Design and manufacturing I - ME250 - Self-Propelled Miniature Vehicle

Self-Propelled Miniature Vehicle Design and Manufacture
1. Objective
The objective of this project is twofold: to improve your appreciation of the capabilities and limitation of basic machining processes -- turning, milling, and drilling -- through hands-on experience with machines; and to exercise your ingenuity in designing, building, and testing a device that meets prescribed functional specifications using only limited resources. After the completion of the project, you will gain an experience in working as a team to solve an open-ended engineering design problem, and to deliver a manufactured product by a specified deadline.

2. Design specifications
You are designing and building a self-propelled miniature vehicle capable of climbing
an inclined plane in accordance with the following specifications:
(a) It must use only the supplied battery holders and switches.
(b) It must use only the supplied DC motors and gearboxes.
(c) It must not use off-the-shelf wheels, tires, rims, and/or treads, such as the ones for toy cars/tanks.
(d) It must have rims/legs (or whatever propels the vehicle) and chassis manufactured by you from the supplied or purchased materials.
(e) It must use only up to four C size alkaline non-rechargeable batteries as energy supply.
(f) It must not use adhesives (e.g., tapes or glues) to contact any surfaces on the test rig.
(g) It must not damage or otherwise alter any surfaces of the test rig.
(h) It must fit within an 12” X 9” X 6” space when it crosses the start line and the finish line.
(i) It must stay within the designated 12” wide lane during the climbing (can contact side walls) and must not cross into other lanes.
(j) It must be aesthetically pleasing to satisfy demanding customers

Each team's vehicle will be evaluated by means of a sequence of climbing tests on a special test rig, whose picture is shown. The test rig is an unfinished plywood board with an adjustable angle of inclination, divided into four lanes separated by side walls --- it is designed to test four vehicles simultaneously. The overall length is 4 feet (3ft between start and end lines) and the width of each lane is 12 inches. On each lane, there are five bolts, two plywood bumps, an acrylic top surface with an open slot in the center, and some round tips on the bottom surface and side walls. Note that due to the construction materials of the test rig, the lane widths can vary by 0.75 in places, and the side walls may be bowed.
The slope of the inclined plane is not specified a priori -- rather, you should design a vehicle that can climb a slope as steep as possible. Accordingly, each vehicle will be tested at the increasing slope angles 10, 15, 20, 25, 30, … The speed at which the vehicle climbs the slope is also a design target. Among the vehicles that succeed in climbing the specified distance up a given slope, those that do so in the shortest time will receive the highest score.

The Cat Play Place - For Casey the Cat

My girlfriend Kim got a cat like 6 months ago now [his name is Casey, pictured below], and about two months ago we wanted to get a nice "play place" thing so he can climb it and have something to do. I though we would pick one up from the store, but upon going to the pet store they wanted like $150 plus for one of the models that we wanted! I'm not going to pay that much for something made out of cheep wood and carpeted, so I decided to make my own.

My girlfriend and I sat down and talked about what we wanted this play place to look like, and upon a lot of talking we finally decided what we wanted. Lucky for us I took a drafting class and learned how to use a program called Pro Desktop, so I made up our design on it [pictured to the right].


I don't know if anyone cares, but I'll give a run down of the size of everything. In the top right had corner [where the tallest part of the cat play place is] is what we call the top perch, and it is 12" x 12" (12 inches x 12 inches). The 4x4 it's attached to is 4 feet tall. The rounded piece that is under the top perch is a 16" x 16" square that was rounded off on one side [I'll name it the middle perch]. Moving to the left, the smaller box is a 1 foot cubic box. The pole that is is attached to it is 30" tall (or 2.5 feet). Under the small box is the lower perch and it is 10" x 12". Now, right in the front, we have the bigger box which is 2' x 1' x 1'. The bigger box is only raised 1 foot off the ground. Finally it is all attached to a 2 foot by 3 foot piece of plywood.

After finalizing these designs, Kim and I were kind of lazy in starting to build this masterpiece for Casey. We probably spent 3 weeks thinking about it, and finally our local home depo had some 4x4's and plywood on sale, so we grabbed my truck and scurried over there to pick it up for a good price. All we needed was an 8ft piece of 4x4 and one sheet of plywood [4' x 8' x .5"]. I had some spare 4x4's around the house for the other pieces that we needed.

As soon as the wood was at my house, we immediately got out a piece of paper and drew out the best way to cut out the wood. If i find that scrap paper sitting around I'll post a picture later. I didn't take many pictures of us cutting the wood out, but there is not very much left of the 4' x 8' piece of plywood that we bought.

It did not take too long to cut all the pieces out. I used a jigsaw to cut everything that I needed. When the cutting was done, we had to nail all the pieces together [thats kim a couple pictures up hammering nails into the bigger box of the cat play place]

Hammering the plywood together was actually extremely easy, aside from finding the nails that we were going to use. After it was all nailed together, we then had to put the carpet on it. I thought that putting the carpet on it was going to be easy; however, it ended up being the hardest part. We probably spent the better part of 2 days stapling the carpet to the wood. It's much harder to pull the carpet taught and staple it than it looks! We carpeted the entire outside and the bottom of all the pieces. It actually came out a lot better, and bigger than I thought. It seemed smaller when I made the CAD drawing on my computer.

Now that all the carpeting was done, all that was left was to assemble it. We put the legs on first and then put it together piece by piece. When we were done, I brought it over to Kim's house and we put it in her room so that cat can enjoy it whenever he wants to.