Patent Publication Number: US-2023159159-A1

Title: Systems and methods for improved rotor assembly for use with a stator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a continuation of U.S. patent application Ser. No. 16/744,897, filed Jan. 16, 2020, which is a continuation of P.C.T. Application No. PCT/US2019/027938, filed Apr. 17, 2019, which claims the benefit of and priority to U.S. Provisional Application No. 62/659,013, filed Apr. 17, 2018, and U.S. Provisional Application No. 62/775,253, filed Dec. 4, 2018, the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to vertical takeoff and landing. More particularly, the present disclosure relates to magnetic levitation for vertical takeoff and landing. 
     BACKGROUND 
     Various airborne platforms can perform vertical takeoff and landing (VTOL), in which the platforms can hover, take off, and land vertically. VTOL platforms can include fixed wing platforms and rotary wing platforms. VTOL platforms can include unmanned aerial vehicles. VTOL platforms can have distributed electrical propulsion, and can have tilt rotor and/or tilt wing configurations. 
     Typically, VTOL platforms rely on combustion-based power generation to generate lift and other movement forces. In addition, VTOL platforms may have relatively large form factors. As such, existing VTOL platforms may have technical limitations that make such platforms difficult to use in urban environments and personal use modes. 
     SUMMARY 
     At least one aspect of the present disclosure relates to a VTOL platform. The VTOL platform includes a rotor, a stator, a flight controller, and a motor controller. The rotor includes a plurality of rotor blades oriented about a rotor axis and radially spaced from the stator. Each rotor blade is coupled to a rotor arm such that rotation of the rotor arm causes the rotor blade to rotate about a rotor pitch axis. The rotor arm is coupled to a first rotor magnet spaced from a second rotor magnet. The stator includes a plurality of electromagnets. The flight controller is configured to receive a movement instruction, extract a desired movement from the movement instruction, and generate one or more flight commands configured to cause the rotor to generate at least one of thrust, moment of force about a yaw axis, moment of force about a platform pitch axis, or moment of force about a roll axis. The motor controller is configured to receive the one or more flight control commands and drive electrical signals through the electromagnets based on the one or more flight control commands. The plurality of electromagnets are configured to output electromagnetic fields corresponding to the electrical signals to drive the rotor magnets of the rotor to rotate the rotor about the rotor axis, rotate the rotor blade about the blade neutral pitch axis, and cause the rotor to generate the at least one of the thrust, the moment of force about the yaw axis, the moment of force about the platform pitch axis, or the moment of force about the platform roll axis. 
     At least one aspect of the present disclosure relates to a rotor for operation with a stator. The rotor includes an annular rotor base defining a rotational axis and comprising a plurality of rotor segments arranged around the stator. Each rotor segment includes a sidewall spaced from the rotational axis, a first rotor wall extending from a first end of the sidewall and towards the rotational axis, and a second rotor wall extending from a second end of the sidewall and towards the rotational axis, the second rotor wall spaced from the first rotor wall, the rotor defining a rotor axis through the first rotor wall and the second rotor wall and parallel to the rotational axis. Each rotor segment includes at least one first rotor magnet coupled with the first rotor wall, the at least one first rotor magnet configured to maintain a first space between the first rotor wall and a first stator magnet along the rotor axis. Each rotor segment includes at least one second rotor magnet coupled with the second rotor wall, the at least one second rotor magnet configured to maintain a second space between the second rotor wall and a second stator magnet along the rotor axis. Each rotor segment includes at least one third rotor magnet coupled with the sidewall and spaced from one or more propulsion magnets of the stator. The rotor is configured to be driven by the propulsion magnets via a magnetic field of the one or more propulsion magnets interacting with the at least one third rotor magnet. 
     At least one aspect relates to a stator for operation with a rotor. The stator includes an annular stator base comprising a plurality of stator segments, the stator base defining a central axis. Each stator segment includes a sidewall, a support structure extending from the sidewall, at least one first stator magnet coupled with a first surface of the support structure, at least one second stator magnet coupled with a second surface of the support structure opposite the first surface, and at least one propulsion magnet. The at least one first stator magnet and the at least one second stator magnet define a stator axis parallel to the central axis, the at least one first stator magnet configured to maintain a first space between a first rotor magnet of the rotor and the at least one first stator magnet along the stator axis, and the at least one second stator magnet configured to maintain a second space between a second rotor magnet of the rotor and the at least one second stator magnet along the stator axis. The at least one propulsion magnet is coupled with the support structure and spaced from one or more third rotor magnets of the rotor, the at least one propulsion magnet configured to output a magnetic field responsive to a control signal to drive the rotor about the central axis. 
