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Tank Bot for Lets Robot

V3 robot obtained a gripper
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The robot can unflip itself using the camera tilt servo:

Photos

V5 the weak 3d printed camera braket broke after a few days of abuse by random internet drivers
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V5 the new aluminum bracket uses a proper ball bearing so should last a while
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V4 top - 2x 5v regulator for RC Battery Style 2
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V4 underside - Battery "Style 2" - 78Wh / 2x 5,200mah RC Batteries in Parallel
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V3 underside - Battery "Style 1" - USB 99 Wh / 26,800 mAh battery
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V3 battery pack connections
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I bought another RavPower battery pack, but it did not work the same and it did not stay powered on. The over current protection circuit cut off the power output.

So I broke open the battery pack and rewired it from an 8P setup to 4P2S to provide 7.4v just like the RC battery setup.

V5 Custom Battery "Style 3" - 99 Wh / 26,800 mAh 18650 4P2S battery
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V3 gripper with neoprene pads
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Battery Style Runtime Comparison

Style 1 - USB Battery
26,800 mAh @ 5v = 99.2 Wh
15 Hours 12 Minutes

Style 2 - 2x RC Car Batteries
2x 5200 mAh @ 7.4v = 77.6 Wh
11 Hours 29 Minutes
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V2 got everything screwed in
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V2 top close up
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V2 Components
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The LED headlights are connected via a 100 ohm resistor and NPN transistor. This connects to the 3v power rail on the raspberry pi and a GPIO pin for control.

V2 Underside Single Battery Config
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V1 was pretty rough
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V1 had had night vision for a bit
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Scissors were fun
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Controls on Lets Robot
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Parts List

Total Cost ~ $334

Base

Tank Chassis $106 Amazon.com B077HMY3YK

Battery - pick 1

Battery Style 1 - RavPower 26,800 mAh USB Battery $90 Amazon.com B01LRQDAEI
Battery Style 2 - 2x Pcs Floureon 2S 7.4V 5200mAh 30C LiPo RC Battery $27 Amazon.com B06ZZ8TCNV

Electronics

Raspberry Pi 3 B+ $40 Amazon.com B07BDR5PDW
Logitech C920 Webcam $60 Amazon.com B006JH8T3S
Adafruit Motor/Stepper/Servo Shield for Arduino v2.3 $20 Amazon.com B00PUTH3B0
PAM8403 3W+3W DC 5V Mini Stereo Audio Amplifier $7 Amazon.com B078VTYQMT
2x Pcs LM2596 DC to DC High Efficiency Voltage Regulator 3.0-40V to 1.5-35V Buck Converter $10 Amazon.com B076H3XHXP

Servos

2x Pcs MG995 Metal Gear High Speed Torque 12kg Servo $26 Amazon.com B00M8TXSBO

Connectors and Hardware

20 Gauge Silicone JST Connector, SIM&NAT 5.9 inch $8 Amazon.com B071XN7C43
Generic 4.0mm 4mm RC Model Battery Male Banana Gold Plated Bullet Connector Plug For RC Lipo Battery $8 Amazon.com B01CJMVY74
100Packs 3.9mm Brass Bullet Male & Female Wire Terminals Connector $9 Amazon.com B075T13MTM
#2-56 UNC Stainless Steel Phillips Pan Head Machine Screws Nuts Assortment Kit (#2-56UNC) $13 Amazon.com B07BWBPV5G

Misc Parts

3 watt Speaker pulled from an old pair of computer speakers

Wires, Cable Shink Tube, Headers, Resistors, Bare PCBs



Page Revision History

2018-11-30 Published