Low Degree Of Freedom Research Articles

A method of character input for the user interface with a low degree of freedom

In recent times, smart devices equipped with small touch panels have become very popular. Many such smart devices use a software keyboard for character input. Unfortunately, software keyboards have a limitation: the number of buttons and the input degrees of freedom remain the same, because a button and an input value correspond one-to-one. Thus, if we reduce the screen size while the button size remains the same, the number of buttons must decrease. Alternatively, if we maintain the number of buttons and reduce the screen size, the size of the button decreases, making input increasingly difficult. In this study, we investigate a new character input method that is specifically adapted for use on small screens. The proposed input interface has 4 × 2 operational degrees of freedom and consists of four buttons and two actions. By handling two operations as one input, 64 input options are secured. Additionally, we experimentally evaluate the proposed character input user interface deployed on a smart device. The proposed method enables an input of approximately 25 characters per minute, and it shows robust input performance on a small screen compared to previous software methods. Thus, the proposed method is better suited to small screens than were previous methods.

Evaluation of Compensatory Movement by Shoulder Joint Torque during Gain Adjustment of a Powered Prosthetic Wrist Joint.

Powered prostheses with low degree of freedom (DoF) have been developed for people with disabilities to assist daily tasks. These prostheses neglect the user's compensatory movements caused by the low degree of freedom. We assume that the movements can be reduced by well-designed controller of the devices. This paper explores an optimal control gain of the powered prosthesis to prevent the user from compensatory movements through experiments. In the experiments, we developed 1-DoF hand prosthesis with a position-controlled servo, which includes the constant gain as a feed-forward term. The compensatory movements are regarded as a joint torque at a shoulder (abduction/adduction). 4 intact subjects performed a pick-and-place task, using the prosthesis with several control gains. The empirical results show that there was the optimal gain for each subject, which reduces their compensatory movement.

Remote Estimation of Correlated Sources Under Energy Harvesting Constraints

Remote estimation with an energy harvesting sensor with a limited data and energy buffer is considered. The sensor node observes an unknown temporally correlated field and communicates its observations to a remote fusion center using the energy it harvested. The fusion center employs linear minimum mean-square error estimation to reconstruct the unknown field. We provide performance guarantees for the estimation error under a block transmission scheme, where at each transmission block, data and energy buffers are completely emptied. Our bounds provide insights into how statistical properties of the energy harvesting process and buffer sizes may affect the estimation error. In particular, these bounds suggest insensitivity of the performance to buffer sizes for signals with low degree of freedom and suggest performance improvements with increasing buffer sizes for signals with relatively higher degree of freedom. Depending only on the mean, variance, and finite support of the energy arrival process, these results provide insights for the energy and data buffer sizes for deployment in future energy harvesting wireless sensing systems.

Numerical solution of the inverse kinematics and trajectory planning for an all-position welding robot

Versatile welding robots designed for the field welding of box-type steel structures have the problems of low DOF (degree of freedom) and DOF coupling. A numerical solution method was developed for the inverse kinematics of the robot based on the layouts of actual welding processes to solve difficulties encountered in analytic methods. The numerical solution leads to a trajectory planning method based on the recursive algorithm to adjust the position and posture of the welding torch to realize smooth adjustments and transitions of the welding torch during welding of the right-angle turning point of the box-type steel structures. This approach provides trajectory planning for the all-position welding of box-type steel in an automatic algorithm that is applicable to different sizes of box-type steel structures. 摘要 针对所设计的新型箱型钢结构现场全位置焊接机器人存在欠自由度和自由度耦合等问题, 导出了一种基于实际焊接工艺需求的机器人逆运动学数值解法, 解决了采用传统解析法求解机器人逆运动学问题时存在的困难。在数值解的基础上, 进一步提出了一种基于递推算法的机器人运动轨迹规划和焊枪空间位姿调整方法, 实现了机器人在焊接箱型钢结构直角转角过程中的焊枪空间位姿的平滑过渡和调整。该方法不仅实现了箱型钢全位置焊接的轨迹规划功能, 有利于计算机自动求解, 而且可有效适应不同型号尺寸的箱型钢结构。

Modeling and validation of a 2-DOF parallel manipulator for pose control application

