It's more than a box with wheels, I swear!

 Back from a long blog break. When I left off, I was going to the Tucson Gem Show with +Cristin Finnigan. Well we're back now and let me tell you, it's pretty amazing! There were 45 different sites throughout Tucson and each site must have had over 100 vendors at them. We only made it to 2 sites mainly because we made fast friends at Aerolite and Impactika and stuck around to learn a whole bunch about meteorites. We even purchased some. The TSA agent at the airport stopped Cristin and asked if she had rocks in her bag or something. "Space rocks actually!", she enthusiastically replied. We had a blast and will definitely be back! And a big thanks to everyone there for being so wonderful and bringing us into your circle of friends!

 As for the rover project.. I received the springs from McMaster and modified the plastic shoulder parts to accept the new larger springs. As I feared, the springs were still too weak to do much good. I calculated that I apply about 2.5 in-lbs of torque on the shoulder joints and the closest spring I could find on McMaster that would remotely fit the parts I have was only good for 2.1 in-lbs of torque. The springs hold the rover up but don't provide enough power to lift the rover up from its launch/landing position. I tried tightening the springs up a little bit but just caused more problems for myself. But I did manage to get the suspension re-mounted and ended up with this:

 It became very clear to me that this current set-up I have was not going to be stable enough for the rover to drive straight. Since the shoulder joints are attached to the plastic body, it made the whole assembly very wobbly. So now I've decided to build the rover around the suspension instead of the suspension around the rover. Makes total sense now. Wish I would have thought of it sooner. So now the design is to attach the 2 suspension sides together with an aluminum tube. The tube gets attached to the body and then the shoulder joints will slide over the tube and be locked on with a retaining clip. 

 Of course this now means I need to redesign the shoulder joints to fit over an aluminum tube. The good thing about a redesign is you can kind of create whatever you want. So I looked on McMaster's site again for springs that are about double the torque I need and bushings to fit over the 3/8 tubing I decided on. The springs I ordered are 5.5 in-lbs of torque and almost twice the size of the previous ones so now the shoulder joints need to be almost twice their original size as well. I immediately set to work on drawing something that would hold the new springs, bushings, and current polystyrene tubing and still be able to do what I want. This new redesign also calls for these parts to be made out of aluminum so I don't have to worry anymore about breaking them. So currently I am waiting for these parts to be made. I have an instructor at the college working on them and I also have them in queue at a friend's machine shop. Of course the machine shop will cost money but I think it'll be worth it in the long run. 

  After I got the redesign done and now waiting for parts, I started working on mounting the distance sensor and the camera servo and arm. This is what I've got so far: 

  The suspension is still being held on by giant shaft collars so the solar panel doesn't sit down all the way, but you get the idea. Oh, and I decided to upgrade to the Arduino Mega for more inputs and outputs since I'll be needing them for the distance sensor, camera arm, temp sensor, battery sensor, GPS, and metal detector. (Wow, I have a lot to do yet!) 

  Here's  a really quick video of the camera arm in motion. 

 I've made the arm look a bit nicer since I did this video and I'm working on a nice way to mount the camera to it as well. Also, because of the way the arm is mounted now, I think it'll be best for it to lay down over the solar panel instead of out back like it does in this video. I think it will also help a lot with the lander design later.

  It's all finally starting to come together! 2 more months until it's due for school and Space Fest! Hope I finish in time. I'll keep ya posted. The website is updated a bit more now so go check that out!  www.strayrobotics.com and now on Twitter and Facebook. www.twitter.com/strayrobotics
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More suspension work for Inspiration

I've been very busy trying out the suspension parts. First I got all of them printed.

Then an hour of freeing them all from the support material

Then I fit them all together with the wheels and springs in the shoulder parts.

Then I routed the wires through the tubes and fit the suspension on the body.

After getting the suspension on, I found that the springs were not strong enough to hold the weight of the rover so the body sank to the table and things were a little sloppy in the shoulder joint so the wheels slid out away from the body as well. 

 I tried tightening the springs but started to break the printed parts. I got some assistance from some guys at work and we decided to replace the plastic shaft in the shoulder with a metal rolling pin. Today I set to work on that and found it all fits really well! The bearing now fits better on the shaft but the spring still couldn't be wound up enough to provide good torque. A professor at school suggested torsion springs instead so I did the math for how much torque was needed from the spring and set to ordering them on McMaster. Hopefully that will work out. I'm also in the process of making an aluminum U shaped bracket to hold both sides of the suspension to each other for better rigidity. More to come next week. Off to the Tucson Gem Show for the weekend!