Robotic Explorer for Hypothesized Surfaces – Biomimetic Robotics for the Psyche Asteroid
INSTITUTION
University of Georgia (UGA)
CLASS
Iridium Class (2024 – 2025)
STUDENT TEAM
ACADEMIC GUIDANCE
Dr. Beshoy Morkos
Dr. Jorge Rodriguez
PROJECT DESCRIPTION
The ‘Biomimetic Robotics for the Psyche Asteroid’ project explored novel and innovative ways to traverse the uneven, aggressive terrains present on the surface of the Psyche asteroid in preparation for future ground-based missions. The ability to effectively traverse the surface of the asteroid will allow for process sampling, detailed picturing, and the synthesis of other scientific data that will help scientists understand Psyche and the building blocks of early planet formation.
The main bottleneck behind the ability of surface exploration lies within the environmental constraints of Psyche. Among the hypothesized surface conditions include a large temperature gradient, metallic debris fields, areas of fine-grained regolith, rocks ranging from centimeters to kilometers in size, steep inclines, and ground fractures, all of which are not conducive of traditional rover design. These surface parameters propose the question of whether biomimicry can be used to develop designs that are more adaptive for an asteroid environment.
The benefits of biomimicry lie within an ability to draw from evolutionary advantages that enhance performance and efficiency. By mimicking the mobility of organisms that are capable of movement in environments akin to Psyche, designs can be produced that are more effective and are exclusively tailored to these harsh surface conditions.
This team’s capstone project aimed to create an in-depth design of one limb of a proposed six legged rover, alongside conducting thermal and kinematic analysis, CAD simulations, and physical prototyping. Taking inspiration from mobility advantages developed through evolution, this design employed human leg biomimicry to allow for both rolling and stepping motions, making a rover adaptable to most environments.
Featuring independently moving hip, knee, and ankle joints, each with 180° of motion, the mobility of this design benefits from having multiple degrees of freedom and a wide adaptability from various limb configurations. The large range of motion allows for the rover to complete large stepping motions and reorient itself if it is flipped over, as well as gets rid of the risk of hyperextension (a notable vulnerability in the human leg, which can only bend 90°). Attached to the ankle joint are a set of wheels, which apart from providing stable rolling motions, can be rotated perpendicular to the direction of movement in order to prevent slipping when stepping. The thigh and shin sections measure a combined 38” long and feature cylindrical rungs for compatibility with motor, sensor, and equipment installation. This design allows for a clearance of 10 – 45” between the ground and the rover body, a max step height of 36”, and a max step length of 24”.
The effort to enable both rolling and stepping motions is important in the fact that the surface conditions on the asteroid vary drastically, and there are situations that can benefit from either form of transportation. Rolling motions maintain constant contact with the ground and enhance stability through an even weight distribution, which is beneficial for movement across fine-grained terrains that can easily shift. Rolling is also more energy efficient than stepping, which gives the rover the ability to switch between movements depending on energy consumption needs. Stepping motions allow for more versatility and enable vertical climbing, which is beneficial for navigating inclines or stepping on/around obstacles.
In support of this design were the development of a range-of-motion simulation, ANSYS testing, and both structural and electrical prototypes to showcase design feasibility.
ANSYS testing was conducted for kinematic, thermal, and structural conditions. Kinematic analysis of the range of motion showed that there were no positions/configurations that would result in joint lock up. Similarly, thermal analysis under the expected temperature gradient of Psyche showed no temperature that causes joints to bind; tolerances in the CAD model were increased to allow thermal expansion and contraction. Structural analysis indicated room for material optimization, but otherwise showed that the gravitational forces on the rover are negligible.
The structural prototype was made at 50% scale from 0.2 mm PLA filament and was fully functional mobility wise, serving as the backbone for future prototyping. It verified physical range of motion and acted as proof of concept. The electrical prototype showcased a motor configuration that would allow for automated movement of this team’s design and allowed for testing joint control. Ultrasonic sensor development and the associated code demonstrated stepping motions, showing potential for automated movement and real-time decision making.
While future impact and fatigue, fault tolerance, and debris testing will need to be considered, as well as the integration of the structural and electrical prototypes, this leg design offers a novel approach to rover mobility which can support scaling into a full, mission-ready rover.
