Multirotor is the umbrella term for the family of unmanned aircraft, which include the quadrotor, hexarotor and other vertical take-off and landing (VTOL) aircraft that employ multiple main rotors for lift and control. Development and testing of novel multirotor designs has been aided by the proliferation of 3D printing and inexpensive flight controllers and components. Different multirotor configurations exhibit specific strengths, while presenting unique challenges with regards to design and control. This article highlights the primary differences between three multirotor platforms: a quadrotor; a fully-actuated hexarotor; and an octorotor. Each platform is modelled and then controlled using non-linear dynamic inversion. The differences in dynamics, control and performance are then discussed.

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There are two main approaches in order to design biped robots; one is to use precise control and powerful actuators, and the other is based on passive walking optimizing energy consumption. In this paper a simulation method developed in Matlab® is proposed for a passive robot capable to accomplish a virtual passive walking. The proposed method considers three actuators, one at the hip and another two for the ankles. Simulation results are shown for a basic gravity-based control and can be used to develop another control strategies. Index Terms-passive dynamic walking virtual gravity Matlab®