Continuous Rotation Servo Motors and Arduino (Lesson #11)
Differences Between Continuous and Positional Servos
A continuous servo and a positional servo may look similar, but there are key differences between the two. In this article, we will explore these differences and discuss how to control a continuous servo using Arduino code.
Wiring Convention
When it comes to wiring, both types of servos usually have three wires – one for signal, one for power, and one for ground. However, the color coding convention for these wires may vary by manufacturer. For example, in the case of the servo being discussed in this video, the signal wire is orange, the power wire is red, and the ground wire is brown. It is important to consult the information provided with your specific servo to determine the correct wire connections.
Modified Example Code
In the previous video, we looked at an example code for positional servos. For the continuous servo, we will need a modified version of the same code. You can find the example code in the Arduino software by going to File > Examples > Servo > Sweep. In the modified code, we have removed everything from the loop function and only included a single write command in the setup function. This write command will continuously send a number to the servo, causing it to rotate at a constant speed indefinitely.
The Confusing Aspect
One confusing aspect is that the Arduino Servo Library uses the same code for both positional and continuous rotation servos, despite their different motion capabilities. This means that the same code can be used to control both types of servos. However, it is important to understand the differences in their behavior and adjust the code accordingly for the desired outcome.
Watch the Positional Servo Tutorial
If you haven’t already, it is highly recommended to watch the positional servo tutorial before diving into the continuous servo tutorial. This will give you a solid foundation and help you understand the basics of servo control using Arduino code. You can find the positional servo tutorial in the playlist linked in the description of this video.
While continuous and positional servos may appear similar, they function differently and require distinct code adjustments. By understanding the wiring conventions and the slight variations in code usage, you can successfully control a continuous servo using Arduino code. So, experiment with different speeds and directions, and enjoy exploring the capabilities of continuous servos in your projects.
Understanding Servo Motors and Positional Control
Servo motors are widely used in various applications, from robotics to electronics projects. They offer precise control over angular position, making them highly versatile. In this article, we will explore how positional control works for servo motors and some peculiarities you may encounter.
Positional Control with Servo Motors
When it comes to positional control, servo motors operate based on a specific range of numbers. This range typically falls between 0 and 180, where each number corresponds to an angular position in degrees. By sending a specific number, you can control the servo motor to reach a desired position.
Understanding Continuous Rotation Servos
Continuous rotation servos, however, behave differently from standard servos. Suppose we send a 180 to a continuous rotation servo; in that case, it will spin at full speed in a counterclockwise direction. Surprisingly, if we send a zero, instead of stopping, it will spin at full speed in a clockwise direction. This reversal of direction can be unexpected but is important to remember when working with continuous rotation servos.
Making a Continuous Rotation Servo Stop
To make a continuous rotation servo stop rotating, we need to send a number in the middle of the range, specifically 90. By sending a 90 to the servo, it will come to a halt and stay in its current position. However, it’s worth noting that there is a slight range to this stop position. Sending numbers slightly higher or lower than 90 may not result in an immediate stop or restart.
Potentiometer Control for Servos
One convenient way to control a servo motor is by using a potentiometer. A potentiometer can provide analog input, which can then be mapped to the servo’s positional range. By connecting a potentiometer to the servo and using example code like “Servo knob,” you can control the servo’s position in a smooth and precise manner. This can be particularly useful in projects that require continuous adjustment of the servo’s position based on real-time input.
Understanding Servo Control and Range
Servo motors are widely used in various electronic applications, such as robotics and automation. They are compact, versatile, and offer precise control over motion. However, when it comes to controlling servo motors, understanding their range and how to stop them correctly can be a bit tricky. In this article, we will dive into the details of servo control and range.
Exploring the Servo’s Range
Servo motors have a limited range of motion, usually spanning between 0 and 180 degrees. However, it’s important to note that the actual range may vary depending on the specific servo model. Nevertheless, we can still utilize the full range effectively by understanding how to interpret the values.
Stopping the Servo
Contrary to what one might expect, sending a value of 0 to the servo does not actually result in a complete stop. Instead, a value of 90 is needed to bring the servo to a halt. This may seem counterintuitive at first, but it is a crucial aspect to remember when programming the servo’s motion.
Mapping Variables for Intuitive Control
Often, we need a more intuitive range of control for our servo motor. Suppose you want to control the speed of your servo on a scale from -100 to 100, with 0 indicating a complete stop. In such cases, you can use the Arduino map function to map this range to the required 0 to 180 range.
For instance, by defining a variable called “speed” and applying the map function to it, you can convert the range -100 to 100 to the range 0 to 180. This allows you to easily control the servo’s speed by adjusting the “speed” variable accordingly. With this mapping in place, a value of -100 will correspond to full-speed rotation in one direction, while a value of 100 will indicate full-speed rotation in the other direction. A value of 0 will bring the servo to a complete stop.
Code Implementation Example
Let’s take a look at an example of how to implement this in your code:
“`arduino
Int speed = -100; // Set the desired speed between -100 and 100
Int mappedSpeed = map(speed, -100, 100, 0, 180); // Map the speed to the required range
Servo.write(mappedSpeed); // Send the mapped speed to the servo
“`
With this simple piece of code, you can easily control the speed of your servo motor using a more intuitive range while ensuring that a value of 0 corresponds to a complete stop.
Understanding how servo motors work in terms of positional control is crucial for effectively utilizing them in projects. Whether it’s working with standard servos or continuous rotation servos, knowing the specific number range and their corresponding behaviors allows for precise control. By exploring different methods of control, such as using potentiometers, you can further enhance the versatility and functionality of servo motors in your projects.
Understanding servo control and range is essential for utilizing these motors effectively in your projects. By keeping in mind that a value of 90 corresponds to a halt and using the map function to map variables to the appropriate range, you can achieve precise control over your servo motor. Remember to consult the documentation of your specific servo model for any peculiarities regarding its range and behavior. Now you have the knowledge to take your servo control to the next level!