Table 2.
Augmentation PAFOs tested on healthy subjects in level or uphill walking experiments
| Ref. | Actuation (Pf/Df) | Control | Weight PAFO | Subjects | Conditions (n. sessions /repetitions) | Ul / Bl | Portable | Results on metabolic cost | Results on muscle activation |
|---|---|---|---|---|---|---|---|---|---|
| Asbeck, 2015 [22] | SEA (Pf*) | P-Bc | 10.1 kg | 5 H | training:10U-10P; test:8U-8P(x6 powered conditions, different peak passive and active moments)-8U, 34.6kg load (1sess) | Bl | yes | only in 1 condition reduced w.r.t. U (-6.4%) | / |
| Cain, 2007 [35] | PAM (Pf) | P-Bc | 1.1 kg | 6 H | N (1sess), 10U-30P-15U (2sess) | Ul | no | / | SOL, LG, MG similar to U |
| PMc (SOL) | 6 H | SOL, LG, MG reduced wrt U | |||||||
| Galle, 2014 [45] | PAM (Pf) | P-Bc | 0.76 kg | 9 H | U and P, 15% In, every 3 min load = 5% bodyweight added until exhaustion (1sess) | Bl | no | -10% in P and U at exhaustion, but longer walking time in P w.r.t. U | / |
| Galle, 2015 [19] | PAM (Pf) | P-Bc | 0.76 kg | 7 H | training: 24P 0% In; test: 15% In, 4U, 4P(x4 poweredconditions, different onset timings) (1sess) | Bl | no | bigger reduction (-12% w.r.t. U) when onset at 26% and 34% | for onset 34%: TIB increased beginning swing, VL and BIC reduced beginning stride |
| Galle, 2017 [21] | PAM (Pf) | P-Bc | 0.89 kg | 14 H | training: 4N-4U-4P(x12) (1sess); tests: 2N-2U-2P(x12) (1sess); 12 powered conditions: 4 onset timings, 3 power levels | Bl | no | bigger reduction for 43% onset and middle power condition (- 21% w.r.t. U) | SOL: reduced with higher power and earlier timings; MG: reduced with higher power and later timings; TIB: increased with increase power |
| Jackson, 2015 [20] | SEA (Pf) | P-Bc | 0.83 kg | 8 H | 6N-8U-8P(x7 powered conditions: 4 work conditions, 3 torque conditions) (2 sess) | Ul | no | decreased with increased net work, but increased with increasing average torque | Exo-side SOL decreased with increased torque and work; contralateral VL decreased with increased work |
| Koller, 2015 [40] | PAM (Pf) | Ag-PMc (SOL) | 2.08 kg | 8 H | 10U-30P-10U (3 sess) | Bl | no | reduced throughout sessions; 3rd sess: -18% w.r.t U | 1st sess: SOL -20%, RFEM -9%, BIC -18%; 3rd sess: SOL -11%, RFEM -20%, BIC -17% w.r.t. U |
| Koller, 2017 [41] | PAM (Pf) | Ag-PMc (SOL) | / | 8 H | training: 10U-30P-10U (3 sess); test: 10U-10P(Ag-PMc)-10P(P-Bc)-10P(Ag-PMc) (1sess) | Bl | no | similar reduction w.r.t. U with both controllers (-19%) | SOL: reduced 12% more in P-Bc than Ag-PMc w.r.t. U |
| P-Bc | |||||||||
| Koller, 2018 [42] | PAM (Pf) | Ag-PMc (SOL) | 2.08kg | 8 H | training: 10U-30P-10U (3 sess); test: 10U-10P(Ag-PMc)-10P(P-Bc)-10P(Ag-PMc) (1sess) | Bl | no | similar reduction w.r.t. U with both controllers (-19%) | SOL: reduced 19% (peak linear envelope reduced 29%) w.r.t. U; RFEM: reduced 13% (peak linear envelope reduced 39%) w.r.t. U |
| P-Bc | SOL: reduced 28% (peak linear envelope reduced 38%) w.r.t. U, SOL activity in P-Bc 11% lower than in Ag-PMc; RFEM: reduced 9% (peak linear envelope reduced 35%) w.r.t. U | ||||||||
| Lee, 2016 [23] | SEA (Pf*) | P-Bc | 0.89 kg | 7 H | 8U-8P (x3 powered conditions, different power levels), 23kg load (1 sess) | Bl | no | -(11%-15%) w.r.t. U | / |
