Its internal gearing provides a high torque power pack in a small and inexpensive package. Continuous Rotation Servo MotorsĪ standard analog servo motor is constricted in its rotation, usually to 180 or 270 degrees (180 is by far the most common). However the accuracy of potentiometers, especially in low cost servo motors, can affect the overall accuracy of the servomechanism. This works well as these servos typically travel 180 to 270 degrees, well within the range of a potentiometer. On some industrial and high-end hobby servos this is done using an optical interrupter disc, but in most standard hobby servo motors the sensor is a potentiometer. In order to function properly the servo motor needs a sensor that can accurately measure its shaft position. The motor itself is a simple DC motor with a lot of gearing to slow down its speed and to increase its torque. In the analog servo motors we will be working with that control signal is a PWM signal whose pulse width determines the angle the motor shaft is to be positioned at. It then moves the motor into the required position. It is fed a signal that indicates the position that the shaft should be set to. The servomechanism uses a sensor to monitor the motor shaft position and a controller to control the motor. How do Servos Work?Ī servo motor is a motor with a built-in “servomechanism”. The Arduino has a number of PWM capable output pins, making it ideal for controlling servo motors. It can be sent over a single wire or transmitted on a radio or light beam. It can be generated by a simple timer circuit or with a microcontroller. Analog servo motors respond to a Pulse Width Modulation or PWM signal to position their motor shaft. The “analog” part of the analog servo motor is the control signal. Perfect when you need a tiny high-torque motor that can be accurately positioned and that won’t break the bank. Analog Servo MotorsĪnalog servo motors are inexpensive and available in a variety of sizes and ratings. They use the same PWM control signals as analog servo motors and can be controlled using the same circuitry and code. It should be noted however that while we won’t be working with digital servo motors today they are really very much like their analog counterparts. Mounting hardware is also very easy to find as these servos are of a standard set of sizes. We will be using plain ordinary analog servo motors, the most popular type for hobbyist use. We will NOT be working with these types of motors either, although the hookup and code used to drive them with an Arduino is identical to what we will use for our analog servos. Hobbyist servo motors are generally DC motors that can be controlled with either a digital or analog signal.ĭigital servos are used in applications that require quick responses like the elevator on an aeroplane or the rudder on a helicopter. We will NOT be working with industrial servo motors today! Industrial servos are often AC motors with digital control inputs that cost hundreds or thousands of dollars. Servos are used in industry as well as in hobby applications. Types of Servo MotorsĪ servo motor is essentially a motor that has an input for a control signal that is used to specify the position of the motor shaft. Servos can also be used as analog gauges like speedometers and tachometers. They are really useful in robotic work to position cameras, sensors or robot appendages. This arrangement with a single signal makes it simple fo servos to be used in radio and remote controlled designs, as well as with microcontrollers.Ī servo is perfect if you need to position the rudder on a boat or the elevator on an aeroplane. Instead it is limited to a range of 180, 270 or 90 degrees.Ī control signal is sent to the servo to position the shaft at the desired angle. Unlike the DC and Stepper motors the Servo Motor does not normally spin a full 360 degree rotation. There is another type of motor that we have used in many of our experiments but have not (yet) taken a detailed look at – the Servo Motor.Ī Servo Motor is a low-speed, high-torque motor that comes in a variety of sizes. They are widely used in printer and robotics designs. This type of motor has its shaft driven in discrete steps, allowing for very precise control. We built a couple of robotics projects that are based upon DC motors and we also took an extensive look at the H-Bridge Controller that is commonly used to regulate the speed and direction of a DC motor with a microcontroller or microcomputer.Īnother type of motor we’ve worked with is the stepper motor. We have worked with basic DC motors a few times.
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