238 IEEE TRANSACTIONS ON SYSTEMS, MAN, AND CYBERNETICS—PART A: SYSTEMS AND HUMANS, VOL. 30, NO.3, MAY 2000 Robotic Interception of Moving Objects Using an Augmented Ideal Proportional Navigation Guidance Technique Mehran Mehrandezh, Member, IEEE, Naftali M. Sela, Robert G. Fenton, and Beno Benhabib, Member, IEEE Abstract—This paper presents a novel approach to on-line, robot-motion planning for moving-object interception. The pro- posed approach utilizes a navigation-guidance-based technique, that is robust and computationally efficient for the interception of fast-maneuvering objects. Navigation-based techniques were originally developed for the control of missiles tracking free-flying targets. Unlike a missile, however, the end-effector of a robotic arm is connected to the ground, via a number of links and joints, subject to kinematic and dynamic constraints. Also, unlike a missile, the velocity of the robot and the moving object must be matched for a smooth grasp, thus, a hybrid interception scheme, which combines a navigation-based interception technique with a conventional trajectory tracking method is proposed herein for intercepting fast-maneuvering objects. The implementation of the proposed technique is illustrated via numerous simulation examples. Index Terms—Moving object interception, proportional naviga- tion guidance, robot motion planning. I. INTRODUCTION A NOVEL navigation-guidance-based technique is pre- sented herein for intercepting moving objects via an autonomous robotic manipulator. The interception task is defined as “approaching a moving object while matching its location and velocity in the shortest possible time.” The object’s instantaneous location and velocity are predicted using visual feedback. Similar robotic interception problems have been previously addressed in the literature. The targets have been considered as either fast- or slow-maneuvering.A slow-maneuvering target moves on a continuous path with a relatively constant velocity or acceleration. In such a case, accurate long-term prediction of the target’s motion is possible and time-optimal interception methods can be employed. For a fast-maneuvering-type motion, on the other hand, the target varies its motion randomly and quickly, making time-optimal interception a difficult task. A brief review of the pertinent Manuscript received September 16, 1998; revised January 16, 2000. This paper was recommended by Associate Editor R. A. Hess. M. Mehrandezh is with the School of Engineering Science, Simon Fraser University, Burnaby, B.C., Canada, V5A 1S6. N. M. Sela is with the Research and Development Department, RAFAEL, Haifa, Israel. R. G. Fenton is with the Department of Mechanical and Industrial Engi- neering, Universityof Toronto, Toronto, Ont., Canada, M5S 3G8. B. Benhabib is with the Department of Mechanical and Industrial Engi- neering, University of Toronto, Toronto, Ont., Canada, M5S 3G8 (e-mail: beno@mie.utoronto.ca). Publisher Item Identifier S 1083-4427(00)03705-X. literature is, thus, provided below according to the target’s motion class. Slow-Maneuvering Objects: Prediction, Planning, and Ex- ecution (PPE) methods are well suited for intercepting objects traveling along predictable trajectories [1]–[6]. When using a PPE technique, the robot is directly sent to an anticipated ren- dezvous pointon the target’s predicted trajectory. Active Predic- tion, Planning, and Execution (APPE) techniques, which replan robot trajectories on-line in response to changes in the target’s continuously-monitored motion, have also been reported in the literature [7], [8]. However, for fast-maneuvering objects, even such techniques would lose their time efficiency due to lack of reliable long-term predictability of the target’s motion. Fast-Maneuvering Objects: Numerous visual-feed- back-based tracking systems, which continuously minimize the difference between the target and the robot, have been reported in the literature [9]–[12]. Because of their computational efficiency, such systems are well suited for tracking fast-ma- neuvering objects. The performance of these techniques, however, may deteriorate when taking the dynamic constraints of the robot into account. Also, in order to compensate for computational delays, which are inherent in a tracking system, the state of the object has to be predicted a few steps ahead. A heuristic procedure for local-minimum time, on-line tracking of fast-maneuvering objects has also been reported in the literature [13]. In [14], a potential-field-based technique for intercepting a maneuvering object that is moving amidst known stationary obstacles is addressed. The methods mentioned above cannot generate min- imum-time robot trajectories to intercept fast-maneuvering targets. However, minimum time in its absolute sense is not a critical criterion, since the important task at hand is successful interception. Another widely used method for tracking fast-maneuvering moving objects falls under the category of navigation and guidance theory. Such techniques have normally been used for tracking free-flying targets (e.g., missiles tracking evasive air- craft). These techniques are usually designed for time-optimal interception. Unlike a missile, however, the end-effector of a robotic arm is connected to the ground via joints and a number of links, and thus, it is subject to kinematic and dynamic constraints. On the other hand, a robot can maneuver in any direction, while missiles can usually accelerate only laterally in the direction of their velocity. Guidance laws typically fall into one of five categories: Command-To-The-Line-of-Sight (CLOS), Pursuit, Propor- 1083–4427/00$10.00 © 2000 IEEE