Cooperative manipulation of a floating object by some space robots: application of a tracking control method using the transpose of the generalized Jacobian matrix

In future space missions, it is considered that many tasks will be achieved by cooperative motions of space robots. For free-floating space robots with manipulators, we have proposed a digital tracking control method using the transpose of the generalized Jacobian matrix (GJM). In this paper, the tracking control method using the transpose of the GJM is applied to cooperative manipulations of a floating object by space robots. Simulation results show the effectiveness of the control method. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

Digital tracking control of space robots using a transpose of the generalized Jacobian matrix

We have proposed discrete time-control methods using the transpose of the generalized Jacobian matrix (GJM) for free-floating space robots having manipulators. The control methods are robust for singular configurations of robots. Since the methods belong to a class of constant-value control, in this article we propose a digital trajectory tracking control method using the transpose of the GJM. Computer simulations show the effectiveness of the proposed method. This work was presented in part at the 11th International Symposium on Artificial Life and Robotics, Oita, Japan, January 23–25, 2006     

Digital control of space robot manipulators with velocity type joint controller using transpose of generalized Jacobian matrix

For free floating space robots having manipulators, we have proposed a discrete-time tracking control method using the transpose of Generalized Jacobian Matrix (GJM). Control inputs of the control method are joint torques of the manipulator. In this paper, the control method is augmented for angular velocity inputs of the joints. Computer simulations have shown the effectiveness of the augmented method. This work was presented in part and awarded as Best Paper Award at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

A design of digital adaptive control systems for space robot manipulators using a transpose of the generalized Jacobian matrix

We propose a digital control method for space robot manipulators using the transpose of the generalized Jacobian matrix. The method, however, is developed on the supposition that all the physical parameters of the robot manipulator are known. Therefore, if the end-effector of the manipulator captures an object whose mass is unknown, the stability of the control system cannot be maintained because the physical parameters are changed. This article presents the adaptive control version.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004     

基于PMSM驱动的柔性关节空间机械臂轨迹跟踪控制方法

针对目前柔性关节空间机械臂轨迹跟踪控制方法忽略了不同重力影响下的机械臂驱动力变化,导致柔性关节空间机械臂轨迹跟踪控制效果较差的问题,提出了基于PMSM驱动的柔性关节空间机械臂轨迹跟踪控制方法。基于构建PMSM驱动数学模型,采用PMSM的矢量控制方法,分析驱动力矩矢量。根据驱动力矩矢量分析结果,分析不同重力环境下有、无摩擦时的驱动力矩。构建柔性关节模型,分析其在不同重力环境下遇到的重力释放问题,使用自适应反演滑膜控制方法,设计控制率,保证机械臂能够按照既定的方向运动,使机械臂具有鲁棒性。根据柔性关节空间机械臂动力学特性,分析不同重力环境下基于PMSM驱动力矩,确定重力项是随之发生改变的。设计控制器,构建动力学模型,确保空间阶段能够最大限度跟踪运动轨迹。实验结果表明,所提方法X轴、Y轴的末端跟踪结果均与实际运动轨迹一致,误差为0。关节控制力矩在时间为3s时,出现了最大为0.5N.m的误差,说明所提方法的跟踪控制效果较好。     

Online generation and control of quasi-static multi-contact motion by PWT Jacobian matrix with contact wrench estimation and joint load reduction*

In this paper, we propose a generic method of online motion generation and control that realizes quasi-static multi-contact motion for real position-controlled humanoids. The proposed system calculates command joint angle online by prioritized inverse kinematics that realizes the target contact states and the target position/orientation of interaction end-effectors feasibly. In order to enable control of contact wrench and joint torque with position-controlled robots, Jacobian matrixes (PWT Jacobian matrix) focusing on relationships between command joint angle and actual joint position, contact wrench, and joint torque are introduced. In addition, contact wrench is estimated at the body parts where force sensors are not mounted to enable contacts there, and joint load reduction based on the motor temperature is taken into account to enable long-term motions with real humanoids. The proposed method was verified by a real life-size position-controlled humanoid HRP2-JSKNTS, and various multi-contact motions such as desk climbing using the right knee and both arms were realized.     

