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| What is the difference between the Motor block and the Move block? |
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The Motor block is designed to simply turn the motors on and off. You can input the duration of the motion (for example, how many rotations or how many seconds you want the motors to spin), but your robot may move slightly beyond its target. This overshooting can happen because the Motor block does not program the motors to slow down as they near their target duration.
The Move block programs the NXT to slow the motion of the motors and spin them precisely for the goal duration. The NXT monitors the motors' rotation sensors and slows the motors as they approach the target duration. This capability is helpful when you want a car to follow a specific track or to arrive exactly at a physical target that is a known distance away.
In the following example, Motor and Move blocks are placed in seemingly equivalent programs. Each program accomplishes the following:
• Uses one block that is configured to use the motor at Port B.
• Sets the motor to function in the forward direction.
• Configures the motor to run at 75% power for one rotation.
• Programs the block to wait for completion of the one rotation.
• Sets motor to prepare for braking as “Next Action”.
The motion produced by the Motor program is significantly different from the motion produced by the Move program. When the Motor program is executed, the motor spins for a bit more than one rotation and then returns to the exact one-rotation point. In other words, it overshoots and the corrects. When the Move program is executed, the motor spins for almost one full rotation, then gradually slows down until the one-rotation point is reached exactly. In other words, it slows on approaching the target and does not overshoot.
The Motor block is sufficient when a motor needs to be turned on and off, and you are not concerned with how the robot approaches a precise target. The Motor block is less appropriate for applications involving vehicles that need to drive straight or carefully meet a target. The Move block should be used to program precision movement.
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