From: EMG-driven control in lower limb prostheses: a topic-based systematic review
Ref. | Perform-based measurements | Biomechanical measurements | Averaged results | Control delay | Subjects number | Reported limitations |
---|---|---|---|---|---|---|
[64] | QA on locomotion performance | NI | NI | 50–100 ms | > 1 TFA | NS |
[29] | Cadence, Swing and Stance duration | Joint angles and moments, maximum knee flexion | Results in figures only | NS | 1 TFA | Sensitive to movement artifacts |
Error events analysis | Joint angle NRME, CC | Max error events amplitude = 42 (11 SD); NRME < 6.56 (1.85 SD)%; CC = 0.59 (0.9 SD) | NS | 4 ABS | High maximum error amplitudes | |
[56] | Joint flexion/extension CA | Joint angle RMSE | CA = 92 (7 SD)%; RMSE = 6.2 (0.71 SD)\(^{\circ }\) | NS | 2 TFA, 1 BTFA | NS |
\(t_{STRIDE}\); \(v_{WALKING}\) | Joint angle and joint stiffness; RMSE in joint angle trajectory tracking | \(t_{STRIDE}\) = 1.96s; \(v_{WALKING}\) = 2.9Â km/h; able-bodied resemblance joint trajectories (figures only); RMSE statistical different only with haptic feedback and no-visual | 1Â ms | 1 TFA; 2 ABS | Not appropriate swing control; lack of somatosensory feedback; sensitive to movement artifacts and skin perspiration | |
[57] | Motor task CA, MCT and MCP | NI | CA = 90.7 (5.0 SD)%; MCT = 1.26 (0.1 SD)s; CP = 96.3 (4.3 SD)% | < 700 ms | 6 TFA | Sensitive to electrode shifts and impedance; extensive training necessary |
[37] | NI | VAF, RMSE joint angle | VAF > 83%; RMSE < 5.4 (1.2 SD)\(^{\circ }\) | − 100 ms | 3 TTA | Performance being tested only in constant velocity walking task |
[16] | MCT | NI | MCT = 1.9Â s | NS | 5 ABS | Position controller unsatisfactorily during stance phase |
NP | Joint peak power and work respect to state-base controller | Statistical difference of evaluated parameters only with visual feedback (p-val = 0.02) | 33 ms | 5 TTA | Short training session, experienced high muscular fatigue | |
[76] | NI | Joint angle trajectories | Results in figures only | NS | 10 ABS | No walking speed adaptation, no real-time |
[11] | NI | Joint trajectory r-value and SNR | r-value = 0.64 (0.22SD); SNR = 7.42 (2.88SD) | 3.3Â ms | 6 ABS | Position controller unsatisfactorily for limb dynamics |
Number of falling | Joint angle RMSE, EMG contraction level, mean joint torque during balance task | Falling events and applied torque decrease with training; final RMSE = 0.19 (8.78)\(^{\circ }\); no significant changes in muscle activation with training | 10 ms | 6 ABS; 6 TTA | Small sample population; study used visual feedback | |
[98] | NI | QA of EMG signals and joint angle | Figures only | NS | 1 TFA | Sensitive to movement artifacts; sensitive to muscular mass changes |
[70] | Locomotion classification accuracy | QA of ankle joint position and shank angular orientation | CA = 86.53 (8.5 SD)%; biomechanical measurements (figures only) | NS | > 1 ABS, > 1 TFA | NS |
[5] | Stance time; gait symmetry | Toe-off angle; peak torque; joint trajectories | Qualitatively similar to biological ankle trajectories (figures only) | NS | 1 BTTA | Asymmetry on knee flexion during late stance |
Locomotion and transitions CA | NI | Locomotion CA = 91.79–100%; transition CA = 100% | 12 ms | 5 TFA | Sensor fusion and sound leg instrumentation is necessary to increase accuracy | |
[53] | Locomotion CA | NI | CA \(\approx\) 80–100% (figures only) | NS | 5 ABS | NS |
[85] | Locomotion CA | NI | CA = 91.46% | NS | 100Â ms | NS |
Locomotion CA | NI | CA = 91.23% | NS | 3 ABS | Tested only healthy subjects | |
Locomotion and transitions CA | NI | Locomotion CA \(\approx\) 98%; transitions CA > 99% | < 45.2 ms | 4 TFA | Real-time test only on non-powered prosthesis; mechanical sensor feature are necessary | |
Locomotion CA | NI | CA = 97.9 (1.39 SD)% | NS | 5 ABS, 5 TFA | Only limited number of locomotions; major misclassification during gait transitions | |
[120] | Joint DoF motion CA | NI | 1-DoF CA = 93.3 (0.5 SD)%; 3-DoF CA = 84.4 (0.8 SD)%; | 50ms | 5 ABS, 12 TTA | Best results only combining both tibia and thigh muscles |
Locomotion CA, NWB CA, falls occurrences | NI | with TMR: locomotion CA = 8.9%, NWB CA = 91.0 (4.7SD)%, falls occurrence = 0%; no-TMR: locomotion CA = 10.2%, NWB CA = 86.8 (3.0SD)%, falls occurrence = 2% | NS | 4 TFA, 1 TMR | Control degradation over time due to fatigue, electrode shift and skin perspiration; necessity of mechanical sensors for high accuracy; small number of subjects | |
Locomotion and transitional CA, effects on classification errors | NI | Locomotion CA < 99%; transition CA = 87%; classification errors during stairs were more disruptive | < 20 ms | 7 TFA | Control degradation over time due to fatigue, electrode shift and skin perspiration; testing is performed in only one sessions | |
[17] | Questioner on control comfort | Inclination CA | CA > 95%; comfort higher when no classification error (accepted error \(\le 5^\circ\)) | NS | 2 TFA | Experienced high muscular fatigue; lack of sensory feedback |
[106] | NI | QA of EMG signals | Results in figures only | NS | 1 ABS | Not tested on amputee; only walking activity control |
Locomotion CA | NI | CA = 99.06 (0.87SD)% | 32Â ms | 5 ABS | Not tested on-line | |
[6] | NI | Joint angle trajectory frequency content | mean frequency = 5.4 (0.3 SD)Â Hz, qualitatively similar to biological ankle | NS | 1 TTA | Temporal variation of the EMG signals are not accounted for |
[61] | Subject qualitative report | QA of knee joint position and torque | Control interface did not feel natural; able-bodied resemblance joint trajectories (figures only) | NS | 1 ABS with ABA | Experimental tuning of the parameters is necessary |
QA of joint trajectories with respect to ABS | Joint angle trajectory RMSE | Results in figures only | NS | 1 ABS with ABA | Model parameters are tuned manually; control instable with biarticular muscles | |
NI | Toe-off angle, joint net work, peak power, joint torque vs angle | Net work performed higher than the biological norms; not substantial difference in joint moments between intrinsic controller and EMG-driven | 2Â ms | 1 BTTA; 3 TTA, 3 ABS | Further studies on the real metabolic cost benefits are required | |
[19] | NI | Joint torque NRMSD with respect ABS | NRMSD \(\le\) 0.24 (0.11 SD) | < 50 ms | 1 ABS | Complex subject-specific calibration; required validation on more subjects and hardware |