Fun outside!!

 This past week I have been incredibly busy getting Inspiration rolling. I cut the aluminum tube down to length and fit it to a U shaped piece of aluminum which will serve as the load bearing part for the body and all of it's components. I then figured out where I wanted the grooves for the retaining rings to go. Putting these grooves in turned into a fairly odd way of machining. 

Since I didn't have a lathe handy, I used the next best thing.. a drill press. With a good sharp eye and extremely steady hands, I took a small saw with a .030 blade and held it up to the aluminum tube where I wanted the grooves cut. It actually worked surprisingly well and the .025 thick retaining rings fit in perfectly.

After I got the tube cut and the chassis put together, I took a few pictures of it sitting next to the, now too small, body and then another with a wheel up on it showing the amazing capabilities of Don Bickler's rocker-bogie suspension system.

Once I got it all wired up, I just had to get it outside to do some "victory doughnuts"

 It was really nice to finally get it outside in the dirt since the entire time I've been working on this suspension, there has been at least a foot of snow on the ground. There was one issue though with turning around on higher traction surfaces. You'll see in the video how one wheel comes up off the ground. If I continue rotating, the entire suspension side will roll over on the tube and leave the rover kind of laying on its side. So while I've been thinking about how to fix this problem, I started work on the new body.

 I went down to the Hack Factory and used their laser cutter to produce some nice accurate cuts and holes for all the wires and screws.

Once I put all the cut pieces together, I mounted the body to the aluminum U with some screws so now the body can be easily separated from the chassis by turning out 4 screws. Here's a couple pics with most of the electronics inside:

 This weekend, I set to work on the metal detector arm and reprogramming the speed of the wheels while turning which seems to solve the rolling-over-suspension problem. And just a few hours ago, I finished wiring up one side of the rover so now if I needed to take an arm off for some reason, I just unplug the wires and pull the retaining clip and the whole suspension arm will slide off. A nice modular design just in case I end up designing another system, it can be easily swapped or if I needed to replace a motor, it will make it that much easier. 

 Next up is wiring the other side and finish the metal detector arm. I also have some more wire harnesses to add to the camera system and the battery. 

T minus 1 month

 The ticking clock is really starting to get loud now. I can't believe it's been a month since my last post. Time is really flying by and I still have so much to do. The good thing is, it's actually taking shape. This project was originally something that I thought's I'd spend a couple of months on and then focus on the rocket portion. After a couple of years of trying to build it between school and work, I kind of started to think that I'll never actually finish this rover. It really makes me happy to see it almost finished. Here's some pictures I've taken over this past month:

I had my friend Paul at Paul's Speed & Machine, Inc machine these new aluminum shoulder joints out for me. I asked for 4 and he was nice enough to make 8 just in case I screw up on the holes for the springs. These things are EXACTLY what I drew up on inventor and fit perfectly! Having these work how I planned took a huge burden off of this project. Thanks so much for your help Paul!

 

These were the parts all laid out. The new shoulder halves, the 5.5 in-lb spring, the 3/8 inch aluminum tube, and the high-performance plastic bushings.

I fought with the springs for a couple of days last week, trying to bend the ends 90 degrees so they would fit in the holes that I had drilled in the shoulder parts. I managed to get this one to work great but then I had difficulty duplicating it on the joint. My biggest problem was getting the ends of the springs bent in the exact right place so that the 2 halves of the shoulder joint would be where I needed them. I decided, after much frustration, that maybe bending the springs was not the way to go and I should just drill some holes so that I don't have to bend the springs at all.

So I settled on drilling at an angle like this. Actually since the drill bit walked a lot, I had to start by drilling straight on with the side of the part and then slowly change the angle until I got what I needed.

Once I got the shoulder joints worked out, I set to work on the aluminum tube and a metal bracket to hang from the tube to then mount the plastic body onto. 

I soon decided that the metal bracket should be inside the body so I had to shorten it and re-drill the holes. I've settled on making the rover wider now so that I have more room inside for all the things that are going in there. This means that the current body I have made won't work and will need to be re-designed a little. 

 I should be getting the retaining clips soon so the suspension should be fully mounted to the tube this week. And after running the wires through the tube, I noticed that I should almost make this thing more modular by adding little wire harnesses to the motor wires up by the shoulders so that way I can just unplug the wires and pull a clip to be able to take the suspension off. And then the plastic body will be screwed onto the metal bracket so that will be removable also. 

