Parts of a Robot: Controller, Manipulator, End Effector, Sensor
Science & Technology › Materials Science, Nanotechnology and Robotics · Topic 15.7
A robot has five main parts. The controller is the brain, a computer that stores the program, processes sensor data and sends commands. The manipulator is the arm, made of links and joints that move the end effector through space. The end effector is the tool at the end of the arm, such as a gripper, welding torch, spray gun, suction cup or surgical instrument. Sensors give the robot information about itself and its surroundings, for example position encoders, cameras, force sensors, proximity sensors and gyroscopes. Actuators, such as electric motors, hydraulic or pneumatic cylinders, produce the movement, and a power supply drives all of them. Together they form the sense, think and act loop of every robot.
5 min read · UPSC Prelims · Science & Technology · Materials Science, Nanotechnology and Robotics
At a Glance
- Brain Controller
- Arm Manipulator
- Tool End effector
- Senses Sensors
- Muscles Actuators
- Exam link UPSC Prelims, Science & Technology: Materials Science, Nanotechnology and Robotics
Where Does It Fit?
This topic follows the account of robot terms and laws. It opens up the robot into its components, which then helps to understand the classification of robots and their uses. Previous topic: Robotics: Terminology and Laws of Robotics. Next topic: Classification of Robots: Rolling, Walking, Autonomous Robots.
What Are the Main Parts of a Robot?
| Part | Function |
|---|---|
| Controller | The computer or microcontroller that holds the program, reads sensors and sends commands to actuators. It may use artificial intelligence to learn and decide |
| Manipulator | A chain of rigid links connected by joints. It positions the end effector. The first three joints set position and the last ones set orientation |
| End effector | The device at the wrist for the job, either a gripper that holds objects, or a tool such as a welding gun, paint sprayer, drill, laser or scalpel |
| Sensors | Measure the state of the robot and the world. Internal sensors measure joint angles and speed, and external sensors measure force, touch, distance and images |
| Actuators | Electric motors including servo and stepper types, hydraulic cylinders for heavy loads, pneumatic cylinders for fast light tasks |
| Power supply | Batteries, mains electricity or hydraulic pumps |
| Software | Programs for kinematics, path planning, vision and safety |
What Types of Joints, Grippers and Sensors Are Used?
- Revolute joint: rotates about an axis like an elbow
- Prismatic joint: slides in a straight line like a piston
- Arm geometries: Cartesian, cylindrical, spherical, articulated and SCARA, according to the type of joints
- Grippers: mechanical fingers, vacuum suction cups, magnetic grippers and soft grippers
- Position sensors: encoders and potentiometers measure joint angle
- Proximity and range sensors: ultrasonic, infrared and lidar detect distance to objects
- Tactile and force sensors: give a sense of touch and allow gentle handling
- Vision: cameras with image processing for recognising objects and guiding the arm
What Else Should You Remember?
- Wrist: the joints near the end that allow orientation of the tool
- Base: fixed or mobile platform on which the robot stands
- Servo motor: a motor with feedback that holds an exact position
- Stepper motor: moves in fixed steps, useful for simple positioning
- Hydraulic drive: high force, used in heavy machines such as excavators
- Pneumatic drive: uses compressed air, cheap and clean but less precise
- Gyroscope and accelerometer: give balance and motion data, as in smartphones in Smartphone Technology and Related Concepts
- Lidar: light detection and ranging, which maps the surroundings with laser pulses
- Feedback control: the controller compares the actual movement with the target and corrects it
- Open loop and closed loop: without or with feedback
- Teach pendant: a handheld unit to program an industrial robot by moving it
- Programming: by teaching, by offline simulation or by high-level languages, as in Computer Languages and Generations of Computers
- Singularity: an arm position where it loses a degree of freedom
- Safety systems: emergency stops, light curtains and force limits
- Robot hand: multi-finger hands copy the human hand and are an active research area
- Exoskeleton: a wearable robot structure that supports or boosts human movement
- Edge computing: processing on board the robot to reduce delay
- Torque and gearing: gear boxes and harmonic drives raise torque at the joints and give precise movement
- Tool changers: a quick coupling lets one arm switch between several end effectors
- Battery and power: mobile robots depend on battery capacity, so energy use limits working time
- Proprioception: sensors that tell the robot where its own limbs are, like the sense of body position in humans
- Calibration: regular checks keep position sensors and cameras accurate
- Sensor fusion: combining data from several sensors gives a more reliable picture than any one sensor alone
- Maintenance: joints, belts and cables wear out, so regular servicing keeps accuracy
Why Does It Matter for the Exam?
