Fans As Actuators - Revision history

ScottM: /* Usage */

2008-12-22T20:00:57Z

Usage

← Older revision		Revision as of 15:00, 22 December 2008
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	Fans may be used as primary actuators for mobile robots intended to move without direct physical contact with a surface (floor, ceiling, etc). In particular, applications may include flying and hovering agents such as planes, helicopters, blimps, and hovercraft.		Fans may be used as primary actuators for mobile robots intended to move without direct physical contact with a surface (floor, ceiling, etc). In particular, applications may include flying and hovering agents such as planes, helicopters, blimps, and hovercraft.

	It is important to note that fans operate much differently than wheels or legs as they produce motion as a "force source". Without direct physical contact to a surface or ground, this will result in an acceleration ~~with low friction~~. To command the position of the agent, one will need to devise a double integrating controller.		It is important to note that fans operate much differently than wheels or legs as they produce motion as a "force source". Without direct physical contact to a surface or ground, this will result in an acceleration. To command the position of the agent, one will need to devise a double integrating controller.

	===Rating===		===Rating===

ScottM: /* Driving and Controlling */

2008-12-20T03:41:54Z

Driving and Controlling

← Older revision		Revision as of 22:41, 19 December 2008
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	==Driving and Controlling==		==Driving and Controlling==
			Driving a prepackaged fan is simply a matter of controlling the motor. Most fans will be driven by brushed DC or brushless DC motors. In many applications, fans are low power, and can be driven by prepackaged H-bridge circuits or with a single MOSFET. Note that if the fan you have selected is unidirectional, there is no advantage to using an H-bridge over a single MOSFET.

			Most computer cooling fans are designed to minimize EMI, and hence are actuated by brushless DC motors. Inside, they have their own brushless DC motor controller that adjusts the speed of the fan as a function of the input voltage. Although the controller accepts variable input voltages, the controller only functions for a single polarity and hence drives the fan in a single direction. From experimentation, it appears that the motor is not harmed by applying a reversely biased voltage.

	==Important Practical Considerations==		==Important Practical Considerations==

ScottM: /* Phase Lag */

2008-12-20T03:26:09Z

Phase Lag

← Older revision		Revision as of 22:26, 19 December 2008
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	To attain true bidirectional motion, one will typically have to select a bidirectional motor and propeller blade separately (avoid prepackaged fans). R/C airplane and helicopter hobby sites typically offer good starting points for such applications.		To attain true bidirectional motion, one will typically have to select a bidirectional motor and propeller blade separately (avoid prepackaged fans). R/C airplane and helicopter hobby sites typically offer good starting points for such applications.

	===Phase Lag===		===Time Constant (Phase Lag)===
	One of the most significant practical limitations of using a fan as an actuator is the lag when accelerating the fan. Accelerating from one velocity to another velocity (increasing/decreasing thrust) physically takes time. The amount of time is typically proportional to the difference in velocities and can be on the order of seconds.		One of the most significant practical limitations of using a fan as an actuator is the lag when accelerating the fan. Accelerating from one velocity to another velocity (increasing/decreasing thrust) physically takes time. The amount of time is typically proportional to the difference in velocities and can be on the order of seconds.

ScottM: /* Introduction */

2008-12-20T03:21:41Z

Introduction

← Older revision		Revision as of 22:21, 19 December 2008
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	==Introduction==		==Introduction==
			===Usage===
			Fans may be used as primary actuators for mobile robots intended to move without direct physical contact with a surface (floor, ceiling, etc). In particular, applications may include flying and hovering agents such as planes, helicopters, blimps, and hovercraft.

			It is important to note that fans operate much differently than wheels or legs as they produce motion as a "force source". Without direct physical contact to a surface or ground, this will result in an acceleration with low friction. To command the position of the agent, one will need to devise a double integrating controller.

			===Rating===
			Aside from typical input power specifications (voltage / current), the physical performance of a fan is measured by the fan's max flow rate, and max pressure. Flow rate is the measure of volume of fluid (air) through a given area in a fixed amount of time. Pressure is the measure of force per fixed unit area.

