Hi, I was kind of in debt about the preparations for the MMArs (Moon-Mars Atacama Research Stations) expedition. As you probably know, the MMArs facilities are in charge of the Universidad de Antofagasta at the Chilean Atacama desert, the most arid desert in the world and certified by NASA as the most similar Moon and Mars surfaces on Earth.
So, lucky for the AngelicvM Team we have it here on Chile and we went there at the end of May of this year (28 to 31 of May) to test our Dandelion concept robotic rover...we already show some pictures and videos of the dandelion rover test, but here is how we prepare for the expedition...
We start working on the new Dandelion concept rover variation called "Dandelion Heavy-Duty" (AKA: Bastardelion), which is based on the Tyco Shocker Shell toy, so we ripped of! to extract the motors and do some tests on the parts that we can use for our purposes...
Sometime even I do some work :-) ...
Here are our new "Younglings" making their first soldering....ahhh nothing like the tin and finger burn smell in the morning :-)
They get in charge of Hugo to help the preparation of the tension and pressure spur/blade experiment...
Alba and Carlos get in charge of the Dandelion Heavy-Duty build...
Ahhhh Frankendelion is Alive!!, ...is Alive!! :-)
All guys working...
Xino and Pablo get in charge of the Solar Panel/Cells charging experiment, so as usual in our beloved south of Chile, we was forced to use our artificial Sun for preliminary tests... ;-)
Blanco and Pequeño get in charge of the construction of a metric tape to test velocity, acceleration and other parameters from an "outside the rover" point of view...
Of course with the help of a little friend ... :-)
Oscar was in charge of the "Gravity Car", this car will allow us to simulate (in a very raw way by the
way) a lower weight of the rover, since on the Moon gravity is 1/6 of the one on Eart...
The new blades/spurs and aluminium chassis arrive just in time a couple of days before the expedition thanks to Sitecna that is helping us in this matters...
For this expedition we wanted to test a spur variation in which each one is more square...
The new chassis is about 20% bigger than the previous one, this extra space allow us to fit the components more easy and test and measure things more quick...
Nice!!!...
Pequeño and Blanco also build a number of Micro-Dandelion for the MMArs expedition and also as gifts for the GLXP Team Summit...huge success on the Summit!!!
Of course we end up working late the las couple of days, but with the proper amount of sugar and music all is fine :-) ...never forget to get FUN!!! :-)
Ahhh the new Bastardelion variation...
And the whole REAL Group!!!
Once again...an excellent job!!..I'm so pride to be in charge of this group, one of the joys of my life...Thank you guys for believe in this...
Here is a video that summarize the MMArs expedition...
When we begin to work with the AngelicvM Team as part of the Google Lunar X PRIZE competition, we start thinking on what kind of robotic rover we want to build, so of course we start looking of what other teams had (publicly at least), the previous rover designs from NASA and some new concepts from Universities around the world.
The image above shows that analysis, the "Mars Rovers Traction Systems" exemplifies the traditional traction system used by most of the teams and of course used also by NASA in all the Mars rover vehicles. This traction system use the concept of a passive suspension in which 2 or 3 wheels per side of the robot are interconnected by pivot joints that allow the wheels to accommodate to the obstacles, keeping the main chassis body in balance during the travel (4 or 6 wheels in total). This design also incorporate deformable wheels to increase the contact surface with the ground, increasing traction. This is a very probed design and work well, at least on Mars, but the moon is different, the Moon surface is much more uneven than Mars, fill with craters that have other craters in it, big rocks and a fine dust that cover all. The design also need a slow movement, since the passive suspension need time to accommodate the wheels to the obstacle, if not, the robot body became very unstable and tend to rollover. This system also demand a big number of mechanical and structural components that usually involves more volume and more power needs, usually meaning a big size robot. The deformable wheels are also not easy to build, require special materials and specific calculations to allow the correct amount of bending, considering the weight of the robot and gravity considerations, a miscalculation would turn in a non-deformable wheel that is going to have a poor contact surface with the ground and a bad traction.
The next design that we study was "Rhex" from Boston Dynamics, is a bio-inspired robot that use a "Wheel-Legs" concept that mix the wheel and the leg of an insect. The concept is simple, elegant and performs incredible well in raw surfaces, beside, the "inverted mode" design allow the robot to be drive it upside-down, this give us some ideas for our own design. One aspect that we don't like about Rhex (for this particular scenario of a Moon mission, for earth we think that is awesome!), is that the Rhex design again needs 4 or 6 wheel-legs, which again means mechanical components and power consumption.
The "GOAT" design is very interesting, it use traditional wheels but with a very cleaver active suspension system that allow to individual wheels to adapt to the obstacle allowing max traction points to pass it. The system also allow to be recover it from a rollover. The negative aspects is again, the big number of motors and mechanical components involved in the traction system, that mean risks and power consumption.
So, the idea was to think in something different, something unique, considering the Google X PRIZE requirements and also the specific team mission limitations about size, weight, budget, etc. The idea as a robotic group, was to propose something different, there was no point into copy or reproduce a repeated design, no merit in doing that.
The minimum amount of motors needed to have a controlled movement is two, with just one you can control forward/backward but no right/left, with two motor as a minimum you have a differential traction system as the one used with much success by tanks and other vehicles for raw terrains. With two motors you can also consider the "sphere" and two pendulums inside to control the movements, it is a interesting idea and there is some robots that adopt that shape, but they usually are difficult to control in slopes and of course they tend to roll very easy, which is not a problem since they are "balloons" but they easy can end up in a different place that the one that you want. The slope degree in which they can be controlled is also usually very low.
