Showing papers on "Robot kinematics published in 1998"

The development of Honda humanoid robot

Abstract: In this paper, we present the mechanism, system configuration, basic control algorithm and integrated functions of the Honda humanoid robot. Like its human counterpart, this robot has the ability to move forward and backward, sideways to the right or the left, as well as diagonally. In addition, the robot can turn in any direction, walk up and down stairs continuously. Furthermore, due to its unique posture stability control, the robot is able to maintain its balance despite unexpected complications such as uneven ground surfaces. As a part of its integrated functions, this robot is able to move on a planned path autonomously and to perform simple operations via wireless teleoperation.

Control of a nonholonomic mobile robot using neural networks

Abstract: A control structure that makes possible the integration of a kinematic controller and a neural network (NN) computed-torque controller for nonholonomic mobile robots is presented. A combined kinematic/torque control law is developed using backstepping and stability is guaranteed by Lyapunov theory. This control algorithm can be applied to the three basic nonholonomic navigation problems: tracking a reference trajectory, path following, and stabilization about a desired posture. Moreover, the NN controller proposed in this work can deal with unmodeled bounded disturbances and/or unstructured unmodeled dynamics in the vehicle. Online NN weight tuning algorithms do not require off-line learning yet guarantee small tracking errors and bounded control signals are utilized.

Biped robot walking using gravity-compensated inverted pendulum mode and computed torque control

Abstract: This paper proposes a model called the gravity-compensated inverted pendulum mode (GCIPM) to generate a biped locomotion pattern that is similar to the one generated by the linear inverted pendulum mode, but accommodates the free leg dynamics based upon its predetermined trajectory. When the biped locomotion based upon the linear inverted pendulum mode is applied to real biped robots, the stability of the robot is disturbed due to the fact that the neglected dynamics of free legs is not actually negligible, moving the ZMP (zero moment point) away from the presumed fixed point. The GCIPM includes the effect of the dynamics of the free leg in a simple manner This paper also presents a control method for biped robots based upon the computed torque. Simulation results show that the biped robot is more stable with the walking pattern generated by the proposed method combined with the controller than with the one by the inverted pendulum mode.

On the inverse kinematics, statics, and fault tolerance of cable‐suspended robots

Abstract: This paper examines some issues concerning the inverse kinematics and statics of cable-suspended robots and studies some of the inherent workspace limitations that result from the fact that the robot is cable actuated. The paper presents necessary and sufficient conditions for a cable-suspended robot to stay in a given configuration (i.e., to achieve static equilibrium). Another important issue is the extent to which the cables constrain the robot. For example, fully constraining the robot is critical for space applications in which the robot must work in a zero-gravity environment. Conditions for completely constraining the robot are derived. The problems of achieving static equilibrium and fully constraining the robot are formulated in terms of the left null space of a manipulator inverse Jacobian. This null space formulation is also used to study the fault tolerance of cable-suspended robots that are redundantly actuated. © 1998 John Wiley & Sons, Inc.

Three dimensional bipedal stepping motion using neural oscillators-towards humanoid motion in the real world

Abstract: CPG (central pattern generator) and entrainment dynamics together form a promising framework for robust and adaptive behavior generation for a high degree of freedom system in unstructured environment. This paper investigates its possibility in the domain of biped robotic locomotion. We extend a previous work on 2D biped locomotion using neural oscillators to 3D, introducing many more degrees of freedom and complexity in control. While the complexity of the problem has been increased, we have simplified the internal neural mechanism compared to the original 2D work. Our fully dynamic 3D simulation experiments showed that our mechanism can generate 3D stable biped stepping motion as well as tolerance against external perturbations.

