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# Fast Algorithm for Short-Time Collision Avoidance

IP.com Disclosure Number: IPCOM000100060D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 75K

IBM

## Related People

Furuhata, T: AUTHOR [+2]

## Abstract

This article describes a method of generating collision- free motions of a manipulator. The method consists of three parts: calculation of the vector for avoidance, estimation of minute displacements around the current position, and assignment of the vector to each joint (Fig. 1).

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Fast Algorithm for Short-Time Collision Avoidance

free motions of a manipulator. The method consists of three parts:
calculation of the vector for avoidance, estimation of minute
displacements around the current position, and assignment of the
vector to each joint (Fig.  1).

When a potential collision between an obstacle and a
manipulator is detected, a displacement vector between the user-given
edges for avoiding the collision is calculated according to the
relative positions and velocities of the objects (Fig. 2).

Next, minute displacements of the collision point around the
current position of the manipulator are estimated. Then, according to
calculated values, the displacement vector is allocated to the joints
that have the capacity to change these values during motion. The
capacity of a joint is calculated as the difference between its
original angle in the initial motion during the time taken to avoid
the obstacle and the maximum angle that it can traverse during that
time (Fig. 3).

One or more of the joints of the manipulator move at the
maximum speed during the time and are critical. Since the rate of
displacement of a joint that is critical in this motion does not
essentially change, this generated collision-free motion can be
completed in the same time as the initial motion.