MC 4213 – ROBOTICS
MODULE 7
Robot Control Systems
Learning Objectives
• Differentiate open-loop and closed-loop control.
• Explain feedback in a robotic system.
• Identify the role of encoders and other feedback sensors.
• Describe a basic control loop.
7.1 Basic Control Loop
A basic closed-loop system can be represented as: Desired Position → Controller → Actuator → Robot
→ Sensor → Feedback → Controller.
7.2 Open-Loop Control
An open-loop system sends a command without using feedback to automatically correct the result. It
may be simpler but cannot directly compensate for errors caused by disturbances or changes in the
system.
7.3 Closed-Loop Control
A closed-loop system uses feedback to compare actual performance with the desired result and adjust
the command. Encoders are commonly used to measure motor or joint position and sometimes speed.
Activity – Complete the Table
TABLE:Feature|Open Loop|Closed Loop Uses feedback|No|Yes Can automatically correct measured
error|Generally no|Yes Typical sensor feedback|Not required|Required Example|Timed motor
command|Position-controlled servo
Activity – Questions
1. Why is feedback useful in robotics?
2. Give one example of an open-loop system.
3. Give one example of a closed-loop robotic system.
4. What information can an encoder provide?
MODULE 7
Robot Control Systems
Learning Objectives
• Differentiate open-loop and closed-loop control.
• Explain feedback in a robotic system.
• Identify the role of encoders and other feedback sensors.
• Describe a basic control loop.
7.1 Basic Control Loop
A basic closed-loop system can be represented as: Desired Position → Controller → Actuator → Robot
→ Sensor → Feedback → Controller.
7.2 Open-Loop Control
An open-loop system sends a command without using feedback to automatically correct the result. It
may be simpler but cannot directly compensate for errors caused by disturbances or changes in the
system.
7.3 Closed-Loop Control
A closed-loop system uses feedback to compare actual performance with the desired result and adjust
the command. Encoders are commonly used to measure motor or joint position and sometimes speed.
Activity – Complete the Table
TABLE:Feature|Open Loop|Closed Loop Uses feedback|No|Yes Can automatically correct measured
error|Generally no|Yes Typical sensor feedback|Not required|Required Example|Timed motor
command|Position-controlled servo
Activity – Questions
1. Why is feedback useful in robotics?
2. Give one example of an open-loop system.
3. Give one example of a closed-loop robotic system.
4. What information can an encoder provide?
