In Project Collision, I am creating a system to deliver portable charger by drones. The drone will release the package from a height up to 10 meters and my job as an engineer is to develop a solution so that the package is protected during the fall.
For Drop 0, a package with the dimensions of 13x9x8 was dropped from a height of 5 meters . Below is a photograph of the package:
The package held a stapler for drop 0. But, our final product will hold a portable charger. Inside, items are organized like this:
drop 0 package
The purpose of Drop 0 is to get baseline data about our package. The group developed a testing procedure so that we can be consistent on how data is collected throughout the design cycle.
- Secure product
- Prepare the box at 5-meter point, (make sure the bottom of the box is at the 5-meter point.)
- Line the package up at the silver line
- Turn force plate and cameras on
- Start logger pro
- Make sure no one is standing in drop area
- Talk to partner when ready to drop
- Drop the box while starting the timer
- Once the box hits the target stop the timer, camera and logger pro
- Take a picture of data on logger pro
- Airdrop videos from camera to computer
- Check the condition of box and the inside
- Repeat procedure for at least 3 times
- Record data in data table
During the drops I noticed that the package accelerated extremely fast because nothing was really there to slow the speed down. Most importantly, the package smashed down and bounced a bit at the end resulting in damaging the package a bit on the outside. Despite speed being one of our metrics, we do not want it to damage our package or drop down like a rocket.
The average time it took for our package to fall the 5 meters was 466 centimeters/second. Using Logger Pro, we plotted out the fall of the package.
A force plate at the bottom of the drop was used to collect data on the impact force of the package. Our group was pretty successful at hitting the target. We dropped our package four times and we were spot on with hitting the target every time. However, the force of the impact changed dramatically every time. I think this occurred because each time, the package might have hit the force plate at a different angle which resulted in different force.
First drop of Drop 0
As a project metric for accuracy, we want to design a package that can land within 30 centimeters within a target similar to a force plate (this package would be dropped from a distance of 10 meters).
The force on impact of our first time dropping was 138.5 N. As a project metric, our group aims to reduce the amount of force excerted on our package by 40%.
Our team has decided that the three most important criteria to design towards are accuracy, soft landing, and speed
Below, each metric is described and the goals were determined by data from Drop 0.
Our first metric is accuracy, and by that we mean the landing is somewhere around the area that we expect it to land. From drop 0, our accuracy were spot on. Using the force plate as our target, we were able to hit it successfully every time. However, for the final drop, our goal would to have a landing 30 centimeters around a target similar to the size of the force plate.
Our second metric is having a soft landing. We do not want our product to end up being broken or smashing down onto the ground, so a soft landing is needed. For our drop 0, there was a large range from 18.1N to 257.5N. Our goal would be to let the landing be somewhere from 50N to 130N.
Our final metric is speed. No one wants to wait 30 minutes for a portable chargers to land and be delivered. So, we want to have speed and to let our parachute drop down quickly. This doesn’t necessarily mean that the package has to accelerate super fast but we don’t want to let the package hover too much in the air. Our final goal will be to let there be a landing around 2-3 seconds.
Our group is now building the first prototype. I hope that our parachute can successfully slow the speed down for a soft landing. But at the same time, I do not want the parachute to glide and drift around which can lower our accuracy and speed.