- Parts: controller, manipulator, end effector, sensor
- Joints: revolute versus prismatic
- Drives: electric, hydraulic, pneumatic
- Current affairs link: humanoid hands and soft grippers
- Common errors: saying the end effector is the base or that the controller is a sensor
As an analytical point, better sensors and controllers matter more than strong arms for useful robots today. A robot’s skill depends on how well it senses, plans and handles uncertainty.
Why Is This Topic Important?
- Parts Brain, arm, tool
- Joints Types
- Sensors Senses
What Came Next?
The next topic covers the classification of robots: rolling, walking and autonomous. Next topic: Classification of Robots: Rolling, Walking, Autonomous Robots.
Key People and Terms
- Controller Robot brain
- Manipulator Robot arm
- End effector Tool at the arm end
- Actuator Motion producer
- Revolute joint Rotary joint
- Encoder Angle sensor
Exam Corner
Points to Remember
- Controller = brain; manipulator = arm.
- End effector = hand or tool.
- Revolute joint rotates; prismatic slides.
- Hydraulic drive gives high force.
- Six axes can place a tool in any pose.
Do Not Confuse With
- Manipulator and end effector Arm versus tool
- Sensor and actuator Input versus output
- Revolute and prismatic Turning versus sliding
Memory Hook
Brain controls, arm moves, hand works, sensors tell, actuators act.
Mains Angle
Questions ask for parts and their functions. These points help.
- Parts Five components
- Joints Types
- Trend Better sensing
A Question You May Face
An original practice question, not a past paper question.
“Describe the main components of a robot and the role of each in its working.”
How to Answer
- Parts Controller, arm, tool.
- Senses Sensors.
- Drives Actuators.
- Loop Sense, think, act.
GS Relevance
Frequently Asked Questions
What are the main parts of a robot?
The main parts of a robot are the controller, which is its computer brain, the manipulator or arm of links and joints, the end effector or tool at the arm's end, the sensors that give information, the actuators that produce movement, and a power supply. Together they let the robot sense, think and act.
What is an end effector?
An end effector is the device attached to the end of a robot arm that interacts with the work, like a hand or tool. It may be a gripper, a vacuum suction cup, a welding torch, a paint sprayer, a drill or a surgical instrument, and it is changed according to the task.
What is the function of a robot controller?
The controller is the robot's brain. It holds the program, reads data from sensors, calculates the movements needed and sends commands to the actuators, correcting errors through feedback. In advanced robots it also runs artificial intelligence software for vision, planning and learning.
What types of sensors do robots use?
Robots use internal sensors such as encoders and gyroscopes to know the position and motion of their own parts, and external sensors such as cameras, lidar, ultrasonic and infrared range finders, touch and force sensors to learn about the environment. Combining several sensors gives better and safer perception.
What is the difference between revolute and prismatic joints?
A revolute joint rotates around an axis, like an elbow or knee, while a prismatic joint slides along a straight line, like a piston. The choice and arrangement of these joints decide the shape of the robot arm and the region it can reach.
PYQ Practice — Statement Analysis
1 The end effector is the tool at the end of a robot arm.
Such as a gripper.
2 A prismatic joint rotates about an axis.
It slides; revolute rotates.
3 The controller of a robot acts as its brain.
It processes sensor data.
4 Hydraulic actuators are used for heavy loads.
They give high force.
Past Mains Questions on This Topic
This topic comes under Materials Science, Nanotechnology and Robotics. UPSC Mains questions asked on the matching syllabus topic, year-wise with marks:
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