# On the Unification of Legged and Aerial Robots for Planetary Exploration Missions
###### Abstract  
In this article, we address the task of developing a unified solution that incorporates quadruped and aerial robots for planetary exploration missions. The designing process takes recommendations provided by Boston Dynamics for building custom payloads for the Spot robot, as well as its kinematic constraints. The unification task itself encompasses design of a passive drone landing platform as a hardware link between the Spot robot and the drone, which has active locking and unlocking capabilities required to securely keep the drone on the Spot independently whether it is standing or moving. Thus, in the designed unification solution, the landing platform does not impact the overall robot mobility and has no interference with the robot's legs. The initial solution design was extensively evaluated in a series of tests at the laboratory, which demonstrated its viability.  
landing platform; Spot; drone; robot unification; take-off +
Footnote †: journal: Applied  
13 April 202214 April  
Presently, among the existing studies, one can find conceptual designs of a landing platform for wheeled ground vehicles which do not take into consideration the task of carrying an aerial robot over an extended period of time, or the overall kinematics of a legged robot. In [6; 7], the authors presented a concept of a ground-aerial robotic system in which they proposed a passive landing platform with funnels. The authors in [8] presented a concept of a drone landing on a passive landing platform mounted on a ground vehicle. A similar concept was also demonstrated in [9]. The authors in [10] showed a concept of a passive platform for a drone with a ski-type landing gear. In a survey study [11], the authors summarized various drone landing platforms with positioning mechanisms.  
However, in none of the existing works was shown a drone landing platform with active locking and unlocking capabilities that was designed specifically to use with a quadruped robot, more specifically, the Boston Dynamics Spot robot. In opposition to ground (wheeled) and aerial robot unification, the design approach had to follow specific design constraints of Spot payload as weight and dimensions, as well as take into account the locomotion of the Spot, and its degrees of freedom (extensive tilt and roll capabilities). The added value of the presented work is mainly in exploring the challenge of quadruped-aerial robot unification and demonstrating the feasibility of the concept.  
Thus, the main contributions of this article stem from the design and analysis of the drone landing platforms for the Spot robot with corresponding drone designs for each of them and the final concept demonstration of the drone landing platforms in a lab environment.  
Figure 2 shows our proposed solution contribution among the existing approaches [11].  
The rest of the article is structured as follows. Initially, the designs of a landing platform for Spot with corresponding drone designs are presented in Section 2. Results and  
Figure 1: Concept of the unified legged-aerial robotic platform for lava tube exploration.  
Figure 2: Place of drone landing platform with active locking and unlocking capabilities among existing approaches.  
discussions of proposed designs are presented in Section 3. Finally, the article is concluded in Section 4.