Boxing Trainer Uses DIY Force Sensors

A team of Cornell students have designed and built their own electronic boxing trainer system. The product of their work is a game similar to Whack-A-Mole. There are five square pads organized roughly into the shape of a human torso and head. Each pad will light up based on a pre-programmed pattern. When the pad lights up, it’s the player’s job to punch it! The game keeps track of the player’s accuracy as well as their reaction time.

The team was trying to keep their budget under $100, which meant that off the shelf components would be too costly. To remedy this, they designed their own force sensors. The sensors are basically a sandwich of a few different materials. In the center is a 10″ by 10″ square of ESD foam. Pressed against it is a 1/2″ thick sheet of insulating foam rubber. This foam rubber sheet has 1/4″ slits cut into it, resulting in something that looks like jail bars. Sandwiching these two pieces of foam is fine aluminum window screen. Copper wire is fixed the screen using conductive glue. Finally, the whole thing is sandwiched between flattened pieces of corrugated cardboard to protect the screen.

The sensors are mounted flat against a wall. When a user punches a sensor, it compresses. This compression causes the resistance between the two pieces of aluminum screen to change. The resistance can be measured to detect a hit. The students found that if the sensor is hit harder, more surface area becomes compressed. This results in a greater change in resistance and can then be measured as a more powerful hit. Unfortunately it would need to be calibrated depending on what is hitting the sensor, since the size of the hitter can throw off calibration.

Each sensor pad is surrounded by a strip of LEDs. The LEDs light up to indicate which pad the user is supposed to hit. Everything is controlled by an ATMEGA 1284p microcontroller. This is the latest in a string of student projects to come out of Cornell. Make sure to watch the demonstration video below. Continue reading “Boxing Trainer Uses DIY Force Sensors”

Electronic Glove Detects Sign Language

A team of Cornell students recently built a prototype electronic glove that can detect sign language and speak the characters out loud. The glove is designed to work with a variety of hand sizes, but currently only fits on the right hand.

The glove uses several different sensors to detect hand motion and position. Perhaps the most obvious are the flex sensors that cover each finger. These sensors can detect how each finger is bent by changing the resistance according to the degree of the bend. The glove also contains an MPU-6050 3-axis accelerometer and gyroscope. This sensor can detect the hand’s orientation as well as rotational movement.

While the more high-tech sensors are used to detect most characters, there are a few letters that are similar enough to trick the system. Specifically, they had trouble with the letters R, U, and V. To get around this, the students strategically placed copper tape in several locations on the fingers. When two pieces of tape come together, it closes a circuit and acts as a momentary switch.

The sensor data is collected by an ATmega1284p microcontroller and is then compiled into a packet. This packet gets sent to a PC which then does the heavy processing. The system uses a machine learning algorithm. The user can train the it by gesturing for each letter of the alphabet multiple times. The system will collect all of this data and store it into a data set that can then be used for detection.

This is a great project to take on. If you need more inspiration there’s a lot to be found, including another Cornell project that speaks the letters you sign, as well as this one which straps all needed parts to your forearm.
Continue reading “Electronic Glove Detects Sign Language”

Arduino Thermostat Includes Vacation Mode

When [William’s] thermostat died, he wanted an upgrade. He found a few off-the-shelf Internet enabled thermostats, but they were all very expensive. He knew he could build his own for a fraction of the cost.

The primary unit synchronizes it’s time using NTP. This automatically keeps things up to date and in sync with daylight savings time. There is also a backup real-time clock chip in case the Internet connection is lost. The unit can be controlled via the physical control panel, or via a web interface. The system includes a nifty “vacation mode” that will set the temperature to a cool 60 degrees Fahrenheit while you are away. It will then automatically adjust the temperature to something more comfortable before you return home.

[William’s] home is split into three heat zones. Each zone has its own control panel including an LCD display and simple controls. The zones can be individually configured from either their own control panel or from the central panel. The panels include a DHT22 temperature and humidity sensor, an LCD display, a keypad, and support electronics. This project was clearly well thought out, and includes a host of other small features to make it easy to use.

SingLock Protects Your Valuables from Shy People

Two Cornell students have designed their own multi-factor authentication system. This system uses a PIN combined with a form of voice recognition to authenticate a user. Their system is not as simple as speaking a passphrase, though. Instead, you have to sing the correct tones into the lock.

The system runs on an ATMEL MEGA1284P. The chip is not sophisticated enough to be able to easily identify actual human speech. The team decided to focus their effort on detecting pitch instead. The result is a lock that requires you to sing the perfect sequence of pitches. We would be worried about an attacker eavesdropping and attempting to sing the key themselves, but the team has a few mechanisms in place to protect against this attack. First, the system also requires a valid PIN.  An attacker can’t deduce your PIN simply by listening from around the corner. Second, the system also maintains the user’s specific voice signature.

The project page delves much more deeply into the mathematical theory behind how the system works. It’s worth a read if you are a math or audio geek. Check out the video below for a demonstration. Continue reading “SingLock Protects Your Valuables from Shy People”

UAV Coaxial Copter Uses Unique Drive Mechanism

Personal UAV’s are becoming ubiquitous these days, but there is still much room for improvement. Researchers at [Modlab] understand this, and they’ve come up with a very unique method of controlling pitch, yaw, and roll for a coaxial ‘copter using only the two drive motors.

In order to control all of these variables with only two motors, you generally need a mechanism that adjusts the pitch of the propeller blades. Usually this is done by mounting a couple of tiny servos to the ‘copter. The servos are hooked up to the propellers with mechanical linkages so the pitch of the propellers can be adjusted on the fly. This works fine but it’s costly, complicated, and adds weight to the vehicle.

[Modlab’s] system does away with the linkages and extra servos. They are able to control the pitch of their propellers using just the two drive motors. The propellers are connected to the motors using a custom 3D printed rotor hub. This hub is specifically designed to couple blade lead-and-lag oscillations to a change in blade pitch. Rather than drive the motors with a constant amount of torque, [Modlab] adds a sinusoidal component in phase with the current speed of the motor. This allows the system to adjust the pitch of the blades multiple times per rotation, even at these high speeds.

Be sure to watch the demonstration video below. Continue reading “UAV Coaxial Copter Uses Unique Drive Mechanism”

Simple and Elegant Single Digit Nixie Tube Clock

We’ve seen a few Nixie projects around here before, but this one might be the simplest yet. [Pinomelean] designed this simple nixie tube clock with just a handful of components.

The Nixie tube chosen for the project is an IN-12a. This tube can be purchased for around just four dollars. It is capable of displaying one digit at a time, zero through nine. Since the tube can only display one digit at a time, the clock is programmed to flash each digit of the current time one by one. There is a longer pause in between each cycle to make it easier to tell when the cycle begins and ends.

The system is broken into two main components. The first is the clock circuit. The clock runs off a PIC microcontroller with a 4MHz crystal. All of the logic is performed via the PIC and only a handful of other components are required. This includes some resistors and capacitors as well as a few high voltage SMD transistors to control the Nixie tube. [Pinomelean] has made this PCB design available so anyone can download it and make their own clock.

The second component to the clock is the power supply. The system is powered by a lithium-ion rechargeable battery, but [Pinomelean] notes that it can also be powered with USB. The lower voltage works well for the microcontroller, but the Nixie tube needs a higher voltage. [Pinomelean] built his own high voltage supply using components scavenged from an old disposable camera. This power supply board design is also made available for download, but it plugs into the main board so you can use another design if desired.. Check out the demo video below to see it in action. Continue reading “Simple and Elegant Single Digit Nixie Tube Clock”

MIDI Keyboard with Frickin’ Laser Keys

MIDI instruments are cool, but they’re not laser cool. That is, unless you’ve added lasers to your MIDI instrument like [Lasse].

[Lasse] started out with an old MIDI keyboard. The plan was to recycle an older keyboard rather than have to purchase something new. In this case, the team used an ESi Keycontrol 49. They keyboard was torn apart to get to the creamy center circuit boards. [Lasse] says that most MIDI keyboards come withe a MIDI controller board and the actual key control board.

Once the key controller board was identified, [Lasse] needed to figure out how to actually trigger the keys without the physical keyboard in place. He did this by shorting out different pads while the keyboard was hooked up to the computer. If he hit the correct pads, a note would play. Simple, but effective.

The housing for the project is made out of wood. Holes were drilled in one piece to mount 12 laser diodes. That number is not arbitrary. Those familiar with music theory will know that there are 12 notes in an octave. The lasers were powered via the 5V source from USB. The lasers were then aimed at another piece of wood.

Holes were drilled in this second piece wherever the lasers hit. Simple photo resistors were mounted here. The only other components needed for each laser sensor were a resistor and a transistor. This simple discreet circuit is enough to simulate a key press when the laser beam is broken. No programming or microcontrollers required. Check out the demonstration video below to see how it works. Continue reading “MIDI Keyboard with Frickin’ Laser Keys”