Lower leg design and contact sensing of quadruped robot

Quadruped robots are ground mobile platforms with great capabilities to navigate on challenging surfaces, like on natural ground and unstructured environments. The key element behind such great capabilities is the level of adaptation that each single leg can provide with respect to the terrain surfaces and obstacle sizes. In this perspective, an effective leg design exploits as much as possible the range of motion of every joint to allow the robot torso to reach extreme postures during the navigation. During the locomotion, the lower limb of a leg (the shin) is the robot link that has higher chances to make undesired contacts with the environment. Undesired contacts (or collisions) at the shin are dangerous and can make the robot get stuck or even fall, therefore, the design of the lower leg is directly associated to the robot limitations when navigating over irregular shapes, for example, on rocks or stairs. In this thesis, we propose a study to aid in the process of designing the new the lower leg speifically for the task of stairs climbing, both for a generic quadruped robot, and for the new hydraulic quadruped robot HyQReal. An additional study of the lower leg geometric and kinematic is then assessed, by exploring the possibility of adding an additional contact point on the back of the shin, with the goal of improving the robot safety and reachibility. The thesis then tackles the mechanical design of the new foot of the HyQReal robot, studying new shapes and the addition of a contact sensor embedded in the foot. The choice of the sensor was aided by a model developed bt the student which, given certain weigths to each of the benchmarks, returns the most promising sensor technology. Once the sensor has been assessed, it is first validated through numerical simulations performed using the Ansys software. Subsequently, a prototype is made and the goodness of the design and of the sensor are tested on a testing platform with the use of a force plate, and the interface with the robot hardware is defined and tested as well.