Joint Module Research Articles

A pose-based structural dynamic model updating method for serial modular robots

A new approach is presented for updating the structural dynamic component models of serial modular robots using experimental data from component tests such that the updated model of the entire robot assembly can provide accurate results in any pose. To accomplish this, a test-analysis component mode synthesis (CMS) model with fixed-free component boundaries is implemented to directly compare measured frequency response functions (FRFs) from vibration experiments of individual modules. The experimental boundary conditions are made to emulate module connection interfaces and can enable individual joint and link modules to be tested in arbitrary poses. By doing so, changes in the joint dynamics can be observed and more FRF data points can be obtained from experiments to be used in the updating process. Because this process yields an overdetermined system of equations, a direct search method with nonlinear constraints on the resonances and antiresonances is used to update the FRFs of the analytical component models. The effectiveness of the method is demonstrated with experimental case studies on an adjustable modular linkage system. Overall, the method can enable virtual testing of modular robot systems without the need to perform further testing on entire assemblies.

Joint and Link Module Geometric Shapes of Modular Manipulator for Various Joint Configurations

A modular manipulator in serial-chain structure usually consists of a series of modularized revolute joint and link modules. The geometric shapes of these modules affect the number of possible configurations of modular manipulator after assembly. Therefore, it is important to design the geometry of the joint and link modules that allow various configurations of the manipulators with minimal set of modules. In this paper, a new 1-DoF(degree of freedom) joint module and simple link modules are designed based on a methodology of joint configurations using a series of Rotational(type-R) and Twist(type-T) joints. Two of the joint modules can be directly connected so that two types of 2-DoFs joints could be assembled without a link module between them. The proposed geometries of joint and link modules expand the possible configurations of assembled modular manipulators compared to existing ones. Modular manipulator system of this research can be a cornerstone of user-centered markets with various solution but low-cost, compared to conventional manipulators of fixed-configurations determined by the provider.

A Two-Stage Method to Identify Joint Modules From Matched MicroRNA and mRNA Expression Data

MicroRNAs (miRNAs) are a class of small non-coding RNAs, which play key roles in gene regulation. Previous studies have revealed that they are likely to work together to regulate their common target genes. Discovery of the underlying combinatorial regulation between miRNAs and genes can provide useful information for understanding their functions as well as their close relevance to cancer. In this paper, we propose a two-stage method for identifying miRNA-gene regulatory modules by integrating miRNA and mRNA expression profiles and miRNA genomic cluster data. We first develop a multiple-output sparse group lasso (MSGL) regression model to predict a miRNA-gene association matrix (i.e., a miRNA-gene regulatory network). Further, we propose a ${L_{0}} $ -regularized singular value decomposition ( ${L_{0}} $ -SVD) to identify miRNA-gene joint modules from the predicted regulatory network. We test our method on the matched miRNA and mRNA expression profiles in breast cancer from TCGA project and identify ten miRNA-gene regulatory modules. We find that 1) the modules are significantly associated in the predicted miRNA-gene regulatory network; 2) the modules are significantly enriched in GO biological processes and KEGG pathways, respectively; 3) many miRNAs and genes in the modules are related with breast cancer. On average, 51% of the miRNAs and 30% of the genes are related with breast cancer. The results demonstrate that miRNA-gene regulatory modules provide insights into the mechanisms of the combinatorial regulation between miRNAs and genes.

DNA module platform for developing colorimetric aptamer sensors.

Here we present a DNA module platform for developing simple aptamer sensors based on a microarray format combined with secondary structure prediction in silico. The platform comprises four parts: (i) aptamer, (ii) joint module, (iii) terminal stem, and (iv) a DNAzyme that catalyzes a redox reaction controlled by a structural change induced by aptamer/target binding. First, we developed a joint module, capable of sensing a conformational change in the aptamer region, that was linked to the signal transmission activity of a DNAzyme as the reporter in a concentration-dependent manner with the AMP aptamer. This module design was then used to generate an arginine sensor simply by replacing the AMP aptamer region with a previously reported arginine aptamer. Using this DNA module platform, we were also able to customize a microarray containing >10,000 sequences designed by in silico secondary structure prediction and successfully identify a new aptamer against patulin. Our results show that the DNA module platform can be used to readily devise sensors based on known aptamers as well as create new aptamer sensors by array-based screening.

