June 23

I know this is a day late, I just forgot to post yesterday.

Soldered broken 3 phase motor wire back together. Rearranged electronics and wires to lessen the stress on the wires. Calculated necessary motor strength to pivot the intake mechanism. 

Again the test date got pushed back a day but this gave more time to fix some issues like the ripped motor wire. I was able to solder it back together by taking the motor apart and finding where the wire broke. I applied some shrinkwrap onto the wire and then a bigger shrinkwrap to join all three wires so that they share the stress if bent.

The reason the wired broke was likely due to it rubbing against the back section of the chassis when the front section pivots. I did some wire management so that this wouldn’t happen, which also made the rover look a bit nicer.

After a bit of driving the rover making sure that the new wire arrangement worked, I learnt how to calculate torque and how to compare that to servos. Initially I thought that servos would work as the intake would only have to pivot around 30॰, but after the calculations it would be necessary to use a linkage since servos within our price range would be too weak. So I looked into worm gear motors with ultra low rpm, around 15 rpm, which would hopefully provide enough torque to rotate the intake.

The test date also got pushed to tomorrow so the IMU, which arrives tomorrow, would give us a better way to dead reckon. 

June 22

Added more support braces to metal chassis. Rearranged electronics to make room for an intake and worked on autonomous cone slalom. One wire of a wheel motor tore off and needs to be replaced or repaired.

From yesterday’s few tests driving the rover at speeds above 25% the chassis seemed to bend inwards, especially with the new 8” inch wheels. So I designed braces that would go on the back section of the chassis and made a piece to link both L- support braces. 

While the supports printed I rearranged the electronics onto most one side of the chassis in order to fit the intake in the middle.

Since the next test date got moved to Thursday I had more time to try and get the rover to do the cone slalom autonomously. A majority of the time spent was adjusting values like what percentage of the cone should be on the screen before it stopped turning. 

I later decided after a couple hours of not much luck to switch over to dead reckoning. I had CodeX make me a program to record and replay inputs which worked semi consistently but varied a lot since I couldn’t start the rover in the exact same position. 

After running the dead reckoning multiple times I saw that one wheel wasn’t really spinning. I looked into this and realized that one of the 3 phase motor wires has come off the motor. I’ll try and repair it tomorrow but it may not be possible. So for Thursday the rover might just need to run off three motors

June 21

The slight shift of the hubs from the motor shaft was troubleshooted for the first half of the day. The second half was spent working on the autonomous slalom through cones, with it being able to go around one for now.

I started off the day by assessing what had gone wrong previously and found that I should focus on the wheels slipping off the motor shaft if I wanted the rover to clear the obstacle course and hill by Wednesday. I spent a lot of my time designing new hubs but I found that the main issue for why the hubs slipped off was that the Loctite on the screw holes had not dried yet. So I wasted too much time on this but I did learn how to make drawings to send to manufacturers. 

The second half of the day was spent using CodeX to make a program to go around the cone with a camera attached to the Raspberry Pi. A majority of this process was testing values like what percentage or where on the screen the cone should be in order to start turning. I was eventually able to get it to go around one cone but it would target the third cone in the slalom before the second one. I definitely want to work more on this tomorrow. 

Another task for tomorrow is designing and printing support braces for the aluminum chassis which saw some bending especially when turning. (I made the turning back to standard tank drive as the set screws were as big of an issue)

Rover V1

Features

- Metal Chassis

• The chassis is made up of .06-inch aluminum cut in 4 pieces and a central connector so that the position of the front two wheels can rotate when only one wheel drives over an obstacle. The back section is riveted together connecting the two L-channels with a top plate and pillow bearings and a shaft are used to connect the front and back section.

- Wheels

• The rim of the wheels are fully 3D printed and are modified GoBilda Rhino Wheels upscaled to approximately 5 inches in diameter. 3D printing allowed for the wheel to slide on easily as the modified hole would easily fit onto the shaft of the motor. Neoprene rubber was then glued onto the outside of the wheel to provide friction and grip when driving up a flat angled hill. Each wheel is directly connected to a motor.

-Power System

• The Raspberry Pi 5 is powered using a portable battery pack, while the motors are powered using a 14V 4S LiPo battery. Using a power splitter, all four ESCs, each connected to a motor, are connected to the Pi using a PCA9685 breakout board. The breakout board’s logic is powered by the Raspberry Pi.

-Software (Done completely by AI)

• The rover is controlled using the keyboard of a computer connected to the Raspberry Pi. It is currently configured to tank drive with configurable throttle by sending different signals to the ESCs.

-Housings

• Each electronic component has its own 3D printed housing with access to the necessary ports so that the pins do not directly touch the metal chassis.

Issues & Fixes

-The ESCs purchased are unidirectional and therefore the rover is not able to drive backwards and turning is really wide

• Bidirectional ESCs have been bought and should allow for a true tank drive

-Since the motors spin really fast, the inner part of the 3D printed wheel has loosened and now practically free spins on the motor shaft as the PLA is really weak and has shaved down.

• Metal hubs will be screwed into the new printed wheels so that it will not matter whether it shaves off some of the plastic due to the fast rotation. This will require reprinting the wheels with holes in them that align with the hub.

-Since the course is really dusty, the rubber on the tires picked it all up. This reduced the friction on the wheels and did not allow the rover to drive up a steep hill.

• New bigger treaded tires that have to be inflated and are made of a different material should lessen this issue. The inner rim would have to be remodeled to fit these new tires.

-The front U-shaped piece where the front two motors are attached is thin and flimsy, so the wheels bow out and affect the angle at which the wheel hits the floor.

• 3D printed brackets in the corners give stability to the chassis so that it does not bend.

Next Subsystem

-Intake & Outtake

• It will use multiple rows of rollers that push the balls further back into the rover where they will eventually funnel into a fast-spinning flywheel. This subsystem will be able to pivot using a motor in order to increase the angle at which the ball is launched at.

-Elevation

• This is still unconfirmed, but one possibility is using switchable magnets in order to climb on a magnetic pole. Another possibility is using a cascade lift attached to the pivoting intake to raise a hook and then pull itself up.