Simple robot for a school-project

Hi !

I have visited your website and it seems to suit my needs; the problem is that I do not really accurately know which parts to choose, and that is why I am posting right there

I would like to build a simple robot (which can ideally only go in a single direction) with :

  • three wheels, with only one of them being motorized
    (- a motor)
  • a “dimmer” (I am not really sure that the translation (I am far from being an English native speaker) is right; it is a part which can “change the voltage going to the motor”)
  • a captor which can tell us the rotation speed of the wheels
    (- maybe an one-axis-accelerometer (not compulsory))
  • a microcontroller that can read the information given by the captors and can be programmed with orders like computing the speed of the robot when knowing the acceleration, and comparing it with the rotation speed of the wheels

Could you please tell me which parts would suit my needs ? There is no need of high-end components, so, in my case, I think that the cheapest parts would be the most adapted parts.

Thanks in advance !

Hi !

Thank you for your answer !

I still have some questions about the project :

  • are there wheels that would be more adapted to a three-wheeled robot ? (one motorized wheel at the front, two wheels at the back which are not motorized, but are there only to “carry” the robot)
  • we do not need the ability to turn (the robot only needs to be able to go straight forward), what can we change about the components ?
  • would there be any problem about mounting the robot, especially if we use another microcontroller (that is said to be able to be used on robots) ?

Thanks again :slight_smile:

Thanks for your answer !

I would like to be really sure about the compatibility and the suitability of the components : which models would you advise me to buy concerning the potentiometer and the accelerometer ?
And are the programming tools given with the ROMEO microcontroller ?

(And do you know how long would it take to have the components shipped to France ?)

Thanks again !

Ok :slight_smile:, would robotshop.com/eu/capteur-rotation-v2-dfrobot.html and robotshop.com/eu/platine-accelerometre-6g-3-axes-dfrobot-mma7260q.html be good choices ? Especially for the latter, would it be compatible ? (I have chosen this one because of the Arduino specialization, but it is written that it needs a JST connector, so, given that I will choose the components you have advised me, will it be compatible with them ?)

Ok :slight_smile:

So, to sum up, we have the following parts :
robotshop.com/eu/pair-roues-tamiya.html
robotshop.com/eu/moteur-reducteur-essieu-decentre-6v-180rpm-dfrobot.html
robotshop.com/eu/encodeurs-simple-2pk-robots-3pa-ou-4wd-dfrobot-2.html
robotshop.com/eu/microcontroleur-romeo-tout-dfrobot-atmega-328.html
robotshop.com/eu/cable-sirc-04-lynxmotion.html
robotshop.com/eu/cable-analogique-capteurs-paquet-10-dfrobot.html
robotshop.com/eu/capteur-rotation-v2-dfrobot.html
robotshop.com/eu/platine-accelerometre-6g-3-axes-dfrobot-mma7260q.html

If I buy one unit of each link (apart from the “pair of wheels”, which would need to be bought twice …), will it be sufficient to build a working robot ? (How about the amount of cables ?) Is there no need of other things like an “external battery” ?

Thanks for your help !

Concerning the rotation issue, in my case, which precise component would you advise me to buy ? robotshop.com/eu/capteur-rotation-v1-dfrobot.html instead of robotshop.com/eu/capteur-rotation-v2-dfrobot.html ? Thank you again :slight_smile:

The issue I wanted to fix in my last post was : “The one consideration is accidental rotation (if it is moving along a track, it won’t be an issue, but if it is moving on a flat surface, you might consider a single axis gyro).”.
What would you advise me to do, in order to fix it ?
(I mean, especially about the “single axis gyro” advice : what is the component to change, and which precise component can replace it ?)

Concerning rotation sensors, do they really measure the rotation speed of the motor ? It does not seem so from what I can read in the descriptions, but I am as far from being an excellent English speaker as from having some knowledge concerning robots (that is why I would prefer that you make the choices for me)

Thanks again !

Hi blablabla,

Welcome to the RobotShop Forum. Almost all of the platforms we offer use two motors (almost all robots need to be able to turn, unless you are not looking to make a mobile robot). A simple solution would be to use the DFRobot Wheel Encoders and a DFRobot DC Gear motor. This would connec to the DFRobot Wheels. You can use a simple robot controller such as the ROMEO to power the motor(s) and read the encoder(s). This can also interface with a potentiometer for speed control, as well as the accelerometer. Note that this is only one possible solution of many. The main categories for your application would be:

]Wheels, Tracks, Ball casters/:m]
]Potentiometers/:m]
]Encoders/:m]
]Accelerometers/:m]
]Microcontrollers/:m]Hope this helps,

There are no wheels (that we are aware of) specifically for a three wheeled robot with one drive wheel. The component categories indicated would meet your needs, the choice of which products to purchase is ultimately up to you. The list of components we provided was only one of many possibilities. To mount electronic components you really only need to drill several small holes into your frame, and use standoffs or screws/nuts. The frame itself can be as simple or as complex as you want.

Sincerely,

Hi,

The programming software for the ROMEO is Arduino (available to downlaod for free). We have a warehouse in France and you can check the stock status by visiting www.robotshop.com/eu. If your platform will not move fast, you only need one with a maximum rating of 1g. We offer a selection of potentiometers from various manufacturers, so it’s really up to you which “looks” better (note that some can rotate 300 degrees, others are linear etc.).

Sincerely,

Hi,

The products you suggest seem to suit your needs. Compatible cables include RB-Lyn-164 and RB-Dfr-73.

Sincerely,

Hi,

If you get the DFRobot cables, you won’t need the Lynxmotion cable. The list of parts you provided should allow you to create a robot which moves straight. The one consideration is accidental rotation (if it is moving along a track, it won’t be an issue, but if it is moving on a flat surface, you might consider a single axis gyro).

Best of success!

RB-Dfr-43 can rotate 10 times (3600 degrees) while RB-Dfr-44 can rotate 300 degrees. It’s really your choice - it’s a matter of “feel” and how fast you want to change the speed (and how accurate).