A localization system of a mobile robot by fusing dead-reckoning and ultrasonic measurements

Abstract: This paper develops a novel system hardware structure and systematic digital signal processing algorithms for self-localization of an autonomous mobile robot by fusing dead-reckoning and ultrasonic measurements. The multisensorial dead-reckoning (DR) subsystem is established based on the optimal filtering by first fusing heading readings from a magnetic compass, a rate-gyroscope and two encoders mounted on the robot wheels, thereby computing the dead-reckoned location estimate. The novel ultrasonic localization subsystem consists of one ultrasonic transmitter and one radio-frequency (RF) controlled switch mounted on the known location fixed to an inertial frame of reference, four ultrasonic receivers and one RF controlled switch installed on the mobile robot. Four ultrasonic Time-of-Flight (TOF) measurements together with the dead-reckoned location information are fused to update vehicle's position by utilizing the extended Kalman filtering (EKF) algorithm. The proposed algorithms are implemented by using a host PC 586 computer and standard C++ programming techniques. A built system prototype together with its experimental results is used to confirm that the system not only retains its strengths of high accuracy and magnetic interferencing immunity, but also provides a simple and practical structure of use and installation calibration.

A comparative study of three methods for robot kinematics

Abstract: Three methods for the formulation of the kinematic equations of robots with rigid links are presented in this paper. The first and most common method in the robotics community is based on 4/spl times/4 homogeneous matrix transformation, the second one is based on Lie algebra, and the third one on screw theory expressed via dual quaternions algebra. These three methods are compared in this paper for their use in the kinematic analysis of robot arms. The basic theory and the transformation operators, upon which every method is based, are referenced. Three analytic algorithms are presented for the solution of the direct kinematic problem corresponding to each method, and the geometric significance of the transformation operators and parameters is explained. Finally, a comparative study on the computation and storage requirements for the three methods is worked out.

Finding landmarks for mobile robot navigation

Abstract: Localization addresses the problem of determining the position of a mobile robot from sensor data. This paper presents an algorithm, called BaLL, which enables a mobile robot to learn a set of landmarks used in localization and to learn how to recognize them using artificial neural networks. BaLL is based on a statistical localization approach. It is applicable to a large variety of sensors and environments. Experiments with a mobile robot equipped with sonar sensors and a camera illustrate that BaLL identifies highly useful landmarks.

Fractional-order hybrid control of robot manipulators

Abstract: In this paper it is studied the implementation of fractional-order algorithms in the position/force hybrid control of robotic manipulators. The system robustness and performances are analysed, in terms of time responses, and compared with other control approaches. Moreover, it is also investigated the effect of nonlinear phenomena at the robot joints such as nonlinear friction, dynamic backlash and flexibility.

Advances in Robot Kinematics: Analysis and Control

Abstract: From the Publisher: The book provides a state-of-the-art and recent advances in the area of kinematics of robots and mechanisms. The book consists of about fifty outstanding contributions dedicated to various aspects of kinematic modelling and control, emphasising in particular the kinematics performances of robots and mechanisms, workspace and trajectory analysis, numerical and symbolic computational methods and algorithms, analysis, simulation and optimisation. The book is of interest to researchers, graduate students, and engineers specialising in the kinematics of robots and mechanisms. The book should also be of interest to those engaged in work relating to kinematic chains, mechatronics, mechanism design, biomechanics and intelligent systems.

An anthropomorphic biped robot: dynamic concepts and technological design

Abstract: The authors of this study are a part of a joint project, involving four French laboratories, whose goal is the design and construction of a mechanical biped robot with anthropomorphic characteristics. In the first section of this paper, we will examine mechanical architectures of some representatives of state-of-the art biped robots by focusing on their kinematic arrangement. It is widely known that the existence of natural gaits is closely linked to the intrinsic dynamic characteristics of the mechanical structure of the biped robot. In order to further develop this idea, two studies will be presented in the second section: the first is relative to the lateral instability of the system while the second deals with the existence of passive pendular gaits during the swing phase of walking in the sagittal plane. In the last section, in correlation with the observations made, we will gain insight into main characteristics of the mechanical architecture that we have designed for the BIP project: 15 active degrees of freedom (DOF), joints actuated by special transmission system, anthropometric mass distribution.

