Table 1

Comparison of ACSR and HAAS vibration suppression techniques

Fig.1

Layout of HAAS

Fig.2

HAAS signal and power flow situation

Fig.3

Helicopter rotor hub vibratory forces

Fig.4

（N±1）Ω rotating components in hub plane［16］

Fig.5

Top-mounted active actuator for rotor hub

Fig.6

Mass-block motion in actuator unit

Fig.7

Modeling and synthesis of output force for two mass blocks

Table 2

Output force performance metrics of actuation unit

Fig.8

Motor position setting in variable force amplitude dynamic response process

Fig.9

Motor position setting in variable phase dynamic response process

Fig.10

Exploded view of actuation unit

Fig.11

Axis offset structure design

Fig.12

Force analysis of mass block in self-balancing process

Table 3

Bearing-related parameters of actuation unit

Fig.13

Position trajectory optimal strategy control diagram

Fig.14

Control block diagram of the single-motor in actuation unit

Table 4

Drive/brake mode current loop parameters

Fig.15

Simplified transfer function diagram of speed loop［20］

Fig.16

ω sc under different k sp/k si

Fig.17

Frequency domain and time domain characteristic curves of calibrated speed loop

Fig.18

Position change and inner loop given

Fig.19

Speed reference ramp-up and ramp-down

Fig.20

Motor speed path planning

Fig.21

Position command for dual motors when the phase variation is π rad

Fig.22

Loop command after dual-motor trajectory optimization

Fig.23

Output force performance test bench setup

Fig.24

Angle difference of dual motors in an eccentric shaft configuration

Fig.25

Maximum output force waveform at working frequency of 4

Fig.26

Waveform of minimum output force at operating frequency of 6

Fig.27

Waveform of output force during frequency-varying dynamic response

Fig.28

Dynamic response waveform of variable force amplitude at a working frequency of 4

Table 5

Dynamic performance of actuator unit under variable force amplitudes

Fig.29

Phase change to 90° at frequency of 6

Fig.30

Minimum force start-stop output waveform

Fig.31

Speed waveforms of dual motors after trajectory optimization during dynamic process

Fig.32

Bus voltage and current during dynamic response process before and after policy optimization

Fig.33

Force waveform of dynamic response with phase change before and after strategy optimization