Question

Our problem was to create a durable, comfortable to wear, controllable, and has a good grip strength prosthetic hand that young, active individuals can use that must be functional (at least 3 of the 5 fingers have to move), using only one piece of string, using low-cost material (such as cardboard, rubber bands, pencil, scissors, tape, etc.), has to have a mechanism, and that can be secured onto your hand. Some criterias and constraints that guided our build was that there had to be a good grip strength strong enough to hold the cup/can but not too strong to damage the cup/can. It had to be comfortable to wear so that it could be worn for a long time. It had to be durable so that it could stay consistent during the tests and it had to be controllable so that we could actually perform the experiments given. We could also only pull on one piece of string to move our build. It had to be made of lost cost material so it could be more accessible to people. It had to be secured onto the hand so that it could actually move. It had to be functional so that it could actually work on the experiments and it had to have a mechanism so that the fingers could move. The first prototype that we decided to go with was similar to our created design of B. It was the most comfortable as it could be utilized by anyone and it had room to be able to move accommodating in long term usage. It is also the most controllable as it has extra bends assisting in the usability of the hand itself. Although it's not the best in terms of grip strength as it can’t be closed completely it can definitely be used as a cheaper version of a prosthetic because it can perform most easy tasks. It’s also not perfect in the sense that it's not that the most durable but that can easily be fixed with either tape or rubber bands. The rubber bands on the fingers also assist with friction having a greater grip strength. This prototype unfortunately failed very badly so we decided to build a whole new model which was different from all of our previous brainstormed designs. We changed the fact that we now didn’t have a thumb as we didn’t need one in the first place as we realized that the thumb was more of a bother rather than helping with the build. We also made all the fingers the same length so that it could be easier to build as well as assisting with the grip onto the cans. We added tape so that the pencil could stick to the hand rather than us having to pick it up as that is easier. We also added a handle to assist with the grip. The last thing that we changed was to put the strings in the back so that there would be more of a support when we picked up the can/cup in the first place and it also assisted with the picking up and placing portions of the build. We also just knotted all the strings and pulled all instead of just one so that there would be a higher force when we were holding the challenges. We tested our prosthetic hand by completing the 5 tasks given to us: picking up a tennis ball, lifting and placing a cup, grabbing a soda can half full of water, tilting the water into the cup and throwing the can away, and writing with a pencil. During the first round of testing, the design failed most tasks which is mostly because the fingers only moved about half an inch and were unable to even grip the object. After making improvements like moving the strings to the back and knotting the strings together to increase the force produced, the second round of testing showed major improvements. The prosthetic successfully picked up the ball, cup, the soda can, tilted and poured water without spilling water. Writing was still difficult, but securing the pencil with tape helped it so it could be completed. One unexpected result was that the thumb was more of a bother than it helping with the reliability and control of the prosthetic. Our original design struggled because the thumb kept getting in the way of gripping, the fingers were different lengths, and the string didn’t provide enough force to pull the hand close in the first place. Through testing, we learned that consistent finger movement mattered more than having a thumb, so we removed it and made the fingers the same length for better balance. rephrase this sentence in 10th grade sentences

Answer 1

Our project goal was to build a low-cost prosthetic hand that is durable, comfortable, controllable, and has good grip strength for young, active users. The hand had to move at least three fingers, use only one piece of string to operate, be made from cheap materials (cardboard, rubber bands, pencils, tape, etc.), include a working mechanism, and be secured to the user’s hand. Important constraints were that the grip be strong enough to hold a cup or can but not damage it, the device be comfortable for long-term wear, and it be durable and controllable for testing.

Our first prototype was similar to one of our earlier designs (design B). It was the most comfortable, allowed room for movement, and had extra bends that made it easier to control. However, it could not close fully and had weak grip strength. It also was not very durable, although tape and rubber bands could improve that. Rubber bands on the fingers helped increase friction and grip. Because this prototype failed badly in testing, we made a new model with several major changes.

We removed the thumb, since it got in the way, and made all the fingers the same length to simplify construction and improve balance. We added tape to secure a pencil, attached a handle for better grip, and moved the strings to the back of the hand to give more support when lifting objects. Instead of pulling a single string, we knotted all the finger strings together and pulled them at once to increase the closing force.

We tested the prosthetic on five tasks: picking up a tennis ball, lifting and placing a cup, grabbing a half-full soda can, tilting the can to pour water into a cup and throwing the can away, and writing with a pencil. In the first round of testing, the fingers only moved about half an inch and the design failed most tasks. After moving the strings to the back and knotting them together, the second round showed big improvements: the prosthetic lifted the ball, cup, and can, poured water without spilling, and could write when the pencil was taped in place.

A key unexpected result was that the thumb was more of a hindrance than a help. We learned that consistent, even finger movement mattered more than having a thumb, so we removed the thumb and made the fingers the same length to improve grip and reliability.