 |
 |
Are you tired of having your robot not stop where it's supposed to? Do you crave a degree of robotic control that always seems just out of your grasp? Do high monthly checking fees have you singing the blues?
Well, we can't do anything about your checking account, but we can help you with those pesky robot control problems. With the NEW AND IMPROVED RIS 2.0, you can make robot drift a thing of the past. Interested? Of course you are, so read on... |
|
 |
As one of the new features in RIS 2.0, you can control whether the motors brake or coast during a program, which is actually very useful. Here's why....
If you write a program that ends with a Forward command, you should notice that your robot rolls to a smooth, gradual stop. The robot is actually coasting for a little while after the power to the motors is shut off. This is similar to when you let your bike roll to a stop rather than applying the brakes.
Most of the Big Block commands like Forward, Backward, Spin, etc., are set to let the motors coast so that your robot does not stop suddenly once a command ends. If the motors did not coast, your robot would jerk between commands. However, coasting can cause a problem when you want your robot to stop in an exact location. To avoid this problem, you can tell the RCX to brake when you want it to.
To do this, add an Off command immediately after the Forward command. Use the edit tab to set the command to "brake" rather than coast. This will lock the motors immediately after the Forward command and bring your robot to a full stop. Check out the diagram to see the difference. You can also use the Stop command instead of the Off command to do the same thing.
|
|
 |
|
 |
|
 |
|
Stupid Robot Trick
If you are really fascinated by the whole coasting vs. braking issue, here's a little trick that any real RCX pro should know.
Take your robot and try turning any of the wheels that are attached to a motor while the RCX is off. You should be able to spin them easily and hear the gears inside the motor winding as they turn. If you spin them fast enough, the motors will keep turning the wheels for a few seconds before running out of momentum. If you have a Roverbot, you can even push it on the floor and make it coast for a little while.
When the RCX is off, the motors are set to "coast." By this we mean that the motors are free to turn with out any resistance beyond the natural friction in the motors and gears. It's like putting a car in neutral.
Now turn the RCX on and run one of the built-in programs, like program 2. Press Run again to stop the program, but leave the RCX on. Now try turning the wheels. This time you should note that the motors are much harder to turn. This is because the RCX has closed the circuit leading to the motors, acting like an electronic "brake." If you try pushing the Roverbot while the motors are set to brake, you should notice a big difference. |
|
 |
|
 |
|
|
|
|
|
|
|
|
