Student Projects
Contact Information:
Country: United Kingdom
Year Submitted: 2018
University: University of Leicester
List of Team Members (with year of graduation): George Fiddes (2018), Luke Needle (2018), Ben Ward (2018), Peter Thompson (2018), Fan Zhou (2018), Qinyuan Wang (2018)
Faculty Advisers: Dr Luciano Ost, Dr Ioannis Kyriakopoulos
Main Contact Email Address: 06FiddesG@Gmail.com
Project Information:
Title: Mission to Mars - myRIO Controlled Prototype Planetary Rover
Description: A prototype for a myRIO controlled planetary rover was developed to assist with the testing of scientific instrumentation at the University of Leicester Space Research Centre.
National Instruments Hardware/Software: myRIO-1900, LabVIEW 2017, LabVIEW Real-Time Module, LabVIEW Application Builder, Vision Development Module
Other Hardware/Software: Raspberry Pi 3 model B, OpenCV, MatLab, Logitech C270 webcams
The Challenge:
One of the questions which humanity has been discussing for millennia is whether there is life in the universe beyond our planet. This question is very difficult to answer; however, scientists have identified Mars as a potential site. Evidence of water, a prerequisite for life, can be uncovered by studying the planets’ geology. The Space Research Centre (SRC) at the University of Leicester is currently running projects which are investigating this possibility through analysing samples from comets and meteorites which come from Mars, and by developing equipment and instruments to perform cutting-edge experiments. To test this instrumentation, the SRC sought the help of a group of students to design and develop a prototype rover to act as a testbed. To mimic the challenges of a real mission, the rover had to be fully controllable over a wireless network, be entirely battery powered and be able to traverse hazardous terrain to transport the scientific equipment to a target location.
The Solution:
Mechanical Design
The chassis of the rover was built from item frame, to ensure it could be adapted for numerous instrumentation attachments. The aluminium T-profile beams can be moved anywhere along the length of the frame so that balance is maintained as new hardware is mounted on to the test bed. The rover uses a rocker-bogey differential suspension to climb over obstacles such as small rocks that may be encountered on its mission across the Martian surface. This was essential to ensure that the testbed remains stable in motion.
Side view of the rover chassis
Electrical Systems
A myRIO-1900 was used as the central control hub, managing communications with the remote operator and all electrical subsystems - except for the stereo vision. Six wheels with built-in motors were used to drive the rover with a basic differential steering system. Cameras were mounted on the front of the vehicle to enable the operator to effectively steer the rover from a remote location. A raspberry Pi 3 was used to manage the stereo vision calculations and send back the video stream and obstacle distances to the user via the myRIO’s own wireless network, based on commands from the user. Two rechargeable batteries were used to power the vehicle for over 30 minutes, these batteries would be recharged from a renewable power generator during its mission.
Front view of rover prototype showing stereo vision cameras mounted a front beam
The myRIO uses a producer-consumer architecture to receive commands from a network stream and pass down the relevant data to a parallel loop which communicates with the relevant IO. This allows the commands to be processed without interfering with the other functions of the control hub such as temperature monitoring and communications.
Code snippet from myRIO control program showing comamnds being added to a queue and saved to a command log.
PWM signals were sent from the myRIO to electronic speed controllers to set the speed of each wheel and direction was controlled through a relay circuit, triggered by a digital signal from the myRIO, inverting the polarity of the motor signal.
Code snippet from the RT motor control subVI showing how commands are converted into signals to the motor control circuitry.
Remote Control
The prototype system used a local wireless network hosted on the myRIO to mimic the long-range radio network that is used in real space exploration missions. Commands and data were sent back and forth between the rover and operator using a network stream to prevent commands from being lost due to a drop in the network connection. All commands were logged both on the user and myRIO side of the connection so that lost commands could be tracked. Commands were built in a modular process to make future expansion simpler when adding new functionality to the system.
Screenshot of remote operator UI
The power of NI LabVIEW and myRIO
NI myRIO-1900 with wiring connected to the MXP prototyping board
The rugged design of the myRIO-1900 would give it additional protection from the harsh environment that a fully developed Mars rover would need to endure. The wide range of IO allowed the system to adapt to the changing hardware requirements of the project. The LabVIEW development environment allowed for a modular design approach to be taken, simplifying the process of adding new functionality during the project and future-proofed the system by allowing the core code to be hardware agnostic. During development, LabVIEW also offered a range of options for each problem enabling the group to select the solution that best suited the project and allowing for the design to change when unexpected issues were confronted. The pre-built functions within the Vision Development module allowed a video stream from the rear vision camera to be set up effortlessly. Finally, the simple graphical programming environment made prototyping quick and easy to bring functionality from proof of concept to full integration.
Result
A prototype rover was fully manufactured and can successfully be controlled through the NI myRIO-1900 from a laptop using a stereo vision system to steer around and over small obstacles. Unfortunately, the planned development of the rover was not fully completed as the instrumentation control was not finished. However, with the framework established, the system is ready for the instrument to be mounted and control sub VI’s to be introduced so the rover can one day complete its mission.
Link to Video
