{"id":6471,"date":"2019-10-19T14:38:15","date_gmt":"2019-10-19T18:38:15","guid":{"rendered":"https:\/\/dronebotworkshop.com\/?p=6471"},"modified":"2023-04-12T11:13:08","modified_gmt":"2023-04-12T15:13:08","slug":"analog-feedback-servo-motor","status":"publish","type":"post","link":"https:\/\/dronebotworkshop.com\/analog-feedback-servo-motor\/","title":{"rendered":"Analog Feedback Servo Motor"},"content":{"rendered":"\n

\"Download \"Parts<\/a> \"View<\/a> \"Download<\/a><\/p>\n

Today we will look at a special type of servo motor, an \u201cAnalog Feedback\u201d Servo.\u00a0 This type of servo motor has an additional connection that outputs the motor position. Interestingly, this motor can also be used as an input device.<\/span><\/p>\n

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Introduction<\/h2>\n

Servo motors<\/a> are pretty popular items here in the DroneBot Workshop. I\u2019ve used them in several projects and demonstrations, and have also produced an article and video that covers them in-depth.<\/span><\/p>\n

There is a very good reason for their popularity, both around the workshop and among hobbyists in general.\u00a0 Servo motors are inexpensive, have a great size-to-torque ratio and, most importantly, can be easily controlled with a great deal of precision.<\/span><\/p>\n

\"Analog<\/p>\n

But despite all of their virtues servo motors do have some limitations. They are essentially a \u201cclosed-loop\u201d system, so once you send them a command to move into a specific position you need to depend upon the servo motors internal controller to perform this accurately.\u00a0<\/span><\/p>\n

You have no way of easily determining a servo motors\u2019 actual shaft position, you have to assume that the servo has obeyed your command and is now resting where you want it to. This may not be true, especially if the motor has been subject to an external force.<\/span><\/p>\n

An Analog Feedback Servo Motor can resolve these issues.<\/span><\/p>\n

Analog Feedback Servo<\/span><\/h2>\n

An Analog Feedback Servo Motor is essentially a \u201cregular\u201d servo motor with an additional connection. This connection is an output from the servo motors internal potentiometer.<\/span><\/p>\n

To understand this a bit better let\u2019s take a look at how a \u201cregular servo motor operates.<\/span><\/p>\n

Regular Servo Motor Operation<\/span><\/h3>\n

A servo motor operates using what is sometimes called a \u201cclosed-loop\u201d system.\u00a0\u00a0<\/span><\/p>\n

\"Standard<\/p>\n

In this type of system, a microcontroller or other device is connected to the servo motors control input. A PWM (Pulse Width Modulation) signal is sent over this connection, the width of the pulse determines the desired motor position.<\/span><\/p>\n

This signal is sent to the servo motors internal controller. The controller drives the motor, which is a DC motor with a lot of gearing on its output shaft. Most servo motors limit the amount of rotation on the output shaft, usually to 180 or 270 degrees of rotation.<\/span><\/p>\n

The output shaft is also coupled to a potentiometer, which measures the shaft position. The output of the potentiometer is sent back to the internal controller, to let it know the position of the motor. The controller uses this information to move the shaft into the correct position.<\/span><\/p>\n

For the most part, this arrangement works pretty well, however, a few issues can arise:<\/span><\/p>\n