TABLE 1.
Comparative study of the MR conditional actuation method.
| Actuation Type | Projects | Features | References | |
|---|---|---|---|---|
|
| ||||
| Pneumatic | PneuStep | (a) Torque: 600 N mm at low speed, 150 N mm at
high speed (b) Not backdrivable (c) Accuracy of 0.5 mm (d) No SNR reduction in 7T environment |
76–78 | |
| Sajima motor | (a) Torque: 140 N mm at low speed, 5 N mm at
high speed (b) Not backdrivable (c) Accuracy of 0.43 ± 0.15 mm (d) No SNR reduction observed (e) Simple structures |
70,71 | ||
| Pen-size motor | (a) Torque: 2.5 N mm at lo w speed, 1.25 N mm
at high speed (b) Not backdrivable (c) Accuracy not mentioned (d) SNR reduction of 2.49% (e) Compact design (10 mm) |
11 | ||
| Stormram motors | (a) Force: maximum 63 N for latest
version (b) Not backdrivable (c) Accuracy of 0.7 mm for latest version (d) No SNR reduction observed |
1,35–37 | ||
| Dual-speed motors | (a) Force: maximum 24 N, torque: 74 N
mm (b) Not backdrivable (c) Accuracy of 0.09 mm (d) SNR test not reported (e) Fast targeting (10 times faster than PneuStep, Stormram linear motor) |
34 | ||
| Cylinder-based rotary motor | (a) Torque: maximum 800 N mm at low speed, 500
N mm at high speed (b) Backdrivable (c) Accuracy of 2° (d) SNR reduction of 2.35% |
10 | ||
| Cylinder-based linear motor | (a) Force: maximum 47 N (b) Backdrivable (c) Accuracy of 0.26 mm (d) SNR reduction 4.2% in T2W TSE (e) RAPID response time (4 ms) |
26 | ||
| PneuAct | (a) Torque: 140 N mm at low speed, 10 N mm at
high speed (b) Backdrivable (c) Small stepper resolution (1.5°) () No SNR reduction observed |
23 | ||
| Bellow-based actuator | (a) Force: maximum 33 N (b) Not backdrivable (c) Accuracy of 0.013 mm and 0.018° (d) No SNR reduction observed in 3T scanner |
18 | ||
| Auxetic materials linear actuator | (a) Force: tested on 2 N load (b) Not backdrivability (c) Accuracy not reported (d) No SNR reduction observed in 1.5T scanner |
67 | ||
| Turbine-based motor | (a)Torque: maximum 919 N mm (b) Backdrivable (c) Accuracy of 2.19 mm (d) Max SNR reduction of 5% in 3T scanner |
8,12,13,73,95,96 | ||
| Fan-based motor | (a) Torque: 28 N mm at low pressure, 3 N mm at
high pressure (b) Backdrivable (c) Accuracy not reported (d) SNR test not reported |
92 | ||
| Piezoelectric | USR series | MR-SoftWrist | (a) Force: maximum 8 N, torque: maximum 630 N
mm (b) Not backdrivable (c) Accuracy of 2.25° (d) SNR reduction of 6% in 3T scanner |
22,75 |
| Neurosurgery robot | (a) Force or torque not reported (b) Not backdrivable (c) Accuracy of 1.37 mm (d) 10.3% SNR reduction in T1 scanner |
53,58,60,82,85 | ||
| HR series | Transrectal prostate robot | (a) Force: stall force of 24 N, torque:
maximum 1080 N mm (b) Not backdrivable (c) Average accuracy of 2.4 mm (d) SNR reduction of 5% with novel ceramic motor driver |
50 | |
| PiezoMotor | Needle placement robot | (a) Force not reported (b) Not backdrivable (c) Accuracy not reported (d) No SNR reduction observed in 3T scanner |
40 | |
| Concentric tube robot | (a) Concentric tube manipulation (b) Not backdrivable (c) Maximum error of 2.24 mm (d) SNR reduction of less than 2% |
51,81 | ||
| Stereotactic neural intervention system | (a) FORCE not reported (b) Not backdrivable (c) Accuracy not reported (d) No noticeable artifact in T1 and T2 scanner |
56 | ||
| Piezoworm | Piezoworm | (a) Torque: theoretical 5 N mm (b) Not backdrivable (c) Accuracy not reported (d) SNR reduction not reported |
20 | |
| Hydraulic | Master-slave hydraulic actuator | (a) Torque: 1470 N mm (b) Not backdrivable (c) Accuracy of 4.5 mm (d) SNR loss less than 2% (e) Dynamic lag of 66 ms for 10 m hydraulic transmission |
19,39,41,52 | |
| Hydraulically-actuated joint | (a) Force: 18.4 N (b) Not backdrivable (c) Accuracy not reported (d) SNR reduction not reported |
5,6,66 | ||
| Hybrid hydrostatic actuator | (a) Torque: delivered 2700 N mm (b) Backdrivable, but has passively-safe system (c) Accuracy not reported (d) SNR reduction not reported |
7,93 | ||
| Others | Shape-memory alloy actuator | (a) Force: maximum 1.5 N (b) Not backdrivable (c) Accuracy not reported (d) SNR reduction of 10% |
42–44 | |
| MR-powered motor | (a) Force: maximum 0.76 N (b) Not backdrivable (c) Accuracy not reported (d) No SNR reduction observed (e) Wireless powered |
88 | ||
| Elastic actuator | (a) torque: maximum 2000 N mm (b) Backdrivable (c) Accuracy not reported (d) SNR reduction not reported, but compatible to MRI |
74,98 | ||
| Electrostrictive actuator | (a) Force or torque: not reported (b) Backdrivability not available (c) Accuracy not reported (d) SNR reduction not reported, but imaging shows compatibility to MRI (e) Reconfigurable surface-imaging coil |
89 | ||