TORSIONAL STEPPING MOTOR AND EXCITER APPARATUS THEREFOR

• US 3,739,252 A
• Filed: 10/12/1971
• Issued: 06/12/1973
• Est. Priority Date: 10/12/1971
• Status: Expired due to Term

• Current Assignee: Harlen L. Baswell, John D. Hays, Johnny F. Schauerte
• Original Assignee: Harlen L. Baswell, John D. Hays, Johnny F. Schauerte
• Inventors: Hays, John D., Baswell, Harlen L., Schauerte, Johnny F.
• Primary Examiner(s): Simmons, G. R.
• Application Number:
  US05/188,419
• Time in Patent Office: 609 Days
• Field of Search: 318/153,254,696,685,439 101/93 352/187
• US Class Current: 318/696
• CPC Class Codes: H02K 37/04 with rotors situated within the stators
• CPC Class Codes: H02K 37/24 Structural association with auxiliary mechanical devices

Abstract

A stepping or indexing motor including plural electrical-tomechanical energy transducer devices and a torsionally resilient coupling member for connecting transducer device rotor members and for storing rotor member mechanical energy between rotor member movements; the torsionally resilient coupling member also providing starting torque for the stepping motor, and a means for driving separately the inertia component and the friction component of the stepping motor load; and the torsionally resilient coupling member also providing means for achieving high torque-to-inertia and torque-to-motor volume rations in the motor. In one embodiment a transducer device takes the form of a rotor, a stator, and a winding carried at each end of the coupling member with the output torque at a motor shaft being derived both from an adjacent transducer device and from energy stored in the torsionally resilient coupling member during alternate sequential energizing and deenergizing of transducer windings, such alternate sequential energizing and deenergizing action subjecting the coupling member to a twisting action and a relaxing action during each step of operation. Electrical circuitry for controlling the flow of energy into the stepping motor and for removing energy from the motor magnetic circuit is also described along with a method for achieving a novel energy conserving release of rotor and stator magnetic engagement.

Claims

1. A stepping motor comprising a shaft, a first rotor secured to one end of the shaft and a second rotor secured to the opposite end of the shaft, a first stator and a second stator circumferentially associated with their respective rotors, each stator having a coil contained therein, and means for alternately energizing and de-energizing each respective coil for rorating the ends of the shaft in incremental manner in the same direction, the energization of the first coil capturing the first rotor and stator in locked position, and the energization of the second coil advancing the second rotor a predetermined angular distance in relation to the second stator, thereby rotating the second rotor shaft end in said direction eyond the locked position of the first rotor and stator, thereby subjecting the shaft to a twisted condition, the de-energization of the first coil releasing the first rotor shaft end and permitting rotation of the first rotor shaft end a predetermined angular distance equal to the advancement of the second rotor, and the energization of the first coil locking the first rotor and stator in the advanced position.

2. The motor of claim 1 wherein the shaft is a torsion bar capable of incremental rotation alternately at the ends thereof in response to energization and de-energization of the respective coils.

3. A stepping motor comprising a torsional shaft, a first rotor secured to one end of the shaft and a second rotor secured to the other end of the shaft, a first stator and a second stator circumferentially associated with their respective rotors, the rotors each having teeth on the outer periphery thereof and the stators each having corresponding teeth on the inner periphery thereof, a first stator coil and a second stator coil capable of being energized and de-energized independently of each other, and means for energizing and de-energizing said coils for rotating the ends of the shaft in incremental manner in the same direction, the first rotor and its shaft end being rotated a predetermined angular distance equal to the spacng between stator teeth in response to energization of the first coil, the second rotor and its shaft end being rotated in the same direction a distance equal to that of the first rotor, and tHe de-energization of the respective coils permitting rotation of the shaft ends in alternate manner while holding the opposite end against rotation through energization of its respective stator coil, the rotation of one shaft end causing twisting of the shaft to advance the rotor teeth on said one end beyond the predetermined distance position of the other end.

4. The motor of claim 3 wherein the shaft is a torsion bar capable of alternate rotation at the ends thereof in response to energization and de-energization of the respective coils for advancing the shaft ends in intermittent fashion.