So back to the 2 wheel robot, we begin to think in something like the one in the "Dandelion" picture, something with just 2 wheels and each of them as a Wheel-Leg bio-inspired design.
The last one, "Rhexalion", was the mix of a bad drinking night between Rhex from Boston Dynamics and Dandelion :-) ...it was actually a simplified Rhex design which just 4 motors using the wheel-leg concept. The Rhexalion was also been build it, but the motors chosen was very big and end up with a heavy robot that don't meet the expectations...more about Rhexalion in other post.
So, why think into a bio-inspired design?, the answer is easy: Nature takes millions of years to develop a locomotion system that allow to travel with comfort and security in very uneven surfaces, and that design is the one use it by all insects today. As we mention, the Moon have an incredible raw surface that cover from fine dust to big rock and earth insects are pretty good on those terrains (I bet that any of you as seeing an insect slippering in the ground :-) ...
We start digging into the insects locomotion, specially the "march" insects legs that are particularly good for long walks distances, and after some studies we realize that each leg of the insect repeat a circular pattern that in conjunction with the "invert triangle" scheme that the insect use to alternate his six legs, allows a incredible traction power (the little fellow in the image above is no longer with us, it gave his life for science :-) , it seems that insects don't like fluorescent spots on the legs :-P ). But replicate 4 or 6 legs with all the articulations, joints and tendons is hard to do it in a exact mechanical way, so this is where the 6 engineering years of study came into place :-) ...we can take the abstract concept of the insect walk and simplified it to a wheel shape in which the leg is repeated a number of times in a circle. This "Wheel-Leg" or Blades/Spurs act as an insect leg each time that they touch the ground. Adding some flexibility to the blade/spur you can imitate the tendon in the insect leg that hold potential energy in each step when the leg press the ground, this energy is important for the "next step" since is liberated and produce additional push/force to the locomotion system. One thing that you miss is the inverted tripod walk schema, but you win simplicity, a low number of motor and other mechanical components and a reduce power consumption schema.
As the previous images shows, the design evolve and incorporate requirements of the mission like be able to be drive it in any direction or been able to recover from a rollover/tip-over (reversible), be able to been scaled in size to fit different mission scenarios, minimalistic and also as is show it in the bottom left part of the image, been able to be drive it in big front and lateral big slopes as the ones that are probably be founded on the Moon. The rounded shape at the end of each blade on the wheels allows that. We like a design that feels comfortable on the Moon, something that could evolve there, something that don't care if it rollover (since is very possible to happen), not a traditional wheel design that feels strange on that kind of surfaces.
So, we end up with a multipurpose robotic rover platform for different contexts and mission scenarios, that cover from a simple toy for marketing purposes to a Heavy-Duty variant for heavy tasks. A "Nano-Dandelion" variation is also underway...But please keep in mind that all this designs are protected by intellectual and industrial rights, so ANY USE MUST have the authorization of the AngelicvM Team and the R.E.A.L group. That also goes for all images and schemes that are show it here.
One thing is to think that is a good idea, but prove it is a totally different history, so, we perform a series of studies including simulations and animations to virtually see how good/bad the design performs, of course the insect walking to see how close we are in terms of that schema and potential benefits and the necessary software that could allow the robot to make 3D mapping of the world, obstacle detection and path planning...sounds easy, but it is not, believe us..
The more common topologies on the Moon are 7, from find dust layers from 2cmt to 20cmt, long slopes, craters (a lot of them) and rocks of different size. The rover design must be prepared to deal with any of those without preferences. To test those scenarios we perform a search to allocate a terrain that can have similarities with these topological aspects of the Moon, lucky for us, in Chile we have the MMArs (Moon-Mars Atacama Research Stations) facilities that are under the administration of the "Universidad de Antofagasta" and there was certified by NASA as the most similar Moon and Mars terrains on Earth!, in these terrains NASA test his Mars rovers concept too, here a couple of examples of the Moon topologies and the analogue ones at MMArs:
One disadvantage of the Dandelion design is that the Wheel-Legs occupied a big space, for that we are researching different collapsing schema and alternate uses for the blades/spurs as is show it in the next image:
The picture show us different collapsing modes, one of them like a fan and other taking the sphere shape, which is specially beneficial to reduce size during launch and travel but later have a big wheel size for exploration. Also, the spheric shape is one of the bests in terms of vibration and pressure release, protecting in that way the main body during the extreme launch conditions. The antenna and linking schemes are also possible with this wheel design.
The construction of some of the Dandelion robotic concept rover variations was made in "stages", each one with preliminary tests and improvements for the next round in a prototyping fast approach. Here a couple of examples of the variation versions:
After each stage round we test, test and test again to exhaustion, the end result after our first trip to the MMArs facilities end up with some amazing results that we can summarize here:
The Dandelion rover design performs amazingly, the specification are superior that the ones on most of the roves in competition and the numbers here are "conservatives", they are a little bigger and with some improvements after the MMArs expedition can be even bigger. The engineering calculations and final schematics is under way and is expected to be ready for the final construction very soon...but of course they can't be public...is still a competition... ;-)
The design gets the attention of the other teams, from the Google X PRIZE organization team and even from other international Space Agencies and space related entities receiving very good critics.
Here some videos of the experiments at MMArs:
Take care and stay tune for more news...cheers!
One other summary video about the Dandelion Design..:
