Test machine for phone with EV3, possible?

[Bernard90]

Hi everybody,

I am new to Lego robotics and would like ask you if it's possible to build an idea I have, with a Lego Mindstorms EV3 set (+ additions if needed). Before I make a big Lego order, only to later realize it's not possible to build.

I have the idea to build a test machine for a phone. It is basically an automatic device that can touch a phone screen on certain locations in a programmed sequence. Looking at other Lego mindstorms builds (could not find a similar build), I think this can be realized by building it like an XY-plotter with 2 axis (like a gear rack) and a motorized pointer/stylus that can go 1 step up and down. The concept is best explained with a YouTube video or see the attached picture. It does not need to have a camera functionality as shown in the video. I will use this device to test phone applications I am developing.

The requirements it should meet are:
- Touch the phone screen on programmed locations with a precision of +/- 5 mm.
- Be able to do this in a sequence on certain time intervals, every hour it should repeat the same programmed steps, then stop and repeat every hour during the entire day.
- Besides programming, the device should work independent of a computer/laptop.
 

Will it be possible and relatively easy to build this (since I am new to Lego robotics)? If so, does a single EV3 set (e.g. 31313) be enough or do I need to buy additional sets?

I will share of course the build after it's finished .

[JopieK]

Interesting idea. B.t.w. e.g. an iPhone can also be used to test UI through a test application that can monitor performance etc, so maybe a good combination?!

[Bernard90]

2 hours ago, JopieK said:

Interesting idea. B.t.w. e.g. an iPhone can also be used to test UI through a test application that can monitor performance etc, so maybe a good combination?!

Thanks, indeed I am aware. Do you think that it will be possible to build this device with a EV3 set?

[dr_spock]

The EV3 comes with 2 large servo motors and 1 medium servo motor.   There is enough motors for each axis of a plotter.   A computer is required to create the program for the EV3 and to upload it to the EV3.  Then the EV3 can operate independent of the computer. 

 

[Bernard90]

2 hours ago, dr_spock said:

The EV3 comes with 2 large servo motors and 1 medium servo motor.   There is enough motors for each axis of a plotter.   A computer is required to create the program for the EV3 and to upload it to the EV3.  Then the EV3 can operate independent of the computer. 

 

Thanks dr_spock! So I assume it is possible to build with Lego Mindstorms. 1 large servo motor for each axis and the medium servo motor for the stylus to go up and down, will hopefully do. I will probably need to buy an expansion pack to the 31313 set, since I'm afraid I will need quite a lot of gears (such as gear racks). Can I use the EV3 intelligent brick in such a way that it can stay on all day, and run the programmed sequence of steps in certain time intervals?

[Coder Shah]

Perhaps you'll find this helpful

https://jkbrickworks.com/telegraph-machine-and-printer/

[dr_spock]

10 hours ago, Bernard90 said:

Thanks dr_spock! So I assume it is possible to build with Lego Mindstorms. 1 large servo motor for each axis and the medium servo motor for the stylus to go up and down, will hopefully do. I will probably need to buy an expansion pack to the 31313 set, since I'm afraid I will need quite a lot of gears (such as gear racks). Can I use the EV3 intelligent brick in such a way that it can stay on all day, and run the programmed sequence of steps in certain time intervals?

 

You can set the sleep timer to "never" on the EV3 for it to stay on all day.

For continuous power, you can get the LEGO EV3 rechargeable DC battery and 10V DC transformer.  And leave the 10V DC transformer plugged into the battery.

Another option would be to make some dummy batteries and connect a generic 9V DC adapter to them.

 

[Bernard90]

2 hours ago, Coder Shah said:

Perhaps you'll find this helpful

https://jkbrickworks.com/telegraph-machine-and-printer/

Thanks a lot, that will definitely help! Especially the building instructions are useful since several other plotter like examples did not have a building manual.

2 hours ago, dr_spock said:

You can set the sleep timer to "never" on the EV3 for it to stay on all day.

For continuous power, you can get the LEGO EV3 rechargeable DC battery and 10V DC transformer.  And leave the 10V DC transformer plugged into the battery.

Another option would be to make some dummy batteries and connect a generic 9V DC adapter to them.

Thanks dr_spock! That's very useful information. Looking at the need for a rechargeable battery it might be more interesting for me to buy the 45544 educational EV3 set instead of the 31313.

[Bernard90]

I am still wondering if it wouldn't be better and easier to build this device like a robot arm (as in the picture) compared to a printer type of build with 2 axis.What do you guys think?

Is there a limitation to how many motors can be connected to to the 8 ports of 1 intelligent brick? I figured to buy 2 additional motors (5 in total) to also build a functionality to turn the phone on and off (by pressing the sideways on/off button and home button).

[Coder Shah]

The EV3 brick has 4 motor ports and 4 sensor ports. So max no motors for 1 brick is 4.

[JopieK]

You need three degrees of freedom so three motors should be possible. You could make the bed movable to have a X/Y movement and then an additional Z-axis for the 'pen'. See also https://openbuilds.com for different types of XYZ machines.

[dr_spock]

On 3/30/2020 at 2:46 AM, Bernard90 said:

Thanks dr_spock! That's very useful information. Looking at the need for a rechargeable battery it might be more interesting for me to buy the 45544 educational EV3 set instead of the 31313.

45544 would be more interesting.  It has a bigger selection of gears too.