5. In a stepping motor having an output end for delivering rotary motion in incremental manner, a shaft capable of having one end rotated a predetermined arcuate distance while holding the other end against rotation, a first rotor and a second rotor secured to respective ends of the saaft, the rotors hav1ng teeth on the periphery thereof, a first stator and a second stator circumferentially associated with the respective rotors, the stators having teeth on the inner periphery corresponding to the teeth of the rotors, a first coil and a second coil contained in the respesctive stators, said coils being capable of independent energization and de-energization thereof, and means for alternately energizing and de-energizing the respective coils to cuase rotation of one end of the shaft and its rotor while holding the other end and its rotor from rotation, the energization of the firs1 coil aligning the teeth of the first rotor with the teeth of the first stator, the energization of the second coil causing rotation of the second rotor and its shaft end to a position wherein the teeth of the second rotor are aligned with the teeth of the second stator, thereby twisting the shaft the predetermined arcuate distance resulting in stored energy therein, and the de-enerization of the first coil thus permitting releasing of the stored energy to rotate the first rotor shaft end the predetermined distance to align the rotor teeth with the next successive stator teeth and the re-energization of the first coil locking the aligned teeth in the advanced position.

6. In the stepping motor of claim 5 wherein the shaft is a torsion bar for stroing energy therein and for releasing energy therefrom upon energization and de-energization of the respective stator coils in alternate manner.

7. In the stepping motor of claim 5 wherein the shaft is a torsion bar having a central portion of reduced cross-section to permit twisting thereof upon energization of the respective coils. 8 In the stepping motor of claim 5 wherein the shaft is of a material selected for low losses from torsional binding to permit storing and releasing of energy for rotating one end of the shaft while holding the other end against rotation.

9. A method of incrementally rotating alternately each end of a shaft in stepping motor having a first and a second rotor-stator assembly, comprising the steps of energizing the first rotor-stator assembly to fix the position of one end of the shaft, energizing the second rotor-stator assembly to initially rotate the other end of the shaft, thereby subjecting said other end of the shaft to a torsional condition in relation to said one end, de-energizing the first rotor-stator assembly thereby releasing the shaft to freely rotate an angular distance in one direction and subjecting said one end of the shaft to a torsional condition in relation to said other end, re-energizing the first rotor-stator assembly to lock said one end of the shaft when it has rotated said distance, de-energizing the setond rotor-stator assembly, thereby releasing the shaft to freely rotate said angular distance in said direction and subjecting said other end of the shaft to a torsional condition in relation to said one end, and re-energizing the second rotor-stator assembly to lock said other end of the shaft when it has rotated said distance.

10. The method of claim 9 wherein the shaft is a torsion bar selected from materials having low losses in torsional bending and includes a central portion of reduced diameter.

11. The method of claim 9 wherein the rotor-stator assemblies include corresponding teeth thereon and the shaft freely rotates, upon releasing thereof, an angular distance equivalent to one tooth spacing. 12. A stepping motor comprising a torsional shaft having an output end and a restore end, a first rotor member secured to the output end of the shaft and having a first stator member circumferentially associated therewith, a second rotor member secured to the restore end of the shaft and having a second stator member circumferentially associated therewth, the respective rotors and stators each having teeth thereon arranged for magnetic attraction therebetween, a first coil and a second coil contained in the respective stators and capable of independent energization, means for energizing the first coil for attracting respective teeth of the first rotor and stator to hold the output end of the shaft in fixed condition, means for energizing the second coil for attracting respective teeth of the second rotor and stator to move the restore end of the shaft to a rotated position in one direction, thereby subjecting the restore end to a twisted condition in relation to the output end, means for de-energizing the first coil to release the output end of the shaft for rotation an angular distance in said direction thereby subjecting the output end to a twisted condition in relation to the restore end, means for re-energizing the first coil during rotation of the output end from the fixed condition to the released condition whereby teeth of the first rotor are attracted to teeth of the first stator to lock the output end of the shaft in the next position, means for de-energizing the second coil to release the restore end of the shaft for rotating said angular distance in said direction thereby subjecting the restore end to a twisted condiiion in relation to the output end, and means for re-energizing the second coil during rotation of the restore end from the fixed condition to the released condition whereby teeth of the second rotor are attracted to teeth of the second stator to lock the restore end of the shaft in the next position.

