Electronics

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The LocoKit electronics is built around a GumStix module.

The architecture of the LocoKit electronics platform is shown in the figure above. The two top boards, the "Processor Board" and the "Power Board", are mounted on top of each other. A robot only contains one of these sandwich-boards. Communication to the peripheral motor boards goes through a wired connection (six wires to be exact). There is no dedicated board for integrating external sensors because they can be connected directly to the Processor Board or any of the Motor Boards in the system using the available pins

Processor board

The main component is the "Processor Board", which as mentioned is an interface board for the GumStix module. Besides interfacing to the GumStix, it provides onboard sensors as well as available port for external sensor inputs. The GumStix board has the following specifications:

  • Interfaces to a Gumstix Overo Air standard processor board, 600MHz OMAP3, 512MB RAM
  • Runs Angstrom Linux, but other distributions are possible
  • Onboard accelerometer and gyroscope
  • General sensor interface
  • SDCard reader (used as harddrive)
  • 8 general purpose I/O ports
  • 4 analog inputs
  • 1 I^2C interface
  • 2 Buttons and 5 LEDs

Power board

To support LocoKit with a stable power supply, a custom-design Power Board is provided. The Power Board has the following specifications:

  • A 6S LiPo battery provides the power
  • Fuse for short-circuit protection
  • Battery undervoltage protection is implemented in hardware
  • Voltage is regulated to a stable 24V
  • Maximum cont. current 10A
  • Efficiency of 90-95%

Motor board

We have chosen to use Maxon motors despite their high cost because they provide great stability, efficiency and power density. On top of this they are designed in a way that makes it possible to overdrive them without damaging them. For this reason we have made the Motor Board compatible with many of the connectors from Maxons Brushless motor series.

The Motor Board have the following specifications:

  • Controls 1 brushless DC motor
  • Interfaces to most Maxon BLDC motors
  • Designed for 24V, 48W
  • 48MHz ARM7 processor for time critical control and motor commutation
  • 4 general purpose I/O inputs multiplexed with analog inputs for local sensor interface