The work reported here is concerned with methods used to provide partial pose data for robot calibration tests. Rather than focussing on traditional, precision measurement techniques, the paper discusses calibration using end point motion constraints of various kinds. The preferred method consists of using a wire potentiometer attached to the robot tool by means of two specially designed fixtures. Suitable modeling of the measurement system as well as the internal kinematics of the manipulator allows simulation of the calibration process. Experimental results obtained in the calibration of an industrial manipulator is presented, and means to make the complete calibration process automatic is discussed.>

This paper is concerned with modeling the haptic exploration and recognition of objects using a teleoperator mechanism, mainly underwater. Three factors are identified which determine the success with which objects may be recognized: a) correct feature identification, b) interpretation of spatial data between features, and c) the ability to retain in memory the sequence of features identified. A haptic cognitive model is proposed which incorporates these factors, with emphasis on part c). The performance of the cognitive model is assessed with respect to previously obtained data, and further experiments are conducted to determine the number of features an operator can correctly recall when probing a remote object.>

An automatic partial-pose measurement system for robot calibration, called the vision-based automatic theodolite (VBAT), is described. It uses low-resolution rotation stages and resolution enhancement from a vision system to determine the line of sight to a spherical illuminated target. Automatic tracking, focusing, and centering provide the calibration system with speed, reliability, and repeatability. It is proposed that such a measurement prototype may be constructed without expensive precision machining, provided it is calibrated before use. Simulations demonstrate that such a system may be identified by precalibration of the vision parameters, followed by calibration of the rotation stage parameters. All parameters are determined from measurements using a coordinate measuring machine. The parameter identification is formulated as a nonlinear regression problem. Verification of the VBAT calibration experiment shows that the identified model can predict the target position to a root mean square miss-distance of 0.2 mm.>

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.

The paper describes the use of a gray scale tactile array sensor available in two specific geometric configurations. A larger pad, which has a 16 by 16 element array of sensors, is used to demonstrate the "image," processing capabilities of the system including a pose estimation algorithm for regular objects placed in contact with the pad. Following this, a smaller sensor with an 8 by 16 element configuration is developed for mounting directly in the fingertip of a robot gripper. The transfer of the software and hardware into a turnkey system suitable for factory-floor manufacturing assembly operations is described, along with an appropriate computer architecture for realizing the real time capabilities of the sensor.