Interfacing ultrasonic sensor with vibrator motors as navigational aid for blind

Using Arduino Project Guidance
1

Hello!

I am very new to working with Arduino, so I would be very thankful for some help with my project.

As part of a science fair my friend and I are participating in, we would like to create a navigational aid for the blind using vibrator motors to transmit information regarding the distance of particular objects from the users. The motors that we will most likely use are linear resonant actuators (LRAs), specifically the Precision Haptic C08-001 8mm ones.

The distance would be sensed using an ultrasound range finder, such as SEN136B5B Ultrasonic Range Finder or HC-SR04, and transmitted to an Arduino Mini or Flora. If possible, we would like it to be powered by a rechargable lithium battery.

We are planning for four LRAs to be mounted on a glove in a vertical row - wrist to base of fingers - if an object is located in a particular range of distances, a particular LRA should vibrate to indicate this. The sensor will also be mounted onto the glove so that the person can manually point or sweep the ultrasound sensor as needed.

While we seem to have planned out the concept, we are having some difficulty with figuring out how to set up the equipment, what equipment would be best and how to code the motion of the LRAs in response to the sensor.

We would be grateful for any help or suggestions you can provide, especially with regard to the following questions:

  1. What kind of ultrasound sensor would be best for this particular project / purpose? We are currently considering the SEN136B5B Ultrasonic Range Finder or HC-SR04, but we are uncertain which would be the best among all the available options.

  2. How could we incorporate this into a wearable device (glove)?

  3. How could we code the LRAs to respond to the ultrasound sensor? I am (most likely) able to code just receiving information from the sensor or just activating the LRAs at a particular time, but I am very unsure how to make them interact in a continuous process?

  4. Would the Arduino Mini and lithium battery be able to support so many devices in terms of energy? If that is possible, how would we connect the components to allow this to occur?

I am sorry for the great number of questions, but we are both very new to this and so would very much appreciate your support.

Thank you very much!

Tina

2

OK, so you have now excluded by your choice of topic (you can modify your first post and change it), everyone who does not immediately know what you mean by a "LRA".

Yes, we can Google it.

3

Paul__B:
OK, so you have now excluded by your choice of topic (you can modify your first post and change it), everyone who does not immediately know what you mean by a "LRA".

Yes, we can Google it.

Thank you very much for your feedback on the terminology used. I have editted it now and hope that it is clearer. Thanks!

4

OK, so I suppose I will have to make reply now!

You cite these transducers.

Let's look at your questions.

tina_chernova:
The motors that we will most likely use are linear resonant actuators (LRAs), specifically the Precision Haptic C08-001 8mm ones.

Jolly expensive! I bought five of these a while back.

These operate at 3.3 V - the voltage of your lithium battery.

tina_chernova:
The distance would be sensed using an ultrasound range finder, such as SEN136B5B Ultrasonic Range Finder or HC-SR04, and transmitted to an Arduino Mini or Flora. If possible, we would like it to be powered by a rechargeable lithium battery.

Pro Mini (3.3 V, 8 MHz) sounds practical, the Flora is of course, flatter, but not much. You need also a charge controller for the lithium battery.

tina_chernova:
We are planning for four LRAs to be mounted on a glove in a vertical row - wrist to base of fingers - if an object is located in a particular range of distances, a particular LRA should vibrate to indicate this. The sensor will also be mounted onto the glove so that the person can manually point or sweep the ultrasound sensor as needed.

That is going to be one funny looking glove - whichever way you look at it, usable microcontrollers, batteries and particularly the ultrasonic modules are bulky. I think you might be better with something resembling the form factor of a TV remote, hand-held, with the vibrators under the fingers.

tina_chernova:
While we seem to have planned out the concept, we are having some difficulty with figuring out how to set up the equipment, what equipment would be best and how to code the motion of the LRAs in response to the sensor.

Well, noting that the vibrators you cite - and I presume the ones I illustrate - have a proportional response of amplitude to supply voltage and presumably can be controlled by PWM, then you should be able to do just that. In which case you probably only need one or two transducers. The code is relatively straightforward.

tina_chernova:

  1. What kind of ultrasound sensor would be best for this particular project / purpose? We are currently considering the SEN136B5B Ultrasonic Range Finder or HC-SR04, but we are uncertain which would be the best among all the available options.

I can't really compare - I haven't at this point looked up the SEN136B5B. Either will probably do the job. Check their range specifications.

tina_chernova:
2. How could we incorporate this into a wearable device (glove)?

With difficulty - as above.

tina_chernova:
3. How could we code the LRAs to respond to the ultrasound sensor? I am (most likely) able to code just receiving information from the sensor or just activating the LRAs at a particular time, but I am very unsure how to make them interact in a continuous process?

Your code must be written without any "delay()" or "while" instructions - it continuously alternates between making a sensor reading and defining a PWM value. If you have multiple sensors, it would perform these two steps for one, then the other, and continuously alternate between the two. That is what the "loop()" is for, it must be a continuously and rapidly cycling chain of decisions which never waits for any action to complete (except perhaps for the ultrasonic "pings" which therefore require a time-out function) but takes immediate steps if and only if the logic determines them to be necessary

tina_chernova:
4. Would the Arduino Mini and lithium battery be able to support so many devices in terms of energy? If that is possible, how would we connect the components to allow this to occur?

Given about 80 mA maximum for the vibrators, that should be no great problem. Note that the SEN136B5B has a maximum of 1.8 V but that it requires more current than the Arduino can switch directly, a transistor or logic FET will be required to actually switch it.