13. The stepping motor of claim 12 wherein the torsional shaft is selected from materials having low losses in torsional bending and includes a central portion of reduced diameter.

14. The stepping motor of claim 12 wherein the rotors and stators have equal number of teeth thereon and are respectively aligned upon locking of the ends of the shaft.

15. A torsional stepping motor system comprising a first stepping motor device having n discrete stepping positions and including as parts thereof a first n poled stator member, a first n poled rotor member, and first electrical windings, a second stepping motor device having n discrete stepping positions and including as parts thereof a second n poled stator member, a second n poled rotor member, and second electrical windings, a torsionally resilient motor shaft member connected at one end thereof to said first rotor member and at the other end thereof to said second rotor member, the quiescent arrangement of the torsionally resilient shaft member and the first and second rotor and stator members being such that when the n rotor and stator poles of one motor are aligned, the n rotor and stator poles of the other motor are misaligned by substantially one-half of a pole space, the rotor and stator poles of both motors being simultaneously alignable against force from the torsionally resilient shaft member by simultaneously exciting said first and second electrical windings, and exciter means including a source of electrical energy and a plurality of electrical energy controlling elements for supplying both timed and continuous quantities of elecTrical energy independently to said first and second electrical windings.

16. The torsional stepping motor system of claim 15 wherein said first and second stepping motor devices are each incremental motion rotary magnetic exciters having a single time phase magnetic circuit.

17. Stepping motor apparatus comprising a first stepping motor including as members thereof a first stator member containing a first set of stator teeth, a first rotor member containing a first set of rotor teeth, said rotor and stator members being concentrically mounted with the rotor member being magnetically rotatable sequentially into any one of n tooth aligned first motor incremental rotation positions, a second stepping motor including as members thereof a second stator member containing a second set of stator teeth, a second rotor member containing a second set of rotor teeth, said rotor and stator members being concentrically mounted with the rotor member being magnetically rotatable sequentially into any one of n tooth aligned second motor incremental rotation positions, one or more additional stepping motors each including as members thereof a stator member containing a set of stator teeth, a rotor member containing a set of rotor teeth, each of the rotor and stator members being concentrically mounted with the rotor member being magnetically rotatable sequentially into any of n tooth aligned motor incremental rotation positions, first torsionally resilient coupling means for mechanically coupling the first rotor member with the second rotor member, and second and subsequent torsionally resilient coupling means for respectively mechanically coupling the second rotor member with the third rotor member and the third rotor member with any subsequent rotor members and for coupling together any additional subsequent rotor members, the rotational alignment of the three and any additional stator members with the three and any additional rotor members and with the two and any additional torsionally resilient coupling means for mechanically coupling being such that the incremental rotation positions of the first and the second and subsequent motors are uniformly and successively rotationally displaced in a larger rotational increment each from the other through twisting action of said first and second and any subsequent coupling means, there being within each 360/n degree arc of rotor shaft rotation a number of pole-aligned incremental positions equaling the number of stepping motors in said apparatus, the arrangement of all the rotor and stator members and all the torsionally resilient coupling means being such that two adjacent rotor teeth located on two adjacent rotor members are aligned with their closest adjacent stator teeth by magnetic excitation of the respective stator members to overcome torque from the torsionally resilient coupling means located between said two adjacent rotor members.

18. The stepping motor apparatus of claim 17 wherein said apparatus also includes means for independently and periodically exciting each of the stepping motors.

19. Incremental motion apparatus comprising first electrical-to-mechanical energy transducer means including a first rotor means for converting electrical energy into incremental rotation mechanical energy, second electrical-to-mechanical energy transducer means including a second rotor means for converting electrical energy into incremental rotation mechanical energy, rotationally resilient coupling means connected at one end thereof to said first rotor means and the other end thereof to said second rotor means for torsionally storing and for transmitting between said two rotor means portions of said incremental rotation mechanical energy and for urging said first and second rotor means toward rotationally displaced rotational positions through twisting and releasing action of said rotationally resilient coupling means, and electrical exciting means for exciting said first and second energy Transducer means.

