No abstract

Snakes utilize irregularities in the terrain, such as rocks and vegetation, for faster and more efficient locomotion. This motivates the development of snake robots that actively use the terrain for locomotion, i.e. obstacle aided locomotion. In order to accurately model and understand this phenomenon, this paper presents a novel non-smooth (hybrid) mathematical model for wheel-less snake robots, which allows the snake robot to push against external obstacles apart from a flat ground. The framework of non-smooth dynamics and convex analysis allows us to systematically and accurately incorporate both unilateral contact forces (from the obstacles) and isotropic friction forces based on Coulomb's law using set-valued force laws. The mathematical model is verified through experiments. In particular, a back-to-back comparison between numerical simulations and experimental results is presented. It is furthermore shown that the snake robot is able to move forward faster and more robustly by exploiting obstacles.

Modeling and analysis of planar rigid multibody systems with translational clearance joints based on the nonsmooth dynamics approach

Reserve requirements are a prominent policy instrument in many emerging countries. The present study investigates the circumstances under which reserve requirements are an appropriate policy tool for price or financial stability. We consider a small open-economy model with sticky prices, financial frictions, and a banking sector that is subject to legal reserve requirements and compute optimal interest rate and reserve requirement rules. Overall, our results indicate that reserve requirements can support the price stability objective only if financial frictions are important and lead to substantial improvements if there is a financial stability objective. Contrary to a conventional interest rate policy, reserve requirements become more effective when there is foreign currency debt.JEL Codes: E580, E520, F410, G18.

No abstract