Mechatronics and Robotics + Robotics, IoT and Hardware
Build a robotic arm with servo motors
Build a four-axis arm controlled by knobs, then record and replay a pick-and-place routine.
- DifficultyIntermediate
- Estimated time2–4 weeks
- Budget₹1,000–₹2,500
- ClassClass 10 to college
- Team2–3 people
- You needArduino required
Prerequisites: Arduino basics
Original · by TechnifyedArduino ProjectRobotics ProjectHardwareWell documentedTwo subjects
Overview
Four servos give a base rotation, shoulder, elbow and gripper. Potentiometers let you drive each joint by hand, and the Arduino can record the positions and play them back.
Why build this?
It combines mechanics, electronics and code in one desk-sized machine and is a popular exhibition project.
What you will learn
- How servos are positioned with PWM
- Why servos need a separate power supply
- How joint angles determine the gripper position
- How to record and replay motion
Skills you will use
Safety
- Use only batteries or a low-voltage supply (12 V or less). Never connect a project to a wall socket.
- Power tools and moving parts can injure. Use them only with training and supervision, wear eye protection and keep hair and sleeves clear.
Materials and tools
- Arduino Uno
- Four servos
- Four potentiometers
- Arm kit or cut acrylic or card parts
- 5 V supply rated for the servos
- Breadboard
Tools and software
Step-by-step roadmap
Start
You will finish with: a working arm with record and replay, and a video.
- 1
Prerequisites
Know this first: arduino basics. Then collect the 6 items in the materials list.
- 2
Learn
- How servos are positioned with PWM
- Why servos need a separate power supply
- How joint angles determine the gripper position
- How to record and replay motion
- 3
Plan
Sketch the design, list every part with its price and decide how you will know it works.
- 4
Build
- Sweep one servo and confirm its range.
- Map a potentiometer reading to a servo angle.
- Assemble the arm and attach all four servos.
- Power the servos from a separate supply with a common ground.
- Add a button that stores the four angles at each press.
- Replay the stored positions smoothly in a loop.
- 5
Test
The arm should repeat a pick-and-place ten times without dropping the object.
- 6
Document
Photograph each build stage, keep the circuit or drawing, and note what failed and how you fixed it. Report structure
- 7
Present
Demonstrate it working first, then explain how it works and what you would improve. Presentation structure · Viva questions
- 8
Publish
Share a short video, the parts list and the drawing or code so someone else can build it.
Expected outcome
A working arm with record and replay, and a video.
Other versions of this project
Beginner version
Control only two joints with two knobs.
Advanced version
Implement inverse kinematics so you give a position and the arm computes the angles.
Research version
Measure the repeatability of the gripper position over 50 cycles.
No-hardware version
Simulate the arm's kinematics in Python and animate it.
Make this project better
- BasicControl only two joints with two knobs.
- This projectBuild a robotic arm with servo motors
- AdvancedImplement inverse kinematics so you give a position and the arm computes the angles.
- ResearchMeasure the repeatability of the gripper position over 50 cycles.
Ways to do this project
Text marked "You write this" is a prompt for your own work; everything else is specific to this project.
- Research question
- You write thisOne question you can answer with data, narrow enough to finish in the time you have.
- Hypothesis
- You write thisWhat you expect to find, and why.
- Variables
- You write thisWhat you change or compare, what you measure, and what you hold constant.
- Methodology
- Measure the repeatability of the gripper position over 50 cycles.
- Data collection
- You write thisSay what you will record, how many times, and how you will keep the records safe.
- Analysis
- You write thisChoose the table, chart or test that answers the question; report averages with their spread.
- Limitations
- You write thisList what could have affected the result: small sample, instrument limits, things you could not control.
Literature review
Find five to eight sources (your textbook, review articles, reports) and note what each says about your question. Group them by idea, not one after another, and end with what is still not known.
References
List every source you used in one style throughout (author, year, title, where it was published, link and the date you opened it).
- Problem
- Four servos give a base rotation, shoulder, elbow and gripper.
- Target user
- You write thisOne specific person: who they are and when they would use this.
- Solution
- Build a four-axis arm controlled by knobs, then record and replay a pick-and-place routine.
- First version (MVP)
- Control only two joints with two knobs.
- Tech stack
- Arduino
- Architecture
- You write thisA quick sketch of the parts and how they connect.
- Demo
- The arm should repeat a pick-and-place ten times without dropping the object.
- Stretch goals
- Implement inverse kinematics so you give a position and the arm computes the angles.
Team roles
Plan by length
24-hour
- Hours 0–2: agree the problem, the user and the one thing the demo must show
- Hours 2–16: build only the first version
- Hours 16–20: test the demo path end to end and fix what breaks
- Hours 20–24: slides, a 2-minute demo script and a backup recording
48-hour
- Evening 1: problem, user, sketch and task split
- Day 1: first version working end to end
- Day 2 morning: one stretch goal and testing
- Day 2 afternoon: polish, slides and demo practice
1-week
- Day 1: research the problem and talk to two possible users
- Days 2–4: first version
- Day 5: stretch goals
- Day 6: testing and write-up
- Day 7: demo video and presentation
Working as a team
2–3 people. Suggested roles:
Report and presentation
Report structure
- Title and aim
- The problem it solves
- How it works (principle)
- Parts list with cost
- Design: drawing, circuit or block diagram
- Build steps
- Testing and results
- Problems faced and fixes
- Limitations
- Future improvements
- References
Presentation structure
- The problem
- The idea
- How it works (one diagram)
- Parts and cost
- The build (photos)
- Live demo or video
- Test results
- What did not work
- Next version
Viva questions
Try answering before you open each one.
Why a separate supply for servos?
Servos draw large currents that would reset the Arduino.
What is inverse kinematics?
Calculating the joint angles needed to put the gripper at a chosen point.
What are degrees of freedom?
The number of independent movements; this arm has four.
What limits its accuracy?
Servo resolution, gear backlash and flex in the links.
Resources
Source and attribution
Original
Written by Technifyed. Free to use for your own school or college project; write the report in your own words. Added 1 Oct 2026.
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