Move Tank

The move tank block controls 2 motors at a time in sync, just like the move steering block. If the robot is built like a car or tank, (like the pictures shown below) with the two motors attached to wheels, this block will definitely come in handy. Just like the medium motor and large motor tutorials, you can code this block to move however many rotations/degrees/seconds you want, but instead you can move two motors at a time instead of just one.

Move Steering Block

Standard EV3 Two-Motor Driving Robot

http://robotsquare.com/2013/10/01/education-ev3-45544-instruction/

Standard EV3 Two-Motor Tank Robot

https://education.lego.com/en-us/support/mindstorms-ev3/building-instructions

Even though the move tank block has the word "tank" in its name doesn't mean this block can only be used to control a tank-like robot. All blocks can control any type of robot, even though they may be more useful for a certain type of robot or has the type of robot in its name. These blocks just have different inputs depending on how you want to control your robot. Also note that a standard robot is classified by having two regular wheels under the Brick and a trackball in the back of the robot to keep it from falling backward. A tank robot is classified by having tank treads on both sides of the Brick.

Tutorial

When you drag the move tank block to the screen it should look like this:

Just like the move steering block, there are six main components to this block. The first one is the little circle with a "#" symbol in the middle.

When you mouse over this spot, it will turn blue and say "On for Rotations". This tells you what mode the block is set to. There are five modes: Off, On, On for Seconds, On for Degrees, and On for Rotations. These options tell the two selected motors what to do when the program is run. Each option tells the motors to do something completely different, and each one is important when programming your robot.

"Off"- This option turns both motors off and locks them in place
"On"- This option moves the motors forward at a given speed. To control how long they are "On" for, put this block inside a loop block
"On for Seconds"- This option spins the two motors at a given speed for the number of seconds you type in
"On for Degrees"- This option moves both motors forward or backward depending on how many degrees you want them to turn. Just like the other options in this list, the motors spin at a given speed
"On for Rotations"- This is the default setting when you first drag the block into the workspace. This option spins the two motors a complete 360 degrees for every rotation you type in. For example, if you type in 3 rotations, the motors will move a total of 1080 degrees forward. As usual, the motors will spin at a given speed

The second and third main components to this block is the two speed options. One controls the left motor and the other controls the right motor. To tell which motor either speed input controls, hover over the speedometer as shown in the pictures below. Look at the box in the top-right corner of the picture shown above with the "B+C". The speedometer that controls the left motor will control the port to the left of the plus sign, or the "B". The speedometer that controls the right motor will control the port to the right of the plus sign, or the "C". These two speed inputs lets you change the speed of both motors, while only using one block. The default value for both the right and left speeds is 75.

To change the speeds, (or powers) click one of the 75's. It will highlight itself, and then you can change it to any number between -100 and 100. Another way to change the speed is by using the slider bar underneath the number. The line in the middle of the slider indicates 0, or no power. If you change the power to 0, no matter what number you type in for the rotations, degrees, or seconds box, the motor that you changed the speed to will not move.

As a default, the two motors will always spin forward. To make any motor spin backward, set its power (speed) to a negative number. For example, if the speed is 75 and you want on of the motors to move backward at the same speed, change its speed to a negative, or -75. This tells the motor to spin backward at a speed of 75.

The fourth main component to this block is the rotations/degrees/seconds. Each time you change the menu to a different option, (besides on and off) this component changes, as seen below.

This option, "On for Rotations" changes this box to a value of 1 when you first select this option. Changing this number will change how many times the motors spin a complete 360 degrees. For example, if you type in 4 for this box, the two motors will spin forward 1440 degrees. Changing this box to -4 rotations will make the them spin backward 1440 degrees.

Note: You can also change this block to a decimal if you don't want the two motors to spin a complete 360 degrees. For instance, setting the block to 2.25 rotations will make the motors spin 810 degrees. (2 full rotations and one fourth of a rotation)

This option, "On for Degrees" changes this box to a value of 360 when you first select this option. Changing this number will change how many degrees the motors spin. For example, if you type in 270 in this box, the motors will spin forward 270 degrees. Changing this box to -270 degrees will make the motors spin backward 270 degrees.

This option, "On for Seconds" changes this box to a value of 1 when you first select this option. Changing this number will change how many seconds the two motors spin for. For example, if you type in 6 in this box, both motors will spin forward for 6 seconds.

Note: You cannot change the seconds to a negative number. If you do, it will just change into 0, and the motors will not spin. To make them spin backwards, change the speed to a negative number instead.

Another way to make the two motors spin backward is by changing the rotations or degrees (not the seconds) into a negative number. For example, if you set the move steering block to 180 degrees, the motors will spin forward 180 degrees. By changing this value to -180 degrees, the motors will spin 180 degrees backward. However, do not change the rotations or degrees to a negative number and change the speed to a negative number, as these negatives will cancel each other out and the motors will continue spinning forward.

The fifth main component to this block is the brake box. (It's the box with the check mark) This tells the two motors if they should slow to a stop when they are done completing the number of rotations/seconds/degrees inputted or just brake and come to a complete and sudden stop.

To change whether or not the motors come to a slow or a sudden stop, click inside the box with the check mark in it. The drop-down menu will show you two options, like the image to the right. The first is the default option, the immediate, sudden stop. (The check mark) The second option in the list is the slow stop with the two triangles, one gray, and the smaller one, red. (The "X" mark) Once you select one of the two options, it will automatically update the block and will tell the two motors whether or not to come to a sudden stop or a drifting stop.

The sixth and final main component to this block is the port. This is the box with the capital "B+C" in the top right corner of the block. This box tells the Brick (the brain of the robot) which port the two motors are plugged into. The motors can be plugged in port A, B, C, or D, but the default ports for the large motor are ports "B" and port "C", "B" for the left motor, and "C" for the right motor.

To tell the Brick what port the two motors are plugged into, click the "B" in the rectangular box, or click the "C" in the box, depending on what motor you want to change the port to. Clicking the "B" will change the left motor or whatever motor is plugged into port B. Clicking the "C" will let you change the right motor or whatever motor is plugged into port C. The block will automatically update, and tell the Brick what port the two motors are plugged into. Don't worry about the port with the square shape right now, but it will be explained later on in this tutorial. If you click a port that either motor is not plugged into, either the motor that's port is incorrect will not spin and the program will freeze, or it will spin any other motor that is connected to the port you selected.

These six components are all you need to know in order to program the two motors to spin as long as you want and in any direction, either forward or backward, and at different speeds if necessary. Click the previous button at the bottom of this page to go back to the previous tutorial. You can also use the menu button at the top-left corner of the screen to jump straight to any tutorial or page you select.

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