Robotic Arm Passive Stoving/Caging Mechanism

Owned by Ali Kasim Budhwani (Unlicensed)
May 11, 2021
2 min read

Other Teams with Backdriveable Actuators:


Team NameCharacteristics Image

KNR

  • Rest position is relatively horizontal

IMPULS:

  • Rest position is completely horizontal 
  • Low center of gravity
  • Can remain in that position for a max tilt of 60 degrees

MONASH
  • Completely horizontal L2 rest position
  • Arm further back, center of mass further back in rest position 
  • Passive holder/caging mechanisms for Linkage 2 

Electromagnetic Disk Brakes

  • Holds load when power is disconnected
  • Brakes used on the motors/drives
  • Two types
    • Spring applied brakes
    • Permanent Magnet brakes

Spring Applied Brakes


  • When there is no power:
    • Spring pushes against the pressure plate 
    • In turn, the friction disk is squeezed between the pressure plate and cover plate
    • The clamping force is transferred to the hub
    • Preventing the shaft to rotate
  • When there is power:
    • The field coil turns into an electromagnet and cancels out the spring force
    • The friction disk is not clamped anymore (i.e. there is gap between friction disk and pressure plate/cover plate)
    • The motor is allowed to rotate

Magnet Brakes

  • Magnets is used to attract a single face armature
  • When there is no power:
    • Magnets create flux, which attracts the armature to the brake/friction surface.
    • Prevents the shaft to rotate
  • When there is power
    • Power is applied to the coil which sets up a magnetic field that negates the flux of the magnets.
    • The motor is allowed to rotate


References:

https://www.electric-brake.com/