Motion design for autonomous mobile manipulator based on programming style "action primitive"

Our research goal is to realize an intelligent autonomous motion for a mobile manipulator. A model task for mobile manipulators, &#34;returning books to bookshelf&#34; was chosen as our research task. To realize the task, we adopt a programming style named &#34;action primitive&#34; for programming the robot controller. Each action primitive is a basic motion control program, and the whole motion of the robot is generated by executing a sequence of action primitives step by step. The paper describes motion design for the above research task based on the action primitive concept, and reports simulation results of the designed motion </p

Sensor based navigation for car-like mobile robots using generalized Voronoi graph

Our research objective is to realize sensor based navigation by car-like mobile robots. The generalized Voronoi graph (GVG) can describe a mobile robot's path for sensor based navigation from the point of view of completeness and safety. However, it is impossible to apply the path to a car-like mobile robot directly, because limitation of the minimum turning radius prevents following the non-smooth GVG. To solve the problem, we propose a local smooth path planning algorithm for car-like mobile robots. Basically, an initial path is generated by a conventional path planning algorithm using GVG theory, and it is deformed smoothly to enable car-like robots' following by maximizing an evaluation function proposed in the paper. The key topics are: definition of our evaluation function; and how to modify the GVG. We introduce a local smooth path planning algorithm based on the GVG, and explain a detail of the evaluation function. Simulation results support validity of the algorithm </p

Path evaluation for a mobile robot based on a risk of collision

An odometry system that mobile robot uses for positioning has cumulative error because of wheels' slippage and uneven ground. It causes a risk of collision of obstacles. Therefore, we propose a path evaluation method for a mobile robot based on a risk of collision. To evaluate a robot's path, we define an evaluation value as an integral of a risk of collision along the path. To evaluate the risk of collision at each point, we use an estimated positioning error generated in the odometry system. Using the evaluation method, the robot can plan a path based on a risk of collision, not the shortest path. We also consider sensing points planning for position adjustment of the mobile robot, based on the same approach. Some examples of path evaluation results support a validity of the proposed method.</p

Slope Traversal Experiments with Slip Compensation Control for Lunar/Planetary Exploration Rover

2008 IEEE International Conference on Robotics and Automation, Pasadena, CA, USA, May 19-23, 200

Motion planning for mobile manipulator with keeping manipulability

Our research goal is to realize a motion planning for an intelligent mobile manipulator. To plan a mobile manipulator's motion, it is popular that the base robot motion is regarded as manipulator's extra joints, and the whole system is considered as a redundant manipulator. In this case, the locomotion controller is a part of the manipulator controller. However, it is difficult to implement both controllers as one controller, in our implementation experience, because of difference of actuators' character. In this research, we focus on a path planning algorithm for a mobile base with keeping manipulability at the tip of the mounted manipulator. In this case, the locomotion controller is independent from the manipulator controller, and a cooperative motion is realized by a communication between both controllers. In this paper, we propose a motion planning algorithm for a mobile manipulator, and report several experimental results. </p

Improvement of odometry for omnidirectional vehicle using optical flow information

Our research goal is to realize a robust navigation in indoor and outdoor environment for autonomous vehicle. An omnidirectional vehicle driven by four Mecanum wheels was chosen for our research platform. Mecanum wheel has 16 tilted rollers (45 degrees against the direction of wheel rotation) around the wheel, so the vehicle moves omnidirectionally by controlling these wheels independently. However, it has a disadvantage in odometry because of wheel slippage. Particularly, when the robot moves laterally, same wheels' rotations generate different traveling distance depending on friction of ground surface. To cope with the problem, we estimate robot's position by detecting optical flow of ground image using vision sensor (visual dead-reckoning). The estimation method is inaccurate comparing with odometry, but it is independent from friction of ground surface. Therefore, the estimated vehicle position can be improved by fusing odometry and visual dead-reckoning based on maximum likelihood technique. This paper describes an odometry method and a visual dead-reckoning method for omnidirectional vehicle, and fusion technique to improve the estimated position of the vehicle. Finally, experimental results support above technique </p

Three-dimensional localization and mapping for mobile robot in disaster environments

To relieve damages of earthquake disaster, &#34;The Special Project for Earthquake Disaster Mitigation in Urban Areas&#34; have been kicked off in Japan. Our research group is a part of the sub-project &#34;modeling of disaster environment for search and rescue&#34; since 2002. In this project, our group aims to develop a three-dimensional mapping's algorithm that is installed in a mobile robot to search victims in a collapsed building. To realize this mission, it is important to map environment information, and also the mapping requires localization simultaneously. (This is called &#34;SLAM problem&#34;.) In this research, we use three-dimensional map by laser range finder, and we also estimate its location in a global map using correlation technique. In this paper, we introduce our localization and mapping method, and we report a result of preparatory experiment for localization. </p

Vision-based Estimation of Slip Angle for Mobile Robots and Planetary Rovers

2008 IEEE International Conference on Robotics and Automation, Pasadena, CA, USA, May 19-23, 200

Positioning device for outdoor mobile robots using optical sensors and lasers

We propose a novel method for positioning a mobile robot in an outdoor environment using lasers and optical sensors. Position estimation via a noncontact optical method is useful because the information from the wheel odometer and the global positioning system in a mobile robot is unreliable in some situations. Contact optical sensors such as computer mouse are designed to be in contact with a surface and do not function well in strong ambient light conditions. To mitigate the challenges of an outdoor environment, we developed an optical device with a bandpass filter and a pipe to restrict solar light and to detect translation. The use of two devices enables sensing of the mobile robot’s position, including posture. Furthermore, employing a collimated laser beam allows measurements against a surface to be invariable with the distance to the surface. In this paper, we describe motion estimation, device configurations, and several tests for performance evaluation. We also present the experimental positioning results from a vehicle equipped with our optical device on an outdoor path. Finally, we discuss an improvement in postural accuracy by combining an optical device with precise gyroscopes