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Hi guys, I'm new to all the Arduino based projects and have been studying many tutorials based on the Arduino Uno board. I don't want someone to spoon feed me the information but require information on a project I am about to start for example what equipment I require to make the project work.

The idea of my project is (The tutor has said that the project is practical to finish within the 12 week deadline);

When you have a suitcase with two wheels and say your suitcase is filled to the top and is really heavy to pull, I'd like to design a system using the Arduino Uno that makes the wheels on the suitcase to spin so that it makes it easier for the user to pull the suitcase with the help of the suitcase wheels spinning using a motor that is connected to the Arduino Uno board.

For the project, I know I require a Arduino Uno board (of course) and also a pressure sensor, motor and suitcase wheels but what other components will be required to make this project successful?

Your guys help would be much appreciated.
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The Arduino can not directly drive a motor. For that, you need some kind of transistor to switch some external power supply that powers the motor. If you want speed control, and to be able to run the motors in both directions (helpful when the line backs up), then you need an H-bridge. Buying one pre-made is generally better than trying to build your own.

The pressure sensor is, I presume, to determine how heavy the suitcase is, so you know how much help to supply. I'd think that something in the handle to sense when the suitcase is being pulled or pushed would be useful, too.
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Motors and motor controllers designed for robotic use would be a good first stop - what you are talking about is somewhat like an electric golf-trolley but scaled down.  Robotics forums are probably a good place to find out about axles/wheels/motor possibilities, and here for
general design ideas.

Start out listing the requirements (speed and power, human interface, safety issues), then a rough parts list (such as battery, motor hardware, some sort of handle with switch or other sensor), then try to identify possible parts, then try to sketch a rough mechanical design, and then an electrical / electronic design.

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The Arduino can not directly drive a motor. For that, you need some kind of transistor to switch some external power supply that powers the motor. If you want speed control, and to be able to run the motors in both directions (helpful when the line backs up), then you need an H-bridge. Buying one pre-made is generally better than trying to build your own.

The pressure sensor is, I presume, to determine how heavy the suitcase is, so you know how much help to supply. I'd think that something in the handle to sense when the suitcase is being pulled or pushed would be useful, too.

Thanks for your advice smiley
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To keep the project simple, you could get an inexpensive servo tester like below and a big inexpensive servo like the bottom ones (modified for continous rotation) to drive the wheels. Make a push/pull or squeeze setup for the suitecase handle to operate the servo tester pot as needed to control the servo foward/neutral/reverse rotation.

http://www.hobbyking.com/hobbyking/store/__14774__HobbyKing_Servo_Tester.html

http://www.hobbyking.com/hobbyking/store/__8296__Turnigy_Servo_Tester.html

http://www.hobbyking.com/hobbyking/store/__291__189__Servos_and_parts-X_Large_Servo_50g_.html
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To make any useful contribution to something as heavy as a suitcase, you're going to need quite a bit of power. Packaging and installing all the components on an existing suitcase would take a substantial amount of work.

An approach I've seen used successfully on electrically assisted bikes is to fit a powered trolley behind the bike to act as a pusher. It seems to me that you might be able to come up with a two-wheel trolley that one corner of the suitcase can sit in, containing a battery and motors operated by a pressure sensor on the suitcase handle. If you're feeling ambitious you could integrate this with the suitcase's own integral wheels, but I think that will be much harder to package and you might want to defer that. Perhaps you'll have time for that as well during your twelve weeks, but I suggest you get the standalone version working first - very little of the work on that will have been wasted if you decide to continue with 'phase 2' in the same project.

In other words, take an iterative approach and do the parts that will show the greatest value first. That's the electrics and electronics and control logic.
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To make any useful contribution to something as heavy as a suitcase, you're going to need quite a bit of power. Packaging and installing all the components on an existing suitcase would take a substantial amount of work.

An approach I've seen used successfully on electrically assisted bikes is to fit a powered trolley behind the bike to act as a pusher. It seems to me that you might be able to come up with a two-wheel trolley that one corner of the suitcase can sit in, containing a battery and motors operated by a pressure sensor on the suitcase handle. If you're feeling ambitious you could integrate this with the suitcase's own integral wheels, but I think that will be much harder to package and you might want to defer that. Perhaps you'll have time for that as well during your twelve weeks, but I suggest you get the standalone version working first - very little of the work on that will have been wasted if you decide to continue with 'phase 2' in the same project.

In other words, take an iterative approach and do the parts that will show the greatest value first. That's the electrics and electronics and control logic.

Thanks for the information. As my tutor has mentioned I should just make a version of this project where it isn't actually implemented within a suitcase but just to build the prototype design of it being powered involving a Arduino Uno (given to us by the university to keep) board.What I'm just worried about is the actual coding of this project as I haven't even got the slightest bit of experience in Arduino programming never mind java programming. What would you say about the coding side of this project? Is it complex or a simple bit of coding required to spin the wheels around?
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To keep the project simple, you could get an inexpensive servo tester like below and a big inexpensive servo like the bottom ones (modified for continous rotation) to drive the wheels. Make a push/pull or squeeze setup for the suitecase handle to operate the servo tester pot as needed to control the servo foward/neutral/reverse rotation.

http://www.hobbyking.com/hobbyking/store/__14774__HobbyKing_Servo_Tester.html

http://www.hobbyking.com/hobbyking/store/__8296__Turnigy_Servo_Tester.html

http://www.hobbyking.com/hobbyking/store/__291__189__Servos_and_parts-X_Large_Servo_50g_.html

Excuse me for my stupidity in the Arduino project field but does your method involve the use of a Arduino Uno board as the assignment requires that I use and Arduino board included in the project.
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An Arduino and motor drive shield (with separate power supply for the motors) is all you need to drive the motor forwards and backwards at varying speeds. You would need to provide a control input to tell the Arduino what to do, for example a force sensor on the handle (i.e. a sprung lever that operates a potentiometer). The idea would be that the operator applies a very light pull on the handle, and your system applies whatever drive force is needed to make the suitcase keep up. The key point here (IMO) is that the operator is merely pulling the suitcase in the direction they want it to move and not explicitly operating a throttle or speed controller. It should be completely intuitive, just like pulling a much lighter trolley, rather than needing the operator to consciously squeeze or twist a controller. There are various techniques to decide how much drive to apply but the simplest one is to just make the drive force proportional to the force on the handle. That is probably all you need, and would be very simple to code.
« Last Edit: November 13, 2012, 11:10:21 am by PeterH » Logged

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Quote
Excuse me for my stupidity in the Arduino project field but does your method involve the use of a Arduino Uno board as the assignment requires that I use and Arduino board included in the project.

There is a servo library provided in the arduino IDE. Servos modified for continous rotation are often used as simple wheel drive motors in robot projects.
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Mind if I give it a try?

Try to find some motors with a lot of torque, and a motor controller with PWM that can handle a good amount of current,2-3 Amps should be plenty.
As for the pressure sensor, try and get a digital body scale, (cheap one) and take out the sensor inside. You will need to calibrate the values from the sensor, 0 Lbs - 20Lbs (something like that). Those values will determine how much voltage in "PWM terms" to supply to the motors. You also may want a contact button or switch for when the person is trying to pull the suitcase. This switch will enable the motors to move when needed.

The rest is up to you.

Code wise, there are MANY samples for motors, sensors, LEDs, switches,etc...
The arduino comes with those types of examples, you just have to combine the ones you need into one main program.
« Last Edit: November 13, 2012, 04:21:18 pm by HazardsMind » Logged

Created Libraries:
TFT_Extension, OneWireKeypad, SerialServo, (UPD)WiiClassicController, VWID

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