The personal range finder is an idea-based assistive device that translates physical space into a tactile input on your arm. The goal of this project was to make an affordable mobile machine that is rugged, runs off a common power supply (9volt battery) and is easy to use. The range finder utilizes sensor input to create a map of the surrounding physical space. This map is then translated to a scaled pressure gradient which is applied to your forearm. In this way you are able to “see” the surrounding space, allowing for informed movement without the use of your eyes.

 

 

There are many concerns dealing with alternative navigation, the largest challenge is to make a usable translation from one sense experience to another. It is important to consider the normative motion and thought that goes into a particular sense in order to describe it correctly. If you are successful you can trigger the logical patterns that are normally linked with that sense, giving the user a much quicker learning curve.

This project focused on the visual sensations that are used to navigate a physical space. In observing my visual cognition I recognized a linear sensation that is employed in describing ones location in space. In order to “perceive” a space there has to be a constant reference of change. From this observation I designed an interface that applies a linear pressure that increases or decrease in regard to an objects distance from you. This gives a simple straightforward interpretation of space that can be utilized without any prior explanation.

In terms of the physical construction I tried to use an approach that could be as versatile as possible, leaving room for an easy modification. This translated into a design for maximum simplicity and flexibility, so it could be used with an arm mount or can be front mounted to a shirt and used for crowd navigation.

 

 

 

 

Operation:
The device is mounted to your forearm or other positions on your body allowing for a directional scanning of the environment. The range finder operates by utilizing a sonar sensor paired with a micro-controller to achieve data input and output. Any number of sensors can be used with this design from IR to ping sensors making it an easily customizable device. To get usable input of a space the micro-controller takes information from the sensor and digests it with an algorithm, this gives informational output which can describe a spatial distance as a tactile pressure on your arm. 

The major concern with the output is to find a tactile response that matches a physical space in regard to the rate of change your skin can discern. In my testing the responsiveness of your arm is only sensitive enough to describe about ten feet. This distance can be changed according to an individual’s sensitivity.

Ideology:
In making the personal range finder I focused on four things in terms of the design. I wanted to make a device that was:

1.  immediate usefulness-- to design a object that had application and utility without the need of much explanation;

2.  accessible-- based on technology that is off-the-shelf, making it affordable;

3. scaleable-- to be able to be easily customizable to the individual owner; and

4. production cost based on labor hours--make the concept
essentially open source so the actual implementation would generate the cost and design advancements.

 

The following are the issues that I try to keep in mind when designing an object.

The current mode of design and product understanding lags behind the technological implementations that now exist. Most industry and design functions are from an industrial revolution mind-set where achievement and advancement were only possible through industries of scale. This is no longer true for 70 percent of the product market. The ability to have flexible applications and devices has blossomed with the advent of dependencies based on software and accessibility instead of the justification of large centralized labor and the modern day consumer it created.

It is once again feasible to try and design for the individual in a cost effective manner or better yet have the individual be able to customize their devices by themselves. This design technique also is able to allow for the ability to reuse and retrofit technologies to new uses cutting down on production cost and waste. The job of the designer is now not to produce a mode of function but to let the individual function better in their own mode. This point is especially true in the field of medical and physical assistance where the vast majority of problems are as individualized as the people themselves. With every individual a new implementation of a device needs to be designed and built.  The real solutions will come from the ability to implement product systems that will allow the individual to easily harness the power of a device while it adapts to their own personal life.

 

Technology:
Currently the range finder implements a LV-MAXSONAR-EZ sonar “ping” sensor as the primary input. This sensor is relatively robust and needs a minimum of software adjustment on the data in, meaning there is a good range of data to explore. The logic control is from an atmega 8 microcontroller that is a small versatile microcontroller. For the physical actuation a small 9v stepper motor is used driven by a bank of Darlington arrays for the power switching. See attached spec sheets.

 

Future improvements:
The three areas I am trying to improve on for the next version are:

Power usage;
Size/ ergonomics;
And obtaining a better “feel” for space;

Power usage ideas.
Currently the device chews up batteries due to the implementation of the stepper motor. In the next version I would like to implement a small dc motor linked with a rotary pot.  With this setup I could power the motor on and off leaving the “holding” power to mechanical means (such as a power screw) instead of constantly having to hold the pressure with a electromechanical force. Also I would like to implement a rechargeable lithium polymer battery so it would be able to be plugged in and powered up from a cell phone charger.

Size/ ergonomics ideas:
Since this device is made to be constantly worn the issues of size and placement are very important. This device needs to be able to be used not just on sunny warm days but also in the winter and rain as well, without causing hassle. So for the next version I am working with a new surface mount microcontroller (The atmega 168) which is much smaller than the current microcontroller. The new motor is also smaller and lighter than the current motor, giving a smaller overall footprint to the device.
With the smaller size I believe the device will be able to slip under any shirt or jacket making it multi seasonal. The mounting considerations are also important and I would like to develop a system that would be comfortable as well as versatile, allowing the user to strap it to her hand or the brim of a hat if needed.

 

Spatial “feel” ideas:
The feel of the space that is presented to you is very important and varies from individual to individual. There are different methods and considerations when dealing with the output, ranging from the actual strength of the pressure on your arm to the rate and location of that pressure. I would like to gauge and deploy four sets of adjustment to allow the user to scale and manipulate the description of space.

The first would deal with the max and min pressure that would be applied to your arm in regard to the farthest and closest distance you wish to perceive.

The second would be the rate of responsiveness you would perceive for example:
If you scan your arm across a room very quickly it will pick up and return all the minor jumps in space as outputs which might be hard to navigate as an applied pressure on your arm. But if you average those numbers out so you get a general description of the space, the tactile input becomes easier to decipher.

The third would be weighting the input data in terms of the distance of an object. For instance:
if you scaled the data so there is a faster rate of change the closer you are to an object even when the space covered is the same. This would give you a sense of urgency the closer an object was to you.

The forth is to add on a IR sensor on the front that would pick up the sonar’s dead spot which is about 8-12 inches from the sonar. This would give a complete range even in close proximity situations.

 

 

 

 

More information and contact:
www.johnhenryshammer.com
email: footloose_757@hotmail.com