Table 2.

Comparison of SAFOs in mass and effect.

Author	Motion Control Elements	Mass	Effect	Ref.
Blaya, J	Series Elastic Actuator	2.6 Kg	——	[25]
Furusho, J	Magnetorheological Fluid	1.6 Kg	Provide 24 N·m resistance torque	[28]
Kikuchi, T	Magnetorheological Fluid	0.99 Kg	Provide 10 N·m resistance torque	[29]
Chang, Y	Spring Clutch	0.9 Kg	10–20% decrease in gastrocnemius muscle activation	[30]
Wang, C	Spring Clutch	0.754 Kg	6% reduction in metabolic cost	[31]