Table 7.

Quasi-passive single-joint assisted lower limb exoskeletons.

Study	Year	Joint	App.	Weight & Load	Element	Attribute	Subject	Speed
Slovenia [126]	2020	$\mathrm{H}\prime$	MA	W (1.75)	Clutch, servo motor, encoder, and spring	——	7-HS	Walk, sit, squat and lift load randomly
USA [127]	2004	$\mathrm{K}\prime$	MA EWB	W (< 8.13)	Series elastic actuator	P (0.634)	——	——
Canada [128]	2008	$\mathrm{K}\prime$	MA	W (11.7); L (36)	Spring, clutch, and variable damping	P (0.06)	1	Optional speed walking
USA [129]	2012	$\mathrm{K}\prime$	MA	W (2.31)	Leaf spring and clutch	TS (3.6)	6	3.2 m/s running
Italian [130]	2014	$\mathrm{K}\prime$	MA	——	——	TS (200) ${\mathrm{MT}}_d$ (45)	——	Standing and sitting
USA [131]	2014	——	——	——	——	0%, 33%, 66%, and 100% of the knee stiffness	7	Walking
USA [132]	2014	$\mathrm{K}\prime$	MA	W (2.63); W (2.45);	Motor, worm gear set, and spring	——	——	4.83 km/h walking
Italian [133]	2016	$\mathrm{K}\prime$	MR ME	——	——	——	——	——
USA [134]	2017	$\mathrm{K}\prime$	MR	W (0.76)	Two outboard motors	${\mathrm{MT}}_d$ (25)	$1 \mathrm{M}\prime$	1.25 m/s walking
USA [135]	2017	$\mathrm{K}\prime$	MA		Air spring and solenoid valve	——	$1 \mathrm{F}\prime$	Walk at a speed of 1m/s with a slope of −5°
USA [5]	2018	$\mathrm{K}\prime$	MA	W (3.2)	Gear and 1-DOF rolling joint	——	3-HS	——
Italian [136]	2021	$\mathrm{K}\prime$	ME	W (5.5)	Soft clutch and elastic belt	${\mathrm{MT}}_d$ (12)	1-HS	3 km/h walking
China [137]	2015	$\mathrm{A}\prime$	MR MA	——	Motor, clutch, and ball screw	SC (17.97) P (0.15) ${\mathrm{MT}}_d$ (15)	$1-\mathrm{SM} \mathrm{M}\prime$	1.0 m/s walking
USA [138]	2020	$\mathrm{A}\prime$	MA	W (1.323)	Motor and slider	SC (5.8) TS (169–362)	1-HS	1.0 m/s & 1.5 m/s walking
Slovenian [139]	2020	$\mathrm{A}\prime$	MA	W (1.09)	Ratchet and pawl clutch	——	$7-\mathrm{HS} \mathrm{M}\prime$	Walking

App.: Application. $\mathrm{H}\prime$: Hip;$\mathrm{K}\prime$: Knee; $\mathrm{A}\prime$: Ankle; $\mathrm{F}\prime$: Foot; W: Weight (kg); L: Load (kg); $\mathrm{S}\prime$: Solider; $\mathrm{M}\prime$: Male; $\mathrm{F}\prime$: Female; HS: Heath subjects; SP: stroke patient; PSCI: patient with spinal cord injury; SM: simulation model; MA: Movement assistance; MR: Medical rehabilitation; ME: Motivation enhancement; EWB: Enhanced weight bearing; O: Orthosis; SC: Stiffness coefficient(N/mm); TS: Torsional stiffness (Nm/rad); P: Power (kW); ${\mathrm{MT}}_m$: Maximum torque of motor (Nm); ${\mathrm{MT}}_d$: Maximum torque of device (Nm); $\mathrm{P}\prime$: Normalized peak power (W/kg); P: Power (kW).