The document proposes building a robotic arm that mimics human motion and is controlled by human movement. It describes the initial design of the arm in Autodesk Inventor with an elbow joint. Diagrams show how gear ratios and motors will allow the forearm to move up and down. The document also discusses a prototype ball and socket joint, omni-wheels, and potential applications for robotics.
9. Intro
Gear ratios use different sizes and
types of gears to change the speed and
torque.
10. Speed
With the same input speed
● Gears with more teeth (bigger) rotates proportionally slower because it takes more
teeth/rotation
● Gears with less teeth (smaller)rotates proportionally faster because it takes less
teeth/rotation
Therefore
● Speed in*Teeth in=Speed out*Teeth out or
● Speed in*(Teeth in/Teeth out)=Speed out or
● Speed in/(Teeth out/Teeth in)=Speed out or
● Speed in/Gear reduction=Speed out
(“Teeth out/Teeth in” is gear reduction)
11. Torque
Torque=Force*Distance so Torque in=Force in*Distance in or
Force in=Torque
in/Distance in
Force in is exerted on the gear out teeth so
Torque out=Force in*Distance out or
Torque out=(Torque in/Distance in)*Distance out or
Torque out =Torque in*(Distance out/Distance in) or
Torque out =Torque in*(Teeth out/Teeth in) or
Torque out =Torque in*Gear reduction
(distance is radius)
(radius is proportional to teeth)
14. What is a motor?
A machine, especially one powered by electricity or internal combustion, that
supplies motive power to a vehicle or a device with moving parts.
16. Motor Strength
● Motor strength comes from the motor’s rotation speed and
torque
● Depending on operating voltage, the stall torque can either be
25.5 kg x cm or 31.6kg x cm
● What this shows is how much weight a motor can hold when
it isn’t rotating
17. Our Motors
● The motor we selected has the strongest stall
torque within our budget.
● The resolution will help the arm mimic actions
precisely
● The motors will be light enough to attach to
the arm without weighing it down
18. Introducing the Omni Wheel
● Rotate like normal wheels
● Smaller wheels roll
perpendicular to rotational
axis
● Two degrees of freedom