histories, phase plane portraits, power spectral densities, Poincare` maps and exponents of Lyapunov, are used in the identification of the responses. These bifurcation diagrams show many sudden qualitative changes, that is, many bifurcations in the chaotic attractor as well as in the periodic orbits. The results show that the system can exhibit various types of motion, from periodic to quasi-periodic to chaotic, and is sensitive to small changes of the system parameters.

On a method for the uniformization of solutions in central motion problems

Availability analysis is an important issue in robotic swarm systems. It can help the designer to construct a cost-effective system with high availability and fewer resources. For the model and analysis to be fully specified and practical, this paper systematically investigates the major issues that need to be addressed in the analysis of various robotic swarm applications. Four models are established to consider systems with dependent and independent robots, homogenous and non-homogenous systems, and the effect of various types of motions on the overall system failure pattern. Detailed analysis of each of these models is performed based on renewal theory and continuous Markov Chain techniques. Numerical availability evaluations for two applications are also presented.

How Much the Eye Tells the Brain

We present novel techniques for interactive editing the motion of an animated character by gesturing with a mobile device. Our approach is based on the notion that humans are generally able to convey motion using simple and abstract mappings from their own movement to that of an animated character. We first explore the feasibility of extracting robust sensor data with sufficiently rich features and low noise, such that the signal is predictably representative of a user's illustrative manipulation of the mobile device. In particular, we find that the linear velocity and device orientation computed from the motion sensor data are well-suited to the task of interactive character control. We show that these signals can be used for two different methods of interactively editing the locomotion of an animated human figure: discrete gestures for editing single motions, and continuous gestures for editing ongoing motions. We illustrate these techniques using various types of motion edits which affect jumps, strides and turning.

A generic kinematic model is presented for a unified hydrodynamics study covering the various types of motion found in real as well as hypothetical fish-like undulation. Undulating motion is presented here as a generic motion, considering chordwise forced flexibility—modelled by wavelength of undulation λ*—of a rigid NACA0012 hydrofoil in a free-stream flow. Using a level-set immersed boundary method-based in-house code, a non-dimensional study is presented for various wavelengths, λ* (0.8–8.0), and frequency of undulation, St (0.2–0.7), at a constant maximum amplitude of undulation of 0.1 and Reynolds number of 5000. A unified cause-and-effect-based analysis is presented with the help of flow patterns and propulsive performance parameters. Pressure contour demonstrates how the travelling wave distributes momentum in the streamwise direction and reduces the lateral force coefficient. Vorticity contours elucidate the mechanism of formation of reverse von Kármán vortex street and the secondary vortices. A correlation is proposed for thrust coefficient as a function of λ* and St. Good qualitative agreement is observed between the simulated results at smaller λ*-based undulating and larger λ*-based pitching foil and the published results for the anguilliform and thunniform fishes, respectively. The agreement with the real fishes is presented for the relative magnitude of thrust coefficient, propulsive efficiency, dynamic stabilization, and signal of the prey fish for the predator fish. Similar to propulsive performance of real fishes, larger (smaller) flexibility-based undulation (pitching) results in larger propulsive efficiency (thrust generation)—which can be used for the design of fish-like biomimetic propulsion system.

Optimal joint trajectory planning for coordinated point-to-point motion of two-arm manipulators

A simple model equation is proposed to understand a mechanism of localized states in dissipative systems. This is a very simplified model for filament-like discharge patterns and can be expressed as a nonlinear resistor network model through spatial discretization. The model equation is piecewise linear and can be solved exactly. We propose another simple and solvable model equation to understand a mech- anism of localized states in dissipative systems. The model equation is related to filament structures in discharge patterns. There are varieties of spatio-temporal pat- terns such as standing and moving striations in gas-discharge systems. A reaction diffusion-type equation for the current density and the electric potential was pro- posed to study spatially periodic patterns and localized patterns transverse to the current flow. 18), 19) We consider a simpler model equation. §2. Model equation and the solution Our model is related to arc discharge. The current density is high and the temperature becomes ∼ 10 4 K in the localized arc region, and strong light is emitted from the filament-like region. Many complicated ionization and reaction processes occur both on the electrodes and in the gas region between the electrodes. However, we consider only the energy balance or heat equation. The temperature T (r ,t )i s assumed to obey

Animals locomote robustly and agile, albeit significant sensorimotor delays of their nervous system and the harsh loading conditions resulting from repeated, high-frequent impacts. The engineered sensorimotor control in legged robots is implemented with high control frequencies, often in the kilohertz range. Consequently, robot sensors and actuators can be polled within a few milliseconds. However, especially at harsh impacts with unknown touch-down timing, controllers of legged robots can become unstable, while animals are seemingly not affected. We examine this discrepancy and suggest and implement a hybrid system consisting of a parallel compliant leg joint with varying amounts of passive stiffness and a virtual leg length controller. We present systematic experiments both in computer simulation and robot hardware. Our system shows previously unseen robustness, in the presence of sensorimotor delays up to 60 ms, or control frequencies as low as 20 Hz, for a drop landing task from 1.3 leg lengths high and with a compliance ratio (fraction of physical stiffness of the sum of virtual and physical stiffness) of 0.7. In computer simulations, we report successful drop-landings from 3.8 leg lengths (1.2 m) for a 2 kg quadruped robot with 100 Hz control frequency and a sensorimotor delay of 35 ms.