20. The incremental motion apparatus of claim 19 wherein said electrical exciting means includes at least one source of electrical energy and plural electrical switching means connected with said electrical to mechanical energy transducer means for controlling the flow of electrical energy between said source and said electrical windings.

21. The incremental motion apparatus of claim 19 wherein each of said first and second electrical-to-mechanical energy transducer means is an electromagnetic exciter device having a unitary time phase electrical winding circuit and a unitary time phase magnetic circuit that includes all of the rotor and stator poles in said exciter device whereby magnetic flux induced in said electromagnetic exciter by said unitary time phase electrical circuit acts upon all rotor and all stator poles in said electromagnetic exciter device leaving no poles idle for energization during succeeding time phases, and wherein each of said magnetic exciter devices is free of inactive rotor and stator poles needed for starting torque generation and thereby is capable of producing high torque output per unit of exciter weight and high torque output per unit of rotor inertia.

22. The incremental motion apparatus of claim 19 wherein said first and second electrical-to-mechanical transducer means are multi-phased stepping motors having a plurality of phase displaced electrical and magnetic circuits that are excitable in time displacement.

23. The incremental motion apparatus of claim 19 wherein said rotationally resilient coupling means is a torsion bar.

24. The incremental motion apparatus of claim 23 wherein said torsion bar is composed of alloy steel.

25. The incremental motion apparatus of claim 23 wherein said torsion bar is composed of steel identified as Ball Bearing Steel.

26. The incremental motion apparatus of claim 25 wherein said torsion bar is composed of American Iron and Steel Institute Number 52100 Ball Bearing Steel.

27. The incremental motion apparatus of claim 24 wherein said torsion bar is composed of steel and fabricated into a shape having a length to diameter ratio near 16.

28. The incremental motion apparatus of claim 23 wherein the material composition of said torsion bar includes an aluminum alloy.

29. The incremental motion apparatus of claim 19 wherein the incremental rotation positions of said first rotor means in said first electrical to mechanical energy transducer means are located substantially one-half way between the incremental rotation positions of said second rotor means in said second electrical-to-mechanical energy transducer means and wherein at least one of said first and second electrical-to-mechanical energy transducer means includes plural stator means with at least one of said plural stator means being rotationally misaligned from the other of said plural stator means, the amount of said misalignment being small with respect to the rotational displacement between said first and second rotor means incremental rotation positions whereby the initial rotation direction of said electrical-to-mechanical energy transducer means rotor engaged with said plural stator means is made predictable by said rotationally misaligned stator means.

30. A stepping motor system comprising a first stepping motor device having n discrete stepping positions and including as parts thereof, a first n poled stator member, a first n poled rotor member, and first electrical windings, a second stepping motor device having n discrete stepping positions and including as parts thereof, a second n poled stator member, a second n poled rotor member, and second electrical windings, a resilient coupling member joined at one end thereof to said first rotor member and at the other end thereof to said second rotor member, the arrangement of said resilient coupling member, said first and second rotors and said first and second statOrs being such that when the n rotor and n stator poles of one motor device are aligned, the n rotor and n stator poles of the other motor device are quiescently misaligned by substantially one-half of a pole space, the rotor and stator poles of both motors being simultaneously alignable against force from the resilient coupling member by simultaneous excitation of the first and second electrical windings.

