We would like to introduce you to our newest robot. Her name is Alumini, which is pronounced Ah-lu-min-ee. She’s a 12-legged running creature. She’s made out of custom, CNC-machined aluminum components designed to be like vertebrae and bones in keeping with the idea that is a creature not just a machine. Our goal was to create a little beastie without any visible wires or electronics (other than her sonar eyes). She does not have a box filled with electronics like our other robots. We wanted her to look like she was all legs. This meant we needed to use very small electronic parts and we had to do some very tricky wiring. The soldering on this project proved to be quite a challenge, but we were happy with the end results. Alumini is ten inches wide and consists of over 500 parts. Like her much larger 16-legged predecessor, Aluminalis, she uses gear motors to drive two crankshafts, one for each side. Alumini uses a tiny Arduino Pro Mini 328 microcontroller. She can operate via remote control (using an on-board xbee radio) or autonomously using her sonar eyes.
We are happy to announce the birth of our latest creation, Aluminalis, a sixteen-legged walking creature. Along with her sixteen legs and feet, Aluminalis has a fast and lively brain (an Arduino Nano), strong muscles (gear motors), elegant bones (custom machined aluminum linkages), two multi-segmented spines (custom designed crankshafts), ears (Xbee Radio), forward and rear sight (ultrasonic sensors), and a voice (tone buzzer). If you communicate with her in the right way, she will respond to your requests, but she prefers operating on her own, and in some moods, she can be very shy.
Aluminalis is pronounced Ah-lumin-alis. Her full scientific species name is actually Animaris Aluminalis. We derived the name from the word aluminum. As far as we know, she is the only species of the Animaris genus that evolved entirely out of machined aluminum components. Be sure to watch the video. Read below for a species description, evolution, and behavior. At the end of this post, we discuss the original inspiration for Aluminalis.
Aluminalis is about 6″ tall and 22″ wide. She consists of a central thorax and two multi-legged sides. Each side is driven by a motor, which drives a pinion gear, which drives a main gear, which drives a four-section crankshaft, which drives a complex set of linkages, which drives the legs. The four crankshaft sections on each side are 90-degrees out of phase with each other so that at least one pair is always firmly on the ground. This is accomplished because the crankshaft is square rather than round. As the motor rotates the crankshaft, the legs loop through a tear-dropped-shaped stepping motion similar to a horse’s gait, causing Aluminalis to walk similar to other animals. Aluminalis changes direction by putting more or less power to the motor on each side. To go forward, she puts equal power to each motor. To go left, she gives the right motor more power than the left motor. And so on. Aluminalis can also go backwards and pivot in place.
We sketched the original concept for Aluminalis on paper and then designed the various components in SolidWorks. Aluminalis consists of 846 individual components. We machined the segment bars, crankshaft components, thorax plates, and most of the other aluminum components on our CNC mill, vertical mill, table saw, band saw, and drill press. We also used an extensive amount of 1/8” aluminum bar, 1/8” set collars, #4-40 set screws, #6-32 set screws, washers, and ball bearings. There are two long 1/8” steel rods on each side that hold the segments together.
The electronics include an Xbee radio, the Explorer Regulated Board, two Maxbotix ultrasonic sensors, the tone buzzer, wires, resistors, LEDs, 20mm 73:1 gear motors, and main power switch.
Aluminalis uses an Arduino Nano as the main microcontroller, a 12V 3-cell Lithium-Polymer Battery, and a Sabertooth 2 x 5 amp motor controller.
Aluminalis operates on command (i.e. remote control using the Xbee radio) or on her own. She is still learning and developing, but so far, she has two autonomous modes: The first is roaming. She roams around the workshop using her ultrasonic sensors to find the optimum path and avoid obstacles. The second mode is what we call “shy mode” where she scurries away from people. The only difficulty with this mode is that once you let her off the leash she’s very difficult to catch! 🙂
The Inspiration and Naming of Aluminalis
Aluminalis was inspired by the renown Dutch artist Theo Jansen and his wonderful Strandbeest creatures, which are large kinetic sculptures that he builds out of PVC plastic pipes on beaches in the Netherlands. His awesome sculptures are actually wind driven, rather than motor driven, which makes them even more impressive. Theo always refers to his creations as living animals, for in his heart and mind they are new forms of life. In honor of Theo’s amazing work, we have adopted Theo’s view on this issue, and we’ve also adopted his naming convention, which is to give each species of artificial animal a scientific name with the genus Animaris. So, the full name of our creature is Animaris Aluminalis. As far as we know, Animaris Aluminalis is the only aluminum strandbeest alive today, although we expect them to multiply over time like all living creatures.
