When are hydraulic actuators used instead of electric motors in robots?

Hydraulic actuators are utilized in robotic and industrial applications when there is a requirement for high-force, straight-line motion or when the system must produce greater power than electrical systems of an equivalent size.1

While electric motors are common, hydraulic power systems are preferred in specific scenarios due to their distinct advantages:

• Force Multiplication: Hydraulic systems are highly efficient at multiplying forces, making them ideal for heavy-duty tasks where significant mechanical output is necessary.12
• Power Density: They can produce more power than mechanical or electrical systems of equal size, allowing for compact designs in high-power applications.1
• Flexibility and Control: Hydraulic systems offer greater flexibility and provide rapid, accurate responses to control inputs, which is essential for complex machinery.12
• Specific Motion Requirements: Linear hydraulic motors (cylinders) are specifically utilized when an application requires high-force, straight-line motion, whereas rotational hydraulic motors are used when high torque is required for rotary motion.1

These systems are standard in environments where heavy industrial machinery, construction equipment, or precision control of large loads is required, as they effectively convert pressurized fluid into mechanical work.12