LUNAR ZEBRO’S MODULES
The rover is comprised of six leg modules. Especially designed leg provide the perfect balance between grip and resist sinking. Each leg is powered by a space grade motor which is encased in a bushing along with a temperature and hall sensor. Each module is independently operated by the on-board computer and has reflex control built into every module. This low-level reflex behavior allows the module to protect itself from overheating, overcurrent and adapt to terrain independently of each other to maximize survivability of the rover and overcome obstacles of its own height with ease.
The leg design is based on the RHex project’s research.
Navigation module is composed of two components, the camera and obstacle avoidance algorithm. The camera, also known as SHRIMP (Small High-Resolution Independent Modular Photographer) is a in-house built stereo camera system which has a mass of less than 3 grams. The camera subsystem also has 6-axis IMUs (Initial Measurement Unit) and a 6KB non-volatile FRAM. While the camera takes photos and can record short videos, its real power is when the obstacle avoidance algorithm (OPAL) detect an obstacle at 2 m distance and take necessary actions to avoid the rock if it’s bigger than its own leg height and guide it back to its initial path plan.
COMMAND AND DATA HANDLING MODULE
The C&DH module is the brain of the rover. It consists of two On-Board Computers (OBC) and two memory modules. It controls all the modules at a higher level and checks for incoming signals, stores flight data in both the memory modules (one as backup) and manages mission’s primary modes to make sure the rover carries out its mission without risking itself. The OBC also controls the rover’s internal temperature and runs OPAL which helps it to compute all incoming images from SHRIMP, decide and command the locomotion modules individually what to do.
The power system of the rover is divided into four major subsystems; power collector (solar panels), conversion (BMS), storage (batteries) and distribution (PDS). 12 space grade solar cells are mounted on a deployable panel on top of the rover to pin point the sun and face perpendicular to the incoming rays, maximizing energy collecting capacity at any given time. Battery Management System (BMS), a in-house built subsystem, measures charge level and ensures the batteries are charged at the right voltage and current levels as output values of solar panels fluctuates. It takes approximately three hours for the four batteries to fully charge from empty. During charging operations, the rover does not ‘walk’ or carry out any non-critical tasks. As the name suggests, the Power Distribution System (PDS) regulates and distributes the various levels of power from the batteries to meet different demands of the subsystems like camera and motors while also protecting the components from surge and electrostatic charge.
Designing a direct communications system was a challenge as the shoe-boxed rover is very close to the ground and with no relay system between Moon and Earth, the rover is not able transmit a very powerful signal. For this reason we built a custom mother communications boards and power amplifier board, which helps boost the signal just enough for the data reach one of our ground station. The mono pole antenna is clamped to a four-bar Antenna Deployment System (ADS) at the same plane as the solar panel. The simple, yet unique ADS support mechanics helps keep the antenna perpendicular to the ground at all times, no matter at what angle the solar panel is. This allows the rover to keep a direct and continuous connection with Earth and beacon its housekeeping data.
CHASSIS AND THERMAL MODULE
The chassis of the rover has a monoque design, with one uniform hull and one bottom plate. The chassis provides housing for all components and payload while also protecting them from the harsh trans-lunar journey and lunar environment especially the fine dust. The hull is anodized in space grade black coating keeping the internal components safe from harmful radiations. The coating also allows for absorbing and radiating heat at a safe rate and prevent sharp and abrasive lunar dust from weakening the structure over its mission lifespan.