Blind Stick using Ultrasonic Sensor with Vibration Alert and Buzzer

A blind stick using an ultrasonic sensor with vibration alert and buzzer warns a blind person about obstacles before the cane tip touches them. A white cane is the standard mobility aid, but it only reports what it physically touches: a wall, a parked vehicle or a low branch is found only on contact, and by then the user may already have bumped into it. This project adds a second sense to the cane. An HC-SR04 ultrasonic sensor near the handle sends out 40 kHz sound pulses and times their echoes to measure the distance ahead, and an Arduino Nano converts that distance into a vibration felt in the handle and a buzzer that beeps faster as the obstacle gets closer. The user is warned while the obstacle is still about a metre away, in time to stop or step around it. The stick needs no phone, no internet and no screen.

From an obstacle ahead to a vibration in the hand, the blind stick runs a loop that repeats several times a second. The HC-SR04 sensor fires a burst of 40 kHz ultrasonic pulses forward from the cane handle, and its receiver listens for the echo bouncing back from whatever stands in the beam. The Arduino Nano measures the echo pulse width — the time between sending and receiving — and converts it into a distance with the formula distance equals echo time multiplied by the speed of sound divided by two, using the standard value of 343 metres per second at 20 °C. The Nano compares that distance with two design-target thresholds: vibration starts at 100 cm, and the buzzer joins in below 60 cm, beeping faster as the distance falls, with a continuous alert below 30 cm. The loop then repeats, so the alert tracks the obstacle as the user walks toward it or steers away.

1. The builder assembles the system: an HC-SR04 sensor mounted near the handle of a white cane, a vibration motor and a buzzer fitted to the handle, and an Arduino Nano with a 9 V battery pack mounted on the shaft, wired with jumper wires.
2. The Nano sends a 10 microsecond trigger pulse to the sensor, and the HC-SR04 emits a burst of 8 ultrasonic pulses at 40 kHz from its transmitter.
3. The sensor's receiver catches the echo, and the echo pin stays high for the round-trip time; the Nano measures this pulse width in microseconds.
4. The firmware converts the pulse width into a distance with the formula distance equals echo time multiplied by 343 metres per second divided by two, using the standard speed of sound at 20 °C.
5. The distance is compared with the design-target thresholds: above 100 cm there is no alert, from 100 cm to 60 cm the vibration motor runs, below 60 cm the buzzer joins in and beeps faster as the distance falls, and below 30 cm the alert becomes continuous.
6. The loop repeats with a new reading approximately every 100 ms (design target), so the warning follows the obstacle as the user moves; the buyer-run test walks toward a wall from 2 m and records where the vibration starts and where the buzzer joins in.

Tech stack:

• Arduino Nano · ATmega328P microcontroller
• HC-SR04 ultrasonic sensor · 40 kHz ranging module
• Vibration motor module · coin-type alert motor
• Active buzzer · 5 V audible alert
• 9 V battery pack · portable power
• Jumper wires · solderless wiring
• White cane · assistive mobility aid
• Embedded C · Arduino IDE firmware

The blind stick works through four capabilities that together turn a distance measurement into a warning a person can feel and hear. First, the HC-SR04 ultrasonic sensor measures the distance ahead without contact, over a datasheet range of 2 cm to 400 cm. Second, the Arduino Nano converts each reading into an alert: a vibration motor in the handle starts at a design-target distance of 100 cm, and a buzzer joins in and beeps faster as the obstacle gets closer. Third, the alerts are graded rather than on-or-off, so the user can judge whether the obstacle is far, near or very close without looking at anything. Fourth, the whole system is self-contained: it runs on a 9 V battery pack, needs no phone and no internet, and the vibration alert is felt only by the person holding the stick.

• [Ultrasonic obstacle sensing] The HC-SR04 sensor measures the distance to obstacles ahead without contact, over a datasheet range of 2 cm to 400 cm — implemented in the base build.
• [Vibration alert in the handle] A vibration motor in the handle starts at a design-target distance of 100 cm, so the warning is felt silently by the user — implemented in the base build.
• [Graded buzzer alert] A buzzer joins in below a design-target distance of 60 cm and beeps faster as the obstacle gets closer, with a continuous tone below 30 cm — implemented in the base build.
• [Distance from echo time] The Arduino Nano converts the echo pulse width into distance using the formula distance equals echo time multiplied by the speed of sound divided by two — implemented in the base build.
• [Handle-height sensor mounting] The sensor sits near the handle, angled slightly forward, so the cane tip still does its normal ground-contact job while the sensor watches the space ahead — a builder note from the demo build.
• [Self-contained battery power] A 9 V battery pack powers the Nano, sensor, motor and buzzer, so the stick works anywhere with no phone, no internet and no mains supply — implemented in the base build.
• [Adjustable alert thresholds] The vibration and buzzer distances are set in the firmware and can be changed for the student's own demonstration space — configurable in the base build.

• Working white-cane prototype with HC-SR04 sensor, vibration motor, buzzer, Arduino Nano and 9 V battery pack
• Arduino firmware with the distance calculation and graded vibration and buzzer alert logic
• Wiring diagram and component list
• Threshold calibration and buyer-run test procedure (walk-toward-a-wall test with a recording sheet)
• Project report PDF (ultrasonic ranging theory, alert thresholds, honest measurement limits)
• PPT presentation for final review
• Viva Q&A preparation document (how the HC-SR04 measures distance, what the thresholds mean, why the stick is an aid and not a replacement for a white cane, what the sensor cannot detect)
• Setup and demonstration support — wiring and firmware-upload guidance so the student can run the demo independently
• Specific next step: message on WhatsApp for a quotation stating scope (blind stick with HC-SR04 sensor, vibration motor and buzzer alerts, Arduino Nano), with delivery under the built-to-order timeline as a built-to-order project