Simplified mathematical model for the hydraulically actuated 2DOF parallel manipulator has been developed.In the present mathematical modeling, system kinematics, dynamics along with joint friction have been considered.The model has been implemented in MatlabSimulink environment and has been verified with the experimental result.Fuzzy tuned feedforward PID bias controller has been developed for control analysis of the system. Control performance has been studied for different pose demand and external loading condition. The use of hydraulically actuated parallel manipulator in different industries increasing rapidly due to high rigidity, higher accuracy, less error propagation, fast speed of response, very good controllability, high power to weight ratio, self lubricating property, heat dissimilation characteristic etc. Manipulator with low degree of freedom (DOF) is simple to analysis, synthesis and fabrication compare to the higher DOF manipulator. In the present work hydraulically actuated 2DOF parallel manipulator has been considered for simulation study of the pose (heave and pitch) control application. Low cost hydraulic component (proportional valve with dead band, low speed hydraulic cylinder etc.) configuration has been considered for the system model. In the present study the simplified mathematical model of the manipulator has been developed. The model of the parallel manipulator has been verified with the experimental result. The verified model has been used to study the control performance by a model free fuzzy tuned feedforward bias PID controller for pose control application. The effectiveness of the proposed controller also has been studied. To study the robustness of the proposed controller central, eccentric and variable position of the external loading has been considered on the manipulator with sinusoidal and chirp heave and pitch demand.

A low degree of freedom approach for prediction of friction in finite EHL line contacts

A low degree of freedom (LDOF) approach for expedient prediction of friction in finite EHL line contact is presented. Friction prediction are in good agreement with existing results for all of the reference cases tested. With the present LDOF approach, friction predictions can be obtained thousands of times faster than if using a fully coupled FE-based model. It can, therefore be used to simulated the tribological contacts in multi-body dynamic (MBD) systems with millions of degrees of freedoms. The model was utilised to study edge stress concentrations due to roller tilt. The results confirmed that increasing the tilting angle increases the maximum pressure and shifts its location towards the edge of roller. An increase in total friction was also observed.

SU‐F‐J‐138: An Extension of PCA‐Based Respiratory Deformation Modeling Via Multi‐Linear Decomposition

Purpose:To address and lift the limited degree of freedom (DoF) of globally bilinear motion components such as those based on principal components analysis (PCA), for encoding and modeling volumetric deformation motion.Methods:We provide a systematic approach to obtaining a multi‐linear decomposition (MLD) and associated motion model from deformation vector field (DVF) data. We had previously introduced MLD for capturing multi‐way relationships between DVF variables, without being restricted by the bilinear component format of PCA‐based models. PCA‐based modeling is commonly used for encoding patient‐specific deformation as per planning 4D‐CT images, and aiding on‐board motion estimation during radiotherapy. However, the bilinear space‐time decomposition inherently limits the DoF of such models by the small number of respiratory phases. While this limit is not reached in model studies using analytical or digital phantoms with low‐rank motion, it compromises modeling power in the presence of relative motion, asymmetries and hysteresis, etc, which are often observed in patient data. Specifically, a low‐DoF model will spuriously couple incoherent motion components, compromising its adaptability to on‐board deformation changes. By the multi‐linear format of extracted motion components, MLD‐based models can encode higher‐DoF deformation structure.Results:We conduct mathematical and experimental comparisons between PCA‐ and MLD‐based models. A set of temporally‐sampled analytical trajectories provides a synthetic, high‐rank DVF; trajectories correspond to respiratory and cardiac motion factors, including different relative frequencies and spatial variations. Additionally, a digital XCAT phantom is used to simulate a lung lesion deforming incoherently with respect to the body, which adheres to a simple respiratory trend. In both cases, coupling of incoherent motion components due to a low model DoF is clearly demonstrated.Conclusion:Multi‐linear decomposition can enable decoupling of distinct motion factors in high‐rank DVF measurements. This may improve motion model expressiveness and adaptability to on‐board deformation, aiding model‐based image reconstruction for target verification.NIH Grant No. R01‐184173

