/
Robotic Arm Passive Stoving/Caging Mechanism

Robotic Arm Passive Stoving/Caging Mechanism

May 11, 2021

Other Teams with Backdriveable Actuators:

 

Team Name

Characteristics 

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/