This is an early draft, need to define the weight of pib, motor torques and speeds
In this document, we outline the features and capabilities required for the knee of pib, our humanoid robot. By understanding these requirements, we can determine the appropriate transmission ratio and method of transmission to ensure effective movement and stability.
...
The knee should be able to achieve a bending angle of at least 135°. This range of motion is critical for the robot's ability to perform everyday activities, such as squatting, standing up, and walking with stability and balance.
Torque Calculation
The knee experiences its maximum static torque when pib is in the lowest possible squatting position. Assuming that the knee can bend to the maximum angle of 135°, the torque in this position can be calculated using the following formula:
...
Θ is the angular displacement (135° or 2.36 radians)
t is the time (1 second)
Thus:
ω = 2.36 rad/s
We should assume that the dynamic speed for balancing is higher than for the same as the "static" movements. Assuming a factor of 3, the maximum speed of the knee should be 7. 08 rad/s
Transmission Ratio
The motor alone cannot generate such a high torque directly; therefore, a transmission mechanism is required to increase the torque output. However, increasing torque via transmission comes with a trade-off: it reduces the rotational speed of the knee joint proportionally to the transmission ratio.
...
State | Torque Knee (Nm) | Torque Motor (Nm) | Speed Knee (rad/s) | Speed Motor (rad/s) | Transmission Ratio (r) | Power |
|---|---|---|---|---|---|---|
Static | 72.6 | To be determined | 2.36 | To be determined | To be determined | 0.171 |
Dynamic | 435.6 | To be determined | 72.08 36 | To be determined | To be determined | 31.084028 |