31. A method for actuating an intermittent motion apparatus of the type having two electrical-to-mechanical energy transducer devices wherein each device includes an incrementally rotating rotor portion joined to an opposing rotor portion by a torsionally resilient coupling member, the transducers having incremental positions that are rotationally misaligned by substantially one-half of a rotor increment, comprising the steps of electrically rotating the rotor portion of one of the transducer devices into a first rotor incremental position by electrically exciting the first transducer device, electrically moving the rotor portion of the second transducer device against torsional force from the resilient coupling member into a nearby second rotor incremental position by electrically exciting the second transducer device, the torsionally resilient coupling member being thereby distorted through one-half of an increment in a first rotational direction, electrically releasing the rotor portion of the first transducer device from the first rotor incremental position under the urging of torsional force from the distorted resilient coupling member, thereby allowing the torsional force to accelerate the first rotor portion away from the first rotor incremental position toward a position of zero distortion in the resilient coupling member and toward a new first rotor incremental position wherein distortion of the resilient coupling member is reverse that of the first rotational direction, electrically attracting the rotor portion of the first transducer device to the new first rotor incremental position by re-exciting the first transducer device, electrically freeing the rotor portion of the second transducer device from the second rotor incremental position under the urging of torsional force from the distorted resilient coupling member, thereby allowing the torsional force to accelerate the second rotor portion away from said second rotor incremental position toward a position of zero distortion in the resilient coupling member and toward a new second rotor incremental position wherein distortion of the resilient coupling member is in the first rotational direction, electrically drawing the rotor portion of the second transducer device to the new second rotor incremental position by re-exciting the second transducer device, and repeating the steps of electrically releasing, attracting, freeing, and drawing until the rotor portions attain a predetermined rotational position.

32. The method of claim 31 including terminating the steps relating to the first transducer device with an electrically attracting step, and terminating the steps relating to the second transducer device with an electrically drawing step whereby both rotors are retained quiescently in an excited and position determined condition and the torsionally resilient coupling is retained quiescently in a rotationally distorted condition ready for the acts of electrically releasing and electrically freeing the rotor portions.

33. The method of claim 31 including the step of electrically disengaging the rotor portion of at least one of the transducer devices from an incremental position thereby allowing at least one of the rotor portions and one end of the torsionally resilient coupling member to be free during quiescence, whereby total quiescent power dissipation in the transducer devices is decreased during a long holding period.

34. The method of claim 31 wherein the steps of electrically attracting the rotor portion of the first transducer device anD electrically drawing the rotor portion of the second transducer device are steps commenced before the released and freed rotor portions have rotated respectively into the new first rotor and the new second rotor incremental positions.

35. A method for operating a pair of mechanically coupled stepping motors having rotationally displaced stepping positions that are mutually attainable by exerting a rotational distorting force upon a rotationally resilient coupling member that joins the two motor rotors, the force being proportional in magnitude to the differential distorted displacement of the rotors, comprising the steps of:

holding the rotor of a second one of the stepping motors stationary with respect to its stator in a stepping position, imparting a quantity of potential energy to the rotationally resilient coupling member by moving the rotor of a first one of the stepping motors into a step position against the urging of torque from the rotationally resilient coupling member, magnetically retaining the rotor of the first stepping motor in its attained step position against the urging of torque from the rotationally resilient coupling member, transferring a major portion of the imparted resilient coupling member potential energy into kinetic energy vested in the second stepping motor rotor by virtue of rotational motion thereof, releasing of the second stepping motor rotor from said stepping position while the first stepping motor rotor is held in said step position comprising a part of the transferring step, magnetically urging the rotor of the second stepping motor toward its subsequent stepping position, collecting a major portion of the second rotor kinetic energy and energy from the second rotor magnetic urging into rotationally resilient coupling member potential energy by retaining the first stepping motor rotor in said step position while the kinetic energy of the second stepping motor rotor and energy from the magnetic urging carry the second stepping motor into the subsequent stepping position against torque from the rotationally resilient coupling member, magnetically retaining the rotor of the second stepping motor in said subsequent stepping position against the urging of torque from the rotationally resilient coupling member, transmuting a major portion of the collected coupling member potential energy into kinetic energy vested in the first stepping motor rotor by virtue of rotational motion thereof, releasing of the first stepping motor rotor from said step position while the second stepping motor rotor is held in said stepping position comprising a part of the transmuting step, magnetically urging the rotor of the first stepping motor toward its succeeding step position, converting a major portion of the first kinetic energy and energy from the first rotor magnetic urging into rotationally resilient coupling member potential energy by retaining the second stepping motor rotor in said stepping position while the kinetic energy of the first stepping motor rotor and energy from the magnetic urging carry the first stepping motor rotor into the succeeding step position against torque from the rotationally resilient coupling member, magnetically retaining the rotor of the first stepping motor in said succeeding step position against the urging of torque from the rotationally resilient coupling member, and continuing the steps of transferring, magnetically urging collecting, magnetically retaining, transmuting, magnetically urging, converting, and magnetically retaining until the rotors attain a desired rotational position.

