Using the Wait for Sensor block is the typically easiest way to use a sensor.  Note that Move Unlimited is used to make the robot drive an unknown distance until the sensor test triggers.

The main challenge when using a Loop like this is to make sure the sequence of actions is correct at the beginning and end of the loop, and also for the first and last time through the loop.  Note that an additional Move Unlimited block is used to cover all the cases here.

The LeftPivotAngle My Block is used for convenience, but another type of turn would be fine too.

Note that the Wait for Sensor (with Ultrasonic Sensor) block can be configured to test for something closer (less than) a certain distance, or farther (greater than), and both are used in this strategy.

Although somewhat harder to understand than the E3-MagicPush1 program, it is important to understand how this technique works, as it builds the foundation for more complex programs (such as the revisions below).  In particular, note that the loop in this version of the program is always repeating over 100 times per second, whereas the loop in E3-MagicPush1 only repeats once for each time the robot restarts from a stop. 

In most of the repetitions of the loop in this program, the robot will be "retold" to do the same thing it was told last time (go forward or stop), which may seem redundant, but this repetition has advantages in more complex cases.  In particular, the rapid repeating of the loop allows the program to add additional processing inside the loop that will get executed no matter what state the robot is in (moving or stopped) and won't get postponed because the program is stuck at a Wait block.

Understanding how to use the individual Sensor blocks (yellow colored blocks) and how they differ from the Wait for Sensor blocks (orange) is very important for more complex tasks.  Although they look similar and have similar configuration panels, note that the (yellow) Sensor blocks do not wait for the requested condition to become true, but rather just perform an instantaneous test of the condition and produce the Yes/No result on their data hub.  This allows a rapidly-repeating loop to keep repeating as fast as possible without waiting or anything.

Note that the Ultrasonic Sensor block produces both a Distance result (a Number in inches) and a Yes/No (Logic) result based on the threshold test built into the block, and both are used in this program.

The Distance result is only available from the individual Ultrasonic Sensor block, and it is also important that the block does not wait for a result, so that the loop can rapidly repeat and continuously update the motor power many times per second.

To use the program, put the robot in an open area on the floor away from furniture and other objects, and place an object that is large and tall enough to be seen by the ultrasonic sensor (a soda can for example) near the robot (no more than about a foot away), but not right in front of it.

Locating an object in an unknown direction and at an unknown distance is tricky with the ultrasonic sensor, because you don't know what specific distance to test for, and the ultrasonic sensor has a fairly wide field of view, so it will "see" an object before it is really pointing at it.  To try to solve these problems, the FindObject My Block attempts to scan for both the left and right "edges" of the object and then determine a center direction from that.

Note that once the difficult task of finding an object has been solved with the FindObject My Block, the result is easy to re-use in different programs.

If you place an empty soda can somewhere near Multi-Bot (about 5-15 inches away) at the beginning of the program,  Multi-Bot will usually be able to find it and shoot it down!

Ball Shooter Arm