Introduction

Robotic messengers

The human kind has been trying to learn about our world and the rules that govern it ever since we appeared. Just yesterday we were discovering new islands and continents, and today robotic messengers are visiting other planets and moons. These unmanned and autonomous vehicles—rovers—are designed to take samples, which provide invaluable data. The multitude of ongoing and planned missions involving rovers have inspired us to build our own. Below are details of the in-development rover project by SpaceCoffee.

MPER – Multi-Purpose Exploration Rover, is the first original, fully-fledged and the longest in development project our Club is working on.

Goals and objectives of the project

Skill set planned for the rover

• Remote control of tasks and semi-autonomous navigation control, using a UI devoted to remote control created, communication via 2.4GHz/5GHz Wi-Fi.
• A precise manipulation ability, to be made possible through a developed robotic arm with a Manipulator Module.
• Surface and deep-level sample retrieval due to a fully-developed, effective Drilling and Containment Module, keeping up to 5 samples.
• Execution of research purposes – made possible by implementation of environmental soil, atmosphere and radiation sensors, along with a weighing system for collected samples.
• Multiple-angled vision—three cameras for wide-angle, medium-angle night-vision, and AI object recognition are used for the rover. The wide-angle camera can pan in either vertical or horizontal axis using a servo motor.
• Driving up a 30-degree incline.
• Custom-built LIDAR system that allows the rover to move autonomously.
• Path planning algorithm is to be implemented, allowing the rover to navigate terrain autonomously using GNSS, visual markers and obstacle sensors.
• Use of current consumption sensors, gathering diagnostics of the rover’s Modules.

The project of the rover implied coming up with a low-cost and an easily replicable solution for the design, which prompted us to come up with the parameters of less than 18 kg of mass, and 700x450x300 mm base dimensions for MPER. This simplicity is beneficial thanks to the possibility of controlling a number of smaller vehicles at once, which reduces the risk of single-point failure in more complex missions. Instead, a vast terrain can be explored by multiple smaller rovers. The concept of a mission we’ve thought about involves a main non-mobile lander—a science laboratory, with a fleet of tens of rovers and drones of various sizes preparing and bringing samples there.

Modules and their implementation

During the design of our vehicle, many elements had to be taken into account for its operation elements. For this reason, the components were divided into following Modules, with corresponding Systems:

• Driving Platform—Chassis: the constructed drive is meant to provide accommodation to uneven and rugged planetary surface areas for the rover, thanks to its 4-wheel drive with a shock absorption system, which grants it an accessory agility of movement in hard-to-reach or obstructed places. 

• Robotic Arm and Manipulator with a Gripper: the component has to enable precise interaction with the environment; a 4-degrees-of-freedom, five-articulated manipulator arm, where we used a designed combination of 2 gear types—a stepped-planetary gear, fully printed in PETG, which grants us an easiness experimentation with arm parameters, so we can determine the best arm construction design. The rover can pick up materials from surfaces around it, and carry them over to its platform, which is equipped with a weight for a primary determination of a sample’s parameters.


• The whole arm is lightweight, with 4DOF, and utilizes 3 stepper and 2 servo motors for precise movement navigation. Its maximal pickup capacity is planned as 1 kg.
• Sample Containment System: we came up with a smart container system — single force sensor for the front compartment and another single sensor in the back for deep drill samples. The act of placing a sample is recorded, with the weight calculated from the difference in the total weight of the Module, the precision being +/- 0.5 g, while using a single load cell sensor. This allows storage of multiple samples without using more weight sensors. The deep drill revolver storage also has an option of emptying the containers sequentially, using a single servo to rotate the compartment. The front cargo compartment is suitable for storing rocks or other items picked up by the rover, including basic tools that can be used by the Manipulator, and also includes an ionizing radiation sensor which is part of the Environmental (atmosphere) Sensors Module, and a weight sensor.
• The Drilling System: a module responsible for soil-samples collection. The current design depth of a drill is up to 20 cm under the surface. The newest design of the system includes a stepper motor moving a carriage across a V-slot rail, with an endstop at the top. The stepper motor’s torque is increased using our custom-made stepped-planetary gearbox.


• The guide is split in two parts – fixed and moving. The fixed part provides mechanical support and acts as a linear bearing, while the moving part is attached to the carriage and has a tight fit with the drill bit, allowing the soil samples to travel upwards, which is shown on the Drilling System’s diagrams.
• Sample Retrieval System – it is constituted of two other Modules: the Manipulator and the Drilling System. Front cargo compartment is situated within reach of the robot arm. Using the Manipulator, after being picked up the specimens can be transported and preserved in the prepared containers, with a regard to their particular fragility and assuring previous sterilization of the containment. The Drill rotates in a drill guide, allowing the sample to be carried upwards towards the Sample Containment System.
• Main Computer and Subsystems Computers – responsible for coordinating the entire rover. Transfer of information and commands between the subsystems takes place over SPI buses connected to the rover’s main computer. We have developed 3 distinct PCB’s for the main subsystems: Chassis, Manipulator and Sampler, all three driven by an independent microcontroller (Arduino Nano), receiving and sending data to the main controller (Raspberry Pi 5).

• Envorinmental Sensors Module – used for the research of environmental conditions prevailing on planets other than Earth were the collection of sensors meant for separate examinations of the atmosphere and the soil. For the aim of analyzing the atmospheric factors, we completed an Arduino Nano-based system of pressure, temperature, humidity and CO₂ sensors.
• Additionally, our rover is equipped with an ionizing radiation sensor, placed next to the front cargo compartment. It can be used to measure background radiation and solar storms, and also detect radioactivity of objects picked up by the rover.
• The examination of factors related to soil conditions will be possible due to use of humidity and temperature probes.
• The listed above factors are needed for assessing the elements of a planet’s nature, evaluating its habitability and, for example, crop harvest ability. Measurements prepared during the study of the sample are transmitted from the sensory modules through an UART bus to the Raspberry Pi 5-based main computer. The noted values are then sent to the ground base for the conduct of further research. An important addition in the works is a UV radiation sensor.
• Intuitive UI – Full control of the rover can be achieved in browser, with live telemetry and view. We are developing a pathing system where the operator can tap on a point in view of the rover, and the rover will drive there, avoiding obstacles along the way. The user interface can be accessed by browser on any PC or mobile device, allowing intuitive control of the vehicle.

• Custom-built LIDAR-like system – consisting of a two DOF laser sensor “turret”, which can point at any object and return its distance from the rover.

Developments: posts related to the MPER project

Future potential developments

The main two solutions viewed as future extensions of the rover are: current consumption diagnostics, for which we plan to utilize 5 current consumption sensors—their use includes measuring forces of the manipulator’s gripper and joints, as well as sample drill movement. It also allows for drivetrain diagnostics and estimation of time left until the battery is discharged. The second extension is the use of solar panels as part of the Power Supply Module. A design of a collapsible solar array, for preserving the rover’s mobility and stability when not charging, is possible.