After meeting with the family, we identified the main goal of the project, which is to design a mechanism that will assist with getting in and out of a pool. To achieve this, we conducted a brainstorming session to generate ideas that could be incorporated into the design. The primary focus of the project is to provide the client with a controlled pool lift that enables them to enter and exit the pool with ease.
With the help of this project, a child who is unable to enter or exit a pool will be able to sit in an adjustable chair. The chair will also assist them in entering and exiting the pool so she can enjoy her time like other children and will raise them from the pool to the waiting area. Due to necessary medical equipment such as them ventilator, the surface of the water should only reach up to them chest. The limited length of the tube connecting them to the their ventilator will also be accounted for.
While we may not be able to fulfill all of the necessary wants, we can do our best to fulfill some of them.
We researched various existing concepts of pool lift devices and saw different good parts and flaws with each, namely the lack of independence on the user’s part. We also checked on the previous team’s project and ideas so we can build off their designs, and will hopefully meet with them to discuss what they had planned but were unable to finish.
A basic MotionGen Pro model was created to figure out how the child in and out of the pool. Three rigid links and two linear actuators connect to a stationary “pole” (the ground for the mechanism) and enable a single degree of freedom to get in and out of the pool.
Motion Type: servo motor, hydraulic
Torque Rating: The most critical factor is the torque rating of the servo motor. we need a servo motor with enough torque to lift 300 pounds.
Speed: we need to consider the speed at which the lift operates. Ensuring the servo motor can provide the required speed without sacrificing torque.
Environmental Factors: Since this is a pool lift, we will need to take into account the wet and potentially corrosive environment.
Power Supply: Ensure that their power supply can deliver the required voltage and current to operate the servo motor effectively.
This is a simple design where the deck base hangs from the wooden deck via latching mechanism. It’s all rigid and immovable.
This idea is similar to a Smith Machine in adjustability. Two vertical bars with adjusting holes will stand in the pool, rigidly attached to the deck via locking mechanism. Each bar will have a slider with a pin in it. A deck is attached to the sliders. When the deck is folded up, the sliders are free to move up and down with the deck; when the deck is folded down to the desired height, the pins push through the adjusting holes to lock everything in place. This helps the entire mechanism adjust to the child’s growing height as well as easy dismantling for wintertime.
We selected Design 3 due to its ease of manufacturing and its fulfillment of the desired requirements for the client, especially its ability to adjust to the client’s height as they grow.
Design three will be made of stainless steel to limit deviation and prolong lifespan. It will be coated in a water-resistant material to prevent rusting and water damage. A hinge and spring will make the locking mechanism work.
The design uses T-slot extrusions as the holders and railing. We used a rod thought the holder that would hold the base. We would use a pool safe surface on the bottom of the holder to prevent damage to the pool. The base is made of extrusion frame and plastic lumber to last in water. With the parts assembled, the project is able to hold up to 600 lbs without issue.
Stress Analysis and Deviation of the individual parts with 220 lbs of force on each individual part. The visual deviation model greatly exaggerated to show relative deviation – true deviation is in the micrometers, showing how much the base and holder will deform. With this we decided to make a frame with aluminum and use plastic lumber as the main flooring.
After testing and some recommendation from the shop workers, we decided on removing the rod and adding side holders instead. They would be 45 degree right triangles that would hold the base to the vertical rails. It would be made of aluminum and 0.25 in thick.
After doing the analysis, we noticed that we wanted a more stable base frame, so we switched the base frame to T slots. A 1.5in by 1.5in was strong, but didn’t have the needed strength to meet our torque requirement. We decided on 3 in by 1.5 in for the main holder, a 6.5 ft holder, and 1.5 by 1.5 for everything else.
Creating this pool lift was a lot more difficult than anticipated.
We ordered almost all of our parts online, but we had to buy the wood composite for the platform from Lowe’s in-person – it turns out they didn’t have the wood they said they did in the first place, so we had to buy more than anticipated. However, as we were building, we realized we bought the wrong pitch of thread of a certain screw type and had to buy a different set.
The aluminum frame of the deck itself was fairly simple to assemble – take two 4ft T-slot extrusions and four 2ft T-slots to create a rectangular frame with support. However, there was a slight bend in one of the 4ft T-slots that made it appear the other one was half an inch “longer” than it needed to be, so we had to cut that a little.
The planks were cut in half to fit the frame, then sanded down to make rounded edges. The initial drill holes into the planks to connect them to the aluminum frame were incorrectly measured, so we had to pull the frame in slightly to accommodate. The funny bend helped.
There was a 1/2 inch cut along the length of two of the planks to make the width shorter, but a final overhang was nice. We rounded out the edges some to smooth it, and then a little more to make it look nicer. Once bolted into the metal frame, we painted them pink.
Doing a proper test on the build is difficult as the part needs to be bolted to the deck to be properly checked. the build without the bolt in the deck can over 170 lb, but it wobbles quite a bit.
Make sure the side blots in the triangles are put in and are tightened properly.
Rated for maximum weight of 200 lbs.
To make sure the pool isn’t damaged, put the side pool noodles on the back of the holder.
The project had to be adjusted many times for additional safety and adjusting to availability of parts. Making the holes for the bolts on the base and using many sliders was also a bit of an issue due to improper measuring. We ran into a few problems while making cuts in the plastic lumber which made it difficult to adjust properly, but we got it done eventually. The lumber on the bottom was hard to get attached, but it was connected pretty well. The system when assembled but not bolted to the deck leans forwards.
The client, while appreciative of our work, is not wanting to receive the project as it doesn’t meet their needs right now. Hopefully the next group can build off our design or at least find inspiration to help fulfill the client’s needs.