36. The method of claim 35 including terminating the steps of transferring, magnetically urging, collecting, magnetically retaining, transmuting, magnetically urging, converting, and magnetically retaining with at least one of the two rotors magnetically engaged with a stepping motor stator.

37. The method of claim 35 wherein the transferred and transmuted portions of torsion bar potential eneRgy are diminished by the energy imparted to a motor load and by motor losses.

38. The method of claim 35 wherein the releasing of second stepping motor rotor from said stepping position and the releasing of first stepping motor rotor from said step position each include the step of removing substantially all of the magnetic flux linking rotor and stator portions of the stepping motor before the released rotor has traveled through an appreciable portion of the rotational angle between its previous and next stepper positions, rate of travel of the released rotor being significantly related to the natural frequency torsional oscillation characteristic of the rotor and rotationally resilient coupling member combination, whereby only a small fraction of the rotationally resilient coupling member potential energy is lost through generator action between magnetically coupled rotor and stator members and a large portion of said coupling member energy is thereby available for transferring and transmuting into rotor kinetic energy.

39. The method of claim 38 wherein the removing of substantially all of the magnetic flux prior to appreciable travel of the released rotor includes subjecting the motor magnetic structure to a magnetomotive force that is counter to the magnetic flux being removed.

40. The method of claim 35 wherein the removing of substantially all of the magnetic flux prior to appreciable travel of the released rotor includes removing magnetic flux stored energy from the stepping motors in the presence of a large voltage across the electrical terminals of the motor windings.

41. A method for transferring energy into and between a cooperating pair of stepping motors that have rigidly coupled stator members and a rotor system that includes a pair of rotor members joined together by a resilient torsion member capable of torsionally storing mechanical energy, comprising the steps of introducing a first quantity of energy into said rotor system by exciting one of the stepping motors and commencing rotation of the rotor member thereof, the introduced energy being supplied to the first stepping motor as electrical energy and transduced therein into rotational mechanical energy, displacing a portion of the first quantity of energy from the moving first rotor member into the second motor rotor member via the resilient torsion member, thereby placing the second rotor member in rotation and halting rotation of the first rotor member, the displacing including the operations of collecting the displaced portion of the first quantity of energy as potential energy stored in the resilient torsion member by a physical distortion thereof, the displacing and collecting including the operations of maintaining excitation in both motors while collecting energy in and physically distorting the resilient coupling member and removing excitation from the second motor while the rotor thereof is influenced by energy stored in the resilient torsion member, adding a second quantity of energy to said rotor system by exciting the second stepping motor, the added energy being supplied to the second stepping motor as electrical energy and transduced therein into rotational mechanical energy that adds to the energy said second rotor received from said resilient coupling member, transposing a portion of the total energy in the second rotor member from the rotating second rotor member back into the first rotor member via the resilient torsion member, thereby placing the first rotor member in rotation and halting rotation of the second rotor member, the transposing including the operations of collecting the transposed portion of the total energy in the second rotor as potential energy stored in the resilient torsion member by a physical distortion thereof, the transposing and collecting including the operations of maintaining excitation in both motors while collecting energy in and physically distorting the resilient torsion member and removing excitation from the first motoR while the rotor thereof is influenced by energy stored in the resilient torsion member, and selecting the quantities of energy applied to said rotor system as said first and second quantities of energy to be quantities that are sufficiently large to at least compensate for energy losses in the cooperating pair of stepping motors and an energy dissipative motor load and are sufficiently small to at least preclude continuously increasing rotor velocities in said rotor system.

