IEEE Transactions on Robotics and Automation

The application of robotic manipulators to complex tasks such as assembly, or insertion often requires position/force control of the end-effector, and this has been widely studied. A related task is robot compliant motion over unknown objects. The goal is to move the effector, while maintaining contact, about the object. For this application a dynamic hybrid velocity/force controller is studied. T... View full abstract»

The design and analysis of a noncontact electrooptical orientation sensor is addressed. The sensor is based on the intensity measurement of modulated light signals reflected from the surface of an object. The experimental setup of the sensor used in this research was designed and manufactured such that two mechanical-design parameters could be investigated. The operation principle of the 1D inclin... View full abstract»

An alternative coordinated motion control architecture for robot arms manipulating an object is proposed. The motion and the internal force of the object are resolved in the motion of each arm. Each arm's control is based on the virtual internal model so as to operate in coordination even if geometric errors exist in the robot arms and the object. The virtual internal model is a reference model dr... View full abstract»

Dynamic equations are derived for a class of multilink manipulators with the last link flexible. The manipulators have three degrees of freedom and are moved by three actuators. This class includes the elbow manipulator and the five-bar-linkage manipulator. Some reasonable assumptions that simplify the dynamic equations for control purposes are described, and the simplified dynamic equations are t... View full abstract»

The problem addressed is that of efficiently planning a path for a robot between two points when the path is forced to change dynamically by the occurrence of certain events in the environment. An event or an alarm, for example, may be the discovery of another moving object on a collision course with the robot and would require some evasive action. A probabilistic model is given that represents th... View full abstract»

This paper advances two linear operator factorizations of the manipulator mass matrix. Embedded in the factorizations are many of the techniques that are regarded as very efficient computational solutions to inverse and forward dynamics problems. The operator factorizations provide a high-level architectural understanding of the mass matrix and its inverse, which is not visible in the detailed alg... View full abstract»

A path-planning algorithm for the classical mover's problem in three dimensions using a potential field representation of obstacles is presented. A potential function similar to the electrostatic potential is assigned to each obstacle, and the topological structure of the free space is derived in the form of minimum potential valleys. Path planning is done at two levels. First, a global planner se... View full abstract»

High-precision measurements of joint displacements are available on robot manipulators. In contrast, velocity measurements obtained through tachometers are, in many cases, contaminated by noise. It is therefore economically and technically interesting to investigate the possibility of controlling robot dynamics by only using angular position measurements. Two alternative approaches for trajectory ... View full abstract»

The effect of a major source of manipulator compliance, namely, the elasticity of manipulator joints, on the overall stability of robot manipulators during constrained-motion task execution is examined. The stability of the elastic-joint manipulator during constrained-motion contact is investigated separately for the case of two controls applied to the manipulator. Using results from the theory of... View full abstract»

Integration of sensors in a welding system enhances the quality of the welds produced. Variations in three welding process parameters-weld bead width, penetration depth, and torch position-were monitored using an infrared sensor. Intentionally induced variations in each of these welding parameters were found to affect uniquely the plate surface temperature distributions measured by the infrared se... View full abstract»

The problem of dynamic control of a multifingered hand manipulating an object is considered, under the condition that some of the fingertips slide on the object surface. This work has many useful applications when considered in conjunction with work already done in the area of regrasping. In performing certain tasks with grasped objects, it is often necessary to change the contact locations of the... View full abstract»

An analysis of the momentum conservation equations of a redundant free-flying spacecraft/manipulator system acting in a zero-gravity environment is presented. In order to follow a predefined end-effector path, the inverse kinematics at velocity level is considered. The redundancy is solved alternatively in terms of pseudoinverses and null-space components of the manipulator inertia matrix, the man... View full abstract»

The design and experimental results for a suspension-shell tactile sensor are described. The sensor uses a suspension-shell mechanism to make the entire surroundings of a finger-body sensitive. The sensor detects the magnitude and the point of application of an external force operating on the shell by measuring the relative displacement of the suspension shell with regard to the finger-body. Howev... View full abstract»

Dynamic equations are developed in nonrecursive symbolic form for chain-structured robotic manipulators with compliant links. A program is developed in REDUCE to automate the symbolic expansion of these equations for any given chain-structured manipulator. The symbolic nonrecursive form of the dynamic model is particularly suitable for controller synthesis and real-time control implementations View full abstract»

Many useful identities pertaining to quaternion multiplications are generalized. Among them multiplicative commutativity is the most powerful. Since quaternion space includes the 3D vector space, the physical quantities related to rotations, such as angular displacement, velocity, acceleration, and momentum, are shown to be vector quaternions, and their expressions in quaternion space are derived.... View full abstract»

A model that utilizes a contact-stress analysis of an arbitrarily shaped object in a multifingered grasp is developed. The fingers and the object are all treated as elastic bodies, and the region of contact is modeled as a deformable surface patch. The relationship between the friction and normal forces is now nonlocal and nonlinear in nature and departs from the Coulomb approximation. The nature ... View full abstract»