 I started work on the metal detector part as well. I spent almost a week trying to build a very small metal detector circuit but nothing seemed to work right. So I bought one. This thing was perfect for what I needed. I opened it up yesterday and found a nice small circuit that should talk nicely to the Arduino Mega. Oddly enough, it doesn't notice our little Chelyabinsk meteorites we have so I think the metal detector arm will now need a magnet for testing these low iron types of meteorites. (Yes, the Chelyabinsks do stick to a magnet even though there's not much iron in them.)

 But anyway, Lots to do yet but it's coming together nicely. One more month to go and then we're off to SpaceFest and NASA JPL to show this off to some people, and then after that, it needs to be ready for presentation for my student project at school. Yikes! Wish me luck world!

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
www.facebook.com/strayrobotics

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! 

Lots of new things!

So I've finally started at Anoka Tech and am now able to use class time to work on rover things. My second day in, I managed to get some of the suspension parts on the 3D printer. Unfortunately, there was a conversion issue and the parts came out 3 times bigger than they were supposed to. We had to stop the machine in the middle of it's 31 hour run and got this:

Kind of a cool cut-away model I guess. My instructor was really excited to see it anyway. He says it'll make for a good show and tell for the 3D printer and for my presentation at the end of spring semester. 

 After this little over sized issue, we went back and found the problem and got the parts back on a few days later.

Being printed

Finished parts next to large parts

All the parts (minus 2 motor mounts) put together next to the rover

The parts compared to my drawing

 It was really cool to see these parts go from a (technically) 2D drawing to a fully functional 3D object. I had an idea of how small these parts were going to be, but once I got them in my hand, I realized just how small they actually were. I did find out though that the resolution on the prints wasn't very good so today I set the resolution higher and beefed up the thin spots. I'm ready for the next print and should hopefully be able to attach these to the rover by the end of next week. 

 I'm also working with an instructor on making Inspiration GPS guided. I ordered the parts and should have them next week also. Which reminds me, I've decided to upgrade from the Arduino Uno to the Arduino Mega. After conferring with instructors and other students, it was deemed to be a good idea since I still need to add the GPS, temperature sensor, battery monitor, and metal detector which all need inputs and outputs from the board.  

 And in more social news, during the snowball effect of this project, it was decided to start a website and somewhat of a company. The company name is now Stray Robotics (a deviation from Stray Rockets and Robots). You can find the (at this moment, unfinished) website at www.strayrobotics.com 

 Also, the Stray Robotics YouTube channel and the Google+ page. That's about it for now. Hopefully things will start really picking up once I get the suspension parts made. Stay tuned!

Finished suspension drawing

 I have the whole week off from work and school! Know what that means? Yup, plenty of time to work on Inspiration! So I've spent the past couple of days drawing all the suspension parts and making them work together so that I can hopefully print them soon. 

 After a lot of thought and drawing, I decided to go with a design modeled after Don Bickler's rocker-bogie system that was used on Sojourner. This way, I use less bearings, only need 1 hole per side for wires to  run through, and if attached in the correct spots, the body of the rover will self level by hanging from the "shoulder" joints. Here's a picture of what I drew on Inventor:  

 All the suspension parts are interchangeable with the other side's parts so I can simply print 2 of every part and I won't need to worry about which side of the rover it goes on. The grey shafts are going to be 7/16 styrene tubing that can be cut to whatever length I need them, for better customization if I feel I need it and also to run the motor wires inside of for better "housekeeping". The "shoulder" joints are designed to fit a coil spring inside so during launch, the body can be as low as possible and after landing, it will be able to spring to its designed ride height. 

 The sampling arm is my next step in this drawing. It's still roughed out so I can see if it might hit the wheels and also to give everyone an idea of what's going on the front. Hopefully I'll get this drawn up real nice this week.

 Then there's this really quick video to show how the camera arm is going to work. It's way too fast but it's kind of a proof of concept model anyways. 

 I plan to slow this down a whole lot by using one of my extra wheel motors or simply using another coil spring to rotate the arm up. I like the motor idea but it's extra weight that I don't need and I think I'm running out of control outputs on the arduino as well. I'll definitely spend some time on this part soon though.

A Video!

I seem to be having difficulty with Blogger uploading my videos. So I figured out the YouTube way of embedding videos.
Now you get to see more videos like this 'rover's view' video.

 My 8 year old nephew, Will, inspired this video. Just before Thanksgiving, I was showing him how far along the rover is, then he dumped out some Jenga blocks and told me to drive over them. I had never stress tested the motors and wheels before so I totally agreed and found out this thing really has some power! I continued to drive over the blocks for about 10 minutes without any sign of the battery losing power. This quick video I uploaded was a little recreation of that test. Hopefully soon, I'll have suspension on and it'll work even better. Also, you can see the camera displayed on my laptop's screen. In the next few months, I plan on incorporating this into a nice graphical user interface.