We left the high school parking lot around 6:45 saturday morning on our way to waterloo for our first competition. When we arrived, we unloaded our gear onto the table that was labeled with our team number. After checking in, we got right to work mounting our electronics and getting the robot ready for inspection. Almost immediately after inspection, we had our first competition. After the first 10 seconds of the driver controlled period, someones robot lost connection, and we were forced to re-start the match. While trying to knock over the stick supporting the balls, our bucket mount got bent slightly to one side, which caused the edge of the bucket to catch on the scissor lift when we tried to use it. This basically meant that all we could do was park in our teams zone at the end of the game to get a few points. The second match went a little better, but our scissor lift started to slip when we raised it more than a foot off the ground.
On the night before our first competition, at around 9:30 pm, after getting the frame of our robot mostly finished, I began working on the electronics. We used a total of 5 motors; One for the bucket, 2 on the scissor lift, and 2 motors for the wheels. To eliminate some of the confusion we had last year, I laid out all of the components and wired them together, and then labeled them using masking take and a sharpie. This makes it much easer to edit the schematics of our robot without making a mistake. After that, I got on the computer and started programming our controls. After a little less than an hour I was finished, but because of the time we were not able to mount or test all of the electronics. The only challenge left in the electronics department was learning how to set up our robot to communicate with the administrator computers at the game.
The week leading up to our first competition has been very hectic, but we made good progress. We have spent over 2 hours of the school day working on this robot, most of which was spent in the shop. We have also been working after school to get our custom parts made and welded together. Tyler and I have spent several hours every day after school working, and have been able to finish our lift. We mounted it to our robot and started working on the gearbox to power it. We ended up only needing to use 2 motors, but when I tried to lift the scissor lift by spinning the gear with my hands, the tension between the large axle on the scissor lift and the small axle on the gear box forced the large axle to bend downwards almost half an inch. To fix this we used steel square tubing as a wedge and reinforced it with aluminum. After fine tuning and adjusting the mechanical parts of the scissor lift, we were finally able to move on to the electronics.
This year, the game layout and objectives require only one complicated mechanic, instead of last years game, were we had to complete many different tasks. We are using a scissor lift to lift out bucket high enough to score the balls in the high goal, and with this comes the problem of material strength. Last year, we had problems with our mechanical arm being too heavy and twisting our steel axels. Similar problems come up when we use aluminum gears and braces in our gearboxes, which usually are geared above a 20:1 ratio, in order to get the necessary torque out of our motors. This year, because we have more time and simpler mechanics, we are custom making almost all of our parts out of steel. Tyler and I asked our shop teacher to instruct us on how to use the mill, so that we could mill slots in our half inch steel channels. fabricating our own parts has been a great learning experience, and allows us to be more creative with our designs.
Today Dylan and I make the sheet metal bucket. it has a relatively small base, about half the size of last year's, and is 17" tall. The back has a single groove, compared to last year's bucket, which had a flat back. This means that mounting the bucket will be much sturdier due to the stronger mounting point. This will hopefully increase maneuverability of the bucket. Dylan ordered steel to sleeve the bottom portion of the scissor lift, and we will be picking it up after school. We will also trying to mount the slides after school, finish the bucket, and mount the bucket on the scissor lift. This may be rather ambitious, but we need to utilize every second we have if we want to be 100% ready for this competition. Hopes are high.
Today, Tyler and I designed and began fabrication of our bucket. We used last years bucket as a baseline for size, and redesigned the shape to fit this years challenge. We decided that the size of the base of the bucket from last year worked well, but that this year we will need the back of the bucket to be angled, instead of flat, to allow the balls to funnel into the tubes. We started by setting the depth and width of the base of the bucket. After that we decided how high we want it to be. Using those dimensions, we drew out the shape onto a flat piece of drafting paper before scribing it onto sheet metal. We were able to get the bucket completely cut out and bent during class, which means that we will simply need to rivet it together and mount it on our robot. This is one of our major parts for our robot and with a competition in less than a week it is important that me make consistent progress every day.
In just 6 days we will be competing in a league meet in Waverly and we still have a lot of work to do. This means Dylan and I will be staying after school nearly every day this week, except the days I work. The list of things we need to complete seems long, but now we have plenty of motivation to get this project completed. We need to sleeve the outside of our scissor lift for strength where the torque will be applied, weld on the 1/2 axle, make a hub, weld the hub on, bolt a Tetrix gear to the hub, make the gearbox for the scissor lift, make the new bucket, make the mechanism to tip the bucket, and find a place to mount this all. We are very excited for Saturday, and we will be working very hard all week to make the deadline. We anticipate doing very well in the meet, due to our well-made scissor lift, use of steel parts, and the simplicity of our robot's concept.
Today the metal for the scissor lift will be all drilled to fit the axles in. The next step is to find a way to mount the 2 scissor lift sections to the robot. We will then created the axle to evenly distribute power between the two lifts. We believe that a 3/8" axle will suffice. I worry about the axle twisting due to the high-torque application, however I have high hopes that the axle being double the circumference of our previous axles will not twist. Testing will be done to assure the axle can withstand the torque, and if it does not make the cut, a 1/2 dowel will be used. I have no doubt that this will suffice, however I do not want to drill a 1/2" hole in the aluminum gears we will be using, due to the relatively weak nature of aluminum, if we don't have to.
Our first event is scheduled for December 20th, a date for which we are all very anxious. In the recent days and weeks we have decided to use Lab View, our old computer software, to program the robot, for simplicity reasons. The controls are currently somewhat odd, but they will work fine. We have been practicing with controls and looking at various wheel position options and different types of wheels. Our current, and hopefully final setup has 2 sets of parallel, normal wheels. This differs from last year's setup, which had 2 sets of parallel omni-directional wheels that were perpendicular to each other. This year we were forced to optimize traction due to the slippery nature of the ramp. Omnidirectional wheels failed to provide sufficient traction to drag our relatively light robot up the ramp, so we settled with the normal wheels.