42. The method of claim 41 wherein the acts of removing excitation from the second motor and removing excitation from the first motor while the rotors are influenced by energy stored in the resilient coupling member include removing substantially all magnetic flux from the stepping motors before the physically distorted resilient coupling member relaxes through a significant arc of rotation, whereby the energy collected in the distorted resilient coupling member is largely transferred into rotor member rotational kinetic energy and not lost to magnetic flux forces acting on said rotor member.

43. A method for introducing energy to and exchanging energy between a cooperating pair of stepping motors having rotationally misaligned stepping positions, rigidly coupled stator members, and a rotor system that includes a pair of rotor members joined by a rotationally resilient coupling member which is capable of torsionally storing mechanical energy, comprising the steps of placing a first quantity of energy in the resilient coupling members of the rotor system by rotating the rotor of one of the motors against torque from the resilient coupling member into a step position, the rotor of the second motor being held stationary in a stepping position during rotation of the first rotor, the placed quantity of energy being supplied to the first motor as electrical energy and transduced therein into mechanical energy, the placed quantity of energy being stored in the resilient coupling member as a first quantity of potential energy by said first rotor rotation against torque from the resilient coupling, transferring a portion of the first quantity of energy from the resilient coupling member into the second rotor as kinetic energy, the transferring including the act of releasing the second rotor from said stepping position under the influence of stored energy rotational torque from the resilient coupling member, thereby allowing the second rotor to be rotationally accelerated, while holding the first rotor stationary in said step position, introducing a second quantity of energy to the rotor system while the second rotor is moving away from said stepping position toward a subsequent stepping position, the introducing including the act of exciting the second motor, the second quantity of energy being furnished as electrical energy to the second motor and transduced therein into second rotor mechanical energy, the second quantity of energy being added to the transferred portion of the first quantity of energy to provide, in the moving second rotor, a summed quantity of energy at least sufficient to rotate the second rotor end of the resilient coupling member against resilient coupling member torque through an angle substantially equaling the angle of rotational misalignment and thereby carry the second rotor into the subsequent stepping position and thereby convert part of the summed quantity of energy into a third quantity of potential energy that is stored within the rotationally distorted resilient coupling member, transposing a portion of the third quantity of energy from the resilient coupling member into the first rotor as kinetic energy, the transposing including the act of releasing the first rotor from said step position under the influence of stored energy rotational torque from the resilient coupling member, thereby allowing the first rotor to be rotationally accelerated while the second rotor is held in the subsequent stepping position, adding a fourth quantity of energy to the rotor system while the first rotor is moving away from said step position toward a succeeding step position, the adding including the act of exciting the first motor, the fourth quantity of energy being furnished as electrical energy to the first motor and transduced therein into first rotor mechanical energy, the fourth quantity of energy being added to the transposed portion of the third quantity of energy to provide, in the moving first rotor, a summed quantity of energy at least sufficient to rotate the first rotor end of the resilient coupling member, against resilient coupling member torque through an angle substantially equaling the angle of rotational misalignment and thereby carry the first rotor into the succeeding step position and thereby convert part of the summed quantity of energy into a fifth quantity potential energy that is also stored within the rotationally distorted resilient coupling member, and repeating the acts of transferring, introducing, transposing, and adding until the rotors have passed through a desired angle of rotation.

44. The method of claim 43 wherein said acts of releasing the second rotor from said stepping positions and releasing the first rotor from said step positions include removing from the releasing motor substantially more of the magnetic flux that couples the rotor and stator members thereof than that quantity of flux necessary to just release a rotor member for rotation, and removing said substantial quantity of flux during a time interval that is short with respect to the time needed for rotation of the released rotor between step positions and stepping positions, respectively, whereby a large fraction of the potential energy stored within the resilient coupling member is conserved for conversion into rotor kinetic energy during the transferring and transposing acts with minimal amounts of said energy being lost by rotor movement against slowly decaying magnetic flux.

45. The method of claim 43 wherein the removing of magnetic flux includes the acts of quickly dissipating the energy stored in the electrical inductance of the windings of the releasing motor, and immediately following dissipation of the inductance energy, applying to the releasing motor a reverse magnetomotive force capable of overcoming the residual magnetic flux remaining therein.

