軟弱斜面におけるスキッドステア型クローラ移動ロボットの位置推定と経路追従制御

要約のみTohoku University永谷圭司課

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

Slip-compensated odometry for tracked vehicle on loose and weak slope

Abstract Odometry is widely used to localize wheeled and tracked vehicles because of its simplicity and continuity. Odometric calculations integrate the wheel or track’s rotation speed. The accuracy of position thus calculated, is affected by slippage between the ground and the wheel or track. When traveling on a loose slope, the localization accuracy of the odometry decreases remarkably due to slippage. To improve its accuracy in such environments, terramechanics focus on estimating the interaction between a vehicle and the ground. However, because these formulas are complicated and governed by many terrain-specific parameters, they are difficult to use in unknown environments. In this study, we propose slip estimation methods targeted toward use in unknown environments. We consider four types of slippage, based on the slippage direction and maneuver type. Longitudinal and lateral slippage occurring during straight maneuvering are derived by approximating the terramechanics slip model. In contrast, for turning maneuvers, longitudinal slippage is derived from an empirical equation for the relationship between slip ratio and input velocity, and lateral slippage is obtained from a regression function. We also proposed slip-compensated odometry, which applies the slip model to the kinematics of a skid-steering vehicle. To evaluate the proposed slip model and slip-compensated odometry, we conduct several experiments with a skid-steering tracked vehicle on an indoor sandy slope. Experimental results confirmed that position estimation accuracy was improved by introducing slip-compensated odometry compared to conventional odometry

Persistent microporosity of a non-planar porphyrinoid based on multiple supramolecular interactions for nanomechanical sensor applications

Porous substances such as metal–organic frameworks (MOFs), covalent organic frameworks (COFs) and zeolites are important materials for different applications, and several methods have been developed for their processing into device architectures. Solution processing of small molecule precursors into corresponding porous structures would be beneficial for many applications since it facilitates incorporation of the active material component into relevant devices thus reducing complexity and cost. Here we report that a non-planar saddle-shaped N-heterocycle-fused metallo-porphyrinoid forms a persistently microporous crystalline material directly from solution, which can undergo solvent exchange without loss of microporosity. The material is formed by a unique accumulation of intermolecular interactions involving π–π stacking of the fused heterocycle, coordinative interactions at the metalloporphyrinoid unit, and hydrogen bonding. This intermolecular multipoint interaction concept will be key in the future molecular design for on-demand synthesis of porous materials, and the simple implementation of the compound described here indicates the excellent potential for device materials’ synthesis. Sensing properties of the material incorporated into a nanomechanical sensor array are also reported