The use of the knee joint replacement prosthesis after the amputation at the level between hip and knee

This review was designed to characterize the current state-of-the-art of knee joint replacement prosthetics with respect to the cases of the amputation at the level between hip and knee. Various types of knee joint modules are compared. The clinical and biomechanical methods are described that are employed to evaluate the effectiveness of the movements of the disabled patients following the amputation at the level between hip and knee.

토크 오차 감소를 위한 디스크형 커플링을 갖는 토크센서가 내장된 로봇 관절모듈

토크 오차 감소를 위한 디스크형 커플링을 갖는 토크센서가 내장된 로봇 관절모듈

Climbot: A Bio-Inspired Modular Biped Climbing Robot—System Development, Climbing Gaits, and Experiments

Agriculture, forestry, and building industry would be prospective fields of robotic applications. High-rise tasks in these fields require robots with climbing skills. Motivated by these potential applications and inspired by animal climbing motion, we have developed a biped climbing robot—Climbot. Built with a modular approach, the robot consists of five joint modules connected in series and two special grippers mounted at the ends, with the scalability of changing degrees-of-freedom (DoFs). With this configuration, Climbot not only has superior mobility on multiple climbing media, such as poles and trusses, but also has the function of grasping and manipulating objects. It is a kind of “mobile” manipulator and represents an advancement in development of climbing robots. In this paper, we first present the development of this climbing robot with modular and bio-inspired methods, and then propose and compare three climbing gaits based on the unique configuration and features of the robot. A series of challenging and comprehensive experiments with the robot climbing in a truss and performing an outdoor manipulation task are carried out, to illustrate the feasibility, the features, the climbing, and manipulating functions of the robot, and to verify the effectiveness of the proposed gaits.

A Wheel-legged Robot with Active Waist Joint: Design, Analysis, and Experimental Results

This paper presents a wheel-legged robot that features an active waist joint. The proposed wheel-legged robot is composed of a front module, a rear module, and an active waist joint. The proposed robot can perform rectilinear motion and turning motion in both wheeled and legged modes. The active waist joint module is added to make the robot pass through the curved narrow channel. Several experiments have been done to evaluate the performance of the proposed wheel-legged robot. The maximum velocities of the proposed robot in wheeled and legged modes are 17.2 and 10.4 m/min respectively. And the average corresponding deflection rates of the proposed robot in wheeled and legged modes are 3.1 and 3.7 % respectively. The mobility efficiencies of the robot in wheeled and legged modes are up to 96.3 and 94.3 % respectively. Compared with the proposed robot in legged mode, the performance in the turning motion with the active waist joint is better when the proposed robot is in wheeled mode. Two approaches of climbing obstacles are proposed for the proposed robot in legged mode. The wheel-legged robot can climb an obstacle with maximum height of 10 cm.

Toward a Unified Design Approach for Both Compliant Mechanisms and Rigid-Body Mechanisms: Module Optimization

Rigid-body mechanisms (RBMs) and compliant mechanisms (CMs) are traditionally treated in significantly different ways. In this paper, we present a synthesis approach that is appropriate for both RBMs and CMs. In this approach, RBMs and CMs are generalized into modularized mechanisms that consist of five basic modules, including compliant links (CLs), rigid links (RLs), pin joints (PJs), compliant joints (CJs), and rigid joints (RJs). The link modules and joint modules are modeled through beam elements and hinge elements, respectively, in a geometrically nonlinear finite-element solver, and subsequently a beam-hinge ground structure model is proposed. Based on this new model, a link and joint determination approach—module optimization—is developed for the type and dimensional synthesis of both RBMs and CMs. In the module optimization approach, the states (both presence or absence and sizes) of joints and links are all design variables, and one may obtain an RBM, a partially CM, or a fully CM for a given mechanical task. Three design examples of path generators are used to demonstrate the effectiveness of the proposed approach to the type and dimensional synthesis of RBMs and CMs.

