Online Motion Research Articles

Special Issue on Robot Motion Planning

This special issue is devoted to robot motion planning. The main scope of this issue covers research work on mobile robotics. Motion planning is necessary when the robot determines its own actions. For the last decade, the paradigm of motion planning in mobile robotics has shifted from off-line motion planning to on-line motion planning and from planning in a static environment to planning in a time-varying environment. Recent progress of computational power has enabled this paradigm shift, since on-line motion planning and planning in time-varying environments require repeated computation based on sensory information which is always renewed. The guest editors organized this special issue in order to highlight those two new paradigms. We present two survey papers: One is a survey of on-line motion planning for a sensor-based navigation of a mobile robot, and the other is a survey of motion planning for mobile robots in a time-varying environment. Along with the survey papers, distinguished technical papers are provided in this special issue. Concerning path planning, a paper describing a case study on motion planning with teaching is included (Ogata et al). Motion planning based on Fuzzy logic is one approach, and three papers from Maeda, Ishikawa et al. and Nagata et al. also belong to this category. To offer a case study on reactive motion decision making, one paper by Ando et al. is included. A recently emerging subject is related to motion planning for cooperation of multiple mobile robots or a single robot among multiple moving obstacles. Three papers from Yoshioka et al., Ota et al., and Fujimura discuss problems on motion planning for cooperation of multiple mobile robots. One paper from Tsubouchi et al. discussed the motion planning of a single robot among multiple moving obstacles. Motion planning to select an appropriate corner cube as a landmark is addressed in the paper from Hashimoto et al. The guest editors hope that this special issue will provide the readers with a lock at some current issues and new perspectives on robot motion planning.

Motion - A New On-Line Model for Urban Traffic Signal Control

The modular on-line model MOTION is a new approach to urban traffic signal control. It consists of a network and a local level and builds on enhanced dynamic traffic state estimation. Special consideration is given to the priorisation of public transport, which may be treated by different intervention-modes. MOTION provides possibilities for the interaction with integrated urban management systems. It is developed with support of the European Union and will be implemented in 1994 for the first time.

On-line Reference Trajectory Definition with Joint Torque and Velocity Constraints

The most significant control problem to be solved in robotics is the use of sensor information. This article pre sents a new method of on-line motion generation. New joint reference trajectories are calculated to be more adapted to the situation detected by the position and velocity sensors. This motion generation method uses the resolution of a minimum time optimization problem. The constraints are first expressed in terms of joint velocity and torque bounds and are then transformed into joint velocity, acceleration, and jerk limitations. This reference trajectory definition takes into account the manipulator dynamics.

Path planning among unknown obstacles: the case of a three-dimensional Cartesian arm

A generalization to the 3-D manipulator of a 2-D approach to sensor-based robot motion planning in an unknown environment with arbitrary obstacles is considered. For the approach to guarantee convergence, it is vital that the number of options that the arm has for passing around an obstacle be limited. A three-link arm has an infinite number of directions for passing around an obstacle, but, by making use of the natural constraints imposed by the arm kinematics, the 2-D approach is extended to a three-link 3-D arm manipulator with sliding joints (a Cartesian robot arm). The technique exploits certain properties, called anisotropy and monotonicity, of the arm configuration space. The resulting algorithm is the first nonheuristic algorithm for online motion planning in three dimensions, with no prior knowledge of the obstacles. Collision-free motion is guaranteed for every point of the robot body; in no case does the generated path amount to an exhaustive search of the work space. >

On-line motion analysis using a TV system

An electronic method, using a TV system, which analyzes on-line the motion of various things, is described. The single sampled images may be digitized and stored in a minicomputer memory at TV rates, but this limited sampling frequency may be increased with the aid of a triggered stroboflash. The analysis of the acquired data may be made after the acquisition of either an image sequence or a single frame, according to program time and frame sampling frequency.