6.5. Exercise: Actuators

Question 1

Summarise electric, hydraulic, and pneumatic systems in terms of force, speed, precision, complexity, maintenance, cleanliness, and cost.

Solution

System	Force	Speed	Precision	Complexity	Maintenance	Cleanliness	Cost
Electric	Medium	High	High	Low	Low	Clean	Low–Medium
Hydraulic	Very high	Medium	High	High	High	Risk of oil leaks	High
Pneumatic	Low–Medium	High	Low–Medium	Medium	Medium	Clean, but dry air is needed	Low–Medium

Explanation

Electric systems are clean and precise, but they are not as powerful as hydraulic systems. Hydraulic systems can produce very high force, but they are more complex and can be messy because of oil leaks. Pneumatic systems are fast and relatively simple, but they are usually less precise.

Question 2

You are building a small mobile robot that must carry lightweight parts around a workshop. It will run from batteries, and it must be able to start, stop, and steer accurately and reliably.

For this situation, would you select an electric, hydraulic, or pneumatic actuator? Explain your choice.

Solution

Solution is locked

Question 3

You are designing a small 3D printer that must accurately move its print head to exact positions along the X and Y axes. The print head does not encounter much resistance, but it must be positioned precisely and repeatably.

For this situation, would you select a stepper motor or a servo motor? Explain your choice.

Solution

Solution is locked

Question 4

You are designing an automatic door lock that must quickly push a bolt in and out to lock or unlock a door. The motion only needs to move a few centimetres and does not need to stop at intermediate positions.

For this situation, would you select a solenoid or a motor-driven linear actuator? Explain your choice.

Solution

Solution is locked