Nonlinear tracking control in the presence of state and control constraints: a generalized reference governor

This paper proposes a new approach to reference governor design. As in prior literature, the governor accepts input commands and modifies their evolution so that specified pointwise-in-time constraints on state and control variables are satisfied. The new approach applies to general discrete-time and continuous-time nonlinear systems with uncertainties. It relies on safety properties provided by sublevel sets of equilibria-parameterized functions. These functions need not be Lyapunov functions, and the corresponding sublevel sets need not be positively invariant. Technical conditions that capture the bare essentials of what is needed are identified and the usual desirable properties of reference governors are established. The new approach significantly broadens the class of methods available for constructing the nonlinear function that is required in the implementation of the reference governors. This advantage is illustrated in a nonlinear control problem where off-line, computer-based simulation is the basis for constructing the nonlinear function.     

Online construction of the manipulation model of an unknown object by a robot hand using the regrasping primitives

This paper presents a planner which explores an unknown polyhedral object with a multifingered hand in a systematic way by constructing the manipulation-model of the object. The manipulation-model of an object we proposed previously is a database which consists of landmark orientations of the object, the applicability of manipulation primitives to them and intertransformations among them. In this paper, two regrasping primitives, rotation and pivoting, are employed. A multifingered hand probes a given unknown object for pivot/rotation axes. If a new axis is found, the planner recursively performs pivoting or rotation-test (which is similar to rotation but does not actually rotate the object) about the found axis and searches the object for more axes. The manipulation-model of the object is constructed based on the found axes. An experiment for constructing a manipulation-model of a non-convex polyhedral object is conducted using a fourfingered hand. Force/torque sensors mounted on the fingertips collect the data of the object. A geometrical model of the object is also constructed.     

一种步进电机控制面阵CCD摄像机获取大视域目标图像的方法

文章提出了一种利用步进电机控制面阵CCD摄像机获取大视域目标图像的方法，该方法采用上下位机串行通信进行同步，下位单片机控制步进电机移动机械装置，上位PC机控制装置上的面阵CCD进行单帧图像连续采集。整个大视域目标的图像像素数据由每帧图像正中间数行的像素数据逐步填充而成，实现了大视域目标图像的自然无缝获取。实践证明，该方法获取的图像效果非常好，具有较强的实用性和推广价值。     

Globally stable robust tracking of nonlinear systems using variablestructure control and with an application to a robotic manipulator

The globally stable robust output tracking for a class of nonlinear systems is considered. Based only on the knowledge of the bounds on the uncertainties, a variable structure control (VSC) law is developed under the structure matching assumption. It is shown that the outputs of the closed-loop system asymptotically track given output trajectories despite the uncertainties while maintaining the boundedness of all signals inside the loop. All signals inside the loop are shown to be bounded for all time. To illustrate the efficiency of the controller, the approach is applied to the case of a two degree-of-freedom (DOF) robotic manipulator with variable payload. Numerical simulation results are also provided     

Inverse perspective transform using zero-curvature contour points:application to the localization of some generalized cylinders from asingle view

The localization of some kinds of modeled generalized cylinders from a single brightness perspective image is addressed. It is shown how the zero-curvature points of their contours can be used to solve the inverse perspective problem. Three key theorems about the perspective projection of space curves and of the limbs of a straight homogeneous generalized cylinder whose scaling function has at least one zero-curvature point are discussed. In view of the localization of homogeneous generalized cylinders, an algorithm previously developed by the authors which estimates the pose of a line-triplet is adapted. A new theoretical result about the inverse perspective projection of cones of revolution useful for the localization of objects of revolution is presented. The corresponding algorithms have been implemented, and results of experiments demonstrate the feasibility of the proposed localization methods     

Output feedback tracking control of MIMO systems using a fuzzy disturbance observer and its application to the speed control of a PM synchronous motor

