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Task #1:
Qualitative: Our hand was barely able to hold the tennis ball as it either only held the ball for a small duration or the ball just rolled off the table due to being unable to pick it up. We had no successful throws.
Attempting to hold this object caused several pieces to fall off our hand such as straws and tape coming undone.
Quantitative: Across our 5 trials, the average duration we were able to hold the tennis ball before it fell was about 1 second. Our success rate for throwing in the bucket was 0% because we couldn't throw at all.
Task #2:
Qualitative: We were able to successfully hold and transfer the cup to the table on all of our trials. There was some difficulty in attempting to initially grab the cup and some tape and straws came undone.
Quantitative: Across our 5 trials, we had a 100% success rate in transferring the cup. The average time it took to complete the task across the trials was about 18 seconds.
Task #3:
Qualitative: We were barely able to lift the soda can as it was too heavy for our prosthetic and the can kept slipping. Thus we were never able to pour any liquid into the cup. During this task, several pieces like tape, string, and straw came undone from the heavy strain created from gripping the can.
Quantitative: Across our 5 trials, we had a 0% success rate with pouring any of the liquid out of the can.
The average height across our trials, that we were able to lift the can above the ground, was 1/2cm.
Task #4:
Qualitative: We were never able to transfer the empty can into the trash can. We were either unable to lift it up because it was too slippery or it was pushed off the table and knocked to the ground in the process of grabbing. During this task, several pieces like tape, string, and straw came undone from the heavy strain created from gripping the can.
Quantitative: Across our 5 trials, we had a 0% success rate with throwing the can in the bin. The average number of seconds, based on our trials, that we were able to grab before it fell was 0.8.
Task #5:
Qualitative: We weren't able to grip the pencil at all as it was too small. This led to us never being able to write anything with the pencil on the paper.
Quantitative: Across our 5 trials, we had a 0% success rate with writing the word "Hi" on the paper. The task took on average 12 seconds to fail as a result of the pencil rolling off the table.
All Answers 1
Answered by
GPT-5 mini
AI
I can help with this in several ways — e.g., polish into a lab-style results & discussion section, make a concise table, produce conclusions and concrete design fixes, or propose follow-up experiments. Which would you like?
Below I’ve provided a short polished summary of your results, a diagnosis of likely failure causes, prioritized design fixes, and a suggested plan for follow-up tests you can run.
Short polished summary
- Task 1 (tennis ball): Could hold only very briefly or not at all; parts (straws, tape) detached. Average hold time ≈ 1 s; 0% success throwing.
- Task 2 (cup transfer): Consistently successful — transferred cup on all 5 trials. Some difficulty picking up initially; minor tape/straw failures. 100% success; mean time ≈ 18 s.
- Task 3 (soda can pour): Could not pour. Can was too heavy and slipped; parts (tape, string, straw) came undone under load. 0% success; mean lift height ≈ 0.5 cm.
- Task 4 (empty can throw): Unable to get can into bin; slipped or knocked off table. 0% success; mean grab duration ≈ 0.8 s.
- Task 5 (pencil writing): Couldn’t grip small pencil; pencil rolled off. 0% success; mean time to failure ≈ 12 s.
- Overall: 1 task fully successful (cup) out of 5; overall success rate 20% (5 successful trials out of 25).
Likely causes of failure (diagnosis)
- Insufficient grip force and/or poor force distribution — heavy/slippery objects (cans) slip, tennis ball not held.
- Low friction of contact surfaces (straws/tape) — slips and short hold times.
- Structural weakness of the hand assembly — taped/straw elements come undone under load.
- Poor opposing surface or lack of a true thumb/pinch — small-diameter items (pencil) cannot be pinched securely.
- Lack of wrist rotation or controlled wrist DOF for pouring tasks.
- Fingertip geometry not matched to object shapes (round objects, small cylinders).
Concrete prioritized fixes (quick → more involved)
1. Improve contact/friction (high impact, low effort)
- Replace tape/straws on gripping surfaces with high-friction pads: silicone rubber, foam, or bicycle inner-tube rubber.
- Add textured fingertip material or rubber CAPs to increase grip area and shear friction.
2. Increase and stabilize grip force / mechanical advantage
- Improve tendon routing or increase actuator power/lever arm to raise normal force.
- Add a passive elastic preload (spring) that maintains light pinch force without active input, reducing slippage when actuators are off.
3. Add opposing digit or improve thumb geometry (medium effort)
- Introduce a stable opposing surface or a simple opposing thumb to permit true pinch grips for small objects (pencil).
- Re-shape fingertips to better cradle round objects (concave pads for cans and balls).
4. Reinforce structure & attachments (low effort)
- Replace tape/straw structural elements with stronger fasteners or use epoxy/glue, zip ties, or small screws where possible.
- Rework joint bracing so loads don’t peel off attachment points.
5. Task-specific attachments (low–medium effort)
- Add a cup/gripper insert for cups, a clamp for cans, or a pencil holder insert for writing tasks.
- Consider a detachable “pouring adapter” or wrist-rotation module for task 3.
6. Add passive compliance
- Compliant fingertips (soft pads) conform to shape, increasing surface area contact and reducing local stress that causes slippage.
Suggested follow-up experiments / protocol
- Standardize trial setup: same object positions, same initial hand state, same operator. Increase trials (e.g., 10 per task).