一种新型3-CRU并联机构的动力学建模

3-CRU平动并联机构具有3条CRU支链组，具有三个运动方向上的平动特性，对于目前多数并联机构需要较少自由度这一现状以及在生产中的实际情况，本文根据广发的调查取证，设计并验证了一种全新的3-CRU平动并联机械手，在对机构进位置和速度分析的基础上，得到新机构的第一阶影响系数矩阵，继而采用虚功法建立新型3-CRU平动并联机构运动平台的动力学模型，为精密机构平台的精度划分提供帮助。 This 3-CRU parallel mechanism has three CRU branched chain groups and this parallel mechanism has three characteristics of translational movement direction. In practical application, it does not require so much degree of freedom. Based on the investigation and collecting data, the device needs low degree of freedom. A novel 3-CRU translational parallel mechanism has been designed for adapting to this situation. In this paper, the position and speed of the mechanism are analyzed, and the Jacobi matrix of the mechanism has been obtained. According to the principle of virtual work, we established the kinetic model of 3-CRU translational parallel mechanism. It can provide the help for the researching on the accuracy of precision motion platform.

"Characters" in Japanese Communication and Language: An Overview

There are various ideas related to characters in modern Japan (dramatis personae, Ito's (2005) Kyara and its self-professed successors' ideas, and situation-based self). This paper will introduce these ideas, address my definition of character (situation-based self) in detail, and discuss its significance for communication and linguistic research.The major characteristics of this definition are: (i) it is based on the traditionally taboo idea that "humans can change in response to the situation," and (ii) it is not something created by a researcher (the author), but was rather formed by speakers of Japanese in the course of daily life. I merely employed this word as it is, as a technical term.Japanese speakers are keenly conscious of the self’s situation-sensitiveness, but there is no need to think of Japanese society as unique just because it was the first to come out about this fact to the world. This characteristic of Japanese society can be understood as a difference of degree; that is, there is "a low degree of freedom in style, and a correspondingly large degree of freedom in character."

"Characters" in Japanese Communication and Language: An Overview

There are various ideas related to characters in modern Japan (dramatis personae, Ito's (2005) Kyara and its self-professed successors' ideas, and situation-based self). This paper will introduce these ideas, address my definition of character (situation-based self) in detail, and discuss its significance for communication and linguistic research.The major characteristics of this definition are: (i) it is based on the traditionally taboo idea that "humans can change in response to the situation," and (ii) it is not something created by a researcher (the author), but was rather formed by speakers of Japanese in the course of daily life. I merely employed this word as it is, as a technical term.Japanese speakers are keenly conscious of the self’s situation-sensitiveness, but there is no need to think of Japanese society as unique just because it was the first to come out about this fact to the world. This characteristic of Japanese society can be understood as a difference of degree; that is, there is "a low degree of freedom in style, and a correspondingly large degree of freedom in character."

직렬체인 다리를 갖는 평면 병렬형 기구의 강성해석

This paper presents a method for analyzing the stiffness of full and low DOF (degree of freedom) planar parallel manipulators with serially connected legs. The individual stiffness of each leg is obtained by applying reciprocal screws to the leg twist using passive joints and elastic elements consisting of actuators and links. Because the legs are connected in parallel, the manipulator stiffness is determined by summing the individual leg stiffness values. This method does not require the assumption that springs should be located along reciprocal screws and is applicable to a planar parallel manipulator with a generic or singular configuration. The stiffness values of three planar parallel manipulators with different DOFs are analyzed. The numerical results are confirmed using ADAMS S/W.

Robust estimation of motion blur kernel using a piecewise-linear model.

Blur kernel estimation is a crucial step in the deblurring process for images. Estimation of the kernel, especially in the presence of noise, is easily perturbed, and the quality of the resulting deblurred images is hence degraded. Since every motion blur in a single exposure image can be represented by 2D parametric curves, we adopt a piecewise-linear model to approximate the curves for the reliable blur kernel estimation. The model is found to be an effective tradeoff between flexibility and robustness as it takes advantage of two extremes: (1) the generic model, represented by a discrete 2D function, which has a high degree of freedom (DOF) for the maximum flexibility but suffers from noise and (2) the linear model, which enhances robustness and simplicity but has limited expressiveness due to its low DOF. We evaluate several deblurring methods based on not only the generic model, but also the piecewise-linear model as an alternative. After analyzing the experiment results using real-world images with significant levels of noise and a benchmark data set, we conclude that the proposed model is not only robust with respect to noise, but also flexible in dealing with various types of blur.

The examination of reproducibility in hydro-ecological characteristics by daily synthetic flow models

summary Research into synthetic streamflow generation previously focused primarily on engineering purposes, while disregarding hydro-ecological implications with regard to daily flow. This study investigated the applicability of daily synthetic flow models in the representation of hydro-ecological characteristics. This study applied flow duration curves and three performance indices as well as a method of statistical testing to identify whether Indicators of Hydrologic Alteration (IHA) derived from historical and synthetic flow data have the same distribution. This enabled us to evaluate the capacity of the synthetic flow models in capturing other important hydrological characteristics. This study examined various representative methods, most of which proved effective in simulating the magnitude of monthly flow and high flow within short durations. However, low flow conditions remain problematic, particularly over short durations. Among the various models, annual flow simulation using annual–daily disaggregation demonstrated good reproducibility, but its applicability with regard to within year fluctuations may be limited by the relatively low degree of freedom. Direct simulation models (shot noise and Markov-based) proved suitable in dealing with engineering problems based on monthly averages and annual daily maximum flow. Linear regression models, PARMA, and nonparametric models, modified k-NN, were shown to be well-suited to the representation of monthly stream flow. In conjunction with nonparametric bootstrap disaggregation, these methods proved effective in representing daily flow patterns. Coupling these methods with the shot noise disaggregation model was the least recommended due to bias resulting from numerical errors associated with repeated convolutions. 2014 Published by Elsevier B.V.

Kinetic Parameter Determination for Enzyme Hydrolysis of Fish Protein Residue Using D-optimal Design

The objective of this work was to compare the quality of parameter estimation from experiments with protein hydrolysis of fish muscle carried out following a traditional versus D-optimal design of experiments. Traditional design was done from hydrolysis experiments using the rapid titration method, from which a large number of data points was obtained and made available for parameter estimation. D-optimal design is recommended under conditions when it would not be possible to use rapid titration with analytical tools. Such conditions would make it necessary to reduce the number of samples that would need to be taken as well as the error and variance in the estimated parameters needed for the kinetic model. Results have shown that D-optimal and traditional designs of experiments obtained accurate and reliable estimates of kinetic model parameters, with a great difference in the number of data points between both types of design: 18 points in traditional and 3 points in D-optimal design. Nevertheless, a few number of observations in D-optimal design impacted negatively the confidence interval because of a low degree of freedom. Confidence intervals ranging from 7.8% to 87% of the parameters values were obtained with D-optimal design method in contrast with traditional design where confidence intervals ranged from 6.2% to 15% of the parameters values. It is estimated that combining the advantages of both types of design will result in an optimal experimental design in terms of reliability, accuracy, and costs saving of analysis. This would be done by determining the number of observations required to achieve an appropriate confidence interval (about six or more experimental points) and, then, a selection of the best experimental points of a curve of hydrolysis by D-optimal design.

Forward Interference Avoidance in Ad Hoc Communications Using Adaptive Array Antennas

Wireless ad hoc communications such as ad hoc networks have been attracting researchers' attention. They are expected to become a key technology for “ubiquitous” networking because of the ability to configure wireless links by nodes autonomously, without any centralized control facilities. Adaptive array antennas (AAA) have been expected to improve the network efficiency by taking advantage of its adaptive beamforming capability. However, it should be noted that AAA is not almighty. Its interference cancellation capability is limited by the degree-of-freedom (DOF) and the angular resolution as a function of the number of element antennas. Application of AAA without attending to these problems can degrade the efficiency of the network. Let us consider wireless ad hoc communication as a target application for AAA, taking advantage of AAA's interference cancellation capability. The low DOF and insufficient resolution will be crucial problems compared to other wireless systems, since there is no centralized facility to control the nodes to avoid interferences in such systems. A number of interferences might impinge on a node from any direction of arrival (DOA) without any timing control. In this paper, focusing on such limitations of AAA applied in ad hoc communications, we propose a new scheme, Forward Interference Avoidance (FIA), using AAA for ad hoc communications in order to avoid problems caused by the limitation of the AAA capability. It enables nodes to avoid interfering with other nodes so that it increases the number of co-existent wireless links. The performance improvement of ad hoc communications in terms of the number of co-existent links is investigated through computer simulations.

Numeration and type synthesis of 3-DOF orthogonal translational parallel manipulators

Low-degree-of-freedom (Low-DOF) parallel manipulators (PMs) have drawn extensive interests, particularly in type synthesis in which two main formal approaches were established by using the reciprocal screw system theory and Lie group theory. This paper aims at numeration and type synthesis of orthogonal translational parallel manipulators (OTPMs) by resorting to an integration of the group-based method and graphical representation of the topology. For this purpose, the concept of Cartesian DOF-characteristic matrix, originated from displacement subgroup and displacement submanifold, is proposed. A new approach based on the combination of the atlas of Cartesian DOF-characteristic matrix and the displacement group-theoretic method is addressed for both exhaustive classification and type synthesis of OTPMs. The proposed approach is prone to construct an orthogonal structure and is easy to realize the complete classification and exhaustive enumeration of this class of low-DOF PMs.

Underactuated Five-Finger Prosthetic Hand Inspired by Grasping Force Distribution of Humans

Simple grippers with one or two degrees of freedom are commercially available prosthetic hands; these pinch type devices cannot grasp small cylinders and spheres because of their low degree of freedom. This paper presents the design and prototyping of underactuated five-finger prosthetic hand for grasping various objects in daily life. Underactuated mechanism enables the prosthetic hand to move fifteen compliant joints only by one ultrasonic motor. The innovative design of this prosthetic hand is the underactuated mechanism optimized to distribute grasping force like those of humans grasping various objects robustly. Because of human like force distribution, the prototype of prosthetic hand could grasp various objects in daily life and heavy object with the maximum ejection force of 50 N grater than other underactuated prosthetic hands.

Construction of Nonlinear Dynamic MEMS Component Models Using Cosserat Theory

This paper presents a new modelling method for MEMS components based on Cosserat theory. By constructing Cosserat elements, generating symbolic code and development of numeric code in VHDL-AMS for selected demonstrators, we are able to effectively simulate and predict their linear and nonlinear behavior in estimating system performance and guiding the reliability verification process. The simplicity of the Cosserat approach follows from the possibility to formulate interconnected slender components in terms of a network of quasi-rigid bodies (Cosserat elements). This modularization fits well into the behavioral modelling where a relatively low degree of freedom is needed to capture salient features of system. Furthermore, the manner in which Cosserat elements and their interactions are formulated makes this method ideally suited for nonlinear dynamic simulations in the presence of large deflections.

Observation of spontaneously excited chaos-like ion plasma oscillations

An oscillation which behaves quite similarly to chaos under some conditions is observed to exist among ion plasma oscillations spontaneously excited in an ion beam–plasma system. There are two different states of the system, the ‘‘silent’’ and ‘‘chaotic’’ states, sensitively depending on the value of a direct current (DC) voltage VB, which determines the beam energy and is adopted as a control parameter here. In the chaotic state, a spontaneously excited ion plasma oscillation is observed to become chaotic. Here, the correlation dimension for the oscillation in the chaotic state is calculated to be 1.64±0.22. The result shows that an attractor for the oscillation has a low degree of freedom and a noninteger dimension.

An Object-Oriented Approach to Structural Analysis of Truss Structures.

Computational mechanics are based on numerical methods and high-performance computers while artificial intelligence (AI) tools are based on knowledgebases. A new concept on structural analysis by using AI technique is presented in this paper. A fully artificial intelligence approach has some significant meanings: 1) The field of computational mechanics should include problems which shows very complicated phenomenal behavior, but have low degree of freedom. 2) An approach supporting the conceptual design stage of structures should provide a very flexible simulation capability of structural behavior. Artificial intelligence tools will provide some solutions to these. The purpose of this research is to investigate the benefits derived from the application of an artificial intelligence approach to structural analysis fields. A prototype knowledge-based system, called OOTA (Object-Oriented Truss Analysis), is developed to analyze me truss structures. Since the system does not use any numerical method, the computation requires much time. But, it provides many advantages for small but complex problems including material and geometric nonlinearlities.