What is cylinder?
Let's check out what's the definition of Cylinder Wikipedia has given.
"A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work. Cylinders may be sleeved (lined with a harder metal) or sleeveless (with a wear-resistant coating such as Nikasil). A sleeveless engine may also be referred to as a "parent-bore engine"."
The cylinder on RobotDigg's topic is a kind of linear module or linear actuator which are used for factory automation, motion simulator, etc industry. The most cheap option is the 12V brush motor cylinder, followed by brushless motor cylinder which are more reliable and higher torque option. Because it converts rotary motion into linear motion, so a cylinder is equal to linear actuator.
Stepper or servo cylinder
Brush or brushless DC motor cylinder or linear actuator can Not meet precise positioning request. To solve this problem a Captive Linear Stepper Motor is invented but for short stroke.
The stroke can Not be longer let's say 100mm because it's structure of direct connection. 50mm stroke forward means that it will have a 50mm backward drive lead screw rear shaft. Longer stroke of Captive Stepper Motor Linear Actuator is Not working or you could say it's Not a wise design and it's Not cost saving to develop.
Here it comes the stepper motor linear actuator or stepper cylinder
RobotDigg unique design stepper cylinder with integrated stepper controller
Stepper motor can satisfy precise positioning request in low speed, but for high speed and large torque applications, stepper motor can Not gap the needs, moreover servo motor production is growing fast especially after China factories getting involved into competition. Servo Cylinder can now be adopted broadly than ever before in China in industries, take Motion Simulator as example.
To end the topic of stepper or servo cylinder I want to start a discussion and please refer to the following picture.
"Is it a cylinder?"
"Stepper or servo motorized screw pump"
"It's cylinder in fact that which is used to carry the medium doing linear or vertical movement :-)"