Species Range & Habitat
Anamaris Aluminalis is exceedingly rare and highly elusive. This species is believed to favor mountainous regions in Western North Carolina. In particular, it likes living underneath workshop cabinets and usually comes out at night. It feeds on nuts, screws, and small robots.
Here are some photos of Aluminalis’s construction, followed by a link to our original work-in-progress posts with more details. The custom-designed machined-aluminum crankshaft.
One of the funnest, but most challenging parts of building Aluminalis (our 16-legged walking robot) has been the construction of the two crankshafts. Each side of the robot has a motor that rotates a 10” long, multi-link crankshaft, which drives 4 pairs of legs. The leg pairs need to be kept 90-degrees out of phase from each other in order to produce the walking gait. Our initial vision for the crankshaft was to build it out of 1/8” aluminum round shafts, custom crankshaft arms we made on our CNC, and tiny 4-40 set screws, but when we put it all together for real-life testing, the rotational forces were so high that the set screws couldn’t hold the round shafts, the crankshaft arms slipped out of place, and the entire crankshaft tore apart (not a good day). We went back to the drawing board. We needed a new design. We had the idea of using a square shaft to prevent slippage and guarantee that each of the pairs was 90-degrees out of phase with the others. At first I thought maybe it was a silly, impossible idea. The crankshaft ran through a series of round holes in the body of the robot, so how could a square shaft rotate smoothly in a round hole? Then I realized we could use ball bearings to do that. Our hope was that the square shaft would not only guarantee the 90-degree angle, but it would also give our set screws a flat area to take hold. So, in version two, we used a combination of square shafts, round shafts, larger 6-32 set screws, and bulkier crankshaft arms (that gave the set screws more thread length to take hold). The results were fantastic. The new crankshaft works great in all our real-life tests. Runs strong and smooth. Note that the square shafts are made out of high-strength copper rather than aluminum.
This is Tinybot. About 3″ long and just 1.5″ high, this is one of the smallest robots we’ve ever built. Starting with a Pololu Zumo drivetrain, we set out to see if we could get all the components of the robot INSIDE what was originally its 4 AA battery compartment. We used our CNC to make a cool aluminum top plate. Two tiny gear motors drive the rubber treads. We cut the pins off an xbee radio and soldered it directly to an Arduino Nano’s 3V pin and digital pins so that we didn’t need to waste space with an adapter board or wires. The robot also includes a tiny motor controller, a little 800 mAh 7.4V LIPO battery, and a rocker switch. This neat little robot works beautifully. It zips around with incredible agility, either via xbee-based remote control or through a pre-programmed autonomous pattern. It can drive forward, backward, turn, rotate, and even drive upside down. We built this robot quite a while ago and are just getting around to posting it now, but it was this little guy that gave us the confidence to know that we could build small intricate robots like Lunokhod and Mini Mars Rover.
Top view of our Tinybot with our custom CNC-machined aluminum top plate.
The Tinybot with the aluminum plate removed. The green thing on the left is the tiny LIPO battery. The blue thing is an Arduino Nano without headers. The motor controller circuit board and the hacked down Xbee module are laying flat below that, stacked in layers.
Over the years, we’ve used a lot of different parts to build robots. Lately we’ve been using more and more parts from the new Actobotics product line, which we buy from sites like ServoCity.com and RobotShop.com and Sparkfun.com. A short time ago, the Actobotics team approached us about sponsoring our next build. They asked us to design and construct our next robot entirely out of their parts. When we asked about the project requirements, they said, “Use your imagination. Build whatever your want.” We were delighted to accept their offer. They sent us a box of Actobotics parts and we started exploring what we could do.
We were really impressed by the quality of the machined aluminum parts and the powerful flexibility of their modular, interchangeable design. The parts use two overlapping hole patterns and standardized dimensions so that you can build a lot of different things in a lot of different ways. We soon realized that we could make a dozen different kinds of robots with these parts. But eventually, we came up with a super cool, multi-use 6WD rover. We equipped it with a pan-tilt camera turret with changeable mounts for a Wifi Camera, GoPro Camera, or HackHD FPV camera. This platform would also make a great gun turret for an Airsoft pellet gun or a paintball gun. We were on a roll, so we also equipped the rover with a turret of ultrasonic sensors for Arduino-based autonomous roaming and object avoidance. The great thing about a good rover platform is that you can do all sorts of stuff with it. Thus far, we just have the basics for this robot in place. In the future, we’ll expand on capabilities. Among other things, we are currently working on a custom case for the HackHD camera for use with FPV Video Goggles. We’ll keep you posted.
As we built the rover, we discovered a number of features that we really liked about the Actobotics parts.
