Curiosity's suspension

[klond]

 My latest effort has been to re-create the suspension on the Mars Curiosity rover in stock.  I've gone through many versions and further tweaking lately isn't adding anything so it's time to publish.  This one's for you, @Majorjim!

 

K, it's not quite a replica, but we're focused on the suspension.

 

 The rover splits into many (13? 15?) separate craft.  Here's a terrible drawing of the relationships of the different craft.

 

 Pairs of elevons push and pull on the wheels on each side via RCS balls.  It's the only way I could think of to control a craft that's detached.

 

When the wheels are pushed out, landing legs glitches them forward, center is neutral, and sucked in is glitched reverse.

 The wheels had to be big enough to keep the gear teeth off the ground.  The legs had to be positioned to not touch the ground AND follow the wheels as the suspension moved.

 

All the pivots had to have tight tolerances to function properly.

  Making the craft larger/heavier also was working against me as stuff flexed in an unwanted way.  I did have to add weight to the rear wheels to keep from dog-legging from weirdness I couldn't figure out, which was only amplified by the low gravity.

 

 The rear suspension is independent and detached from the front to realistically mimic Curiosity.  So how can it be manipulated?

 When the front end is shifted left/right a separate craft in the rear is also pushed and THAT pushes and pulls the rear 4 wheels.  And those wheels have landing legs that follows them.  I tried to make a terrible diagram but couldn't.

 So essentially, stuff floats in tubes that rotate on an axis and that stuff is shifted left/right by elevons.  The rover turns by making one side go forward, the other reverse.

 

 I took an early version to the Mun to test.  It did not go well.

 

 qzgy and selfish_meme suggested testing on Kerbin by lowering gravity.  Fantastic!  I'll design it specifially for Duna like Curiosity.

 A week or two later I took a version to Duna.  Duna is not Mars.  The two places I visited where very flat.  But getting to Duna was an awesomely difficult challange for me.  Highly recommended.

 This version I took had probe cores on every craft.  I was hoping I could switch to other craft and return.

Spoiler

P.S. The rocks are fake!

Nope.  This is one-shot kinda thing  .

 

I don't actually recommend taking it to Duna, but here's a video so you can see the suspension in action.  Gravity set to .31, which I think is close to Duna's.

 

 Not sure how enjoyable this craft is going to be to others, but it's available for reverse-engineering on

 

KerbalX

 

[qzgy]

I enjoyed taking this for a drive. Amazing work as always.

[Servo]

This has got to be one of the pinnacles of KSP engineering - absolutely bonkers, as usual for you.

[Majorjim!]

Absolutely extraordinary.. I'm dumfounded by your creativity and engineering savvy.

 I have a cup of tea in my hand so it's time to watch the video.

 Great work on this mate, and well done for getting to Duna too! This made my day.

[Rocket In My Pocket]

Awesome, just awesome.

[steve_v]

This is very, very cool. Slightly impractical, but cool.
Shame KSPs terrain lacks the detail to use it on.

[Bubbadevlin]

Cool mechanics man! Not only did you create the suspension, but had the entire system slide to enable turning?!

[Mathers42]

Hi, awesome work !

I would just like to point out that Curiosity's suspension works slightly differently : in your image on a slope on Duna, it seems that the rover body is always horizontal with respect to the gravity. However, in Curiosity, the angle of the body is always the average angles of the rockers. Therefore, on a constant slope, the body is always parallel to the ground.

Cheers !

[klond]

 As work was being completed @EpicSpaceTroll139 mentioned something about a differential or internal gearing to make function what you're describing.  I was not prepared for this additional functionality so I went with what I had.  I am still unsure if it's just a simple differential or something more complex.  If you have any links to material or pictures I am still curious.

 And welcome to the forums!

[qzgy]

2 hours ago, klond said:

 As work was being completed @EpicSpaceTroll139 mentioned something about a differential or internal gearing to make function what you're describing.  I was not prepared for this additional functionality so I went with what I had.  I am still unsure if it's just a simple differential or something more complex.  If you have any links to material or pictures I am still curious.

 And welcome to the forums!

Looking at wikipedia or the nasa website about this system, it says there's a differential inbetween the two rockers.

Wikipedia quote

Quote

The "rocker" part of the term comes from the rocking aspect of the larger, forward leg on each side of the suspension system. These rockers are connected to each other and the vehicle chassis through a differential. Relative to the chassis, when one rocker goes up, the other goes down. The chassis maintains the average pitch angle of both rockers. One end of a rocker is fitted with a drive wheel, and the other end is pivoted to the bogie.

According to this website though, the curiosity rover uses a differential bar to do the same job. It also links some documentation which has a nice diagram of the suspension in a simplified state. - https://trs.jpl.nasa.gov/bitstream/handle/2014/41711/08-0272.pdf?sequence=1&isAllowed=y

Image from document

Blue bar pivots on the yellow central pin relative to the position of the kinda teardrop shape on the main pivot, and transfers that motion. Seems like a lot of joints.

But maybe easier than gears.