High-speed visual servoing of a 6-d.o.f. manipulator using multivariable predictive control

This paper presents a new approach to model and control high-speed 6-d.o.f. visual servo loops. The modeling and control strategy take into account the dynamics of the velocity-controlled 6-d.o.f. manipulator as well as a simplified model of the camera and acquisition system in order to significantly increase the bandwidth of the servo loop. Multi-input multi-output generalized predictive control (GPC) is used to optimally control the visual loop with respect to the proposed dynamical model. The predictive feature of the GPC is used for optimal trajectory following in Cartesian space. Experimental results on a 6-d.o.f. industrial robot are presented that validate the proposed model. The visual sensor used in the experiments is a high-speed camera that acquires 120 non-interlaced images. Using this camera, a sampling rate of 120 Hz is achieved for the visual loop. Furthermore, a precise synchronization method is used to reduce the delays due to image transfer and processing. The experiments show a drastic improvement of the loop performance with respect to more classical control strategies for 6-d.o.f. visual servo loops.     

Practical Point-to-Point Multiple-Goal Task Realization in a Robot Arm with a Rotating Table

This study presents a multiple-goal task realization in a system composed of a 6-d.o.f. robot arm and a one-axis rotating table. The problem is complex due to the existence of multiple goals and the kinematic redundancy of the system. We propose a design approach integrating the base placement, task sequencing and motion coordination methods. We show that this approach reduces the task completion time of the robot arm; the motion planning is realized through straight-line paths in the configuration space despite collision occurrences. Furthermore, we introduce a hybrid graph-search method combining the greedy nearest-neighbor method and the Dijkstra method to solve the motion coordination of the robot arm and the table. We show the effectiveness of the design approach and the search method through a time-constrained simulation-based optimization.     

Non-holonomic Path Planning of a Free-Floating Space Robotic System Using Genetic Algorithms

In this paper, the non-holonomic characteristic of a free-floating space robotic system is used to plan the path of the manipulator joints, by whose motion the base attitude and the manipulator joints attain the desired states. Here, we parameterize the joint trajectory using sinusoidal functions, whose arguments are high-order polynomials. Then, we define the cost function for optimization according to the constraint conditions and the accuracy of the space robot. Finally, genetic algorithms (GAs) are used to search for the solutions of the parameters. Compared with others, our approach has advantages as follows. (i) The motion of the manipulator and the disturbance on the base are practically constrained. (ii) The dynamic singularities cannot affect the algorithm since only the direct kinematic equations are utilized. (iii) The planned path is smooth and more applicable for the control of the manipulator. (iv) The convergence of the algorithm is not affected by the attitude singularity since the orientation error is represented by quaternion, which is globally singularity-free. The simulation results of the spacecraft with a 6-d.o.f. manipulator verify the performance and the validity of the proposed method.     

Executing optimized throwing motion on robot arm with free joint

We address the throwing motion optimization for robot. In order to pursue the best throwing motion, we may need heuristics/intuition free methods. We propose a throwing method that is composed of rapid semi-optimal motion-planning and output zeroing method. So as to execute the optimized trajectories in real rigid body systems, we need some compensations for the noises around the optimized trajectories. We introduce a compensation method for the optimized throwing motions of a robot arm with a free joint. To validate the effectiveness of the proposed method, we conducted a throwing experiment using a two-link arm. As a result of the experiment, the robot arm threw a ball with 63.7 km/h, which was the best record through the past experiments of this arm.     

Kinematics for the whole arm of a serial-chain manipulator

This paper provides a viewpoint for kinematics for the whole arm of a serial-chain manipulator with 2-d.o.f. rotational joints. An in-depth understanding of the duality between a rigid link and a 2-d.o.f. joint allows us to derive simple and geometric equations describing the manipulator kinematics. The obtained kinematic equations are analyzed in two ways compared with the Frenet-Serret formula of a spatial curve which is utilized for a reference shape of the manipulator. One way is based on limit analysis where we increase the number of joints while the total length of the manipulator remains constant. The other way utilizes an extended mechanism through the link-joint duality. The information presented in this paper is useful for mechanism design dynamic analysis, control design and motion planning of the manipulators in whole-arm manipulation.     

Optimization-based scheduling for the single-satellite,multi-ground station communication problem

In this paper, we develop models and algorithms for solving the single-satellite, multi-ground station communication scheduling problem, with the objective of maximizing the total amount of data downloaded from space. With the growing number of small satellites gathering large quantities of data in space and seeking to download this data to a capacity-constrained ground station network, effective scheduling is critical to mission success. Our goal in this research is to develop tools that yield high-quality schedules in a timely fashion while accurately modeling on-board satellite energy and data dynamics as well as realistic constraints of the space environment and ground network. We formulate an under-constrained mixed integer program (MIP) to model the problem. We then introduce an iterative algorithm that progressively tightens the constraints of this model to obtain a feasible and thus optimal solution. Computational experiments are conducted on diverse real-world data sets to demonstrate tractability and solution quality. Additional experiments on a broad test bed of contrived problem instances are used to test the boundaries of tractability for applying this approach to other problem domains. Our computational results suggest that our approach is viable for real-world instances, as well as providing a strong foundation for more complex problems with multiple satellites and stochastic conditions.     

Accurate force reflection method for a multi-d.o.f. haptic interface using instantaneous restriction space without a force sensor in an unstructured environment

This paper proposes an accurate force reflection method for a multi-d.o.f. haptic interface without a force sensor. Sensorless force reflection is possible using position–position (p–p) architecture. However, the conventional p–p architecture in the literature has limitations representing constraint space when it is applied to a multi-d.o.f. haptic interface in that it gives an inaccurate force direction. This paper demonstrates the limitation of the conventional p–p architecture through an example and proposes a novel force reflection method using the instantaneous restriction space (IRS) concept. The IRS can be calculated using the Jacobian and joint angle error of a slave manipulator. Since the proposed method has the form of an impedance two-port architecture in the sense of data flow, it can be easily combined with previous well-known results of two-port haptic display frameworks. The proposed method is especially useful when the slave manipulator collides with unexpected obstacles during motion, even though the slave does not have a force sensor. The performance of the proposed method is evaluated through experiments.     

Adaptive control of free-floating space robots in Cartesian coordinates

An adaptive control scheme is proposed for the end-effector trajectory tracking control of free-floating space robots. In order to cope with the nonlinear parameterization problem of the dynamic model of the free-floating space robot system, the system is modeled as an extended robot which is composed of a pseudo-arm representing the base motions and a real robot arm. An on-line estimation of the unknown parameters along with a computed-torque controller is used to track the desired trajectory. The proposed control scheme does not require measurement of the accelerations of the base and the real robot arm. A two-link planar space robot system is simulated to illustrate the validity and effectiveness of the proposed control scheme.     

Kinematic properties of human arm reaching movements in a three-dimensional space

In this study, kinematic properties of human arm reaching movements have been analyzed by use of experimental results of arm trajectories observed in a three-dimensional (3D) space. In the beginning, hand paths obtained by the experiments are kinematically analyzed to pursue their linearity, and we successfully specify a plane on which a hand moves. In the next place, the hand speed profile is calculated by use of position data observed by the experiment in a 3D space. Besides, the hand speed profile is also analytically produced under the minimum jerk criterion with respect to the displacement along the hand path. These observed and produced trajectories are compared, and the similarity of two trajectories has been demonstrated. As a result of the analyses for path and the speed profile of a hand, kinematic properties of human arm trajectories have been identified.     

Stabilization control for biped follow walking

This paper proposes a follow-walking motion for biped humanoid robots based on a stabilization control and a complete walking-motion pattern. To follow human motion, the unit patterns of the trunk, the waist and the lower limbs are generated and synthesized. During the follow motion, the biped robots are balanced by the stabilization control that calculates the combined motion of the trunk and the waist that compensates for the moments produced by the motion of the lower limbs. For confirmation of the follow-walking motion, we have developed a life-sized humanoid robot, WABIAN-RII (WAseda BIped humANoid robot-Revised II). It has a total of 43 mechanical d.o.f.; two 6-d.o.f. legs, two 10-d.o.f. arms, a 4-d.o.f. neck, 4-d.o.f. in the eyes and a torso with a 3-d.o.f. waist.     

