Table 6.

Quasi-passive lower limb multi-joint assisted exoskeletons.

Study	Year	Joint	App.	Weight & Load	Element	Attribute	Subject	Speed
USA [110]	2005	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	EWB	W (15.5); L (34)	Variable damper	——	1	0.82 m/s level walking
USA [111]	2006	$\mathrm{H}\prime$ $\mathrm{A}\prime$	MA	——	Springs, clutches, and variable damping	——	——	1.3 m/s level walking
USA [112]	2006	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	EWB	W (15); L (20); L (40); L (55)	——	——	10 S	4.83 km/h level walking 8 min
USA [3]	2007	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	MA EWB	W (11.7); L (36)	Variable damping and two springs	P (0.002)	$1 \mathrm{M}\prime$	0.92 m/s walking
France [113]	2010	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	MA EWB	——	Force balancer and driver	——	——	Ascend the stairs or slopes
USA [114]	2013	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{F}\prime$	O	W (3)	Actuator and spring module	P (0.0003) TS (109)	1	0.6 m/s walking
USA [115]	2014	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{F}\prime$	O	W (3)	Control module and support spring	TS (60)	3	——
Korea [116]	2014	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	EWB	W (21); L (35)	Actuator and passive mechanism	${\mathrm{MT}}_m$(1.8422)TS (92.25)	1	6 km/h walking
China [117]	2015	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	MA	——	Actuator and spring	——	——	——
Korea [118]	2015	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	EWB MA	W (23); L (30)	Spring and driver	SC (69.6)	$5 \mathrm{M}\prime$	4 km/h level walking; ascend the stairs
Japan [119]	2016	$\mathrm{K}\prime$	MR ME	W (9)	Passive components and two drivers	${\mathrm{MT}}_m$ (100) TS (1000) ${\mathrm{MT}}_d$ (15)	——	Level walking, squat, stand to sit
Netherlands [120]	2018	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	EWB MA	W (21.8)	Hydraulic piston damping	——	9	4.5~5.3 km/h walking
Italian [121]	2018	$\mathrm{H}\prime$ $\mathrm{K}\prime$	MA MR	W (4.1)	Elastic belt and clutch	——	$1-\mathrm{SP} \mathrm{M}\prime$	——
Italian [122]	2019	$\mathrm{H}\prime$ $\mathrm{K}\prime$	MA MR	W (4.9)	Elastic belt and clutch	——	$1-\mathrm{SP} \mathrm{M}\prime$	10 straight walks
Italian [123]	2020	$\mathrm{H}\prime$ $\mathrm{K}\prime$ $\mathrm{A}\prime$	MA	W (4)	Pressure sensor, solenoid valve, and vacuum generator	——	——	(2) Walk a straight path of 10 m with 10 min.

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).