Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
  • H02K41/02—Linear motors; Sectional motors
  • H02K41/035—DC motors; Unipolar motors
  • H02K41/0352—Unipolar motors
  • H02K41/0354—Lorentz force motors, e.g. voice coil motors
  • H02K41/0356—Lorentz force motors, e.g. voice coil motors moving along a straight path
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K33/00—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system
  • H02K33/18—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system with coil systems moving upon intermittent or reversed energisation thereof by interaction with a fixed field system, e.g. permanent magnets
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
  • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
  • H02P25/032—Reciprocating, oscillating or vibrating motors
  • H02P25/034—Voice coil motors

Definitions

• the present invention relates to actuators, and more particularly to the drive for actuators, which may contain two or more inputs, one of which may be many times larger than the other.
• Actuators which may be used, for example, to position a device in a desired attitude are well-known in the art.
• the device is positioned by a first signal, herein called the coarse signal, usually from a computer through an amplifier to the actuator.
• the device being positioned may also be subject to undesirable changes of position due to, for example, vibration.
• an additional actuator has been heretofore employed to provide a second positioning signal, herein called the fine signal, to counteract the vibration.
• the fine signals may be several orders of magnitude smaller than the coarse, and so the problem of noise in the coarse signal presents a special problem since it may be in the same general magnitude as the fine signals.
• the noise in the coarse signal may swamp the fine signal so that the fine signals are lost. If the noise is filtered out by a low pass filter, then the fine signals may very well be filtered out also. Using a separate actuator for the fine signals is expensive, heavy and often nearly impossible without adding a second platform or stage for the device being positioned.
• an actuator in the form of a voice coil is used and wherein the windings around the armature are two-fold.
• the main windings are from the coarse controller and are relatively large in number, while the fine signals are presented to a smaller number of coils around the same armature. The result is that the noise in the coarse signal may be filtered out without affecting the fine signal.
• FIG. 1 is a block diagram of the present invention.
• Figure 2 is a block diagram of a second embodiment of the present invention.
• a device to be controlled which, for purposes of this description will be considered to be a camera 10 is positioned by an actuator 14, in the form of a voice coil having an stator 16 and a movable armature 18, which operates to position camera 10 through a mechanical connection shown as dashed line 20.
• a position controller, 22, which may be a computer, is shown having a first output on a line 24 which feeds the input of an amplifier 26.
• Amplifier 26 provides an output current, i coarse , at two output terminals 30 and 32 which are connected to a wire 34 wrapped a number of times, N, around the armature of the voice coil 14.
• Amplifier 26 preferably has an associated low pass filter, 35, which filters out the noise, and the output current, i COarse , acting through N turns, causes the armature 18 to exert a force F, on camera 10 through the mechanical connection 20.
• a position feedback shown by box 40 returns a signal via line 42 to controller 22 so that the motion caused by force, F, controls the camera 10 to the desired position.
• a sensor shown by box 46 which may be an accelerometer, produces a signal on a line 48 to controller 22 informing the computer of the vibration which the camera 10 may be experiencing. Since the vibration effect is at least an order of magnitude smaller than the position effect, if the two signals were added directly, the noise in the position signal would be of the same magnitude as the vibration signal and would tend to mask it out. To avoid this, controller 22 produces an antivibration signal on an output line 50 which generally will be smaller in magnitude than the position signal on line 24.
• the signal on line 50 is presented to an amplifier 52 which produces an output current, i f ⁇ ne , at output terminals 54 and 56 connected to a wire 58 which is wrapped a number of times, n, around the armature of the voice coil 14.
• the output of amplifier 52 is of the same general order of magnitude as the output of amplifier 26 and accordingly, the number of turns, N, is made to be much larger than the number of turns, n.
• amplifier 52 may have a very small output compared to the output of amplifier 26 in which case, the number of turns, N, need not be so very much larger than n.
• the important feature is that the force produced by the anivibration signal be proportionately smaller than the force produced by the position control signal. This would normally be at least one order of magnitude. This is most easily accomplished by adjusting the number of turns N, to the number of turns n.
• Amplifier 52 may have an associated low pass filter, 59, therein to filter out any noise but the magnitude of this noise is so small that filter 59 is probably not necessary.
• the output current i f j ne adds a small force to the positioning force F which operates to null the vibration.
• the force F may be expressed by the equation:
• a single actuator with two coils activating the armature, one coil having many turns and exerting a large influence on the movement of the armature and the other coil having few turns and exerting a proportionately smaller influence on the movement of the armature, a single actuator may be used.
• controller 22 would feed a third amplifier, 67, to produce a third, and yet smaller, current into a third winding, 70, around armature 18 to produce a third factor into the force F of considerably less effect than the position signal and the antivibration signal.
• the third output is small enough to be swamped by the noise in the second signal, then the second output would be seperateldy filtered, as shown, and the third output independentldy connected to the coil 70, as shown, to provide protection in the same manner as the first and second outputs avoind the second output from being swamped by the first output.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Electromagnetism (AREA)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)
• Control Of Position Or Direction (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)
• Ultra Sonic Daignosis Equipment (AREA)
• Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
• Accessories Of Cameras (AREA)
• Studio Devices (AREA)
• Control Of Linear Motors (AREA)
• Vehicle Body Suspensions (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=23340221

Family Applications (1)

Country Status (7)

Families Citing this family (1)

Citations (5)

Family Cites Families (14)

• 1999
  • 1999-06-28 US US09/342,074 patent/US6278247B1/en not_active Expired - Lifetime
• 2000
  • 2000-06-28 JP JP2001506671A patent/JP2003504002A/ja active Pending
  • 2000-06-28 EP EP00944941A patent/EP1192705B1/en not_active Expired - Lifetime
  • 2000-06-28 WO PCT/US2000/017749 patent/WO2001001557A1/en not_active Ceased
  • 2000-06-28 AU AU58958/00A patent/AU5895800A/en not_active Abandoned
  • 2000-06-28 DE DE60024089T patent/DE60024089T2/de not_active Expired - Fee Related
  • 2000-06-28 AT AT00944941T patent/ATE310334T1/de not_active IP Right Cessation

Patent Citations (5)

Non-Patent Citations (3)

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