Industrial robots are mechanical manipulators whose dynamic characteristics are highly nonlinear. To control a manipulator which carries a variable or unknown load and moves along a planned path, it is required to compute the forces and torques needed to drive all its joints accurately and frequently at an adequate sampling frequency (no less than 60 Hz for the arm considered). This paper presents a new approach of computation based on the method of Newton-Euler formulation which is independent of the type of manipulator-configuration. This method involves the successive transformation of velocities and accelerations from the base of the manipulator out to the gripper, link by link, using the relationships of moving coordinate systems. Forces are then transformed back from the gripper to the base to obtain the joint torques. Theoretically the mathematical model is "exact. "A program has been written in floating point assembly language which has an average execution time of 4.5 milliseconds on a.PDP 11/45 computer for a Stanford manipulator. This allows an on-line computation within control systems with a sampling frequency no lower than 60 Hz. A further advantage of using this method is that the amount of computation increases linearly with the number of links whereas the conventional method based on Lagrangian formulation increases as the quartic of the number of links.

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In this paper we present a large dataset intended for use in mobile robotics research. Gathered from a robot driving several kilometers through a park and campus, it contains a five-degree-offreedom dead-reckoned trajectory, laser range/reflectance data and 20 Hz stereoscopic and omnidirectional imagery. All data is carefully timestamped and all data logs are in human readable form with the images in standard formats. We provide a set of tools to access the data and detailed tagging and segmentations to facilitate its use.

The problem of computer control of an arm is divided into four parts: modelling, trajectory calculation, servoing and control. !n rnofielling ue use a symbolic data structure to represent objects in the envirjnment. The program considers hew the hand may be positioned to grasp these objects and plans hou to turn and position them in order to make various moves. An arm model if used to calc late the configuration-dependent dynamic properties of the arm before it is moved. The ami is moved along time-coordinated space trajectories in which velocity and acceleration are controlled. Trajectories are calculated for motions along defined space curves, as in turning a crank; in such trajectories various joints must be free due to external motion constraints. The arm is servoed by 6 small computer. No analog servo is used. The servo is compensated for gravity loading and for configuration-dependent dynamic properties of the arm. In order to control the arm. a planning program interprets symbolic arm control instructions and generates a plan consisting of arm motion» and hand actions. The move planning program has worked successfully in the manipulation of plane faced objects. Complex motions, such as locating a bolt and screwing a nut onto it, have also been performed.