Visual homing: surfing on the epipoles

Abstract: We introduce a novel method for visual homing. Using this method a robot can be sent to desired positions and orientations in 3-D space specified by single images taken from these positions. Our method determines the path of the robot on-line. The starting position of the robot is not constrained, and a 3-D model of the environment is not required. The method is based on recovering the epipolar geometry relating the current image taken by the robot and the target image. Using the epipolar geometry, most of the parameters which specify the differences in position and orientation of the camera between the two images are recovered. However, since not all of the parameters can be recovered from two images, we have developed specific methods to bypass these missing parameters and resolve the ambiguities that exist. We present two homing algorithms for two standard projection models, weak and full perspective. We have performed simulations and real experiments which demonstrate the robustness of the method and that the algorithms always converge to the target pose.

On the uniform boundedness of the inertia matrix of serial robot manipulators

Abstract: Reference LA-ARTICLE-1998-002doi:10.1002/(SICI)1097-4563(199812)15:1 3.0.CO;2-VView record in Web of Science Record created on 2004-11-26, modified on 2017-05-10

Kinematic manipulability of general constrained rigid multibody systems

Abstract: This paper extends the kinematic manipulability concept commonly used for serial manipulators to general constrained rigid multibody systems. Examples of such systems include multiple cooperating manipulators, multiple fingers holding a payload, multileg walking robots, and variable geometry trusses. Explicit formulas for velocity and force manipulability ellipsoids are derived and their duality explained. Singularities are classified into two types: 1) unmanipulable singularity; 2) unstable singularity. The former is similar the singularities in serial chains where velocity manipulability ellipsoid is degenerate and force manipulability ellipsoid infinite. The latter is unique to parallel mechanisms, the velocity manipulability ellipsoid becomes infinite and force manipulability degenerate. In the case of multifinger grasp, these concepts correspond to unmanipulable or unstable grasps.

Adaptive hybrid control for visual and force servoing in an unknown environment

Abstract: An adaptive robot controller is proposed to achieve a contacting task with an unknown environment, while the robot is visually guided. Since the proposed controller has online estimators for the parameters of the camera-manipulator system and the unknown constraint surface, the controller needs no a priori knowledge besides the manipulator kinematics. Experimental results validate the proposed scheme.

Probabilistic mapping of an environment by a mobile robot

Abstract: This paper addresses the problem of building large-scale maps of indoor environments with mobile robots. It proposes a statistical approach that describes the map building problem as a constrained maximum-likelihood estimation problem, for which it devises a practical algorithm. Experimental results in large, cyclic environments illustrate the appropriateness of the approach.

Control of redundant manipulators using logic-based switching

Abstract: We study the control of redundant planar robotic manipulators using a switched (or hybrid) control scheme, focusing on manipulators with a degree of redundancy of one. We emphasize the effectiveness of switched control systems with respect to stabilization and performance enhancement for this class of manipulators. We present a simulation study of logic-based switching control of a 3-DOF planar manipulator under end-effector trajectory tracking and demonstrate the capabilities of this scheme.

Active self-calibration of robotic eyes and hand-eye relationships with model identification

Abstract: We first review research results of camera self-calibration achieved in photogrammetry, robotics and computer vision. Then we propose a method for self-calibration of robotic hand cameras by means of active motion. Through tracking a set of world points of unknown coordinates during robot motion, the internal parameters of the cameras (including distortions), the mounting parameters as well as the coordinates of the world points are estimated. The approach is fully autonomous, in that no initial guesses of the unknown parameters are to be provided from the outside by humans for the solution of a set of nonlinear equations. Sufficient conditions for a unique solution are derived in terms of controlled motion sequences. Methods to improve accuracy and robustness are proposed by means of best model identification and motion planning. Experimental results in both a simulated and a real environments are reported.