Sensorimotor synchronization with tempo-changing auditory sequences: Modeling temporal adaptation and anticipation

The current study investigated the human ability to synchronize movements with event sequences containing continuous tempo changes. This capacity is evident, for example, in ensemble musicians who maintain precise interpersonal coordination while modulating the performance tempo for expressive purposes. Here we tested an ADaptation and Anticipation Model (ADAM) that was developed to account for such behavior by combining error correction processes (adaptation) with a predictive temporal extrapolation process (anticipation). While previous computational models of synchronization incorporate error correction, they do not account for prediction during tempo-changing behavior. The fit between behavioral data and computer simulations based on four versions of ADAM was assessed. These versions included a model with adaptation only, one in which adaptation and anticipation act in combination (error correction is applied on the basis of predicted tempo changes), and two models in which adaptation and anticipation were linked in a joint module that corrects for predicted discrepancies between the outcomes of adaptive and anticipatory processes. The behavioral experiment required participants to tap their finger in time with three auditory pacing sequences containing tempo changes that differed in the rate of change and the number of turning points. Behavioral results indicated that sensorimotor synchronization accuracy and precision, while generally high, decreased with increases in the rate of tempo change and number of turning points. Simulations and model-based parameter estimates showed that adaptation mechanisms alone could not fully explain the observed precision of sensorimotor synchronization. Including anticipation in the model increased the precision of simulated sensorimotor synchronization and improved the fit of model to behavioral data, especially when adaptation and anticipation mechanisms were linked via a joint module based on the notion of joint internal models. Overall results suggest that adaptation and anticipation mechanisms both play an important role during sensorimotor synchronization with tempo-changing sequences.This article is part of a Special Issue entitled SI: Prediction and Attention.

Dynamic Output Feedback Based Active Decentralized Fault-Tolerant Control for Reconfigurable Manipulator with Concurrent Failures

The goal of this paper is to describe an active decentralized fault-tolerant control (ADFTC) strategy based on dynamic output feedback for reconfigurable manipulators with concurrent actuator and sensor failures. Consider each joint module of the reconfigurable manipulator as a subsystem, and treat the fault as the unknown input of the subsystem. Firstly, by virtue of linear matrix inequality (LMI) technique, the decentralized proportional-integral observer (DPIO) is designed to estimate and compensate the sensor fault online; hereafter, the compensated system model could be derived. Then, the actuator fault is estimated similarly by another DPIO using LMI as well, and the sufficient condition of the existence ofH∞fault-tolerant controller in the dynamic output feedback is presented for the compensated system model. Furthermore, the dynamic output feedback controller is presented based on the estimation of actuator fault to realize active fault-tolerant control. Finally, two 3-DOF reconfigurable manipulators with different configurations are employed to verify the effectiveness of the proposed scheme in simulation. The main advantages of the proposed scheme lie in that it can handle the concurrent faults act on the actuator and sensor on the same joint module, as well as there is no requirement of fault detection and isolation process; moreover, it is more feasible to the modularity of the reconfigurable manipulator.

Type synthesis and preliminary design of devices supporting lower limb's rehabilitation.

Based on the analysis of existing solutions, biomechanics of human lower limbs and anticipated applications, results of con- siderations concerning the necessary number of degrees of freedom for the designed device supporting rehabilitation of lower extremities are presented. An analysis was carried out in order to determine the innovative kinematic structure of the device, ensuring sufficient mobility and functionality while minimizing the number of degrees of freedom. With the aid of appropriate formalised meth- ods, for instance, type synthesis, a complete variety of solutions for leg joints were obtained in the form of basic and kinematic schemes, having the potential to find application in devices supporting lower limb rehabilitation. A 3D model of ankle joint module was built in Autodesk Inventor System, then imported to Adams and assembled into a moving numerical model of a mechanism. Several conducted simulations resulted in finding the required maximum stroke of the cylinders. A comparison of the angular ranges of ankle joint and similar devices with the ones achieved by the designed device indicated a sufficient reserve allowing not only movements typical of gait, but approximately achieving the passive range of motion for the ankle joint.

