Another device that can be controlled in a similar manner is the OWI Robotic Arm with a USB interface:

This has featured in The MagPi magazine several times, thanks to Stephen Richards's
articles on Skutter; the USB control has been explained in detail in issue 3 (page 14)
at https://issuu.com/themagpi/docs/the_magpi_issue_3_final/14. It can also be found at https://www.raspberrypi.org/magpi/issues/3/.

The robotic arm can be controlled using the following class. Remember that you will also need to adjust the commands, UP, DOWN, and so on, when calling the move() function, as shown in the following code:

class OwiArm(): 
  idVendor=0x1267 
  idProduct=0x0000 
  idName="Owi Robot Arm" 
  # Protocol control bytes 
  bmRequestType=0x40 
  bmRequest=0x06 
  wValue=0x0100 
  wIndex=0x00 
  # Protocol command bytes 
  BASE_CCW    = [0x00,0x01,0x00] 
  BASE_CW     = [0x00,0x02,0x00] 
  SHOLDER_UP  = [0x40,0x00,0x00] 
  SHOLDER_DWN = [0x80,0x00,0x00] 
  ELBOW_UP    = [0x10,0x00,0x00] 
  ELBOW_DWN   = [0x20,0x00,0x00] 
  WRIST_UP    = [0x04,0x00,0x00] 
  WRIST_DOWN  = [0x08,0x00,0x00] 
  GRIP_OPEN   = [0x02,0x00,0x00] 
  GRIP_CLOSE  = [0x01,0x00,0x00] 
  LIGHT_ON    = [0x00,0x00,0x01] 
  LIGHT_OFF   = [0x00,0x00,0x00] 
  STOP        = [0x00,0x00,0x00]