Manipulability and singularity analysis of multiple robot systems: a geometric approach

Abstract: We present a differential geometric analysis of manipulability for holonomic multiple robot systems containing active and passive joints. Our analysis treats both redundant and nonredundant systems, including the case of redundant actuation, in a uniform manner. Dynamic characteristics of the robot system and manipulated object can also be naturally included by an appropriate choice of Riemannian metric. Our geometric framework also suggests a classification of kinematic singularities into three basic types: (i) those corresponding to singular points of the joint configuration space (configuration space singularities), (ii) those induced by the choice of actuated joints (actuator singularities), and (iii) those configurations in which the end-effector loses one or more degrees of freedom of available motion (end-effector singularities). The proposed geometric classification provides a high-level taxonomy for kinematic singularities that is independent of the choice of local coordinates used to describe the robot kinematics.

Posture control of a cockroach-like robot

Abstract: Describes the posture controller for a new cockroach-like hexapod robot developed in the Bio-Robotics Laboratory at Case Western Reserve University. The posture controller is based upon the virtual model control scheme and the problem of redundant kinematics is solved using an optimization approach. It does not just control static posture, but is the major component of a future locomotion controller. The robot has complex, animal-like kinematics with 24 degrees of freedom, yet the controller effectively manages its posture despite large perturbations. The algorithm is also computationally efficient.

Fast local obstacle avoidance under kinematic and dynamic constraints for a mobile robot

Abstract: This paper presents an efficient approach for reactive collision avoidance taking into account both vehicle dynamics and nonholonomic constraints of a mobile robot. Motion commands are generated by searching the space of actuating variables. Vehicle dynamics are considered by restricting the search space to values which are reachable within the next time step. The final selection among admissible configurations is done by an objective function which trades off speed, goal-directedness and remaining distance until an obstacle is hit when moving along the chosen path. The presented approach differs from previous ones in the selective use of precalculated lookup tables. These are the key to efficiency, and they especially allow the use of any-shaped robot contours. Furthermore, obstacle information from different sources can easily be considered without preprocessing. Extensive experiments on different robots have shown robust operation in dynamic and unprepared indoor environments with speed up to 1 m/s.

Kinematics, dynamics and construction of a planarly actuated parallel robot

Abstract: Kinematic and dynamic analysis of a parallel robot consisting of three planarly actuated links, is presented in this paper. Coordinated motion of three planar motors, connected to three fixed-length links, produces a six-degrees-of-freedom motion of an output link. Its extremely simple design along with much larger work volume than the commonly used parallel robots make this high performance-to-simplicity ratio robot very attractive. Experimental model verifies the unique combination of large work volume and high accuracy of this robot.

Singular inverse kinematic problem for robotic manipulators: a normal form approach

Abstract: In this article, a new method of solving the singular inverse kinematic problem for nonredundant robotic manipulators is proposed, based on normal forms of the manipulator kinematics. A complete solution to the inverse problem is presented under assumption that the kinematics are equivalent to the quadratic normal form. Comparisons with other existing methods, including the singularity-robust inverse, are made that reveal advantages of the normal form approach. Experimental results concerned with singular tracking in the AdeptOne manipulator are reported.

A surgical robot system for maxillofacial surgery

Abstract: In this paper, the first active surgical robot system (OTTO) in a clinical environment for maxillofacial surgery is presented. The medical application is described from a technical point of view and the requirements for a robot in this speciality are defined. The paper describes the system architecture of the robotics environment and the need for research and development. The robot's hardware is based on a delta-kinematics robot system. At the current state of development, the robot can be used for inserting nonflexible catheters and for implanting bone fixtures in the skull.

