6. Actuators# 6.1. Overview 6.1.1. Types of Actuators 6.1.2. Motion 6.1.3. Communication and Control 6.2. Electric, Hydraulic and Pneumatic Actuators 6.2.1. Electric Actuators 6.2.2. Hydraulic Actuators 6.2.3. Pneumatic Actuators 6.2.4. Electrification of Hydraulic and Pneumatic Systems 6.3. Rotary Actuators 6.3.1. Stepper Motors 6.3.2. Servo Motors 6.4. Linear Actuators 6.4.1. Solenoids 6.4.2. Motor-Driven Linear Actuators 6.4.3. Rotary Motion to Linear Motion 6.5. Motion 6.5.1. Constraints 6.5.2. Degrees of Freedom (DOF) 6.5.3. Forward and Inverse Kinematics 6.6. Communication and Control of Actuators 6.6.1. Voltage Control 6.6.2. PWM Control 6.6.3. Digital Bus Control