After working on the agBOT v2[Link] during the summer of 2017, I reached out to my advisor, Dr. Sohel Anwar about possible assistantship at the Mechatronics Research Lab. When I joined, I started working with Dr. Yinghui Fan on robust control for an autonomous vehicle, specifically the smaller ones like the agBOT v2. I assisted her in her research and learnt a great deal about controls engineering and robust control, SIMULINK, Matlab and using them for system modelling along with a lot of different motors and actuators.
I was also tasked at assessing the system to find major fallbacks due to which our robot could not perform up to the mark at the agBOT Challenge 2017. One of the issues I realized with then was the lack of systems integration on the previous model. We addressed the issue when we started to work on the IUPUI agBOT v3, which is a 2016 Yamaha Wolverine R-Spec 4×4 with EPS. We opted for cheaper but effective parts to achieve a design that would work and not have the same problems as earlier while also fitting in a budget of $5000. Turning a vehicle into a robot can be challenging, especially with a budget as little as what we had and a vehicle as conventional as the Wolverine.
The steering had an EPS which was isolated on the Yamaha. We ended up using the motor on the EPS with an H-Bridge controller and a quadrature encoder as feedback.
The accelerator and brake paddles were to be controlled using bicycle cables and stepper motors. To stick to the budget, we just used stepper motors which I believe we already had for the acceleration. However, I have been introduced to more powerful servos that could have provided enough torque and more to accomplish the operation with possibly better control.
For braking we used a pneumatic actuator and a solenoid valve. The speeds we were aiming for wouldn’t give the vehicle much braking distance that it would require us to use brakes to slow down. So, we used the brakes for emergencies only.
We also had a spray system that was an adaptation from the previous version with a minor modification – the brakes also used the same compressor.
Here’s the agBOT gallery to check out some of the systems:
We were placed second at the agBOT challenge and were awarded $10000 and a $50000 grant from the university to continue the research. I learnt a lot from my assistantship at the MRL which exposed me to electronics, mechanics, controls and ROS to an extent that I had never been before.
Here’s a video of the agBOT in action with tele-op and a demonstration of the emergency for an article for a local news channel: