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DOG circuits
Brushless Motor Circuit with ESC (One Side Only)
TREAT (using PIC12F752) and Lift Fan
Brake Servo
Audio
IMU
Power Distribution (DOG)
Tiva DOG
Our DOG used a total of three microcontrollers (Tiva, PIC, Teensy), and an XBee module for bi-directional communication with the Farmer.
Our DOG is heavier and bulkier than most other team's DOGs, so in order to get more thrust we decided to use quadcopter brushless motors and electronic speed controllers (ESCs) to drive Sparky. As none of us have worked with brushless motors before, there was a learning curve to figure out how to use them, but they ended up being worth the extra work.
The main design challenge we faced was to devise a way to switch the directions of our brushless motors. The ESC we bought had a setting to change motor direction, however when we bought it we did not realize that changing the direction of the motors was accomplished through a lengthy process where a low throttle command had to be sent during a particular beep sequence. The whole process took almost a minute, therefore it wasn't feasible to change the motor direction during the competition that way. Instead, we decided to use DPDT relays and switch the polarity of the motor connection to the ESC to change direction. Although unusual, our solution worked quite well! (We had to ensure in the code that around ~100ms of no throttle time had to be written into the ESC before switching the relay in order to not damage the ESC and the motor).
A servo was used to lower a brake pad, which helped rotate Sparky in place and stop it when it got too excited.
The Tiva was our main processor. A PIC12F752, interfaced to the Tiva over UART, controlled our lift fan.
A Teensy 3.2 with an SD card attached to it played music over its DAC, which used an audio amp board to drive the loudspeaker.
The Sparkfun LSM6DS3 6DOF breakout provided our DOG with acceleration and orientation information to be transmitted and displayed on the FARMER.
Our DOG is heavier and bulkier than most other team's DOGs, so in order to get more thrust we decided to use quadcopter brushless motors and electronic speed controllers (ESCs) to drive Sparky. As none of us have worked with brushless motors before, there was a learning curve to figure out how to use them, but they ended up being worth the extra work.
The main design challenge we faced was to devise a way to switch the directions of our brushless motors. The ESC we bought had a setting to change motor direction, however when we bought it we did not realize that changing the direction of the motors was accomplished through a lengthy process where a low throttle command had to be sent during a particular beep sequence. The whole process took almost a minute, therefore it wasn't feasible to change the motor direction during the competition that way. Instead, we decided to use DPDT relays and switch the polarity of the motor connection to the ESC to change direction. Although unusual, our solution worked quite well! (We had to ensure in the code that around ~100ms of no throttle time had to be written into the ESC before switching the relay in order to not damage the ESC and the motor).
A servo was used to lower a brake pad, which helped rotate Sparky in place and stop it when it got too excited.
The Tiva was our main processor. A PIC12F752, interfaced to the Tiva over UART, controlled our lift fan.
A Teensy 3.2 with an SD card attached to it played music over its DAC, which used an audio amp board to drive the loudspeaker.
The Sparkfun LSM6DS3 6DOF breakout provided our DOG with acceleration and orientation information to be transmitted and displayed on the FARMER.
Farmer circuits
Sensors and Switches
FARMER's LEDs
LCD
Power for FARMER
FARMER Top
Highlights from our FARMER:
- Single 7.2V cell powering the entire system
- One Tiva as the microprocessor
- XBee for communications with the DOG
- Sensory inputs:
- Rotary encoder attached to the dog bowl for steering
- Potentiometer attached to the dog bone for throttle / direction control
- Capacitive touch sensor for braking
- Button for pairing
- Microphone to sense clapping to activate peripheral function
- Outputs:
- LEDs for status indication
- LCD for IMU reports from the DOG
Our farmer's quiescent current consumption was measured to be 144.5 mA. With a 2000 mAh batteries, this yields a runtime of almost 14 hrs and puts us within runtime spec (> 10 hrs).