For their final project in embedded microcontroller class, [Aaheli, Jun, and Naomi] turned their focus toward assistive technology and created an Electronic Travel Aid (ETA) for the visually impaired that uses haptic feedback to report the presence of obstacles.
We have seen a few of these types of devices in the past, and they almost always use ultrasonic sensors to gauge distance. Not so with this ETA; it uses six VL53L0X time-of-flight (ToF) sensors mounted at slightly different angles from each other, which provides a wide sensing map. It is capable of detecting objects in a one-meter-wide swath at a range of one meter from the sensors.
The device consists of two parts, a wayfinding wand and a feedback module. The six ToF sensors are strapped across the end of a flashlight body and wired to an Arduino Mini inside the body. The Mini receives the sensor data over UART and sends it to the requisite PIC32, which is attached to a sleeve on the user’s forearm. The PIC decodes these UART signals into PWM and lights up six corresponding vibrating disc motors that dangle from the sleeve and form a sensory cuff bracelet around the upper forearm.
We like the use of ToF over ultrasonic for wayfinding. Whether ToF is faster or not, the footprint is much smaller, so its more practical for discreet assistive wearables. Plus, you know, lasers. You can see how well it works in the demo video after the break.
This device is intended to augment the traditional white cane, not replace it. This virtual cane we saw a few years ago is another story.
Continue reading “Find Your Way with Tiny Laser Beams”
Hour glasses have long been a way to indicate time with sand, but the one-hour resolution isn’t the best. [Erich] decided he would be do better and made a clock that actually wrote the time in the sand. We’ve seen this before with writing time on a dry erase board with an arm that first erases the previous time and then uses a dry erase marker to write the next time. [Erich]’s also uses an arm to write the time, using the tip of a sea shell, but he erases the time by vibrating the sandbox, something that took much experimentation to get right.
To do the actual vibrating he used a Seeed Studio vibration motor which has a permanent magnet coreless DC motor. Interestingly he first tried with a rectangular sandbox but that resulted in hills and valleys, so he switched to a round one instead. Different frequencies shifted the sand around in different ways, some moving it to the sides and even out of the sandbox, but trial and error uncovered the right frequency, duration, and granular medium. He experimented with different sands, including litter for small animals, and found that a powder sand with small, round grains works best.
Four white LEDs not only add to the nice ambience but make the writing more visible by creating shadows. The shells also cleverly serve double duty, both for appearance and for hiding things. Shells cause the arms to be practically invisible until they move (well worth viewing the video below), but the power switch and two hooks for lifting the clock out of the box are also covered by shells. And best of all, the tip that writes in the sand is a shell. There’s plenty more to admire about the cleverness and workmanship of this one.
Continue reading “These Sands Of Time Literally Keep Time”
A person who is deaf can’t hear sound, but that doesn’t mean they can’t feel vibrations. For his Hackaday Prize entry, [Alex Hunt] is developing the Shakelet, a vibrating wristband for that notifies hearing impaired people about telephones, doorbells, and other sound alerts.
To tackle the difficulty of discriminating between the different sounds from different sources, [Alex’s] wants to attach little sound sensors directly to the sound emitting devices. The sensors wirelessly communicate with the wristband. If the wristband receives a trigger signal from one of the sensors, it alerts the wearer by vibrating. It also shows which device triggered the alert by flashing an RGB LED in a certain color. A first breadboard prototype of his idea confirmed the feasibility of the concept.
After solving a few minor problems with the sensitivity of the sensors, [Alex] now has a working prototype. The wristband features a pager motor and is controlled by an ATMEGA168. Two NRF24L01+ 2.4 GHz wireless transceiver modules take care of the communication. The sound sensors run on the smaller ATTiny85 and use a piezo disc as microphone. Check out the video below, where Alex demonstrates his build:
Continue reading “Hackaday Prize Entry: Shakelet”
A PS-3 controller has an unbalanced motor inside that vibrates your hand whenever you crash a car into a wall or drive it off a cliff and hit the rocks below but [Rulof Maker] wanted that same feeling all over his body. So he added a serious unbalanced motor to his favorite gaming chair to make his whole body vibrate instead.
