FRA163 Catapult

FRA163 : Robotics Studio 1 , Science in Motion

Febuarary 2021 - March 2022

Eventually Finish!!! Spent a year for this project cause of COVID-19.

For my duty, I'm the one who design catapult's mechanism in tandem with circuit that include power supply and control circuit.

fra163_circuit_sch.pdf

About circuit, There're 2 circuit boards.

Board 1 : Power supply -> Need AC 16V for input and regulate VCC, 12V, 9V, 5V DC for output.

Board 2 : Main circuit -> Get input from 2 sensors, LDR and limit switch. When you push the botton, motor works. Until limit switch is pushed, motor stop and solenoid will work for seconds.

Altium designed with(student edition).

Available Now !!!

Gerber supply

Gerber main circuit

I with my teammates also code simulator program too. It's name is Catapult simulator. You can insert parameter such as angle, K-spring and let program calculate time,velocity,spring-range. You can save those results into file and/or simulate to graphic.

visit github

catapult_PCBV2.pdf

December 2021

We've started our catapult again(after COVID-19 pandemic). I designed control circuit PCBV2 which improved many-thing from V1 such as Low pass filter, relay new circuit, etc.

Everyday after DDCamp @ CU, I got back to FIBO to develop the catapult. Thanks to X2's fabulous idea, Transfer gearset, casset set onto alu profile makes it stronger and easier to calibrate than using acrylic plate.

After finish our Catapult, We shoot squash ball with different spring-pull length. We collect data and analyse the precision and accuracy.

During the shooting, We found many problems happened.

Latch length: During the spinning of gears, If latch go inside the gear with wrong position, Latch 'll be bounced out or stuck in the gear's tooth that disable solenoid to pull out. But in worse case, the catapult's ball holder'll be pulled down and slide back that cause the ball bounced out before shooting.
Motor's bracket: PLA bracket that stands the motor isn't strong enough. Motor's torque sometimes makes the bracket bent out from the accurate position. and It eventually break which disable machine to shoot again.
The bending of spring: We found this fussy problem that the shape of spring that whorl on the small pipe is also affects to the shooting target.

But one of the problem that makes our catapult not accurate and precise is.

The design of encoding gear: With the design that allows the Latch trigged while the encoding teeth is out from main gear. This make the catapult often can't shoot instantly after limit switch is trigged. To solve this problem, We might change ball launching concept to pull the encode gear out instead.

Testing Video

Mechanic works Video

Overall Pictures

Material Xplode

Lab Session

K-Spring Lab

Shooting Range & Position Lab

At first, We record trajection's video and analyse the velocity and position by using "Tracker". But later, we found that it's quite intricate. At final week before present, this method blinks up.

We use whiteboard pen smears on the table. We found that at position where the squash ball falls will be faded, we assume the range from the catapult to this fade as the trajection's range.

This makes measuring and setting easier and more accurate. Although it cause the table so mess.

Page updated

Google Sites

Report abuse