On the Properties of a Dynamic Model of Flexible Robot Manipulators

Abstract: Control design of flexible robot manipulators can take advantage of the structural properties of the model used to describe the robot dynamics. Many of these properties are physical characteristics of mechanical systems whereas others arise from the method employed to model the flexible manipulator. In this paper, the modeling of flexible-link robot manipulators on the basis of the Lagrange’s equations of motion combined with the assumed modes method is briefly discussed. Several notable properties of the dynamic model are presented and their impact on control design is underlined.

Rhythmic robot arm control using oscillators

Abstract: This paper presents an approach to robot arm control based on exploiting the dynamical properties of a simple oscillator circuit coupled to the joints of an arm Using the same architecture, a wide variety of tasks can be achieved without any explicit modeling of the arm or its environment The inherent properties of the oscillators give robustness to perturbations and changes in frequency The approach is implemented on two compliant arms, and is demonstrated to swing pendulums at their natural frequencies, turn cranks and manipulate 'Slinky' toys

Transportation of a single object by two decentralized-controlled nonholonomic mobile robots

Abstract: We propose a decentralized control algorithm for transporting a single object by two nonholonomic mobile robots driven by two wheels. We extend the leader-follower type control algorithm, proposed by Kosuge and Oosumi (1996) for holonomic robots, to mobile robots by introducing the dual caster action. The extended control algorithm is applied to two experimental tracked mobile robots, and the experimental results illustrate the validity of the control algorithm.

Redundancy problem in writing: from human to anthropomorphic robot arm

Abstract: This paper presents the analysis of motion of a redundant anthropomorphic arm during the writing. The modeling is based on the separation of the prescribed movement into two motions: smooth global, and fast local motion, called distributed positioning (DP). The distribution of these motions to arm joints is discussed. It is based on the inertial properties and actuation capabilities of joints. The approach suggested allows unique solution of the inverse kinematics of redundant mechanisms such as human arm and anthropomorphic robot arm. Distributed positioning is an inherent property of biological systems. Humans, when writing, as shown in literature and in our earlier work control their proximal joints, while the movement of distal joints follow them (synergy). To enhance capabilities of robots, new control schema are necessary. We show that robot control can be improved if it is biological analog. The major aim of this study is to promote such a hypothesis by using anthropomorphic robot arm in writing as an example.

Feedback control for robotic manipulator with uncertain kinematics and dynamics

Abstract: Research of robotics aims to realise some aspects of human functions into mechanical system. Human can manipulate things skilfully without the exact knowledge of both dynamics and kinematics of arms. Our arms are also able to overcome singular position by moving along it or passing through it. The exploration of a robot controller to cope with the uncertainties in both dynamics and kinematics is an important step towards understanding the dextrous movement of mechanical systems. In this paper, simple feedback control laws are proposed for setpoint control of robots with uncertain kinematics and dynamics. We shall show that the end-effector's position converges to the desired position in a finite task space even when the actual Jacobian matrix is singular.

Automatic Model Generation for Modular Reconfigurable Robot Dynamics

Abstract: In control and simulation of a modular robot system, which consists of standardized and interconnected joint and link units, manual derivation of its dynamic model needs tremendous effort because these models change all the time as the robot geometry is altered after module reconfiguration. This paper presents a method to automate the generation of the closed-form equation of motion of a modular robot with arbitrary degrees-of-freedom and geometry. The robot geometry we consider here is branching type without loops. A graph technique, termed kinematic graphs and realized through assembly incidence matrices (AIM) is introduced to represent the module assembly sequence and robot geometry. The formulation of the dynamic model is started with recursive Newton-Euler algorithm. The generalized velocity, acceleration, and forces are expressed in terms of linear operations on se(3), the Lie algebra of the Euclidean group SE(3). Based on the equivalence relationship between the recursive formulation and the closed-form Lagrangian formulation, the accessibility matrix of the kinematic graph of the robot is used to assist the construction of the closed-form equation of motion of a modular robot. This automatic model generation technique can be applied to the control of rapidly reconfigurable robotic workcells and other automation equipment built around modular components that require accurate dynamic models.