| Malcolm, 2013 [18] | PAM (Pf) | P-Bc | 0.67 kg | 8 H | 4U-4P(x5 powered conditions, different onset timings) (1sess) | Bl | no | bigger reduction (-17% w.r.t. U) when onset at 43% | |
| Malcolm, 2017 [25] | SEA (Pf*) | P-Bc | 1 kg | 8 H | training: 8P (x4 powered conditions, different power levels) (1sess); test: 8U-8P (x4 powered conditions, different power levels) (1 sess), 23kg load | Bl | no | -(11%-15%) w.r.t. U | / |
| Mooney, 2014 [47] | SEA (Pf) | P-Bc | 4 kg | 7 H | N-P, 23kg load (1 sess) | Bl | yes | reduced w.r.t. N | / |
| Mooney, 2014 [48] | SEA (Pf) | P-Bc | 3.6 kg | 7 H | 10N-20P-20U-10N (1sess) | Bl | yes | -14% w.r.t. N, U | / |
| Mooney, 2016 [49] | SEA (Pf) | P-Bc | 3.6 kg | 6 H | P-U-N (1sess) | Bl | yes | -14% w.r.t. N, U | / |
| Quinlivan, 2017 [24] | SEA (Pf*) | P-Bc | 0.89 kg | 7 H | training: 8warm-up-5U(x2)-5P(x4 powered conditions, different peak moments) (1sess); test: 8warm-up-5U(x2)-5P(x4 powered conditions, different peak moments) (1sess); | Bl | no | decreased with increased peak ankle moment w.r.t. U | / |
| Sawicki, 2008 [36] | PAM (Pf) | PMc (SOL) | 1.21 kg | 9 H | 10U-30P-15U (3 sess) | Bl | no | reduced throughout sessions; 3rd sess: -10% w.r.t U | SOL: reduced throughout sessions; 3rd sess: SOL -28%, MG: -10%, LG: -4% w.r.t. U |
| Sawicki, 2009 [37] | PAM (Pf) | PMc (SOL) | 1.18 kg | 10 H | >90 min training; 7U-7P (4 walking speeds) (1sess) | Bl | no | -(10%-12%) w.r.t. U for every walking speed | SOL, MG, LG, TIB: reduced at higher speeds, no difference at lower speeds |
| Sawicki, 2009 [38] | PAM (Pf) | PMc (SOL) | 1.18 kg | 9 H | >90 min training; 7U-7P (0%, 5%,10%, 15% In) (1sess) | Bl | no | -(10%-13%) w.r.t. U for every incline | SOL: -25% at 0% In, -(16%-18%) with In; LG: -24% in 0% In, -(8%-15%) with In |
| VanDijk, 2017 [50] | SEA (Pf) | P-Bc | 9 kg | 7 H | 12U-12P-12N (1sess) | Bl | yes | increased w.r.t. U | / |
| Zhang, 2017 [46] | SEA (Pf) | P-Bc | 0.83 kg | 1 - 11 H | N-U-64P, several conditions | Ul and Bl | no | optimized pattern changes with subjects; higher metabolic cost reduction with optimized assistance w.r.t. generalized | SOL: -36% w.r.t N, -41% w.r.t. U |
For uphill walking, the inclination is indicated. The type of actuator, the weight and portability of the device, the protocol and the results regarding the reduction of metabolic cost or muscle activation of each study are reported
H: healthy users; In: inclination; PAM: Pneumatic artificial muscle; SEA: Series elastic actuator; Pf: Plantarflexion; P-Bc: Phase-based controller; PMc, Ag-PMc: Proportional myoelectric controller and adaptive gain PMc; SOL, LG, MG, TIB, RFEM, BIC: VL: soleus, lateral and medial gastrocnemius, tibialis anterior, rectus femoris, biceps femoris and vastus lateralis muscles; N, U, P: normal walking, unpowered and powered walking condition; Ul, Bl: uni-/bi-lateral PAFO; the protocol code defines the conditions and the timings in minutes used for each session, e.g. xPyUzN means x minutes of powered walking, y minutes of unpowered walking and z minutes of normal walking. *: the Pf module exerted also hip flexion torques. In the works in which different experiments were performed (for example, different control strategies) the common information between the experiments (for example, same condition) is reported only once