Walking robots that move smoothly are tricky to build and usually involve some sort of compliant leg mechanism — a robot limb that can rebound like natural physiology for much better movement than what a stiff machine can accomplish. In his everlasting quest to build a real working robot dog, [James Bruton] is working on an affordable and accessible Mini Robot Dog, starting with the compliant leg mechanism.
The 3D printed leg mechanism has two joints (hip and knee), with an RC servo to drive each. To make the joints compliant, both are spring-loaded to absorb external forces, and the deflection is sensed by a hall effect sensor with moving magnets on each side. Using the inputs from the hall effect sensor, the servo can follow the deflection and return to its original position smoothly after the force dissipates. This is a simple technique but it shows a lot of promise. See the video after the break.
A project can sometimes develop a life of its own, or in the case of [James]’s OpenDog, spawn experimentally evolving offspring. This is number four, and it’s designed to be a platform for learning how to make a quadruped walk properly, and to be simple and cheap enough for others to build. We’re looking forward to seeing how it turns out.
20 years ago, PCB production was expensive and required a multitude of phone calls and emails to a fab with significant minimum order restrictions. Now, it’s cheap and accessible online, which in addition to curtailing the home etching market has created significant new possibilities for home projects. Now that flexible PCBs are also readily available, it’s possible to experiment with some cool concepts – and that’s precisely what [Carl] has been doing.
The aim is to build a walking robot that uses actuators made from flexible PCBs. The flexible PCB is printed with a coil, capable of generating a small magnetic field. This then interacts with a strong permanent magnet, causing the flexible PCB to move when energised.
Initial attempts with four actuators mounted to a 3D printed frame were unsuccessful, but [Carl] has persevered. With a focus on weight saving, the MK II prototype has shown some promise, gently twitching its way across a desk in testing. Future steps will involve building an untethered version. This will replace the 3D printed chassis with a standard fibreglass PCB acting as both control board and the main chassis to minimise weight, similar to PCB quadcopter designs we’ve seen in the past.
[Project Malaikat] is a 3D printed hybrid bipedal walker and quadcopter robot, but there’s much more to it than just sticking some props and a flight controller to a biped and calling it a day. Not only is it a custom design capable of a careful but deliberate two-legged gait, but the props are tucked away and deployed on command via some impressive-looking linkages that allow it to transform from walking mode to flying mode.
Creator [tang woonthai] has the 3D models available for download (.rar file) and the video descriptions on YouTube contain a bill of materials, but beyond that there doesn’t seem to be much other information available about [Malaikat]. The creator does urge care to be taken should anyone use the design, because while the robot may be small, it does essentially have spinning blades for hands.
Embedded below are videos that show off the robot’s moves, as well as a short flight test demonstrating that while control was somewhat lacking during the test, the robot is definitely more than capable of actual flight.
Fans of technology will recall a number of years when Honda’s humanoid robot Asimo seemed to be everywhere. In addition to its day job in a research lab, Asimo had a public relations side gig showing everyone that Honda is about more than cars and motorcycles. From trade shows to television programs, even amusement parks and concert halls, Asimo worked a busy publicity schedule. Now a retirement party may be in order, since the research project has reportedly been halted.
Asimo’s activity has tapered off in recent years so this is not a huge surprise. Honda’s official Asimo site itself hasn’t been updated in over a year. Recent humanoid robots in media are more likely to be in context of events like DARPA Robotics Challenge or from companies like Boston Dynamics. Plus the required technology has become accessible enough for us to build our own two-legged robots. So its torch has been passed on, but Asimo would be remembered as the robot who pioneered a lot of thinking into how humanoid robots would interact with flesh and blood humans. It was one of the first robots who could recognize human waving as a gesture, and wave back in return.
Many concepts developed from Asimo will live on as Honda’s research team shift focus to less humanoid form factors. We can see Honda’s new ambitions in their concept video released during CES 2018 (embedded below.) These robots are still designed to live and work alongside people, but now they are specialized to different domains and they travel on wheels. Which is actually a step closer to the Jetsons’ future, because Rosie rolls on wheels!
There was a time when a two-legged walking robot was the thing to make. But after seeing years of Boston Dynamic’s amazing four-legged one’s, more DIYers are switching to quadrupeds. Now we can add master DIY robot builder [James Bruton] to the list with his openDog project. What’s exciting here is that with [James’] extensive robot-building background, this is more like starting the challenge from the middle rather than the beginning and we should see exciting results sooner rather than later.
Thus far [James] has gone through the planning stage, having iterated through a few versions using Fusion 360, and he’s now purchased the parts. It’s going to be about the same size as Boston Robotic’s SpotMini and uses three motors for each leg. He considered going with planetary gearboxes on the motors but experienced a certain amount of play, or backlash, with them in his BB-9E project so this time he’s going with ball screws as he did with his exoskeleton. (Did we mention his extensive background?)
Each leg is actually made up of an upper and lower leg, which means his processing is going to have to include some inverse kinematics. That’s where the code decides where it wants the foot to go and then has to compute backwards from there how to angle the legs to achieve that. Again drawing from experience when he’s done it the hard way in the past, this time he’s designed the leg geometry to make those calculations easy. Having written up some code to do the calculations, he’s compared the computed angles with the measurements he gets from positioning the legs in Fusion 360 and found that his code is right on. We’re excited by what we’ve seen so far and bet it’ll be standing and walking in no time. Check out his progress in the video below.
Humans can traverse pretty much any terrain thanks to their legs and fast-acting balancing system. So if you want a robot which should have equal flexibility, legs are a good way to go, this confirmed by all the achievements of Boston Dynamics’ robots. It was therefore natural for [Mike Rigsby] to model his robot dog after Boston Dynamics’ dog-like robot, SpotMini.
The build log on his Hackaday.io page makes for interesting reading. For example, he started out with the legs oriented like SpotMini but found that when trying to stand, the front legs worked fine but the rear ones slid or the dog shifted rearward or both happened. His solution was to take a cue from his 1990s Sony robot dog, Aibo, by reversing the orientation of the rear legs. He then upgraded his servo motors to ones with double the torque and increased the strength of the legs’ structure. In the first video below, you can see that his dog now lifts itself up to a standing position perfectly.
So far, to give it more of a dog-like personality he’s mounted Google’s AIY Vision Kit which changes a light’s color based on the degree to which a person is smiling, though we think a wagging tail would work well too. The possibilities are endless but one step at a time. See the second video below for a demonstration of the use of the Vision Kit.
If you have a few servo motors, an Arduino, and a Bluetooth module, you could make Biped Bob as a weekend project. [B. Aswinth Raj] used a 3D printer, but he also points out that you could have the parts printed by a service or just cut them out of cardboard. They aren’t that complex.
Each of Bob’s legs has two servo motors: one for the hip and one for the ankle. Of course, the real work is in the software, and the post breaks it down piece-by-piece. In addition to the Arduino code, there’s an Android app written using Processing. You can build it yourself, or download the APK. The robot connects to the phone via BlueTooth and provides a simple user interface to do a few different walking gaits and dances. You can see a few videos of Biped Bob in action, below.
This wouldn’t be a bad starter project for a young person or anyone getting started with robotics, especially if you have a 3D printer. However, it is fairly limited since there are no sensors. Then again, that could be version two, if you were feeling adventurous.
We have mixed feelings about the BlueTooth control. BlueTooth modules are cheap and readily available, but so are ESP8266s. It probably would not be very difficult to put Bob on WiFi and let him serve his own control page to any web browser.