Pneumatic impedance control of a 3-d.o.f. physiotherapy robot

Stroke is a common condition resulting in 30 000 people per annum left with significant disability. In patients with severe arm paresis after stroke, functional recovery in the affected arm is poor. Inadequate intensity of treatment is cited as one factor accounting for the lack arm recovery found in some studies. Given that physical therapy resource is limited, strategies to enhance the physiotherapists' efforts are needed. One approach is to use robotic techniques to augment movement therapy. A 3-d.o.f. pneumatic robot has been developed to apply physiotherapy to the upper limb. The robot has been designed with a workspace encompassing the reach-retrieve range of the average male. Slight non-linearities in the response of the pneumatic system are observed and explained. Building upon previous work that used an error-prone custom force sensor, a commercial 6-d.o.f. force sensor is used to apply impedance control in 3 d.o.f. on the robot.     

星载光谱仪摆臂系统的变结构空间抗扰控制

针对高精密星载光谱仪摆臂系统的空间微重力、微振动抗扰问题,提出一种积分滑模变结构控制策略．首先给出了空间微重力、微振动对摆臂系统的干扰模型;然后,根据系统对光程差速度的控制要求以及与电机角速度的非线性关系,给出了积分滑模变结构控制的设计方法;最后,将所提出的控制方法与PI调节控制进行抗干扰对比仿真,所得结果表明,该方法能有效抑制空间微重力、微振动等引起的扰动,保证系统的鲁棒性．     

空间机器人微重力模拟实验系统研究综述

介绍了微重力模拟实验系统的特点,归纳了研究中的关键问题．总结了主要实现方法,包括：基于自由落体运动、基于抛物线飞行、气浮式、水浮式、吊丝配重式实验系统,以及硬件在环内（hardwareinloop）的混合地面实验系统．讨论、比较了各种实验系统的应用背景及优缺点;在此基础上,提出了动力学模拟与运动学等效的两种思想,并建立了实验系统,以对路径规划、控制等关键算法进行评估和验证．     

Generalization of Plate Finite Elements for Absolute Nodal Coordinate Formulation

We propose a way to generate new finite elements in the absolute nodalcoordinate formulation (ANCF) and use a generalization of displacementfields and degrees of freedom (d.o.f.) of ordinary finite elements usedin structural mechanics. Application of this approach to 16- and12-d.o.f. rectangle plate elements as well as to 9-d.o.f. triangleelement gives, accordingly, 48-, 36- and 27-d.o.f. ANCF plate elements.We perform a thorough study of a 48-d.o.f. Hermitian element. Its shapefunction set is a Cartesian product of sets of one-dimensional shapefunctions for beam elements. Arguments of the shape functions aredecoupled, that is why an explicit calculation of terms of equations ofmotion leads to single integration only. We develop several models ofelastic forces of different complexity with their Jacobian matrices.Convergence and accuracy of the finite element is demonstrated ingeometrically nonlinear static and dynamic test problems, as well as inlinear analysis of natural frequencies.     

Study on Non-holonomic Cartesian Path Planning of a Free-Floating Space Robotic System

The non-holonomic characteristic of a free-floating space robotic system is used to plan the path of the manipulator joints, by whose motion the base attitude and the inertial pose (the position and orientation with respect to the inertial frame) of the end-effector attain the desired values. First, the kinematic equations of a free-floating space robot are simplified and the system state variables are transformed to another form composed of base attitude and joint angles. Then, the joint trajectories are parameterized using sinusoidal functions, whose arguments are seven-order polynomials. Third, the planning problem is transformed to an optimization problem; the cost function, defined according to the accuracy requirements of system variables, is the function of the parameters to be determined. Finally, the Particle Swarm Optimization (PSO) algorithm is used to search the solutions of the parameters that determine the joint trajectories. The presented method meets three typical applications: (i) point-to-point maneuver of the end-effector without changing the base attitude, (ii) attitude maneuver of the base without changing the end-effector's pose and (iii) point-to-point maneuver of the end-effector with adjusting the base attitude synchronously. The simulation results of a spacecraft with a 6-d.o.f. manipulator verify the performance and the validity of the proposed method.     

