A two-degree-of-freedom control moment gyro for high-accuracy attitude control.

Liska, D.J.

doi:10.2514/3.29188

Cited by 10 publications

(4 citation statements)

References 2 publications

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“…Scissored pairs, also referred to as V gyros or twin gyros [22], produce torque about a single axis by using antisymmetric (equal magnitude, opposite direction) gimbal angles to cancel unwanted torque on the body. Cross-coupling torques acting on the gimbal motors that result from body motion can be canceled internally to reduce gimbal torque [22][23][24]. Singularities occur in a scissored pair only if the commanded torque exceeds the gimbal-rate capability of the scissored pair in magnitude or if the momentum stored in the pair is at a maximum.…”

Section: B Scissored Pairsmentioning

confidence: 99%

“…Interestingly, systems without meaningful torque amplification remove one objection to double-gimbal CMGs (DGCMGs): the need to transfer large torques through the gimbal motors rather than bearings [21]. A DGCMG could reduce ACS volume [24], though questions remain regarding the reliability and accuracy of such a system [19]. When sp is the limiting factor in a particular CMG-robot application, an estimate of the optimal h r that maximizes _ may be determined as follows.…”

Section: Gimbal Torque and Torque Amplificationmentioning

confidence: 99%

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Energetics of Control Moment Gyroscopes as Joint Actuators

Brown

Peck

2009

Journal of Guidance, Control, and Dynamics

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This work compares the power and energy used by a robotic linkage actuated by either joint motors or scissored pairs of control moment gyroscopes. The objectives are to establish straightforward sizing equations that provide a basis for deciding on a system architecture and to validate them with detailed models. The resulting parallels between joint motor and control moment gyroscope actuation increase intuition for and inform the design of control moment gyroscopes on a single-body satellite. Control moment gyroscopes are chosen as an energy-efficient means of reactionless actuation that reduce nonlinearities and coupling between the robot and the spacecraft attitude control system. Scissored-pair control moment gyroscopes are well suited for robotics applications because the output torque acts only along the joint axis, eliminating undesirable gyroscopic reaction torques. Both analysis and simulation of a single-link robot demonstrate that the control moment gyroscope power is equal to the equivalent joint motor power for a large range of gimbal inertias and maximum gimbal angles. The transverse rate of the link does not affect this result. A two-link robot with orthogonal joint axes gives results similar to the single-link system unless momentum is not conserved about the joint. For a two-link robot with parallel joint axes, control moment gyroscopes outperform joint motors in power required when the joints rotate with opposite sign; the reverse is true when the joints act in unison. These surprising differences arise because control moment gyroscopes produce body torques with a zerotorque boundary condition at the joint, whereas joint motors produce torques that are reacted onto two adjacent links. The analysis concludes with pros and cons of control moment gyroscopes as robotic joint actuators.

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Section: B Scissored Pairsmentioning

confidence: 99%

Section: Gimbal Torque and Torque Amplificationmentioning

confidence: 99%

Energetics of Control Moment Gyroscopes as Joint Actuators

Brown

Peck

2009

Journal of Guidance, Control, and Dynamics

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“…The only effect gimbal inertia has on energy use independent of the total body inertia is its contribution to the gimbal torque of Eq. (14). The baseline parameters for all single-link simulations are given in Table 1.…”

Section: Gimbal Inertia Variationmentioning

confidence: 99%

“…Scissored pairs produce torque about a single axis by using mirrored gimbal angles to cancel unwanted torque on the body. Cross coupling torques acting on the gimbal motors that result from body motion can be cancelled internally to reduce gimbal torque [12][13][14]. The present work considers first a single-link robot to create an intuitive foundation and provide useful equations for sizing CMGs.…”

Section: Introductionmentioning

confidence: 99%

Control Moment Gyros as Space-Robotics Actuators

Brown

2008

AIAA Guidance, Navigation and Control Conference and Exhibit

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Control moment gyros (CMGs) are an energy-efficient means of reactionless actuation. CMGs operate by gimbaling a high-speed rotor to change the momentum of a base body. We investigate a robotic linkage actuated by scissored-pair CMGs. Scissored pairs constrain the output torque from the CMGs to act along the joint axis, eliminating undesirable gyroscopic reaction torques. This work compares the energy required to actuate a robotic linkage with either CMGs or direct drive motors. We show that the CMG power is equal to the directdrive power for a large range of gimbal inertias and peak gimbal angles. The transverse rate does not independently affect this result. We find that the scissored pair's peak gimbal rate is a ratio of body acceleration to body rate. The equations of motion for an n-link robot with CMGs are presented in a recursive form for easy implementation in software. The results for a one-link robot extend easily to two-link robots with orthogonal joint axes when the peak body rate and peak gimbal angle are adjusted to account for the influence of neighboring links. CMGs surprisingly outperform direct drive for a two-link robot with parallel joint axes when the joints rotate with opposite sign, as in reaching tasks; although the reverse is true when the joints act in unison. These differences arise because CMGs produce body torques with a zero-torque boundary condition at the joint, whereas direct drive produces joint torques.

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Torque distribution of The Integrated Magnetically Suspended Inertia Actuator for attitude maneuvers

Fang

Yang

2016

Acta Astronautica

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A two-degree-of-freedom control moment gyro for high-accuracy attitude control.

Cited by 10 publications

References 2 publications

Energetics of Control Moment Gyroscopes as Joint Actuators

Energetics of Control Moment Gyroscopes as Joint Actuators

Control Moment Gyros as Space-Robotics Actuators

Torque distribution of The Integrated Magnetically Suspended Inertia Actuator for attitude maneuvers

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