Actobotics provides a wonderful variety of useful interchangeable components: tubes, clamps, C channel, camera mounts, servo mounts, motor mounts, slides, swiveling hubs, brackets, pan-tilt turrets, motors, wheels, servos, shafts, the list goes on.
In this particular project, by using sections of Actobotics C Channel screwed together back-to-back we made compartments inside the rover chassis where we put the robot’s electronics, wires, and battery. This was a cool way to hide and protect everything “under the hood” and give the robot a clean, professional look.
The pre-drilled hole patterns in the C channel are primarily for attaching the various pieces together in various ways, and they work great for that, but we also found the hole patterns very useful for other purposes, like mounting a standard on/off switch, which fit in the hole perfectly. We also mounted the radio antenna in this way. And of course we utilized the holes when stringing the interior wires.
We discovered that the 5/8″ Bearing Hubs provide an excellent method for mounting Maxbotix ultrasonic sensors. We mounted three of them on a 45-degree Dual Bracket attached to an Actobotics servo horn, which created an awesome multi-directional, panning sensor turret.
On the camera turret, we thought it was great how we could use the 1/4″-20 Round Screw Plate to very easily mount a variety of cameras including a WiFi camera. The Round Screw Plate is also compatible with DSLR cameras.
We used the Actobotics GoPro mount kit to secure our GoPro camera in place.
The Actobotics pan-tilt turrets are second to none. We used one of these on our Mechatron robotic tank. The best part about these turrets is that they have 360-range and are extremely strong so they can handle cameras, airsoft guns, or whatever you want to put on them.
We also love the simplicity and strength of using the Actobotics motor mounts to secure the six motors to the underside of the frame. This is one beefy rover.
If you’ve ever built a wheeled robot before, you know that one of the most annoying challenges is when you’ve found some cool wheels, but you can’t get them to fit correctly on your motor shafts. It can be surprisingly difficult. Actobotics provides a vast array of wheel hubs, shaft adapters, and other parts for handling this problem. In this rover’s case, we utilized their 6mm Set Screw Hubs, 12mm Hex Wheel Adapters, and some burly RC-style rubber wheels.
Here is a complete list of the Actobotics parts we used to build the Actobot rover:
(9) 6″ Aluminum Channel (585446)
(8) Flat dual Channel Bracket (585422
(2) 90-degree Quad Hub Mount C (545360)
(16) 90-degree Side Mount (585470). On 8 of these we drilled out the two threaded thru-holes.
(6) 90 RPM Precision Gear Motors (638238)
(6) Aluminum Clamping Motor Mount (555116)
(6) 18″ Battery/Motor Power Extensions (BE2418S)
(6) 12mm Hex Wheel Adapters (545432)
(6) 6-spoke Wheels (81773)
(6) Speed Paw Tires (PROC1047)
(6) 0.770″ Set Screw Hubs with 6mm Bore (545576)
(2) Channel Mount Servo Power Gearbox – 360 Rotation (SPG5485A-CM-36005A)
(1) 3.75″ Aluminum Channel (585443)
(1) 90-degree Quad Hub Mount C (545360)
(4) 90-degree Single Angle Short Channel Bracket (585506)
(1) 90-degree Hub Mount Bracket A (585494)
(1) GoPro Mount Kit (Hero 3) (585518)
(1) 1/4-20 Round Screw Plate (545468) (For mounting Wifi, DSLR or any other standard camera)
ULTRASONIC SENSOR TURRET
(3) 5/8″ Bore Flat Bearing Mount (534122)
(1) 90-degree Dual Angle Channel Bracket (585426)
(1) 90-degree Single Angle Channel Bracket (595424)
(12) #6-32 Aluminum Standoffs 0.875″ (534-1848)
REMOTE CONTROL (RC)
(1) Futaba Transmitter
(1) Futaba Receiver
Please note that we used a variety of #6-32 socket head machine screws, which can also be purchased from ServoCity. For the electronics, we used an Arduino Leonardo (although any type of Arduino would work), Maxbotix ultrasonic sensors, and a Sabertooth 2×5 RC motor controller from Dimension Engineering. Our version of this robot includes both RC-airplane-style Remote Control (RC) as well as Arduino-based autonomous roaming. In many cases, you’ll only need/want one or the other approach, not necessarily both at the same time the way we did it.
Recently we were asked to build a miniature Mars Rover for a new space museum in the Czech Republic. Although the Mini Mars Rover is only about 8″ long, it is a functional robot, including an Arduino Nano microcontroller, a high-resolution wifi camera, an xbee radio for remote control, a Sabertooth motor controller, six motors, a rocker-bogie suspension system, and other components. We designed and machined most of the robot’s parts using our CNC Mill.