Early diagnosis of gastrointestinal cancer by using case-based and rule-based reasoning

In this paper, we present a medical diagnosis decision support model for gastrointestinal cancer. It should be used by general practitioners whenever there is a suspicion that a patient has this type of cancer. To build our model, we used Case-Based Reasoning (CBR) and Rule-Based Reasoning (RBR). We used real patient data as inputs to our model. We applied RBR to improve the CBR retrieve process. The model’s output presents the probability of the patient having a specific cancer. In order to adjust the attributes weights, we collected data from a general practitioner. To validate our model, we used K-fold cross validation and the paired t-test. The results showed that, with our approach, the accuracy of the diagnosis increased by 22.92% when compared to a CBR approach not using RBR in case retrieval. Furthermore, we evaluated our approach with an online questionnaire and semi-structured interviews. Even though, given the number of respondents, we cannot generalize our conclusions, the results indicate that our approach would be useful for general practitioners.     

Examining cognitive function across the lifespan using a mobile application

Many studies conducted in a laboratory or university setting are limited by funding, personnel, space, and time constraints. In the present study, we introduce a method of data collection using a mobile application that circumvents these typical experiment administration issues. Using the application, we examined cross-sectional age differences in cognitive function. We obtained data from more than 15,000 participants and replicated specific patterns of age-related differences in cognition. Using a subset of these participants, we also examined the processing speed account of age-related cognitive differences, and the association of exercise and leisure activity with cognitive function across the lifespan. We discuss the relative advantages and disadvantages of data collection with a mobile application, and provide recommendations for the use of this method in research.     

Modelling and estimating the pose of a human arm

Pose estimation of 3-D objects based on monocular computer vision is an ill-posed problem. To ease matters a model-based approach can be applied. Such an approach usually relies on iterating when matching the model and the image data. In this paper we estimate the 3-D pose of a human arm from a monocular image. To avoid the inherent problems when iterating, we apply an exhaustive matching strategy. To make this plausible, we reduce the size of the solution space through a very compact model representation of the arm and prune the solution space. The model is developed through a detailed investigation of the functionality and structure of the arm and the shoulder complex. The model consists of just two parameters and is based on the screw-axis representation together with image measurements. The pruning is achieved through kinematic constraints and it turns out that the solution space of the compact model can be pruned , on average. Altogether, the compact representation and the constraints reduce the solution space significantly and, therefore, allow for an exhaustive matching procedure. The approach is tested in a model-based silhouette framework, and tests show promising results.Published online: 8 August 2003Correspondence to: Thomas B. Moeslund     

The development of flight simulation database using handling quality studies

A flight handling quality is a composite measure of performance used to assess how well a pilot responds to flight conditions. Considering the complexity of the aircraft and the human operator model, flight handling parameters as well as the variables can be complex. For many years; however, there a exist a large body of actual flight and simulated test reports on the handling quality measures of various model airplanes from subsonic to supersonic. In order to replicate flight simulation experiments in aircrafts modeled at the hypersonic speed, it would be of advantage to use a data of previous flight handling qualities. Among other things, this procedure will save time in data collection and help to extrapolate the existing knowledge into a new flight condition.

In the presentation, we discuss a new object-oriented data base development from a hierarchy of interacting objects. The data structures are divided into functional nets based on the level of human operator models, the aircraft state space, and the environmental state vectors. Different aircraft models with their data structures are used to cluster the information into domain sets which can later be abstracted to generate test data for a flight simulation experiment.     

运动模型式飞行器气动力参数测试系统研究

为了对飞行器进行气动布局、飞行性能评估,提出了一种运动模型式气动力参数测量方法,并研制了一套运动模型式测试系统,通过运动模型来模拟飞行器在空气中的运动,其构造主要包含载具、测试支架、六分量天平、风速测量模块、数据采集模块、控制模块、便携计算机等部分;该类测试系统在某些特定工况下能准确模拟飞行器的飞行状态,对流场参数和模型所受载荷进行实时测量,预测各运动状态下飞行器的气动特性;通过数值模拟分析和风洞实验对车载试验数据进行了对比验证,结果表明,该测试系统能够准确获得模型的气动力特性数据;该系统具有一定的拓展性和通用性,可使用火箭橇等其他载具开展高速运动模型式气动力参数测量试验。