Mechanical · Agricultural machine · Final year project
Variable Head Solar Grass Cutter Weed Trimmer Robot
A solar-powered robotic grass cutter with an adjustable cutting head. Ultrasonic sensors guide it around the lawn, and it charges itself from a solar panel without fuel.
What is the Variable Head Solar Grass Cutter Weed Trimmer Robot project?
A solar-powered robotic grass cutter with an adjustable cutting head. Ultrasonic sensors guide it around the lawn, and it charges itself from a solar panel without fuel.
Key facts
- Branch
- Mechanical & Automobile Engineering; also suits Mechatronics, Instrumentation
- Type
- Final year project · Advanced
- Suitable for
- Diploma capstone and B.E / B.Tech final year
- Build time
- 6 to 8 weeks
- Estimated component cost
- ₹15,600 – ₹22,900
- Guidance from
- ₹9,999 (Hardware / IoT Final Year)
How the Variable Head Solar Grass Cutter Weed Trimmer Robot works
- The mild steel frame and fabrication forms the base that carries every other part, so it is designed first from the load and size of the machine.
- The DC geared motor provides the driving motion.
- The Motor driver lets the low-current controller run the motors forward, reverse and at variable speed.
- Motion is transmitted through DC geared motor and ball bearings with housing, which set the speed, torque and direction at the working end.
- The Wheels / castor wheels allow the machine or vehicle to move.
- The Ultrasonic sensor measures distance to an obstacle or a liquid surface using sound echoes.
Block diagram
Power
DC geared motorMotor driverSolar panelTransmission
DC geared motorBall bearings with housingWorking unit
Wheels / castor wheelsStructure
Frame and mountsComponents list and cost
Typical prices from Indian online stores and electronics markets (Lamington Road, Budhwar Peth, SP Road). Buy from one store where you can to save on shipping.
| Component | Qty | What it does | Approx. cost |
|---|---|---|---|
| Ultrasonic sensor (HC-SR04) | 1 | Measures distance to an obstacle or a liquid surface using sound echoes. | ₹90 |
| DC geared motor | 2 | Provides the driving motion. | ₹500 |
| Motor driver (L298N) | 1 | Lets the low-current controller run the motors forward, reverse and at variable speed. | ₹180 |
| Solar panel (10–20 W) | 1 | Converts sunlight into electricity to power or charge the system. | ₹900 |
| Charge controller module | 1 | Charges the battery safely and stops overcharging. | ₹250 |
| Rechargeable battery (12 V 1.3–7 Ah) | 1 | Stores energy and supplies power when mains is absent. | ₹650 |
| Mild steel frame and fabrication | 3 | Forms the main structure that holds all parts. | ₹7,500 |
| Wheels / castor wheels | 4 | Allow the machine or vehicle to move. | ₹1,600 |
| Ball bearings with housing | 1 | Support rotating shafts with low friction. | ₹250 |
| Robot chassis (metal / acrylic) | 1 | Needed for this type of build. | ₹1,100 |
| Li-ion battery pack (18650 × 3, 11.1 V) with BMS | 1 | Needed for this type of build. | ₹1,400 |
| Welding, cutting and machining labour | 1 | Needed for this type of build. | ₹2,200 |
| Controller Circuitry | 1 | Part from the design specification | ₹400* |
| Mounts, screws, nuts and small hardware | 1 | Enclosure, mounts and fasteners. | ₹300 |
| Paint, finishing and workshop consumables | 1 | Project overhead | ₹600 |
| Transport of material | 1 | Project overhead | ₹400 |
| Estimated total | Varies with brand, quality and city | ₹15,600 – ₹22,900 |
Prices are estimates for budgeting; items marked * depend on the exact size or model chosen. We confirm the bill of materials when your design is frozen, and components are charged at actual cost with bills.
How much does this project cost?
| Option | What you get | Cost |
|---|---|---|
| Components only | You buy the parts and build it yourself | ₹15,600 – ₹22,900 |
| Hardware / IoT Final Year | Working model or guided build, Circuit diagram and bill of materials, Firmware / code with explanation | from ₹9,999 + components |
| Capstone Project (CPE) | Working project or model, Black book in MSBTE format, Step-by-step explanation | ₹9,999 + components |
| Diploma ITR | 100% working source code, Project report PDF, PPT | ₹1,999 + components |
No GST and no hidden charges. Use the cost calculator for a quote with your deadline and add-ons, or see all plans.
Download the project brief (PDF)
Summary, working, components and cost and viva questions on one branded PDF to show your guide or team. To get it developed, contact us on WhatsApp.
What you submit with this project
- Working model with circuit diagram and program code
- Project report or black book in your university's chapter order (block diagram, circuit, calculations, results)
- Presentation for the review and final viva
- Synopsis for topic approval, if your college asks for one
Mechanical viva questions on this project
What is the aim of the Variable Head Solar Grass Cutter Weed Trimmer Robot project?
A solar-powered robotic grass cutter with an adjustable cutting head. Ultrasonic sensors guide it around the lawn, and it charges itself from a solar panel without fuel.
Explain the working of your project in short.
The mild steel frame and fabrication forms the base that carries every other part, so it is designed first from the load and size of the machine. The DC geared motor provides the driving motion. The Motor driver lets the low-current controller run the motors forward, reverse and at variable speed. Motion is transmitted through DC geared motor and ball bearings with housing, which set the speed, torque and direction at the working end.
How does the ultrasonic sensor measure distance?
It sends a 40 kHz pulse and measures the time until the echo returns. Distance = (time × speed of sound 343 m/s) ÷ 2. The HC-SR04 works from 2 cm to about 4 m.
Why is a geared motor used?
The gearbox reduces speed and multiplies torque, so a small DC motor can move a vehicle or mechanism smoothly. Torque increases roughly by the gear ratio.
Why can't the motor be connected directly to the microcontroller?
A motor needs far more current (hundreds of mA to amps) than a controller pin can supply (about 20–40 mA). The H-bridge driver switches the motor current and allows direction control.
What is the efficiency of a typical solar panel?
Commercial polycrystalline panels convert about 15–17% and monocrystalline about 18–22% of sunlight into electricity. Output depends on sunlight, angle and temperature.
Why is a charge controller needed?
It regulates the charging voltage and current, cuts off when the battery is full and prevents deep discharge, which protects battery life.
Which material did you select for the main parts and why?
Mild steel (MS) is used for the frame because it is strong, cheap, easy to cut and weld and available everywhere. Shafts are made of EN8 or bright mild steel for strength, and parts that do not carry load can be aluminium or acrylic to reduce weight.
What factor of safety did you take in your design?
A factor of safety of 2 to 3 is taken for static parts and 3 to 5 for parts under shock or fatigue loading. Allowable stress = yield strength ÷ factor of safety, and each part is checked against it.
How did you estimate the cost of the project?
The cost is the sum of raw material, bought-out parts, machining or fabrication and overheads. Our estimate for this model is about ₹15,600 to ₹22,900, depending on size, material and the workshop rates in your city.
Which manufacturing processes were used?
Cutting and grinding of sections, arc or MIG welding of the frame, drilling for mounting holes, turning of the shafts and fitting of bearings and the drive, followed by assembly, alignment and painting.
Is your system open-loop or closed-loop?
Closed-loop: sensors measure the actual position, distance or condition and the controller corrects the actuators until the target is reached.
Related projects
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Want to build Variable Head Solar Grass Cutter Weed Trimmer Robot?
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