     At least one aspect relates to a rotor control system. The rotor control system includes a rotor and a stator. The rotor includes a first rotor magnetic component aligned with one or more first stator coils, a second rotor magnetic component aligned with one or more second stator coils and adjacent to the first rotor magnetic component, an arm connecting the first rotor magnetic component and the second rotor magnetic component, and a first rotor blade fixed to the arm. A first arm end of the is arm coupled with the first rotor magnetic component and a second arm end of the arm coupled with the second rotor magnetic component defining an arm angle which changes based on a first magnetic force applied to the first rotor magnetic component relative to a second magnetic force applied to the second rotor magnetic component. The first rotor blade extends from the arm along a blade pitch axis, the first rotor blade defining a blade pitch angle relative to the blade pitch axis, the blade pitch angle corresponding to the arm angle. The stator includes a plurality of electromagnets configured to output at least a first magnetic field that drives the first rotor magnetic component and a second magnetic field that drives the second rotor magnetic component responsive to at least one control signal, the at least one control signal causing the first magnetic field to apply the first magnetic force on the first rotor magnetic component and the second magnetic field to apply the second magnetic force on the second magnetic component to control the blade pitch angle. 
     At least one aspect relates to a rotor control system. The rotor control system includes a rotor and a stator. The rotor includes an annular rotor base defining a rotational axis and comprising a plurality of rotor segments arranged around the stator. Each rotor segment includes a first rotor blade configured to be rotated about a blade pitch axis perpendicular to the rotational axis, a power receiver circuit, a motor that rotates using power received via the power receiver circuit for rotating the first rotor blade about the blade pitch axis, a motor controller that provides a motor signal to the motor for rotating the first rotor blade about the blade pitch axis responsive to a control signal, and a first wireless transceiver that receives the control signal and provides the control signal to the motor controller. The stator includes a second wireless transceiver that receives a control command and wirelessly transmits the control signal to the first wireless transceiver based on the control command, and a power transmitter circuit that outputs a magnetic field that interacts with the power receiver circuit to provide power to the power receiver circuit. 
     At least one aspect relates to a system. The system includes a rotor and a stator. The rotor includes a sidewall, a first rotor wall extending from a first end of the sidewall, and a second rotor wall extending from a second end of the sidewall, the second rotor wall spaced from the first rotor wall, at least one first rotor magnet coupled with the first rotor wall, and at least one second rotor magnet coupled with the second rotor wall. The stator includes a support structure extending between the first rotor wall and second rotor wall, at least one first stator magnet coupled with a first surface of the support structure and proximate to the at least one first rotor magnet, the at least one first rotor magnet inducing a current in the at least one first stator magnet corresponding to a first distance between the at least one first stator magnet and at least one first rotor magnet, and at least one second stator magnet coupled with a second surface of the support structure opposite the first surface and proximate to the at least one second rotor magnet, the at least one second stator magnet electrically coupled with the at least one first stator magnet to receive the current from the first stator magnet, the at least one second stator magnet outputting a magnetic field having a magnetic field strength based on the current from the first stator magnet, the magnetic field interacting with the at least one second rotor magnet to control a second distance between the at least one second stator magnet and the at least one second rotor magnet. 
     At least one aspect relates to a system. The system includes a rotor and a stator. The rotor includes a sidewall, a rotor wall extending from an end of the sidewall, and at least one rotor magnet coupled with the rotor wall. The stator includes a support structure adjacent the rotor wall, a first stator magnet coupled with a surface of the support structure proximate to the at least one rotor magnet, the at least one rotor magnet inducing a current in the first stator magnet corresponding to a first magnetic force of a first magnetic field between the first stator magnet and the at least one rotor magnet, and a second stator magnet coupled to the surface of the support structure, the second stator magnet electrically coupled to the first stator magnet, the second stator magnet receiving the current from the first stator magnet to control a second magnetic force of a second magnetic field between the second stator magnet and the at least one rotor magnet. 
     At least one aspect relates to a system. The system includes a rotor and a stator. The rotor includes a rotor sidewall defining a rotational axis, at least one rotor blade coupled with and transverse the sidewall along a first surface of the sidewall, and a rotor magnet coupled with the sidewall along a second surface of the rotor sidewall opposite the first surface. The stator includes a plurality of stator magnets circumferentially arranged along a surface of a stator sidewall facing the second surface of the rotor sidewall, and a controller wirelessly coupled to the plurality of stator magnets, the controller controlling the plurality of stator magnets to selectively produce a respective magnetic field interacting with the rotor magnet of the rotor to rotate the rotor and the rotor blade about the rotational axis to produce lift along the rotational axis. 
