Department Publications

Tunable laser system requires high resolution and accuracy in position of the wave selective optical element, which can be attained through the use of stepper motor. This paper focuses on the stepper motor controller, with the feedback to improve the accuracy and the microstepping technique to improve the resolution. Sine cosine and trapezoidal current controlling techniques for the micro stepping are used in two different types of situations. The proposed controller uses the linear interpolation and sine cosine current controlling technique to double the rotation accuracy than the resolution of the encoder and detect the obstacle by using the encoder and the static characteristic of the stepper motor. Also, the variable step interval technique is proposed to overcome the speed variation in the trapezoidal current controlling technique. The simulation and the experimental results show that, proposed controller can …

This paper describes a fuzzy based mathematical model to recover the motion path of an obstacle observed via a single camera. The strategy is analysing a sequence of images captured in regular time intervals, more specifically, studying the variation of the apparent size of an obstacle and the relative position change on reference frame. Those two measures are the only inputs to the fuzzy-mathematical model, the major emphasis of the research, which recovers the motion path as an equation. Necessary feature extraction is being achieved via a real time image processing module which relies on an optical flow technique as the key technique to recognize dynamic objects. It was reported a 91.98% average accuracy from the fuzzy-mathematical model in simulation environments, where the inputs were generated by a simulator program in order to study the precision of the fuzzy-mathematical model as a standalone application. An average accuracy of 59.8% was experienced at the real time application, an artefact to test the postulated concept in real time dynamic environment, which comprised of three major modules: a real-time image processing module, the fuzzy mathematical model and a mobile robot.

For high scientific return, planetary rovers need to navigate longer distances autonomously and be less dependent on Earth station. Collaboration between rovers can substantially increase the localization accuracy for all the rovers and therefore, opens up opportunity for future exploration missions. This study aims at introducing a decentralized cooperative SLAM technique for two rovers based on EKF-SLAM and FastSLAM algorithms. Several data fusion methods and motion strategies are formulated. Furthermore, a novel SLAM technique called, cooperative positioning SLAM is proposed. The results show that by fusing information, better localization accuracies can be achieved. To validate algorithms a 3D simulation environment has been developed using opensource tools.

第 23 回アストロダイナミクスシンポジウム (2013 年 7 月 29-81 日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)), 相模原市, 神奈川県