	==Most Common Types of Fans==		==Most Common Types of Fans==

ScottM: /* Most Common Types of Fans */

2008-12-20T02:56:42Z

Most Common Types of Fans

← Older revision		Revision as of 21:56, 19 December 2008
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	==Most Common Types of Fans==		==Most Common Types of Fans==
			For more information, [http://www.engineeringtoolbox.com/fan-types-d_142.html this link] gives a good overview including pressure/volume comparison graphs.
	===Axial (Propellor)===		===Axial (Propellor)===
	[[Image:AxialFanPicture.JPG \|thumb\|150px\|right\| Axial Fan]]		[[Image:AxialFanPicture.JPG \|thumb\|150px\|right\| Axial Fan]]

ScottM: /* Axial (Propellor) */

2008-12-20T02:48:18Z

Axial (Propellor)

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 [[Image:AxialFanPicture.JPG |thumb|150px|right| Axial Fan]]
 This type of fan uses a fixed blade that produces airflow parallel to the direction of rotation.  This fan design can be seen in many cooling applications, as it is designed to maximize the volume of air moved.
 ===Centrifugal (radial)===

ScottM: /* Most Common Types of Fans */

2008-12-20T02:48:11Z

Most Common Types of Fans

← Older revision		Revision as of 21:48, 19 December 2008
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	[[Image:CentrifugalFanPicture.JPG \|thumb\|150px\|right\| Centrifugal Fan]]		[[Image:CentrifugalFanPicture.JPG \|thumb\|150px\|right\| Centrifugal Fan]]
	A centrifugal fan is constructed with an impeller inside of a rigid housing and resembles a paddle wheel. Airflow is input through the center of the impellor and is output at a single radial vent. This type of fan is designed to increase the air pressure at its output, and is used in many blowing and inflating applications		A centrifugal fan is constructed with an impeller inside of a rigid housing and resembles a paddle wheel. Airflow is input through the center of the impellor and is output at a single radial vent. This type of fan is designed to increase the air pressure at its output, and is used in many blowing and inflating applications
			<br clear=all>

	==Driving and Controlling==		==Driving and Controlling==

ScottM: /* Centrifugal (radial) */

2008-12-20T02:45:48Z

Centrifugal (radial)

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 [[Image:CentrifugalFanPicture.JPG |thumb|150px|right| Centrifugal Fan]]
 A centrifugal fan is constructed with an impeller inside of a rigid housing and resembles a paddle wheel.  Airflow is input through the center of the impellor and is output at a single radial vent.  This type of fan is designed to increase the air pressure at its output, and is used in many blowing and inflating applications
 ==Driving and Controlling==

ScottM: /* Driving and Controlling */

2008-12-20T02:45:37Z

Driving and Controlling

@@ Line 21: / Line 21: @@
 [[Image:CentrifugalFanPicture.JPG |thumb|150px|right| Centrifugal Fan]]
 A centrifugal fan is constructed with an impeller inside of a rigid housing and resembles a paddle wheel.  Airflow is input through the center of the impellor and is output at a single radial vent.  This type of fan is designed to increase the air pressure at its output, and is used in many blowing and inflating applications
 ==Driving and Controlling==

ScottM: /* Types of Fans */

2008-12-20T02:45:28Z

Types of Fans

← Older revision		Revision as of 21:45, 19 December 2008
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	==Introduction==		==Introduction==

	==Types of Fans==		==Most Common Types of Fans==
	===Axial (Propellor)===		===Axial (Propellor)===
	[[Image:AxialFanPicture.JPG \|thumb\|150px\|right\| Axial Fan]]		[[Image:AxialFanPicture.JPG \|thumb\|150px\|right\| Axial Fan]]
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	[[Image:CentrifugalFanPicture.JPG \|thumb\|150px\|right\| Centrifugal Fan]]		[[Image:CentrifugalFanPicture.JPG \|thumb\|150px\|right\| Centrifugal Fan]]
	A centrifugal fan is constructed with an impeller inside of a rigid housing and resembles a paddle wheel. Airflow is input through the center of the impellor and is output at a single radial vent. This type of fan is designed to increase the air pressure at its output, and is used in many blowing and inflating applications		A centrifugal fan is constructed with an impeller inside of a rigid housing and resembles a paddle wheel. Airflow is input through the center of the impellor and is output at a single radial vent. This type of fan is designed to increase the air pressure at its output, and is used in many blowing and inflating applications









	==Driving and Controlling==		==Driving and Controlling==