Continuous Servo Movement Panel

How to use the Continuous Servo Movement Panel robot skill

This movement panel controls two continuous servos, which have continuous rotation. Unlike a Standard Servo, a continuous servo has its internals changed to allow continuous 360° rotation. The two parts that are removed from a standard servo to create a continuous rotation servo are:

1. Mechanical Stop: The spindle will stop if you attempt to rotate a standard servo further than 180 degrees. That is due to a mechanical stop built onto the output gear within the servo. Continuous servos have that stop removed.
2. Potentiometer: The potentiometer in a standard servo records the position of the output gear. A potentiometer can only rotate to the physical limits of the internal wiper. When the potentiometer is removed (or replaced with resistors), the circuit does not know its position, and therefore the ability to specify positions is gone.

Two continuous rotation servos are great for moving your robot. Attach wheels directly to the servos and watch it go! Rather than using a standard DC Gear Motor, a continuous servo provides you with greater speed rotation accuracy. Due to the variety of servo attachments, continuous servos make great movement motors for wheels and tractor treads.

This skill operates like the other movement panels and can be controlled by scripting or other skills that interact with it. Movement Panels are skills that move your robot forward, reverse, left, and right. The Movement Panel directions can be modified by other skills, such as camera, voice, script, joystick, and radar.

Main Window

1. Movement Panel
These buttons will allow you to control the directional movement of the entire robot (left, right, forward, reverse, and stop).

2. Speed Sliders
You can select the speed of the servos with these sliders. Be aware that the speed range is (0-100%) and the default setting is 0% (OFF). These sliders can allow you to adjust for one servo being faster than the other. Note that not all continuous servos support speed selection.

Settings

1. Title Field
This field contains the title of the skill. You can change it if you'd like.

2. Left Servo Port Drop-down
This drop-down selects the digital port that your Left continuous servo is connected to.

3. Left Servo Forward/Reverse/Stop Value Drop-downs
These drop-downs select the movement values for the Left Servo. A 180-degree signal causes the servo to move forward. A 1-degree signal causes the servo to move backward. The stop value for most continuous servos is 90 degrees.

4. Test Buttons
These buttons test the Left Servo Forward/Reverse/Stop values without returning to the main window.

5. Use Checkbox
This checkbox is unchecked by default and means that a PWM signal will stop being sent to the servo when the Stop button is pushed. If checked, this checkbox will make the stop button use the stop value of the servos. This is advantageous if you'd like your robot to break instead of coast to a halt instantly. Analog continuous servos tend to drift away from their stop value over time, so leaving the checkbox unchecked is beneficial.

6. Right Port Drop-down
This drop-down selects the digital port to which your Right continuous servo is connected.

7. Right Servo Forward/Reverse/Stop Value Drop-downs
These drop-downs select the movement values for the Right Servo. A 1-degree signal causes the servo to move forward. A 180-degree signal causes the servo to move backward. Notice that this is the opposite of the Left servo. The right servo is usually mounted in a mirrored configuration from the left. The stop value is 90 degrees.

8. Test Buttons
These buttons test the Right Servo Forward/Reverse/Stop values without returning to the main window.

How to Use Continuous Servo Movement Panel

1) Physically connect the two continuous servos to an EZ-B.

2) Add the Continuous Servo Movement Panel Skill to your ARC project (Project -> Add Skill -> Movement Panels -> Continuous Servo Movement Panel).

3) In the Settings menu, select the ports you connected the servos to (D0 & D1, for example).

4) In the main window, press the direction buttons to move your robot. If the directions seem reversed, you can swap your motors from each side or swap the ports in the settings menu.

Video

Requirements

• 1 x EZ-B I/O Controller
• 2 x Continuous Servos

Resources

Read more about how Movement Panels work here.

View the Servo Tutorial for technical details of how servos work.