Post to Robo sumo blog

Week 4:

Week was very an important one on planning as we made our final decisions for our robot design we agree that the robot should be close to the finished product we will use in the robo sumo competition with subtle changes.

Having spent hours attempting to fit our original 250gram motor into the base, I assured the team it simply wouldn’t be a possibility given the time frame. However I managed to find two separate motors half the size which would be suitable for the job after reviewing the data sheet:

These motors have a combined mass of 176g, these motors will sit facing opposite directions and on opposite ends of the robot (see drawings below). The steering for our sumo bot will be tank driven sides move in opposite directions to rotate overall vehicle. This offers great mobility, plans to Offer 4 wheel drive using pulleys are in place however no certain decision has yet been made. There will be no gearing ratio as the wheels will be connected directly to the motor shaft this benefits us as it keeps things simple and the weight and costs down.

We Believe the 6v battery we were supplied with should suit our robot sufficiently (if it ain’t broke don’t fix it) altering this voltage would require circuit board changes and lots of time for likely little benefit.

The largest and most controversial discussion we had were the wheels as there are so many factors to take into account. I had studied into the wheels in particular believing they were the key to victory for the final battles.

A four-wheel-drive car can utilize the traction of all four tires. Too much torque will cause slippage The more weight on a tire, the more traction it has Wheel slip occurs when the force applied to a tire exceeds the traction available to that tire. Knobby tires have good traction if the road surface is rough, but the trade off is that they are

inefficient and use more energy than smooth tires. Greater surface area = greater traction

Because the decision had been left between the two of us (Kevin and Myself) We decided not to vote but to create a chart in which we both graded the different setups possible. The below chart is our actual decision where 1 is excellent and 4 is the least good. The lowest scoring class would be used and in our case it was the 4 large wheels which Kevin provided which would be driven with two driver wheels by two motors scoring 22 marks.

Deciding on our wheel setup Classes 2 large 2 small

with two wheel drive

Trike With two wheel drive

4 large with 2 wheel drive

4 large with 4 wheel drive

Weight 3 1 2 4Speed 3 3 3 1Space 3 4 3 4Aesthetics 3 4 2 2Torque 3 3 3 1Simplicity 2 3 1 4Time 2 3 2 3Voltage Required 2 2 2 4Cost 2 2 2 4Mobility 2 4 2 1Total marks= 25 29 22 28

During the week prior to week 4 andrew set up a facebook page where we could easily contact all three other members and communicate issues we encountered outside the lab. Here’s an example of our discussions.

The following images are doodles that were done throughout the project many are simply concepts but all are feasible, these are only the designs that I had produced.

Left Image: A concept I drew after a trip to the toy store for some primary research. The concept came from a star wars lego ship which I altered. The idea behind this is that you have very high traction as a large amount of surface space is against the growned. The electronics and motors are built into the inside of the wheel

Right image: same again but with a siringe which would squirt oil on the growned removing the oposing robots

traction entirly.Left image: Shows a concept which would have enabled our robot to sit glued to the growned while the other robot eventualy fell out of the ring. A syringe would be activated by a motor and the suction cup would glue the robot to the surface. No wheels would have been necisary and an arm could have extended to knock the opposing robot of the board

these are some rather messy images of doodles where I tried to combat solutions to gearing and drive shafts Right image was the final design which stuck.

The left image is an aireal veiw of the robot in an attempt to efficiantly place items.

The right image is the original concept design which encorperated the tank tracks and movable pusher I so badly wanted. The idea didn’t stick but the team name Plow kings was certainly inspired by it so it was of some use I suppose.

Before we left at the end of the day we decided what was to be done for homework by each member and we weighed all of the resources for our robot to be sure we were under the 500g mark.

As you see in the image we are nearly exactly half of the allowance this included a breadboard, plastic base, gears, two motors and steel rods.

Week 5:

This is an important week as next week is the day ‘race to the wall takes place’. Between this and last week I have spent hours in the garage working on the base, measuring, drilling, tapping for screws and in some cases bending. I managed to recycle some motor supports and worked enlarging holes and including further holes to attach the motor with nuts. Kevin has the robot and the pieces i have spent the week on this week to finalise the project. We wanted to share the physical production of the robot as we knew it would benefit our blogs even though it further complicated the engineering as Kevin had no light to work with in his shed.

Kevin and I had a meeting at the beginning of the Lab class and created a time table of tasks to be completed during the class. We divided up these between each other equally and set to work. All but one were completed which was the drawing of the circuit diagram done on inscape. I can’t see the benefit in using it as in the time it will take to understand it properly I can have drawn the image manually. I have since drawn our circuit diagram and for this week’s homework i am to try and create a PCB board as well as a CAD drawing of our work.

Work on the PCB board:

The idea behind this was to reduce weight and space as the breadboard is bulky and ugly. I began by drawing up the Circuitry on a page:

Then I began placing the schematic onto the double sided copper plated PCB with Letraset transfer lines and dots.

I then Drilled the holes were components would need to fit in

The next task is to dip these semi completed boards into a solution of diluted ferric chloride which will dissolve the un-covered copper.

After this i can begin soldering and end up with a finished product