One of the most important objectives in the design of control systems is to achieve the good tracking performance in the presence of the internal parameter uncertainty and external disturbance. In this paper, a new multiple-input-multiple-output (MIMO) fuzzy disturbance observer (FDO) based on output measurement is developed to achieve the goal. A filtered signal is introduced to resolve the algebraic loop encountered in the conventional FDO. The contribution of the disturbance observation error /spl zeta/ to updating the parameters of the fuzzy system is analyzed in the sense of L/sub 2/ and L/sub /spl infin//. Then, the MIMO FDO is modified and the high gain observer (HGO) is employed to implement the output tracking control system. It is shown in a rigorous manner that the disturbance observation error, the tracking error and the state observation error converge to a compact set of which size can be kept arbitrarily small. Finally, the suggested method is applied to the speed control of a permanent magnet synchronous motor (PMSM) in the presence of the internal parameter uncertainty and external disturbance. The effectiveness and the feasibility of the suggested method are demonstrated by computer simulation.     

Solution of stiffened problems for a finite internally cracked plate by using complex potentials and the generalized variational method

In this paper the decrement ratio of the stress intensity factor for a finite internally cracked plate reinforced by a circular disk welded over the crack is studied by using complex potentials and the generalized variational method. The plate is divided into two regions by the weld, and the complex potentials for these regions and those for the reinforced plate are expressed in a series form whose coefficients are determined from the stationary conditions of a new functional. The conditions of compatibility and equilibrium around the weld are enforced through a Lagrange multiplier technique in the functional. Numerical results are given which may be referential to engineers.     

A parameter control method of evolutionary algorithms using exploration and exploitation measures with a practical application for fitting Sovova's mass transfer model

Exploration and exploitation are omnipresent terms in evolutionary computation community that have been broadly utilized to explain how evolutionary algorithms perform search. However, only recently exploration and exploitation measures were presented in a quantitative way enabling to measure amounts of exploration and exploitation. To move a step further, this paper introduces a parameter control approach that utilizes such measures as feedback to adaptively control evolution processes. The paper shows that with new exploration and exploitation measures, the evolution process generates relatively well results in terms of fitness and/or convergence rate when applying to a practical chemical engineering problem of fitting Sovova's model. We also conducted an objective statistical analysis using Bonferroni–Dunn test and sensitivity analysis on the experimental results. The statistical analysis results again proved that the parameter control strategy using exploration and exploitation measures is competitive to the other approaches presented in the paper. The sensitivity analysis results also showed that different initial values may affect output in different magnitude.     

Spectral expansion solution for a class of Markov models: application and comparison with the matrix-geometric method

Many two-dimensional Markov models whose state space is a semi-infinite strip (i.e. finite in one dimension and infinite in the other) can be solved efficiently by means of spectral expansion. This method and its application are described in the context of an M/M//N queue with general breakdowns and repairs. The results of experiments aimed at evaluating the relative merits of the spectral expansion and the matrix-geometric solutions are also presented.     

Modelling of an interactive system with an agent-based architecture using Petri nets, application of the method to the supervision of a transport system

This article presents an original method using high level Petri nets for the specification and design of interactive systems. We suggest an agent oriented architecture based on the classic components of an interactive application (application, dialogue control, interface with the application). Our approach is validated via the specification and design of a human–machine interface used in the supervision of a land-based transport system (bus/tramway).     

A feedback finite element method with a posteriori error estimation: Part I. The finite element method and some basic properties of the a posteriori error estimator

This paper is the first in a series of two in which we discuss some theoretical and practical aspects of a feedback finite element method for solving systems of linear second-order elliptic partial differential equations (with particular interest in classical linear elasticity). In this first part we introduce some nonstandard finite element spaces, which, though based on the usual square bilinear elements, permit local mesh refinement. The algebraic structure of these spaces and their approximation properties are analyzed. An “equivalent estimator” for the H¹ finite element error is developed. In the second paper we shall discuss the asymptotic properties of the estimator and computational experience.