DELTA ROBOT Motor Selection

Motor Selection

Because of the wide variation of the motors types from DC to AC from Servo to Stepper, some Specifications-Limits must be specified and compare these motors and their specifications with them, which finally ended with comparing Servo Motor with Stepper Motor. These Specifications-Limits are:

 The acceptable holding torque.

 The speed of the motor in RPM6.

 Angular Positioning VS Linear Positioning.

 The complexity of the control circuit e.g. Micro-Stepping circuits.

Based on the above, Servo and Stepper motors features can be compared as shown in Table 3-10 

More Details about Servo Motors

A Servo is a small device that has an output shaft. This shaft can be positioned to specific angular positions by sending the servo a coded signal. As long as the coded signal exists on the input line, the servo will maintain the angular position of the shaft. As the coded signal changes, the angular position of the shaft changes.

Servo motors may be classified according to size or torque that it can withstand into mini, standard and giant servos. Usually mini and standard size servo motors can be powered by Microcontrollers directly with no need to external power supply or driver.

A typical Servo motor has 3 wires:

 Black wire: GND (ground).

 RED wire: +5V.

 Colored wire: control signal.

Advantages and Disadvantages of Servo Motors

Servo motors are used in many robotics applications, due to many reasons:

 Servo motors usually have a small size

 Servo motors have a large angular force (torque) comparing to their size

 Servo motors operate in a closed loop, and therefore are very accurate

 Servo motors have an internal control circuit

 Servo motors are electrically efficient – they required current is proportional to the weight of the load they carry.

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