     At least one aspect relates to a system. The system includes a rotor and a stator. The rotor includes a rotor sidewall defining a rotational axis, at least one rotor blade coupled with and transverse the sidewall along a first surface of the side wall, and a rotor magnet coupled with the sidewall along a second surface of the rotor sidewall opposite the first surface. The stator includes a plurality of stator magnets circumferentially arranged along a surface of a stator sidewall facing the second surface of the rotor sidewall, and a controller electrically coupled to the plurality of stator magnets, the controller controlling the plurality of stator magnets at a switching rate to selectively produce a respective magnetic field, the magnetic fields interacting with the rotor magnet of the rotor to rotate the rotor and rotor blade at a rotational velocity corresponding to the switching rate to produce lift at a lift velocity. 
     At least one aspect relates to a system. The system includes a rotor configured to rotate about a rotational axis and a stator. The rotor includes a rotor sidewall, at least one rotor blade rotatably coupled with the sidewall along a first surface of the side wall, the at least one rotor blade rotating about a blade axis extending transverse the side wall, and a first rotor magnet and a second rotor magnet coupled with the sidewall along a second surface of the rotor sidewall opposite the first surface. The stator includes a plurality of first stator magnets circumferentially arranged along a stator sidewall facing the rotor sidewall, at least one of the plurality of first stator magnets proximate to the first rotor magnet, a plurality of second stator magnets spaced from respective first stator magnets and circumferentially arranged along the stator sidewall, at least one of the plurality of second stator magnets proximate to the second rotor magnet, and a magnet controller electrically coupled to the plurality of first stator magnets and the plurality of second stator magnets, the magnet controller controlling the plurality of first stator magnets at a first switching rate and controlling the plurality of second stator magnets at a second switching rate to produce rotation of the rotor blade about the blade axis. 
     At least one aspect relates to a system. The system includes a stator and a rotor. The stator includes a plurality of stator magnets circumferentially arranged along a surface of the stator. The rotor is configured to rotate about a rotational axis and has an annular rotor base surrounding the stator. The rotor includes a plurality of rotor segments. Each rotor segment includes a sidewall spaced from the rotational axis having a first surface and a second surface opposite the first surface, at least one rotor magnet coupled to the side wall along the first surface, the rotor configured to be driven by the plurality of stator magnets via respective magnetic fields of the plurality of stator magnets interacting with the at least one rotor magnet, and at least one rotor blade having a first blade end coupled with the second surface of the sidewall and a second blade end, the first end and second defining a rotor blade length, the second end and rotational axis defining a radius of rotation, a ratio of the rotor blade length to the radius of rotation of the tip being less than or equal to 0.75. 
     At least one aspect relates to a system. The system includes a rotor configured to rotate about a rotational axis and a stator. The rotor includes a rotor sidewall, a first rotor blade rotatably coupled with the sidewall along a first surface of the side wall, the first rotor blade rotating about a first blade axis extending transverse the side wall, a second rotor blade rotatably coupled with the sidewall along the first surface of the sidewall, the second rotor blade rotating about a second blade axis extending transverse the sidewall, a first set of rotor magnets including a first rotor magnet and a second rotor magnet coupled with the sidewall along a second surface of the rotor sidewall opposite the first surface proximate the first rotor blade, and a second set of rotor magnets including a third rotor magnet and a fourth rotor magnet coupled with the sidewall along the second surface of the rotor sidewall proximate the second rotor blade. The stator includes a plurality of first stator magnets circumferentially arranged along a stator sidewall facing the rotor sidewall, at least one of the plurality of first stator magnets proximate to the first rotor magnet and at least one of the plurality of first stator magnets proximate the third rotor magnet, a plurality of second stator magnets spaced from respective first stator magnets and circumferentially arranged along the stator sidewall, at least one of the plurality of second stator magnets proximate to the second rotor magnet and at least one of the plurality of second stator magnets proximate to the fourth rotor magnet, and at least one controller electrically coupled to the plurality of first stator magnets and the plurality of second stator magnets, the at least one controller configured to receive a movement instruction, extract a desired movement from the movement instruction, generate a plurality of control signals based on the desired movement, and provide the plurality of control signals to the plurality of first stator magnets and the plurality of second stator magnets to cause the plurality of first stator magnets and the plurality of second stator magnets to output magnetic fields corresponding to the plurality of control signals that drive the rotor magnets of the rotor to rotate the rotor about the rotational axis, rotate the first rotor blade about the first blade axis, and rotate the second rotor blade about the second blade axis to produce the desired movement. 
