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M.A.R.S.

MADspace Advanced Robotics System: Open source 3D printed Mars rover

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This project was created on 04/08/2014 and last updated 4 months ago.

Description
M.A.R.S. is being developed by the Eindhoven Hacker/Makerspace MADspace. After recently gaining a 3D printer we got the idea of manufacturing it mostly out of 3D printed parts.

The team: Paul Wagener (lead software), Tom Geelen (Embedded control and mathematics), Serdar Yildirim (all round), and Guus van der Sluijs [me] (Project leader and lead mechanical).

The STL files, bill of materials, and software will be released as open source. Every store bought item is widely available.

Summary:
- 6 driven wheels of which 4 can steer (pod wheels)
- Rocker bogie suspension (semi-active, 2 shoulder servos for body attitude)
- Gyroscope
- 16 channel I2C PWM driver
- Raspberry pi
- 2 logitech c270 webcams with pan/tilt
- Web interface written in web.py
- Two 10Ah 5V battery packs, one for drive and one for logic.

Videos:
- First steps: https://www.youtube.com/watch?v=J_J_HG9FMns
- Trials: https://www.youtube.com/watch?v=hqvWwhBxQXo
Details

6 driven wheels of which 4 can steer (pod wheels) 

Rocker bogie suspension (semi-active, 2 shoulder servos for body attitude) 

Gyroscope 

16 channel I2C PWM driver 

Raspberry pi 

2 logitech c270 webcams with pan/tilt 

Web interface written in web.py 

Two 10Ah 5V battery packs, one for drive and one for logic. 

Lots and lots of 3D printed parts

Components
  • 6 × Parallax continuous rotation servo Hub motors
  • 4 × Sparkfun servo small (Pod) Steering
  • 1 × Adafruit 16-Channel servo driver i2C Servo driver
  • 2 × XXODD Power Bank PB-B10 10400mAh Batteries
  • 78 × M4x10 cilinder head (allen) Wheel bolts
  • 4 × 1 meter aluminium tube 10*1mm Tube frame, used in body and rocker bogie assembly
  • 10 × 15x10x4mm ball bearings Wheel and shoulder bearings
  • 6 × M4x12 countersunk head (allen) Hub motor center bolt
  • 2 × Parallax standard servo Body stabilization servo
  • 1 × Triple Axis Gyro ITG-3200 Breakout Gyroscope

See all components

Project logs
  • STL files released

    4 months ago • 0 comments

    Although some parts may need improvement (we're revising the pod axial bearings now) the stl files have been made available to the public.

    Feel free to get a copy of these files and edit them to you liking. Be sure to get in touch if you have any suggestions / ideas.

    Have fun!

    https://drive.google.com/folderview?id=0B5pLRClac1i-Tmp4dW5wMGdnVFE&usp=sharing

  • To Every Rover (Turn! Turn! Turn!)

    4 months ago • 0 comments

    The software running on the Raspberry Pi is responsible for driving the Rover around. But with 10 distinct servo's controlling the wheels we need some smarts to drive around.

    The software takes two parameters as input: A driving speed and a turning radius. All the wheels are in different positions so they all need to be driving at different angles and speeds to prevent the wheels from slipping. Just like with a car, the wheels on the inside track need to drive more slowly than those on the outside track.

    To solve this the wheels are angled to drive along imaginary circles. This makes the rover drive gracefully around every obstacle.

    In our test drives we found out that the rover is capable of some very sharp cornering allowing the platform to navigate tight spaces with relative ease.

    Next step: rotating in place.

  • Upgraded suspension and a new video

    4 months ago • 2 comments

    The hotmelt in the joints gave way when we were driving around some. I took the opportunity to rework every joint. Here's a couple of pictures:

    The cross-bar is just there to keep it together for now.

    Lower right is a little drilling guide I printed, makes drilling holes in the center of the tubes easier.

    Hope you're liking these close-ups


    Let's see what obstacles it can conquer now!


    Thanks for all your skulls! We appreciate it. 

    Pauls log on the software is up and coming, he just seems to be even a bit busier than I am.


View all 8 project logs

Discussions

sgtburned wrote 4 months ago null point

It seems like you guys could do with using this board?
http://www.pridopia.co.uk/pi-9685-l293d-pw.html

Are you sure? [yes] / [no]

Guus van der Sluijs wrote 4 months ago null point

We're already using an i2c 16-channel pwm controller. This just has it incorporated in a raspy shield. For a cool open source project that does exactly the same: Check out http://roverpi.com/. It has a project page here on hackaday projects.
Thanks for thinking of us though!

Are you sure? [yes] / [no]

jim.deane wrote 4 months ago null point

I'm new to the HAD project site, maybe this is addressed somewhere I haven't seen, but do you have the 3d printed component files available somewhere for download?

Are you sure? [yes] / [no]

Guus van der Sluijs wrote 4 months ago null point

They will be released soon. We're currently still redesigning the pod bearings. But I guess we can put the files we have now online. I will give you a heads up. Any plans?

Are you sure? [yes] / [no]

jim.deane wrote 4 months ago null point

To Guus van der Sluijs: (I see no way to nest a reply under your comment...)
Thanks for your reply! I don't have any plans, but I could see using articulated rover wheels and suspension on other projects. I didn't know whether you planned to share the design, so I thought I'd ask.

Are you sure? [yes] / [no]

Guus van der Sluijs wrote 4 months ago null point

100% right arko, we thought stabilizing the body with a gyro and two servos would be a cool option. It ads the ability to keep the body as level as possible whereas a differential only keeps it aligned to the terrain. It should work a charm on slopes, we can cope with plus and minus thirty degrees.

Are you sure? [yes] / [no]

arko wrote 4 months ago null point

Are you able to break/stop the servos at a certain position without using power? I imagine this system would require more power (as to keep it balanced). Especially if your bodies center of gravity is not at the same axis as the servos, you'll end up fighting your own weight. Regardless, I'd like to see how it works out, its like a rover + segway.

Are you sure? [yes] / [no]

arko wrote 4 months ago null point

I noticed that your CAD design does not have a mechanical differential strut across the body (the rocker), rather it has two servos where the suspension meets the body. Are you using an IMU & control system to balance the body relative to the ground and to counter-position the suspension?

Are you sure? [yes] / [no]

Guus van der Sluijs wrote 4 months ago null point

Hey vp, thanks for taking interest. We got the basic dimensions down by studying photographs and animations of curiosity. It seems the rocker bogie is hard to get very wrong, the thing seems to keeps six wheels on the ground no matter what!

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Viva Penguinos wrote 4 months ago null point

I had a similar idea of making a rover similar to what you were planning but was put on the backburer. Where are you getting your diagram and information from? Would love to hear about it. Great job on the project!

Are you sure? [yes] / [no]

Guus van der Sluijs wrote 4 months ago null point

It started out as just a platform, 'curiosity' about the rocker bogie suspension. We're getting a lot of positive reactions and one of the idea's was to have a couple of them in an augmented reality game; 'defend the flag' or 'kill all martians' spring to mind.
I'd really like to make it as autonomous as possible, it has the range and agility. For now the goal is a 'point and click' interface where you would command it to go to a certain region visible on camera.

Are you sure? [yes] / [no]

Eric Evenchick wrote 4 months ago null point

Looks like a versatile robot. Any particular applications for it? Also, what type of things are you using the camera for, is autonomous operation in the works?

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