창의력 증진을 위한 놀이 및 교육용 모듈러 로봇 개발

본 연구에서는 교육 및 놀이를 통해 창의력 증진이 가능한 재구성 모듈러 로봇에 대하여 다루고 있다. 보통 모듈러 로봇은 각각 셀들의 조합으로 변형 재구성하고 다양한 형태의 구조를 만드는데 적합한 로봇으로 설계되어 있지만 이를 이용하여 교육과 놀이를 주제로 한 연구는 국외에 소수 있으며 국내에는 전무하다. 제안하는 형태는 기존 모듈러 로봇과 같이 같은 동작만 반복하는 모듈이 아니라 소리를 내는 소리모듈, 바퀴가 달린 바퀴모듈, 시각적 표현을 위한 LED모듈, 전원공급을 위한 전원모듈, 통신을 위한 블루투스모듈, 움직이는 동작을 구현 가능하도록 하는 관절모듈이 있는 구조로 설계되어 있다. 이와 같은 다른 능력이 부여된 각 모듈의 다양한 결합을 이용하여 창의적 활동이 가능하도록 하고, 아이들이 쉽게 사용 할 수 있도록 한다. 본 연구에서는 모듈별 각기 다른 능력을 부여하여 교육과 놀이가 가능하도록 하는 방식의 모듈러 로봇의 설계 및 동작을 다루고 있다. 그리고 연구된 동작은 실제 제작 및 실험을 통해 동작의 유용성을 보였다. This study deals with reconfigurable modular robot with respect to the compact and capability of representing the various actions for promoting creativity through education and play. Generally modular robot can be designed as a suitable robot that is transformed to various structure by reconstructing each cells, However, there are only few research on the education and play using those robots in the world and still nothing domestically. Unlike the existing modular robots only having a repeating motion, the proposed modular works by individual module such as sound is produced by sound module, wheel is driven by wheel module, LED module controls the visual expression, power is supplied by battery module, bluetooth module for communication, and dynamic motion realization is possible by using joint module. By manipulating the abilities endowed by individual modules, diversity of creative activities is possible and thus made an easy access for children. This study deals with the design of modular robotic by using the variety of different modules to endowed the learning and playing ability. And the study showed the utility of the operating behavior over the actual production and testing.

인간과의 안전한 상호 작용을 고려한 휴머노이드 조인트 모듈 개발

In this study, we have developed the humanoid joint modules which provide a variety of service while living with people in the future home life. The most important requirement is ensuring the safety for humans of the robot system for collaboration with people and providing physical service in dynamic changing environment. Therefore we should construct the mechanism and control system that each joint of the robot should response sensitively and rapidly to fulfill that. In this study, we have analyzed the characteristic of the joint which based on the target constituting the humanoid motion, developed the optimal actuator system which can be controlled based on each joint characteristic, and developed the control system which can control an multi-joint system at a high speed. In particular, in the design of the joint, we have defined back-drivability at the safety perspective and developed an actuator unit to maximize. Therefore we establish a foundation element technology for future commercialization of intelligent service robots

Bibot-U6: A Novel 6-DoF Biped Active Walking Robot - Modeling, Planning and Control

Most of current biped robots are active walking platforms. Though they have strong locomotion ability and good adaptability to environments, they have a lot of degrees of freedom (DoFs) and hence result in complex control and high energy consumption. On the other hand, passive or semi-passive walking robots require less DoFs and energy, but their walking capability and robustness are poor. To overcome these shortcomings, we have developed a novel active biped walking robot with only six DoFs. The robot is built with six 1-DoF joint modules and two wheels as the feet. It achieves locomotion in special gaits different from those of traditional biped robots. In this paper, this novel biped robot is introduced, four walking gaits are proposed, the criterion of stable walking is addressed and analyzed, and walking patterns and motion planning are presented. Experiments are carried out to verify the locomotion function, the effectiveness of the presented gaits and to illustrate the features of this novel biped robot. It has been shown that biped active walking may be achieved with only a few DoFs and simple kinematic configuration.

A large deflection and high payload flexure-based parallel manipulator for UV nanoimprint lithography: Part II. Stiffness modeling and performance evaluation

This paper presents a flexure-based parallel manipulator (FPM) that delivers nanometric co-planar alignment and direct-force imprinting capabilities to automate an ultra-violet nanoimprint lithography (UV-NIL) process. The FPM is articulated from a 3-legged Prismatic-Prismatic-Spherical (3PPS) parallel-kinematic configuration to deliver a θx–θy–Z motion. The developed FPM achieves a positioning and orientation resolution of ±10nm and 0.05″, respectively, and a continuous output force of 150N/A throughout a large workspace of 5°×5°×5mm. Part I mainly focuses on a new theoretical model that is used to analyze the stiffness characteristics of the compliant joint modules that formed the FPM, and experimental evaluations of each compliant joint module. Part II presents the stiffness modeling of the FPM, the performance evaluations of the developed prototype, and the preliminary results of the UV-NIL process.

