Rotary actuator

A rotary actuator comprising:

• a motor;
• a harmonic drive;
• an electro-magnetic brake;
• a gear;
• and
• a motor pinion extending from the motor, through the electro-magnetic brake, to mesh with the gear;
• the rotary actuator being configured to transition between an operating mode, a hold position mode, and an unpowered mode, the motor driving the harmonic drive when the rotary actuator is configured in the operating mode, the harmonic drive being held stationary when the rotary actuator is configured in the hold position mode, and the harmonic drive being allowed to freewheel independent of the motor in a first direction and being inhibited from freewheeling in an opposite second direction when the rotary actuator is configured in the unpowered mode;
• wherein the electro-magnetic brake engages the motor pinion when the rotary actuator is configured in the hold position mode and in the unpowered mode;
• and wherein the electro-magnetic brake does not engage the motor pinion during the operating mode.

A rotary actuator comprising:

• a motor;
• a harmonic drive;
• and
• an electro-magnetic clutch operationally disposed between the motor and the harmonic drive, the electro-magnetic clutch including a stator, a rotor that is operationally coupled to the harmonic drive, and an armature that is operationally coupled to the motor, the electro-magnetic clutch being configured to transition between an engaged state and a disengaged state, the armature being engaged with the rotor to operationally couple the motor and the harmonic drive when the electro-magnetic clutch is configured in the engaged state, and the armature being disengaged from the rotor to decouple the harmonic drive from the motor when the electro-magnetic clutch is configured in the disengaged state;
• the rotary actuator being configured to transition between an operating mode, a hold position mode, and an unpowered mode, the motor driving the harmonic drive when the rotary actuator is configured in the operating mode, the harmonic drive being held stationary when the rotary actuator is configured in the hold position mode, and the harmonic drive being allowed to freewheel independent of the motor in a first direction and being inhibited from freewheeling in an opposite second direction when the rotary actuator is configured in the unpowered mode.

A rotary actuator assembly comprising:

• a motor;
• an electro-magnetic brake;
• a gear;
• a motor pinion extending from the motor, through the electro-magnetic brake, to mesh with the gear;
• a one-way clutch aligned with the gear;
• an electro-magnetic clutch aligned with the gear, the electro-magnetic clutch including a stator, a rotor, and an armature, the electro-magnetic clutch being configured to transition between an engaged state and a disengaged state, the armature being configured to transfer torque between the gear and the rotor when the electro-magnetic clutch is configured in the engaged state, and the armature being configured to transfer torque to the one-way clutch when the electro-magnetic clutch is configured in the disengaged state;
• a harmonic drive;
• and
• a mechanical slip-clutch operationally disposed between the electro-magnetic clutch and the harmonic drive so that torque is transferred from the rotor of the electro-magnetic clutch, through the slip-clutch, to the harmonic drive when the electro-magnetic clutch is engaged, the mechanical slip-clutch enabling slipping of the harmonic drive relative to the rotor of the electro-magnetic clutch when a predetermined amount of torque is applied to the harmonic drive from outside of the rotary actuator assembly.

A method of operating a rotary actuator including a motor configured to rotate a motor pinion, the rotary actuator also including a gear turned by the motor pinion, the method comprising:

• configuring an electro-magnetic brake in a powered state to release the motor pinion;
• operating the motor to rotate the motor pinion relative to the electro-magnetic brake to rotate the gear to a desired position, wherein operating the motor to rotate the motor pinion comprises transferring torque from the motor, through the motor pinion, through the gear, through an electro-magnetic clutch, through a slip-clutch, to a harmonic drive output;
• and
• configuring the electro-magnetic brake in an unpowered state to engage the motor pinion, thereby inhibiting rotation of the motor pinion, when the gear reaches the desired position.