46. The method of claim 43 wherein the magnetic flux removing included in the releasing act is accomplished substantially within a period that is less than one-fourth of the time of a torsional oscillation period of the rotor and resilient coupling member combination in the rotor system.

47. The method of claim 45 wherein the magnetic flux removing is accomplished substantially within a period of less than one-fifth millisecond in a motor having winding inductance that is near the value of three millihenrys and a rotor resilient coupling member torsional oscillation period that is near five milliseconds in duration.

48. The method of claim 44 wherein the magnetic flux removing is accomplished rapidly by steps that include applying a reverse magnetomotive force to the motor structure.

49. The method of claim 44 wherein rapid magnetic flux removing is aided by briefly connecting the motor windings to a current source device that is polarized to induce a reverse magnetomotive force into the motor structure.

50. The method of claim 43 wherein the first quantity of potential energy and the third quantity of potential energy are substantially equal quantities, each being substantially that quantity vested in the resilient coupling member when the ends thereof are held differentially displaced by a rotational angle substantially equaling the angle of rotational misalignment between stepping positions of the two motors.

51. The method of claim 43 wherein the act of introducing a second quantity of energy to the rotor system and the act of adding a fourth quantity of energy to the rotor system are acts commenced near the time instant when the accelerated rotor and the accelerated rotor end of the resilient coupling member are rotating through the non-distorted zero differential displacement state of the resilient coupling member.

52. The method of claim 43 wherein the act of introducing a second quantity of energy to the rotor system and the act of adding a fourth quantity of energy to the rotor system are acts commenced after the accelerated rotor and the accelerated rotor end of the resilient coupling member have rotated past the non-distorted zero differential displacement point of the resilient coupling member and have rotated into the proximity of the succeeding stepping and subsequent step positions, respectively.

53. The method of claim 43 wherein the act of introducing a second quantity of energy to the rotor system and the act of adding a fourth quantity of energy to the rotor system are acts commenced at some instant of time before the accelerated rotor and the accelerated end of the resilient coupling member have rotated so far as the non-distorted zero differential displacement point of the resilient coupling member;

the rotating members being urged toward the succeeding stepping position and the subsequent step position, respectively, and away from the preceding stepping position and former step position, respectively, by kinetic energy imparted to the moving members before the introducing and adding acts are commenced.

54. The method of claim 43 wherein the act of introducing a second quantity of energy to the rotor system and the act of adding a fourth quantity of energy to the rotor system are acts commenced after the accelerated rotor and the accelerated rotor end of the resilient coupling member have rotated past the non-distorted zero differential displacement point of the resilient coupling.

55. The method of claim 43 wherein the energy difference between the third quantity of energy and the portion of the third quantity of energy that is transposed into the first rotor as kinetic energy is energy that is transferred into a motor load and into energy dissipative loss mechanisms in the motor and load, said mechanisms including motor rotation in the presence of incompletely removed magnetic flux linking the rotor and stator portions of the motor.

56. The method of claim 43 which also includes the act of halting the sequence of transferring, introducing, transposing, and adding with the first motor rotor and the second motor rotor held in a step position and a stepping position, respectively;

the rotors being held in these respective positions following completion of an introducing and an adding act.

57. The method of claim 43 which also includes the act of terminating the sequence of transferring, introducing, transposing, and adding with at least one of the two motor rotors released from its stepping position.

58. A method for operating a cooperative pair of stepping motors having a stator system that includes a pair of rigidly coupled stator members and a rotor system that includes a pair of rotor members fixed to opposite ends of a rotatable torsionally resilient coupling member comprising the step of walking the rotor system in rotational increments by successively holding the rotor at one end of the resilient coupling member immobilized while advancing the rotor at the opposite end from a lagging to a leading position with respect thereto, a combination of stator to rotor magnetic force and torsional force from rotational distortion of the resilient coupling member acting upon the rotor during said advancing, each rotor being alternately held immobilized and then advanced by one step while the opposite rotor is simultaneously advanced by one step and then held immobilized whereby the rotor system is walked around the periphery of the stator system by a sequence of motion steps accomplished at alternating ends of the resilient coupling member.