A large deflection and high payload flexure-based parallel manipulator for UV nanoimprint lithography: Part I. Modeling and analyses

This paper presents a flexure-based parallel manipulator (FPM) that delivers nanometric co-planar alignment and direct-force imprinting capabilities to automate an ultra-violet nanoimprint lithography (UV-NIL) process. The FPM is articulated from a novel 3-legged prismatic-prismatic-spherical (3PPS) parallel-kinematic configuration to deliver a θx–θy–Z motion. The developed FPM achieves a positioning and orientation resolution of ±10nm and 0.05″ respectively, and a continuous output force of 150N/Amp throughout a large workspace of 5°×5°×5mm. Part I mainly focuses on a new theoretical model that is used to analyze the stiffness characteristics of the compliant joint modules that formed the FPM, and experimental evaluations of each compliant joint module. Part II presents the stiffness modeling of the FPM, the performance evaluations of the developed prototype, and the preliminary results of the UV-NIL process.

Screw theory based motion analysis for an inchworm-like climbing robot

SUMMARYTo obtain better performance on unstructured environments, such as in agriculture, forestry, and high-altitude operations, more and more researchers and engineers incline to study classes of biologically inspired robots. Since the natural inchworm can move well in various types of terrain, inchworm-like robots can exhibit excellent mobility. This paper describes a novel inchworm-type robot with simple structure developed for the application for climbing on trees or poles with a certain range of diameters. Modularization is adopted in the robot configuration. The robot is a serial mechanism connected by four joint modules and two grippers located at the front and rear end, respectively. Each joint is driven by servos, and each gripper is controlled by a linear motor. The simplified mechanism model is established, and then is used for its kinematic analysis based on screw theory. The dynamics of the robot are also analyzed by using Lagrange equations. The simulation of the robot gait imitating the locomotion of real inchworm is finally presented.

Local joint information based active fault tolerant control for reconfigurable manipulator

This paper is concerned with the active fault tolerant control problem for reconfigurable manipulator actuator based on local joint information. It is considered that the entire reconfigurable manipulator system consists of a couple of independent joint modules as subsystems, which are controlled using unified radial basis function neural network adaptive algorithm using local joint information when actuators are fault free. For the subsystem in actuator fault situation, fault detection is achieved through comparing the user defined threshold to the residual between actual velocity value and nonlinear velocity observation value. The unknown input state observer is exploited for fault identification. Based on the information aforementioned, a compensation term is added to the proposed control algorithm for switching to realize active fault tolerant control when subsystem in fault. The advantages of the presented scheme are that unlike the complex control structure in centralized control, this scheme possesses simple control structure, as well as could isolate and tolerant the fault in subsystem. Furthermore, it can be easily applied to different configurations without any parameters modification. It means that the local fault could not affect the joint in normal situation. In order to demonstrate the effectiveness of the proposed method, two different 2-DOF reconfigurable manipulators are employed for simulation.

1A1-R02 汎用モジュールシステム(MMS)の四足連結形態での二足支持時における姿勢の安定化(脚移動ロボット)

The Multi-purpose Module System (MMS), which is one of the module robots, consists of joint modules and function modules. It is possible to transform the MMS such as series-connected form and quadruped form and add appropriate sensors. Therefore, the MMS is useful as rescue robot at unknown situation. This paper presents a quadruped form MMS (MMS-G02). Especially, modeling and simulation of the MMS-G02 for stability control is discussed. An inverted pendulum model is proposed and the MMS-G02 is controlled using a state feedback control to stay in balance. And the effect of friction force between the MMS-G02 and the ground is also evaluated by simulation. The maximum value of the lean of the MMS-G02 decreases with increasing the friction coefficient. The maximum value of the lean is 0.21 rad at condition of the friction coefficient 0.1. The results also indicated that the MMS-G02 can stay in balance and keep on the two legs.