Ultrasonic Sensing Haptic Feedback Motorbike Safety System

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Ultrasonic Sensing Haptic Feedback Motorbike Safety System

Release status: unknown [box doku]

Description Ultrasonic Safety Helmet
Author(s)  Roger Mu

The Ultrasonic Sensing Haptic Feedback Motorbike Safety System is an electronic system is designed to sense fast-approaching vehicles behind a motorbike rider using ultrasonic rangefinders and alerting the rider using a haptic feedback vibration motor mounted within a motorcycle helmet.


Safety checks using mirrors

Motorcycle look.png

The mirror has been used to give riders and car drivers the basic ability to look behind their vehicles for various safety reasons:

  • To check for vehicles in adjacent lanes and prevent hard stopping (lane status checking)
  • To check for vehicles in adjacent lanes to prevent collision with other vehicles (blind spot checking)
  • To see if suspicious vehicles are following the rider (mirrors in movies) :D

Although a mirror is simple and reliable, it has several drawbacks. For most motorbikes, the mirror is placed close to the handlebar with relatively short arms that position the mirror to the outside of the vehicle. While this is effective for seeing behind a motorbike, this requires the rider to take his eyes off the road (green line) in order to check his mirrors (red line).

Motorcyle blind.jpg

Simple solutions for this would be to raise the height of the mirrors by replacing the arms with longer, higher arms, but this will then present problems of ergonomics when squeezing between vehicles in congested urban settings. Finally, even if these issues were all solved in some way, the mirror still provides a limited view of what is happening behind the vehicle. As a result, most riders that have mirrors often just turn their heads to directly view what is happening behind them, which allows for a full view, but which takes all attention away from the front view.

New Solutions

In terms of advanced systems, there are several systems currently in the market:

These provide vision of what is happening behind a rider using rear facing cameras and video output through helmet mounted displays, but these systems are extremely expensive and draw away the attention of the rider away from where they should be looking: in the front of the vehicle where the vehicle is headed.

While these systems only require the rider to view a video feed that is a few degrees off from the front view, the value of providing full motion video of the rear view and the attention it requires from the rider is questionable.

For example, the use cases of mirrors are listed above and of these use cases, video only provides a substantial advantage for third, humorous use case. For the first use case, the speed differential between a static motorbike and traffic moving through a lane is rarely greater than 30 kph, which means that unless the motorbike is entering a highway lane from the shoulder and the speed differential can be as great as 100 kph, a 30-60 frame per second video stream won’t provide a huge advantage over a simpler system.

In the second use case, the rider is checking the rear blind spots to make sure that his lane change won’t result in a collision with a vehicle. Here again, video would certainly work to check this area, but it would be overly complex and overly expensive since the demand is relatively low: check to see if there is a vehicle within 1-3 meters of the motorbike.

The Ultrasonic Sensing Haptic Feedback system

The Ultrasonic Sensing Haptic Feedback system attempts to address the same safety concerns and use cases as mirrors and camera-display helmets, but at a significantly lower cost and without distracting visual attention away from the front view.



This safety system uses 3 ultrasonic rangefinders controlled by an Arduino and mounted at the tail of the motorbike to sense the presence of objects behind the motorbike. Each of the 3 ultrasonic sensors (right, middle, left) correspond to a vibration motor installed in the motorcycle helmet which alert the rider where objects are being sensed. However, rather than simply vibrating when any object is detected, which would result in an inconvenient amount of haptic feedback, this system only notifies the rider with vibration feedback in two of the following situations:

  • Case 1: A vehicle is approaching at unsafe speed (i.e. a speed differential of over 40 kph)
  • Case 2: A vehicle is within 0-2 meters of the vehicle

Case 1: Rapidly Approaching Object

The system only counts an object as a vehicle if it senses the object for at least half a consecutive second. For the first use case, the speed of the oncoming vehicle is calculated using range values from one reading to the next, and if the speed is greater than the target value (i.e. 40 kph), then the rider is alerted with 100% strength haptic feedback.

Case 2: Too Close Object

For the second use case, vehicles which are travelling at nearly the same speed of the motorbike are not communicated to the rider through haptic feedback, but if the distance of the vehicle closes within 2 meters of the rider, the rider will be alerted with progressively stronger haptic feedback, starting from about 25% for 2 meters up to 100% for 0.5 meters.


The range of the ultrasonic sensors is limited to

How to make it


Key Step 1

Key Step 2

Key Step 3



  • Motorbike Helmet



#include <Servo.h>

const int trig = 7;
const int echo = 8;

unsigned long duration, t, start;
int angle;
Servo myservo;

void setup() {
  // initialize serial communication:
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  delay(500);//let servo turn to zero
  start = millis();
  angle = 0;



See also

External Links