Robot Overlord 2.7.0: Vehicles

Today I’m delighted to announce that Robot Overlord 2.7.0 is out and it adds vehicles. Build your own or use presets like front-wheel drive, rear-wheel drive, motorcycle, mecanum, omni, or tank.

Here are the basic driving controls:

This is what it looks like in the scene graph:

all vehicles start with a CarComponent:

Some wheels can be steered by adding a ServoComponent in the suspension:

I’m especially pleased by the graph tool I made for the PID controller and Torque Curve.

A PID controller (Proportional, Integral, Derivative controller) is a type of control system used to regulate different types of processes. It’s like an auto-pilot mode for controlling systems. Imagine you’re driving a car. You want to keep your car at a constant speed, say, 60 km/hour.

• The “Proportional” part is like your foot on the gas pedal. If you’re going below 60, you press the pedal down more. If you’re going above 60, you let up on the pedal. The more you are below the target, the harder you press, and vice versa.
• The “Integral” part is like your memory of what you’ve done so far. If you’ve been below 60 for a while, even if you’re close now, you might press a bit harder on the gas pedal because you remember you’ve been going too slow. It helps to correct sustained, systematic errors (like if your car was carrying heavy weight in the back).
• The “Derivative” part is like your anticipation of what’s coming. If you’re below 60 but rapidly accelerating, you might ease up on the gas a little, because you’re anticipating hitting the target soon. It helps to mitigate sudden changes (like if you’re about to go downhill).

The torque curve is the relationship between motor speed and motor power. The example graph below is for a NEMA 17 stepper motor used in the Makelangelo art robot.

There’s also a WheelComponent that holds the size and shape of the tires

And of course vehicles need at least one motor

Why cars?

The goal of Robot Overlord is to simulate any kind of robot including robot cars. I would like to see Robot Overlord become the sim/control app used everywhere: All the goodness of free open source, no funky linux like ROS. Tell your teachers, your friends, your preacher, your boss, your employees, your lover, your best friend…everybody.

Plus! The previous way of making robot arms had bones and was missing motors. Now that vehicles have been used to test motors all the arms can be upgraded to use the new system. In app I made one motor with one output and then copy/pasted to LEGO together a 6 axis robot arm. Stepping the motors makes the arm move.

That’s incredibly powerful modular design at work. Love it!

Final thoughts

This is the first version that can be downloaded in all three flavors: Windows, OSX, and Linux. Choose your favorite from the Robot Overlord store page. Huzzah!

2.8.0 will likely be an interim version that converts the existing robot arms to the new motor-driven system.

Full instructions for building custom vehicles are in the Robot Overlord wiki.

As always, you can find me on Discord where I often live code and talk robots.