Hello,
I have done some torque tests. But the results are quite underwhelming.
I have tested with a load cell and a fish scale. With different currents and different lever arms - all with the same kind of result:::
From the formula: 8.3*(Current)/(Kv)*6. (the *6 coming from the gearbox that was used)
I should have gotten about 50%more torque. For example, at 30A the torque should be 11.5NM (See graphs below of my testing - one plot is current compared to torque the other one is the power in watts at that current)
Other people that I found for example:
OpenTorque Actuator Test (developed by Gabrael Levine) - YouTube (at 12:00min)
came very close to the calculated value.
Setup:
- Motor: Eaglepower 8308 Brushless Motor 130kv
- Encoder: AS5047P
- Battery: Li-Ion 5S(running 21V to 15V) and continuous max current 80A
- Controll USB
Do you have any idea what the problem could be? I also tested Without the gearbox and got the same result with a small margin of error.
Note on testing: For the load cell I just commanded a position about a half turn further then the load cell would let the lever arm go. For the fish scale I just pulled while the motor was in closed loop control.
I also tested different control loop tuning parameters with no difference at max torque.
Thanks a lot for you ideas!