- Record for each trial: success/failure, hold time until slip (s), time to complete (s), number and type of structural failures, notes on how slip occurred (rotation/translation).
- Measure peak grip force (if possible) or document actuator torque settings used.
- After each design change (e.g., add rubber pads), run the full task set and compare:
- Success rate per task
- Mean and standard deviation of hold times
- Number of component failures
- Video record trials for qualitative analysis.
Quick sample plan for next iteration
1. Replace gripping surfaces with rubber/silicone pads and reinforce all taped joints with glue/zip ties. Test all 5 tasks (10 trials each).
2. If slips persist for cans and ball, increase actuator tension or change lever geometry to increase normal force and re-test.
3. Add opposing thumb and concave fingertip inserts; test pencil and pouring tasks again.
4. If pouring still fails, add wrist rotation or two-step transfer (hand places can on table, second mechanism tips it).
If you want, I can:
- Turn your existing text into a polished lab-results + discussion section (ready for a report).
- Put the results into a compact table for presentation.
- Produce a step-by-step build-change list and parts/material recommendations.
- Generate a test protocol (checklist) and sample data table for re-testing.
Which would you like me to do next?
Below I’ve provided a short polished summary of your results, a diagnosis of likely failure causes, prioritized design fixes, and a suggested plan for follow-up tests you can run.
Short polished summary
- Task 1 (tennis ball): Could hold only very briefly or not at all; parts (straws, tape) detached. Average hold time ≈ 1 s; 0% success throwing.
- Task 2 (cup transfer): Consistently successful — transferred cup on all 5 trials. Some difficulty picking up initially; minor tape/straw failures. 100% success; mean time ≈ 18 s.
- Task 3 (soda can pour): Could not pour. Can was too heavy and slipped; parts (tape, string, straw) came undone under load. 0% success; mean lift height ≈ 0.5 cm.
- Task 4 (empty can throw): Unable to get can into bin; slipped or knocked off table. 0% success; mean grab duration ≈ 0.8 s.
- Task 5 (pencil writing): Couldn’t grip small pencil; pencil rolled off. 0% success; mean time to failure ≈ 12 s.
- Overall: 1 task fully successful (cup) out of 5; overall success rate 20% (5 successful trials out of 25).
Likely causes of failure (diagnosis)
- Insufficient grip force and/or poor force distribution — heavy/slippery objects (cans) slip, tennis ball not held.
- Low friction of contact surfaces (straws/tape) — slips and short hold times.
- Structural weakness of the hand assembly — taped/straw elements come undone under load.
- Poor opposing surface or lack of a true thumb/pinch — small-diameter items (pencil) cannot be pinched securely.
- Lack of wrist rotation or controlled wrist DOF for pouring tasks.
- Fingertip geometry not matched to object shapes (round objects, small cylinders).
Concrete prioritized fixes (quick → more involved)
1. Improve contact/friction (high impact, low effort)
- Replace tape/straws on gripping surfaces with high-friction pads: silicone rubber, foam, or bicycle inner-tube rubber.
- Add textured fingertip material or rubber CAPs to increase grip area and shear friction.
2. Increase and stabilize grip force / mechanical advantage
- Improve tendon routing or increase actuator power/lever arm to raise normal force.
- Add a passive elastic preload (spring) that maintains light pinch force without active input, reducing slippage when actuators are off.
3. Add opposing digit or improve thumb geometry (medium effort)
- Introduce a stable opposing surface or a simple opposing thumb to permit true pinch grips for small objects (pencil).
- Re-shape fingertips to better cradle round objects (concave pads for cans and balls).
4. Reinforce structure & attachments (low effort)
- Replace tape/straw structural elements with stronger fasteners or use epoxy/glue, zip ties, or small screws where possible.
- Rework joint bracing so loads don’t peel off attachment points.
5. Task-specific attachments (low–medium effort)
- Add a cup/gripper insert for cups, a clamp for cans, or a pencil holder insert for writing tasks.
- Consider a detachable “pouring adapter” or wrist-rotation module for task 3.
6. Add passive compliance
- Compliant fingertips (soft pads) conform to shape, increasing surface area contact and reducing local stress that causes slippage.
Suggested follow-up experiments / protocol
- Standardize trial setup: same object positions, same initial hand state, same operator. Increase trials (e.g., 10 per task).
- Record for each trial: success/failure, hold time until slip (s), time to complete (s), number and type of structural failures, notes on how slip occurred (rotation/translation).
- Measure peak grip force (if possible) or document actuator torque settings used.
- After each design change (e.g., add rubber pads), run the full task set and compare:
- Success rate per task
- Mean and standard deviation of hold times
- Number of component failures
- Video record trials for qualitative analysis.
Quick sample plan for next iteration
1. Replace gripping surfaces with rubber/silicone pads and reinforce all taped joints with glue/zip ties. Test all 5 tasks (10 trials each).
2. If slips persist for cans and ball, increase actuator tension or change lever geometry to increase normal force and re-test.
3. Add opposing thumb and concave fingertip inserts; test pencil and pouring tasks again.
4. If pouring still fails, add wrist rotation or two-step transfer (hand places can on table, second mechanism tips it).
If you want, I can:
- Turn your existing text into a polished lab-results + discussion section (ready for a report).
- Put the results into a compact table for presentation.
- Produce a step-by-step build-change list and parts/material recommendations.
- Generate a test protocol (checklist) and sample data table for re-testing.
Which would you like me to do next?
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