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Author Topic: Dagu Rover 5 Motors - Increase torque with Higher voltage and lower PWM  (Read 1180 times)
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McDonough, GA
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Hi All,

I have a Dagu Rover 5 chassis (2 motor model) with the rubber track drive.  I am working on an internet-controlled rover that would carry a wireless IP camera so I can drive it "First Person" around my home/yard.  I have many of the project pieces working, but I have a question about voltage and PWM motor control of the Rover 5's motors.

I also have a DFRobot motor shield and I can control the two motors with PWM.

I have driven the rover around the house a bit (via the internet as I was planning) but the motors seem to be a little "sluggish" to me - especially compared to some of the "lively" Rover 5 videos I've seen on the web.

I know the motors are rated at 7.2 volts, and have been powering them with said 7.2 volts.  What I want to do is to increase the motor torque with higher voltage (like 12 volts say), and at the same time, back down the maximum duty cycle on the motor PWM signal so that my average voltage to the motors still comes in at the approximate 7.2 volts as to not burn up the motors.

I've read a lot on the boards about the Dagu Rover 5, and it seems to be a great little platform, but nowhere have I seen any recommendations on increasing the motor torque using the "higher voltage, lower duty cycle approach."

Does anybody have experience doing this, and if so could you make any recommendations as to voltage to use?  I plan on proceeding experimentally, but I thought if this has already been on by anybody here (especially on the Dagu Rover 5), then why should I re-invent the wheel.

Thanks in advance for any suggestions/expertise you might offer.
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How did you accomplish this? I'm new to arduino, and I'm wanting to create a similar vehicle, but controlled with an Android app.
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McDonough, GA
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Hi MarkEdge,

This is a summary of what I have:

1 Dagu Rover 5 tracked vehicle chassis (2 motor version)
1 DFRobot Motor shield (2 channel PWM control -- 1 channel for each motor on the Rover 5)
1 Arduino UNO Rev3
1 Arduino Ethernet shield
1 Arduino Wi-Fi shield
2 Medialink Wireless Routers (1 to create my home Wi-Fi bubble, 1 as a Wi-Fi access point on the rover)
1 Internet camera (it is a web-based camera and SERVER onto itself)

I also have a 1st generation (old) Apple iPod touch.

The rover drive is relatively simple, using the Arduino and motor shield to PWM (Pulse-width modulate) the power to the left and right motors.

the "interesting part" is creating the Rover's Internet" Presence".  I have presently done this in 2 different ways.

The first method I used was to have the Arduino Ethernet shield plugged into the wireless router (set up as a Wi-Fi access point), all located ON THE ROVER.  The Wireless router (access point) gave me the Wi-Fi link to my home Wi-Fi.  I then followed and modified the "Web Server" example in Arduino -- I actually made the Arduino on the Rover into its own little website.  Then, using any web-browser (like on my computer or even on my ipod touch, or probably an Android device with internet capabilities) I could log into the Rover's website, and I could click on the website's drive buttons to drive it forward/backward/turn.  I actually had this working some weeks ago.

The second method that I'm currently playing with is different...  I now have an Arduino Wi-Fi shield which plugs into the Ardunio board (I have removed the Ethernet shield and have removed the Rover-based wireless router Wi-Fi access point, because the Arduino Wi-Fi shield now serves that purpose.)

I also changed the software...  the Rover is now a Web CLIENT (no longer a server).  Therefore, as a client, it has to go out on the internet and GET its drive commands.  To do this I have setup an account on www.cosm.com.  I have set up a FEED that the Rover now reads from at programmed intervals (currently every 30 seconds).  Now, using an internet browser, I log into COSM and I can send Drive command (motor PWM values and drive DURATION) up to COSM.  Every 30 seconds (currently) the Rover logs into COSM as well, and retrieves the Drive command values and then executes the drive.  This would be similar in nature to the NASA ROVERS currently driving around on the planet MARS.  Every so often the Rovers listen for drive commands.  Once they receive a command they execute the drive.  If you visit www.cosm.com and search on dsmavis (my username) you will find my Rover's Data "Feed".

I am playing around with different web interfaces.  I'm not sure yet which one I like better... the Rover as a SERVER, or the Rover as a CLIENT.  Once I get the Rover driving around more, I will put the Internet Camera (a stand-alone device) on the Rover so I can "see" from the Rover's point of view.

I also plan in putting additional features on the Rover such as Ultrasonic sensors to sense obstacles, and maybe an electronic compass for more precise direction control.  I may also create a charging Dock for it somewhere in my house, so when I'm done driving it around I can return it to its charging dock to "fill up the tank".

I am also currently playing around with different voltages and PWM drive values for the 7.2 volt motors on the Dagu 5 chassis.  That was the whole reason for my first post, wondering if anybody else had experience with this.

The internet camera I have is "a lot of bang for the buck".  It is a pan/tilt model with infra-red "night vision" as well.  It can plug into Ethernet (I did this while using the Rover-based Wi-Fi router), but it also has its own on-board Wi-Fi (which I will now use after ditching the on-board Wi-Fi router).

The camera I have is the FOSCAM FI8910W, and I bought it on Amazon for about $90.  In addition to the infra-red emitters for night vision, the camera also has on-board speaker and microphone, so you can hear and talk to people that are near the camera, all via the internet.  Like I said, a lot of bang for the buck!

Depending on the success I have with the overall project, I hope to post more information about my rover project on this board (in the show and tell section), and maybe even give readers on the board the ability to drive my rover around in my house, complete with First Person live video view from the rover.

So, stay tuned for that.  I hope I've given you some information that may help you on your quest.

--dsmavis
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Thank you, that was very informative. Right now I'm working on the web page for using the arduino as a SERVER, just because I'm building a 4 wheel vehicle that will be operating at about 10 times the speed of the rover. If you have a large area you want to cover with the rover I'd look into an ubiquiti system. http://www.ubnt.com/ We have one that covers about a 1 mile radius if there are no obstructances. And if your ping board has 4 wires instead of the Arduino guide's 3, find the revised NewPing sketch.
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