Table 6.

Low-level control strategies used in PAEs.

Low-Level Control Scheme		References
Classical PID		PID [39,53,54,55,56,67,68,76,77,78,79,82,86,101,102,108,109,110,114,119,120,121,136,138,139,140,154,155]
		P [100,106,107,113,146,172,178,185,186,187,204]
		PI [85,100,105,178,185,186,187]
		PD [10,57,65,66,69,70,71,72,73,81,137,147,148,149,150,151,152,153,161,162,163,164,165,180,181,202,206,207]
		Adaptive PID [37,64,80,83,84]
Iterative Learning		[58,68,69,70,71,72,73,131,181,182,202]
Adaptive		[40,68,159,160,189]
Sliding Mode		[53]
Open-Loop Feed-Forward		[94,158,184,206,207]
Pneumatic Actuation Controls	On-Off Solenoid Valves	[146,156,166,167,170,171,173,174,175]
	Pulse Width Modulation (PWM) with Solenoid Valves	[38,62,63,141,173,188]
	Proportional Pressure Regulators with Solenoid Valves	[11,43,49,50,88,89,90,91,92,93,95,96,97,98,99,132,133,134,135,142,168,169,190,191,192,193,194,195,196,197,198,199,200,201,203]