NXT Motors
De WikiEAFIT
This motor is specific to the NXT set (2006).
Includes a rotation encoder, returning to the position of the shaft with 1° resolution.
Because of the special connector of this motor (non-standard phone plug type), a cable adapter is required to drive this motor with regular 9V sources.
The NXT motor is not recommended for use with a RCX which can't deliver the high current that this motor can consume.
Slow rotation speed, minimizing the need of external gear train.
[editar] NXT Motor Data
| Voltage | Torque | Rotation Speed | Current | Mechanical Power | Electrical Power | Effiency |
|---|---|---|---|---|---|---|
| 4,5 V | 16.7 Nm | 33 rpm | 0.6 A | 0.58 W | 2.7 W | 21.4 % |
| 7 V | 16.7 Nm | 82 rpm | 0.55 A | 1.44 W | 3.85 W | 37.3 % |
| 9 V | 16.7 Nm | 117 rpm | 0.55 A | 2.03 W | 4.95 W | 41.0 % |
| 12 V | 16.7 Nm | 177 rpm | 0.58 A | 3.10 W | 6.96 W | 44.5 % |
The curves below shows NXT motor rotation speed (Rotations per Minute) vs. motor power level (supply duty cycle). Motor not loaded, 9V NXT power. Most noticeable here is the linear relationship between power level and motor speed. Much more practical than what we got with RCX where unloaded motor ran almost full speed at power level 2. Since there is no load to overcome, Power Control would have no effect here.
Motor not loaded, but this time the NXT is powered at 7.2V (what you get with NiMH batteries). Of course, rotation speed is proportionally lower.
Motor behaviour with a 11.5 N.cm load applied, no Power Control, 9V NXT power. Below 40% motor is stalled (horizontal region of the curve). Once enough power is applied, speed increases proportionally.
Motor loaded with a 11.5 N.cm, 9V NXT power. This curve shows the efficiency of Power Control: up to 70% the speed is the same as an unloaded motor. After that the curve is flat, the motor is actually running at full power. Note that motion as 10% was very irregular, even if average rpm is OK.
Motor loaded with a 11.5 N.cm, 7.2V NXT power. Up to 50% the speed is the same as a no-load, 9V powered motor (and actually faster than a 7.2V powered motor without Power Control!). The plateau appears at a lower duty cycle, since there is less energy available.
