We will introduce a convention, an agreement, how and in which cases we are going to use each types of blocks.
- 28 Apr 2017
When to use Steering block
What kind of a turn is going to happen if you adjust Move Steering Block to 25% ? No one knows for sure and it will be a different arc for different robots.
The percentage value of the steering setting means nothing to a person, so we will not use it at all.
We use Steering block only for forward and backward movement!
When to use Tank block
We can control the power of each motor in this block and we will use it for spin turns (equal power, different directions) and for arc turns (same direction, different power).
When to use Large Motor block
Large block controls only one motor and it will be used for pivot turns (one motor is stopped and one motor turns the robot).
So far we've looked at 3 different blocks for controlling the motors. The Large motor block, the Tank block and the Move steering block. And now it's a good opportunity to discuss the difference and when to use each of these blocks. The rule is very simple and in this course and most of the other resources that you see at fllcasts.com we have this rule. You use the Steering block only for moving forward and backward. Yes, it is called Steering block but you use this block only for moving forward and backward. You use the Tank block for turning - spin turn, arc turn. And you use the Large block for pivot turns. So, 3 blocks, 3 different ways to use them. Steering block - move forward, move backward. Tank block - arc turn, spin turn. Large motor - pivot turn. Why? Let's look at the program and we'll discuss why we do this. First, the Steering block. If you drag and drop the Steering block, you'll see that it has only one setting for power. And when you have only one setting you can just drag and drop this block, set the power and it will just move forward or backward depending on the value of the power. This is much easier than using the Tank block for moving forward because in the Tank block you have 2 different settings for power. For power to the left motor and to the right motor. So, we just use the Steering block for moving forward not for steering. Yes, it is called steering but we don't use it for steering. In the Steering block the first arrow that you see it's the steering option. With this option you can move to the right or to the left. And this will make the robot steer to the right or to the left. And this will make an arc turn. What's important for this option is that when you use this option you don't have a lot of control of how the robot moves. You just set a value of let's say 10 and it will do some kind of an arc but you have little to no control of what kind of an arc and how exactly it turns. That's why we don't use the Steering block for steering. We use the Tank block when we know the two values. We can also use the Tank block and the Large motor block for turning and for pivot turns. For example, if I take the Move tank block, we can set the power of one of the motors to 0 and this will stop motor B and it will be just motor C working. So, it's a pivot turn. And we can do a pivot turn with the Tank block. But since we want to control only one of the blocks
it is much more clear to use the Large motor block where it is clear that we are controlling only one of the motors not the two motors. Because here we see in the Tank block we have motor B and motor C. And one of them is with power 50 and the other is 0 and it's much more difficult to understand the program than to just use the Large motor block where we set motor B - 50 a number of rotations and the other motor will not be working. Last thing we need to discuss is the Tank block. And with the Tank block you can do two types of turns. You can turn in an arc or you can do a spin turn. And we saw the spin turn - we set one of the powers to 50 and the other to -50. This will make the two wheels rotate in opposite directions and this will make the robot spin. But if you set one of the wheels to a power of 30 and the other to a power of 50, this will make the robot move in an arc. And we can control this arc because we have two values. We can control the power of the inner motor and the power of the outer motor. Let's just run the program and see how it works so that you get the idea. I'll set this to rotate with power of 70 and this with power of 30.
The robot with the Tank block does an arc turn where the inner wheel, the left wheel is turning with the power of 30 and the outer wheel, the right wheel is turning with the power of 70.