Agility: Gyroscopic Stabilisation
Do a quick survey of robotics projects today and a majority, if not > 90%, of them will be electrically driven and stabilised by solid state (MEMS) chips driving feedback servos. In a word: compensate. If you’re anything like me, walking is not an exercise is preventing falling over – rather it is a fluid motion with a purpose. I find many of the (albeit great!) projects out there discouraging – because they don’t walk like a human, but like a machine.
Measure - measure - measure - adjust - adjust - Meep! Meep!
If platforms such as the International Space Station took this approach, they’d be firing thrusters all the time to adjust orientation (which poses a minor fuel problem). But that is not what they do! The ISS uses control moment gyroscopic stabilisation to keep things in line (and only use thrusters when gyros need a bit of a reset).
What happens when this logic is applied to earth-bound vehicles or walking robots? You get fluid like stabilisation that the Lit Motors C-1 exhibits:
Related: Gyro: The Heart of a Mech
By literally shifting forces around it moves the centre of gravity and can also change the angular momentum of the entire vehicle. With enough power, they could conceivably stand this bike on its head. And still drive.
What does all this mean from a #Maker standpoint?
We need more folks building innovative components like gyroscopes at a scale that can power human-sized machines. Do some searching gyroscopes that are for sale and you’ll be lucky to find anything other than aeronautical navigation equipment, camera stabilisers, and tiny toys with no purpose.
Dig a bit deeper and you may find some unidentified type of gyro on ebay that might work for something. Otherwise, you’re kind of stuck with tiny useless stuff or big expensive stuff built for the ISS. Thankfully the principles of gyros are not so complex that you can’t get started with a heavy wheel and a motor. The real strength of a gyro comes when it can be heavy and/or fast. The warning here is that when things spin too fast (i.e. 10,000+ RPM) they can eventually tear apart – a process called delamination – and send the entire core of the machine ploughing through whatever is near by, Makers included!
As an aside, the history of doing research into Flywheel Energy Storage ended with some tragedies due to delamination. It appears that not much has been done in decades though there are a few newer projects have popped up the past few years.
The point here is that gyros can be used for stabilisation, navigation, energy storage and locomotion!
They do this in a way that is quite different from other technologies and, in a way, much more natural, fluid and humanlike manner. However, it is treated as such an obscure science that there are not many folks manufacturing options for us to use, test, and build upon. I’m thankful to see all the work that Lit Motors is doing and hope one of their spinoff businesses will be gyro manufacturing.
So What About Robots?
By placing one or two Control Moment Gyro (CMG) setups in a large robot, it is possible to adjust its centre of gravity (CoG), just like we do when us humans walk. The gyro doesn’t have to be able to move the world, but just provide enough force to balance the ‘mech while lifting a leg and stepping. (If it’s going to be hit by an incoming Gauss Rifle, a bit of extra gyro power won’t hurt either.) Of course there is a whole dance of interacting movements needed simultaneously – where the CoG moves from side to side and front to back while going through a walk cycle.
I’ll get my spreadsheet and notepad out in a later post – but consider that if a small ‘mech weighs in at 4,000 pounds, the gyro doesn’t need to be able to push the full weight around. In a simple world, only 2,000 of force would be required to move the weight all over to one leg and stand still. But in reality you only need that kind of force for a short moment in time when actually making a step.
Does 2,000 pounds of force sound like a lot? Lit Motors “little” CMG under the seat of their motorcycle can provide more than half that! Each of the two gyros still only weigh a moderate amount – i.e. a human can lift them. Scale up the design a little bit and you’ve got even more power and agility at your fingertips.
Can you build that? Let us know at @minterstellar 🙂