Morris R. Driels

Kinematic modelling for robot calibration

There is a considerable amount of literature dealing with robot calibration. A classification hierarchy of calibration procedures is discussed which groups robot calibration by objective. The state of the art for each classification is discussed with citations from recent literature. Several proposed models are described. Based upon the common assumption of all lower pair joints, three concepts are discussed which may be applied for comparing most of the calibration models proposed in the literature. These concepts are completeness, equivalence, and proportionality. Each of these are discussed in detail in the text. Attention is also paid to the possibility that joints may actually be higher pairs. Although this possibility is commonly accepted in coordinate measuring machine calibration, it is not widely recognized in the robot literature. The paper discusses possible causes and effects of higher order joint pairs and demonstrates how they might be modeled.

Generalized joint model for robot manipulator kinematic calibration and compensation

A generalized model that goes beyond the usual assumption of “ideal” joint behavior is proposed. The “real” joint has five ancillary degrees of freedom besides the dominant motion. The resulting manipulator transformation with its greater degree of sophistication is expected to help in calibration and compensation of the various kinematic contributions to robot inaccuracy. The procedure to compute this generalized manipulator transformation is presented. The generalized model also results in manipulator differential relationships and these are discussed.

The application of Newton-Euler recursive methods to the derivation of closed form dynamic equations

The article presents, in tutorial format, a development of the Newton-Euler (NE) approach to the analysis of robot dynamics. Beginning with fundamental concepts drawn from vector calculus and mechanics, a set of recursive equations are developed which allow the calculation of the dynamics of a manipulator in closed form. An example based on conventional manipulator design is evaluated in some detail and shows that, for kinematic models of some complexity, the NE approach is as fast as other techniques based on Lagrangian methods for deriving closed form dynamical equations.

Robot manipulator kinematic compensation using a generalized jacobian formulation

The kinematic error compensation of robot manipulators is at present being attempted by improving the precision of the nominal robot kinematic parameters. This paper addresses the problem of kinematic compensation using a new mathematical joint model proposed to account for shortcomings in existing methods. The corrected manipulator transformation is formulated in terms of “generalized Jacobians”: relating differential errors at the joints to the differential change in the manipulator transformation. The details of application are discussed for a particular industrial manipulator.

PreGrasp Pose Estimation of Objects Using Local Sensors on Dexterous Hands

In order to successfully grasp an arbitrary object, one must know the pre-grasp position and orientation (pose) of the targeted object. This knowledge may help propose a grasping strategy which will ensure grasping, increase the stability of the grasp, and provide a grasp which will either not require further manipulation of the object or will make manipulation of the object easier. The pose estimation problem is the determination of the pose of an object based on sensor data. The sensor data is generated by simulating the response of noncontact proximity sensors having spherical detection ranges. The pose of the object is solved using the concept of triangulation to derive the equations and a nonlinear least-squares technique to solve for the unknown sensor parameters and object frame location relative to the reference frame. For simplicity, the object is modeled as spherical.

Subminiature binary camera design for inspection and robotic assembly applications

The article describes the design and utilization of a small, lightweight digital camera intended to assist in robot assembly tasks and to provide a low cost visual inspection tool. The main operational features of the design are outlined together with some sample applications involving the identification of integrated circuit devices, and the location of assembly sites on a printed wiring board.