One of the more interesting parts of the ball catching robot is the algorithm used to estimate the 3D trajectory of the ball while it is flying through the air. This post describes in more detail how this algorithm works.
This is a delta robot built with LEGO Mindstorms to catch a ball thrown through the air. The robot is programmed using ev3dev, an alternative operating system for the EV3 brick. It uses two NXTcam cameras to track the ball and estimate its trajectory in 3D.
Here is a video of the robot in action.
The purpose of LiveSPICE is to simulate circuits for audio signals in real time. Simulating a circuit requires solving for the relationship between the current state of the circuit and a new input signal, to produce the new state of the circuit. This post describes the algorithm LiveSPICE uses to evaluate this relationship quickly enough to run in real time.
My hope is that this post fills what I found to be a gap in the literature I could find on solving this kind of system. It took me several months to converge on this solution (numerical analysis pun!); maybe this approach is supposed to be obvious, but it certainly was not obvious to me.
LiveSPICE is a SPICE-like circuit simulation tool for processing live audio signals. The motivation for developing LiveSPICE is to help prototype guitar effects and amplifiers, without requiring constructing a physical circuit or waiting for an offline simulation to run to try it out. With LiveSPICE, you can design the circuit in an easy to use visual schematic editor, and simulate it using your real instruments as input signals and your speakers as the output, in real time.
The main website for downloads, documentation, and other information about LiveSPICE is www.livespice.org.
Touchpad is a free Android app to enable you to control your windows computer from your Android device. It provides a simple multitouch touchpad interface to control the mouse, and accepts keystrokes from the keyboard on your device to send to your computer. Touchpad has the following features:
- Full remote control over the mouse left and right buttons from your Android device: drag n' drop, double clicking, and right clicking functionality is readily accessible - now with multitouch!
- Keyboard support allows typing on the remotely controlled computer.
- Media controls for easy control over media playback.
- Web browser controls for easy browser navigation.
- Automatically find servers from your device to make connecting to your computer simple and painless.
- Clean, minimalist design.
- Completely free and contains absolutely no ads!
I've been searching for a simple, working, free guitar tuner program, but there seems to be a gap in the free simple working tuner market on the web. So I decided to make a chromatic tuner, which works for many instruments.
When I was at my parents for Christmas, we were visiting one of their neighbors who owned an old style mechanical clock. It was simple, a small box with the clock face, and the pendulum and weights coming out the bottom of the clock. It got me thinking that I could build one with the same principles in LEGO Technic. Here are the goals I had for the clock, in priority order:
- Accurate, within a few seconds per hour.
- All of the key operating mechanisms should be visible at the front of the clock.
- Be able to wind the clock without interrupting the operation.
- Be able to change the time easily.
- The pendulum should have a period of 1 second.
- It should run for at least one hour.
After a few weeks of tinkering, I have met all the above goals, and have the clock running for 4 hours!