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Table 3 RMS values of the constraining forces and moments during VV tests

From: Evaluation of three force-position hybrid control methods for a robot-based biological joint-testing system

Control method

0° Knee flexion

30° Knee flexion

Force (N)

Moment (Nm)

Angle (deg)

Force (N)

Moment (Nm)

Angle (deg)

AP

PD

LM

IE

FE

FE

AP

PD

LM

IE

FE

FE

Total

 CT

7.6

(0.3)

9.0

(2.3)

12.1

(1.1)

0.22

(0.00)

0.31

(0.03)

0.08

(0.01)

2.4

(0.2)

9.3

(3.1)

5.9

(1.2)

0.22

(0.01)

0.23

(0.01)

0.13

(0.00)

 FPH

5.7

(0.5)

5.6

(0.4)

8.6

(0.2)

0.23

(0.01)

0.33

(0.01)

0.09

(0.06)

3.4

(0.1)

7.9

(0.5)

2.5

(0.1)

0.13

(0.01)

0.28

(0.01)

0.05

(0.01)

 FPA

3.9

(0.1)

5.6

(0.4)

2.3

(0.2)

0.12

(0.00)

0.33

(0.01)

0.54

(0.00)

1.6

(0.1)

5.2

(0.1)

1.2

(0.1)

0.08

(0.01)

0.23

(0.01)

0.36

(0.02)

 FPHFM

3.1

(0.4)

4.7

(0.1)

2.2

(0.2)

0.13

(0.00)

0.30

(0.01)

0.66

(0.07)

1.3

(0.1)

4.9

(0.2)

1.1

(0.1)

0.07

(0.01)

0.23

(0.00)

0.28

(0.05)

Valgus

 CT

5.3 (0.5)

7.0

(2.3)

20.2

(0.9)

0.25

(0.02)

0.27

(0.04)

0.05

(0.01)

1.9

(0.3)

11.4

(3.9)

7.4

(1.6)

0.33

(0.01)

0.18

(0.01)

0.06

(0.00)

 FPH

4.5

(0.5)

4.4

(1.1)

11.9

(0.4)

0.24

(0.03)

0.31

(0.03)

0.06

(0.06)

3.3

(0.1)

8.5

(0.5)

3.6

(0.1)

0.22

(0.01)

0.25

(0.00)

0.04

(0.01)

 FPA

4.7

(0.0)

5.8

(0.6)

2.5

(0.2)

0.12

(0.00)

0.37

(0.01)

0.30

(0.00)

1.8

(0.1)

4.2

(0.1)

1.2

(0.1)

0.13

(0.00)

0.23

(0.01)

0.45

(0.02)

 FPHFM

4.0

(0.1)

4.9

(0.2)

2.5

(0.2)

0.13

(0.01)

0.33

(0.02)

0.31

(0.07)

1.9

(0.1)

3.6

(0.2)

1.4

(0.1)

0.19

(0.00)

0.26

(0.00)

0.41

(0.05)

Varus

 CT

11.7

(0.2)

12.1

(1.8)

4.9

(0.7)

0.13

(0.00)

0.36

(0.01)

0.11

(0.01)

4.1

(0.3)

7.9

(3.0)

1.7

(0.9)

0.10

(0.01)

0.34

(0.01)

0.20

(0.00)

 FPH

8.2

(0.6)

7.6

(0.3)

4.7

(1.2)

0.21

(0.01)

0.37

(0.01)

0.14

(0.06)

3.6

(0.1)

7.4

(0.5)

2.0

(0.1)

0.06

(0.00)

0.31

(0.00)

0.07

(0.01)

 FPA

1.8

(0.1)

5.1

(0.2)

1.7

(0.3)

0.22

(0.00)

0.27

(0.01)

0.78

(0.00)

1.5

(0.1)

6.1

(0.2)

1.3

(0.2)

0.01

(0.01)

0.24

(0.01)

0.23

(0.02)

 FPHFM

1.7

(0.4)

4.4

(0.1)

1.7

(0.3)

0.23

(0.01)

0.27

(0.01)

0.94

(0.07)

1.0

(0.1)

5.4

(0.2)

0.9

(0.2)

0.01

(0.01)

0.22

(0.01)

0.22

(0.05)

  1. Means (standard deviations) of the RMS values of the residual constraining forces (AP, PD, ML) and moments (IE) during VV tests of the knee at 0° and 30° flexion during the constrained test (CT), and unconstrained tests using force-position hybrid control (FPH), force-position alternate control (FPA), and force-position hybrid control & force-moment control (FPHFM). As expected, CT needed the largest constraining forces and moments. For unconstrained tests, FPHFM achieved much smaller constraining forces and moments than FPH. The performance of FPA was similar to FPHFM except for AP and PD constraining forces that were in between those of FPHFM and FPH. The FE moments required to maintain the knee flexion angle are also provided
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