Quadbot Puppy

Let's Make Robots Robots
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Dagu Quadbot Chassis

Picaxe 40x2

256k Eeprom

Maestro 12 Servo Controller

Sound Sensor

Compass Sensor

Switch Mode 3.5 Amp Power Supply for Circuits

5 x AA NiMh

Servo Power Connected direct to Batteries (via diode to drop voltage)

Solar 9v @ 390mA w/ diode

Latching Relay to turn on Solar

Pan / Tilt Servo Head with:

    4 x Sharp 10 - 80 cm IR Sensors (Up, Down, Left, Right Tracking)

    2 x Sharp 20 - 150 cm IR Sensors (Left, Right Long Range Tracking)

 

The Servo Controller has been programmed with all the movement scripts for the 8 leg servos. The picaxe 40 decides which of these to run. The eeprom and Tilt Compensated Compass use i2c, while the servo controller is connected via serial.

The Sharp Sensor LEDs are turned via 2 x BC337 transistors (4 short range and 2 long range). I'm not happy with this setup as I believe I'm not getting full LED brightness. My range for these sharp sensors are not even close to spec.

Still waiting for the sound sensor and solar cells to arrive.

I haven't started the software yet (except small test scripts for each of the hardware).

My idea for power is...

    Currently have setup 6v NiMh going into 3 x Power Diodes to drop voltage, directly connected to all servos.

    Power from batteries also go into a 3.5 Amp switch mode power supply to drive all the circuits and sensors.

    I have a latching relay onboard (driven by BC337 transistors) to turn on/off the solar panel when I install it.

    I will also setup a voltage divider on the Solar and the batteries to monitor them with the picaxe.

I will get the puppy to find light as the voltage drops. When light is found, puppy will lay down putting all servos to rest. All hardware will be turned off except picaxe, which will be place in sleep mode and only wake up every so often to check the charge level.

Wiring messy... Will cleanup later...

 

Originally had 10 x AA NiMh (2 x 5 in Parellel) but under the advice of "OddBot", dropped it down to 5 AA.

Like he stated, the excess weight will damage the servos. Thanks "OddBot"!!!

I will look into Lipos...

  • Actuators / output devices: 8 Servo, 2 Servo Pan/Tilt
  • Control method: autonomous
  • CPU: Picaxe 40X2, Pololu Micro Maestro Servo Controller
  • Power source: 6.0v AA NiMh 2200 mAh, 3.5 A Switch Mode
  • Programming language: Basic
  • Sensors / input devices: compass, accelerometer, X-Y Tilt Sensor, 6 x Sharp IR
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/quadbot-puppy
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Lipos

Yes, you are right. It is quite sluggish also. I’m looking at getting this thing to self charge from solar and have looked at lipos. My concern is lack of knowledge in that area. I would have to place 2 x 3.7v in series to get required power. I have plenty Li-Ion batteries laying around and would be great if I could put them to use. How can I charge that through solar? Is it ok to charge 2 in series? If not, how to balance charge from solar?

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Our fellow member Krumlink

Our fellow member Krumlink was looking into making a charger for a dual cell LiPo (also works for dual cell LiIon) by using a MCP73213 chip. He did not complete this project unfortunatelly, but perhaps you can take a look at the chip’s data sheet and make your own charger. I think that will be my next step. There are LiIon batteries out there with the same size as regular AA and AAA cells so you can use a regular battery holder for a couple of cells in series. This will reduce the weight of the robot, not as much as a LiPo, but at least it will charge from a USB port or wall USB charger.