To do that he opened up the controller and found the wires going to the unbalanced motor. There he added a small relay, to be activated whenever the motor was energized. Wires from that relay go to a female connector mounted in the side of the controller, keeping the controller small and lightweight.
Next he needed to attach a much bigger unbalanced motor to the underside of his favorite gaming chair. For the unbalanced mass he poured concrete powder and molten lead into a tin can mold and attached the result to the motor’s shaft. Using a piece of wood he attached the motor to the chair’s underside.
All that was left was to power the motor and turn it on when needed. For that he wired up a bigger relay, with the relay’s coil wired to a male connector to plug into the PS-3 controller. Now when the PS-3 wants to vibrate, that relay is energized. All that was left was to wire the relay’s normally open switch, the motor and a power cord in series, plug it into the wall socket, and he was ready to shake.
Continue reading “Gaming Chair gives Full Body Feeling to Collisions”
Only about 10% of blind people around the world can read Braille. One primary reason is the high cost of Braille displays. The cost is a result of their complexity and reliability – required to ensure that they are able to handle wear and tear.
[Vijay] has been working since 3 years on a Refreshable Braille Display but has only recently been able to make some substantial progress after teaming up with [Paul D’souza]. During his initial experiments, he used dot matrix printer heads, but the current version uses tiny vibration motors as used in mobile phones. He’s converting rotary motion of the tiny motors in to linear movement for pushing the Braille “cell” pins up and down. The eccentric weight on the vibration motor is replaced with a shaped cam. Continuous rotation of the cam is limited by a stopper, which is part of the 3D printed housing that holds the motors. Another 3D printed part has three cam followers, levers, springs and Braille pins rolled in one piece, to create half a Braille cell. Depending on the cam position, the pins are either pushed up or down. One Braille cell module consists of two cam follower pieces, a housing for six vibration motors, and a cover plate. Multiple modules are chained together to form the display.
The next step would be to work on the electronics – in particular ensuring that he is able to control the motor movement in both directions in a controlled manner. Chime in with your comments if you have any ideas. The 3D design files are available from his Dropbox folder.
Continue reading “Refreshable Braille Display and Braille Keyboard”
[Lee] continues with his exploration of the U8Plus (a cheap smartwatch). He hasn’t got it all cracked, yet, but he did manage to get a dump of the device’s ROM using an unusual method. At first, [Lee] thought that the JTAG interface (or, at least, the pins presumed to be the JTAG interface) would be a good way to explore the device. However, none of the people experimenting with the device have managed to get it to work.
Instead, [Lee] went through the serial bootloader and dumped the flash memory. He found out, though, that the bootloader refused to read the ROM area. It would, however, load and run a program. Unfortunately, no one has found how to access the UART device directly, but they have found how to drive the vibration motor.
[Lee] took off the vibration motor and used it as an output port for a simple program to dump the ROM. An Arduino picked up the data at a low baud rate and produced an output file. This should allow more understanding of how to drive the watch hardware.
We covered the initial teardown of this watch earlier this year. Of course, if you don’t want to reverse engineer a smartwatch, you could always build your own.
If you are a soldering ninja with a flair for working with tiny parts and modules, check out the Open Source Watch a.k.a. OSWatch built by [Jonathan Cook]. His goals when starting out the project were to make it Arduino compatible, have enough memory for future applications, last a full day on one charge, use BLE as Central or Peripheral and be small in size. With some ingenuity, 3d printing and hacker skills, he was able to accomplish all of that.
OSWatch is still a work in progress and with detailed build instructions available, it is open for others to dig in and create their own versions with modifications – you just need to bring in a lot of patience to the build. The watch is built around a Microdunio Core+ board, an OLED screen, BLE112A module, Vibration motor, a couple of LEDs and Buttons, and a bunch of other parts. Take a look at the schematics here. The watch requires a 3V3, 8MHz version of the Microdunio Core+ (to ensure lower power consumption), and if that isn’t readily available, [Jonathan] shows how to modify a 5V, 16MHz version.
Continue reading “OSWatch, an open source watch”