ANT+ is a wireless protocol specifically designed for use with sensors, and has similar functionality in some respects to Bluetooth Low Energy. It’s found a place among various bicycle equipment manufacturers, to connect smartwatches, cycle computers and electronic gear shifters. Of course, as soon as something becomes a defacto standard someone has to start coloring outside the lines. In this case, Shimano went off book with their DI2 groupset, leaving [kwakeham] with a reverse engineering job on his hands.
[kwakeham] gives us a great example of how to approach reverse engineering. Researching the Shimano hardware by its FCC ID shows that the device communicates using an NRF24AP2 chip, common in ANT+ devices. The Shimano device is then opened, and a logic analyser attached to various test points until the SPI interface between the transceiver and microcontroller is found. At this point, it’s a simple matter of putting the hardware through its paces and capturing data until the protocol can be pulled apart, piece by piece.
Walking robots come in many forms, and each presents their own unique challenges. Bipedal style locomotion is considered particularly difficult to do well, however designs with more legs offer certain advantages. Hexapods offer the possibility of keeping several legs on the ground while others move, providing a useful degree of stability. [How To Mechatronics] developed this ant robot, which is an excellent example of the form.
The hexapod has as the name suggests, six legs, each of which consist of 3 joints. This necessitates 3 servos per leg, for 18 servos total just for locomotion. Further servos are then used to control the abdomen, head, and mandibles. This gives the robot strong ant credentials, above and beyond being simply a 3D printed lookalike.
Brains come courtesy of an Arduino Mega, chosen for its ability to control a large number of servos. A custom PCB is printed as a shield to ease the connection of all the necessary hardware. An HC-05 Bluetooth module is used for communication with an Android app, which controls the ant. The piece de resistance is the ultrasonic sensors in the head, which allow the ant to automatically defend itself against predators that get too close.
It’s an involved build, requiring plenty of 3D printing and over 200 fasteners. Fundamentally though, it’s a fully working and tested hexapod build with full plans available for download, ready to toil in your underground sugar caves.
[FESTO] keeps coming up with new tricks that make us both envious and inspired. Take their bionicANTs for example. Watching a group of them cooperate to move objects around looks so real that you’re instantly reminded of the pests crawling across your floor, but looking at them up close they’re a treasure trove of ideas for your next robot project.
The exoskeleton is 3D printed but they then use the outer surface of that exoskeleton as a circuit board for much of the circuitry. The wiring is “painted on” using a 3D MID (Molded Interconnect Device) process. While FESTO didn’t give specifics about their process, a little research shows that 3D MID involves the 3D printed object being made of a special non-conductive metal material, a laser then “drawing” the traces in the material, and then dipping the object in various baths to apply copper, nickel and gold layers. We mortal hackers may not have the equipment for doing this ourselves in our workshops but seeing the beautiful result should be inspiration enough to get creative with our copper tape on the outer surfaces of our 3D printed, CNC’d, or hand-carved parts.
We also like how they took a the mouse sensor from under a regular computer mouse and attached it to the ant’s underside, pointing down for precision dead reckoning. For the legs they used three piezo bending transducers. However, these give a deflection of only 1.5mm in both directions, not enough for walking. They increase this to over 10mm with the addition of a plastic hinge, another idea to keep in mind when building that next tiny robot. And there are more ideas to be taken advantage of in their ants, which you can see being built in the video below.
[Jbremnant] wanted to try his hand with ANT+ wireless networks. This protocol is designed for light-weight and low-power consumer electronics, like heart rate chest straps and bicycle computers (Garmin brand devices for example). There are already libraries out there for Arduino, but [Jbremnant] found that most of them were written as slave-only code. He set out to use an MSP430 to drive a fully functioning ANT network including a computer and an Android phone.
The TI Launchpad is used as the master node in the network. [Jbremnant] chose the smaller of the two MSP430 processors that came with the dev platform. After starting down this road he realized that chip didn’t have a hardware UART needed to communicate with the SparkFun ANT board (based on the nRF24AP1 radio chip). Rolling with the punches, he used a software UART he had previously worked with. Now he’s able to transmit test data from the Launchpad. It is picked up by both a USB dongle on his computer and the Android phone seen above. Check out his demo video after the break.
We know it was just two days ago that we were ranting about the hexapods known as Phoenix, and their creator [Zenta]. In the comments on that post, [Bluehash] pointed us to [Zenta’s] latest creation. This is A-pod. The sheer articulation and believable motion here made this robot worthy of a post all it’s own. A-pod has a 2 dof “tail” and a 3 dof head with a total of 25 servos to drive it. The addition of the head adds so much character, add some face tracking and it would really blow us away. Well, after it fetched us a beer. He notes that he’s still working on the leg mechanicals, so it doesn’t do much walking yet.