Technology

The RoboSeal’s entry, Licorice Sticks, will be a technically advanced robot focused on fusing the leasons learnt over many years through the FIRST Robotics Competition (FRC) with new technology and skills from the University of South Australia. It is an exciting opportunity to try new things in robotics – and to have a lot fun.

The Platform

All RobotX teams have been provided with a WAM-V 16 from Marine Advanced Robotics. The WAM-V is a cutting edge Unmanned Surface Vehicle (USV) that provides a stable platform for the electronics by using two hulls that move independently. This allows for technologies such as the inclusion of the drone, which is (theoretically, as we haven’t achieved this yet!) able to launch and land on the USV. The WAM-V is a beautifully engineered piece of technology.

Propulsion 

One thing that robotics has taught is is that manoeuvrability is essential, but so too is speed. If your robot can’t accurately position itself it can’t complete the tasks. But if it lacks the power to get there, it has Buckley’s chance of getting through. In many competitions, omni-directional drives dominate, as they allow the robots to move in every direction. However, many omni-directional drives sacrifice power in return for manoeuvrability. In recent years a new form of omni-directional drive has become common in robotics competitions – the swerve drive. A swerve drive rotates each wheel independently, allowing for fine directional control with no loss of power. Of course, there has to be some sacrifice – swerve drives are horribly complicated, and making them strong enough to survive can be a real challenge! 

In spite of the risks, a working swerve drive on Licorice Sticks was a challenge we were willing to take, as the possible rewards were well worth the trouble. The result has been everything we could hope for: the four motors are able to independently provide thrust in any direction, and the boat can move forward, back, left, right, and spin, exactly as we had hoped.

Communications

Students from the University of South Australia, under the guidance of Jeremey Hamlin from Intrusion Inc, developed a complete communications system for the boat, covering everything from talking with the base station on shore through to managing the drone (more on that later).

In case their work can help future teams, their final report is available.

Distributed Systems

Having many different people working on the robot made for some unique challenges. One was catering for the requirements of the university course that many students came from. This meant that they had to work independently to each other, and in some cases hadr to start work months before the boat even arrived. To facilitated this a distributed model was developed – instead of using one or a small number of high powered computers for the system, we used a large number of low powered computers. Each student team that was given a task were provided with one or more Single-board computers to work with. Each computer will work on one task, and when it is completed it will tell the others that it is done.

Sadly we were soon hit by the global supply shortage, and many of the computers we wanted were in short supply – some were even impossible to buy. Thus not only did we end up with a distributed system, but we also had a patchwork distributed system (which we presume is a thing). It was more of a challenge than we would have predicted, but the team did a wonderful job.

Safety

Robots are fun. Lot’s of fun. But we all know what happens when they start thinking on their own, become sentient, and try to take over the world. Safety should always be an important consideration when building robots. if you are interested in working on the robot, or just visiting us, there are some basic rules to follow.

  • Safety glasses are a thing. If you are working with tools, you are wearing safety glasses. If you are near someone who is working with tools, you should also be wearing saftey glasses.
  • If you are accessing the boat while it is in the water, you’ll need safety floatation. Two lifejackets are kept with the boat and will be available to anyone who is working on the boat while it is floating. 
  • The boat uses Lithium Ferro-Phosphate (LiFePO) batteries, which are far safer than LiPo batteries. Nevertheless, if the boat is otside the workshop, a dry chemical fire extinguisher must be with it. And if it is in the workshop, multiple dry chemical fire extinguishers are with it. (btw, that goes for the first aid kits, too).

In addition, RoboNation require the boat to be fitted with multiple safety features. These include:

  • A light tower to indicate the robot’s state.
  • Emergency stops fitted in easy reach on all four sides of the vessel that automatically kill the power to the motors.
  • A remote emergency stop that, when pressed, will cut power to the motors within one second.

For that third requirement we used a LoRa system and two Arduinos.