This paper presents the development of a quadrotor vehicle capable of movement between air and water environments. The design challenges, including torque matching in the propulsion system, balance maintenance in different mediums, and waterproofing requirements, are discussed. A prototype is constructed to demonstrate the feasibility of the proposed design. Through the tilting mechanism in four rotors, the vehicle can not only fly in air like a normal quadrotor vehicle, but also propel in water with two configured rear thrusters. Moreover, the four tilted rotors cooperate in aligning the center of gravity and buoyancy, addressing limitations observed in traditional aerial-aquatic vehicles. The prototype has been verified through experiments in both air and water.

To access rough terrain and enhance the mobility in sandy terrain, a configurable paddle-wheel robot was pro-posed. This report addresses the paddle terradynamics, and the experimental verification of the locomotion performance of the robot over dry sandy terrain. To study the interactive forces between the paddle and the media, a terradynamic model is built and verified through experiments. To explore the locomotion performance, an indoor platform that allows the paddle-wheel module to move freely in both horizontal and vertical directions is created. Forward locomotion speed, height variant, and specific resistance are evaluated with different con-figurations. The protruding paddles have successfully reduced the slippage so as to increase the locomotion efficiency in sandy terrain. The performance of the whole robot has also been verified in outdoor sandy terrain.

Nonprehensile manipulation produces underconstraint motions that are sensitive to environmental dynamics. Legged locomotion constitutes a floating-based movement, whose dynamic is underactuated with respect to the inertial frame. When these two tasks are combined, system motion planning and control are complex due to their inherent underactuated features. This article presents a motion planning framework for a legged robot that uses its limbs for nonprehensile manipulation, as well as locomoting motions. First, issues related to the description of the robot-object-environment system and the task are presented. The velocity constraint that prevents separation and the force constraint that restricts interactive forces are then integrated into the system dynamic model to produce bounds on the system acceleration as a function of the system state. Then, we solve the motion planning problem by reducing the system dimensions in operational space and programming feasible trajectories within the phase plane. This approach is employed to control the quadruped robot TITAN-VIII to manipulate objects and locomote itself using Drive Mode, Inchworm Mode, Scoot Mode, and Throw Mode. Experimental results obtained through simulations and physical tests are reported to demonstrate the effectiveness of our approach.