Robobuilder

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Assembled Robobuilder "Huno"
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Assembled Robobuilder "Huno"
One can control the Robobuilder from within an interactive Ruby session (also available as 15.5 MByte DivX3 video and available on Youtube)
The Robobuilder Kit contains components for assembling a humanoid robot
Enlarge
The Robobuilder Kit contains components for assembling a humanoid robot
Table of contents
1 Robobuilder

1.1 Capabilities

2 Ruby Examples

2.1 Using the RBC controller

3 Todo
4 External Links
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Robobuilder

Currently all our Robobuilders are in disrepair (plastic gears of multiple servos are broken). We are trying to order metal gear (https://robosavvy.com/store/product_info.php/products_id/524) replacements. According to Mark Williamson's thesis (https://groups.csail.mit.edu/lbr/hrg/1995/mattw_ms_thesis.pdf) (MIT) ideally one should replace the rigid servos with series elastic actuators to avoid the large shock loads which result from unexpected collisions which can cause the gear teeth to break. However it may be better to use a sliding clutch since introducing elasticity will limit the dynamics of the system.

Update: A temporary solution might be to lower the overload parameter of the wCK servos. Furthermore it is possible to specify an upper and lower limit for the joint angle.

Image:Working.gif

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Capabilities

  • main body
    • AVR microcontroller
      • motion programs
      • direct control
    • 16 servo controllers, serial bus
      • self-running mode
      • interpolation + closed-loop control
    • LiPo akku, DC power connector
  • sensors
    • 3-axis accelerometer (add-on)
    • ultrasound distance sensor
  • communication
    • RS232 interface
    • Bluetooth interface (add-on)
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Ruby Examples

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Using the RBC controller

You can get the Ruby-extension for controlling the Robobuilder with a GNU+Linux PC here:

github.com/wedesoft/robobuilder

Here is a small example program which makes the robot get up if it's lying on its back or its front. 

#!/usr/bin/env ruby
require 'robobuilder'
require 'matrix'
class Vector
  def norm
    Math.sqrt inner_product( self )
  end
end
robot = Robobuilder.new '/dev/ttyUSB0'
puts "Robobuilder"
puts "Serial number: #{robot.serial_number}"
acceleration = Vector[ *robot.accelerometer ]
if acceleration.inner_product( Vector[ 0, 0, 1 ] ) >
    acceleration.norm * 0.97
  robot.basic
  robot.a
elsif acceleration.inner_product( Vector[ 0, 0, 1 ] ) <
    -acceleration.norm * 0.97
  robot.basic
  robot.b
end
acceleration = Vector[ *robot.accelerometer ]
if acceleration.inner_product( Vector[ 0, 1, 0 ] ) >
    acceleration.norm * 0.97
  robot.run 1
end
robot.close
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Todo

  • Implement various commands of direct mode
  • Implement commands for uploading motion sequences and action sequences
  • Add support for Bluetooth communication
  • Port wired and wireless serial communication to Windows
  • Computer vision feedback using (external) webcam
[edit]

External Links

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