     At least one aspect relates to a rotor for operation with a stator. The rotor includes an annular rotor base defining a rotational axis and comprising a plurality of first rotor segments arranged around the stator and configured to be driven in a first direction about the rotational axis, and a plurality of second rotor segments arranged around the stator adjacent to the plurality of first rotor segments and configured to be driven in a second direction about the rotational axis opposite the first direction, each rotor segment including a sidewall spaced from the rotational axis, a first rotor wall extending from a first end of the sidewall and towards the rotational axis, and a second rotor wall extending from a second end of the sidewall and towards the rotational axis, the second rotor wall spaced from the first rotor wall, the rotor defining a rotor axis through the first rotor wall and the second rotor wall and parallel to the rotational axis, at least one first rotor magnet coupled with the first rotor wall, the at least one first rotor magnet configured to maintain a first space between the first rotor wall and the first stator magnet along the rotor axis, at least one second rotor magnet coupled with the second rotor wall, the at least one second rotor magnet configured to maintain a second space between the second rotor wall and the second rotor magnet along the rotor axis, at least one third rotor magnet coupled with the sidewall and spaced from one or more propulsion magnets of the stator, the rotor configured to be driven by the propulsion magnets via a magnetic field of the one or more propulsion magnets interacting with the at least one third rotor magnet. In some embodiments, the at least one rotor blade is a first rotor blade and the rotor magnet is a first rotor magnet corresponding to the first rotor blade, the first rotor blade configured to rotate about the rotational axis in a first direction, and the rotor includes a second rotor blade spaced apart from the first rotor blade, the second rotor blade coupled with and transverse the sidewall along a first surface of the sidewall, and a second rotor magnet corresponding to the second rotor blade, the second rotor magnet being driven to drive the second rotor blade in a second direction about the rotational axis opposite the first direction. 
     Those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices and/or processes described herein, as defined solely by the claims, will become apparent in the detailed description set forth herein and taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, aspects, features, and advantages of the disclosure will become more apparent and better understood by referring to the following description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a schematic diagram of an embodiment of a VTOL platform. 
         FIG.  2    is a schematic diagram of a portion of the VTOL platform of  FIG.  1   . 
         FIG.  3    is a block diagram of various systems of the VTOL platform of  FIG.  1   . 
         FIG.  4    is a partial perspective view of a motor region of the VTOL platform of  FIG.  1   . 
         FIG.  5    is a section view of the motor region of the VTOL platform of  FIG.  1   . 
         FIG.  6    is a schematic diagram of an embodiment of levitation and guidance systems. 
         FIG.  7    is a block diagram of an embodiment of a flight dynamics system of a VTOL platform. 
         FIG.  8    is a schematic diagram of collective pitch control executed by the flight dynamics system of  FIG.  7   . 
         FIG.  9    is a schematic diagram of cyclic pitch control executed by the flight dynamics system of  FIG.  7   . 
         FIG.  10    is a block diagram of an embodiment of a motor controller of a VTOL platform. 
         FIG.  11    is a block diagram of an embodiment of a stator of a VTOL platform. 
         FIG.  12    is a block diagram of a rotor control system of a VTOL platform. 
         FIG.  13    is a flow diagram of an embodiment of a method of controlling a VTOL platform. 
         FIG.  14 A  is a schematic diagram of an embodiment of a rotor having motor-driven rotor blades. 
         FIG.  14 B  is a block diagram of an embodiment of a rotor control system using motor-driven rotor blades. 
     
    
    
     DETAILED DESCRIPTION 
     For purposes of reading the description of the various embodiments below, the following enumeration of the sections of the specification and their respective contents may be helpful:
         Section A describes embodiments of systems and methods of a VTOL platform that operates using magnetic levitation;   Section B describes embodiments of systems and methods of levitation and guidance of a VTOL platform that operates using magnetic levitation; and   Section C describes embodiments of systems and methods of controlling a VTOL platform that operates using magnetic levitation, including flight dynamics, motor control, and pitch control.       

     A. Systems and Methods of VTOL Platforms Using Magnetic Levitation 
     Referring generally to  FIGS.  1 - 5   , a VTOL platform in accordance with the present disclosure can use magnetic levitation and specific control mechanisms to efficiently drive a rotor with a stator to enable vertical takeoff and landing, as well as flight control operations such as lift, pitch, roll, and yaw control. The VTOL platform can have improved size, weight, power, and cost (SWAP-C) factors relative to existing systems, including increased power density relative to internal combustion-based systems. The VTOL platform can achieve high rotor rotation rates for an annular platform configuration. 
     The VTOL platform can have reduced noise relative to existing systems with similar performance capability by reducing both mechanical and aerodynamic noise generation. Existing systems that rely on mechanical operation of gearboxes, swashplates, and generators may generate significant noise. In turbines mechanical noise may be transmitted along the structure of the turbine and radiated from its surfaces, and aerodynamic noise may be produced by the flow of air over the blades. In helicopters, noise may be generated by the main rotor and tail rotor interactions with air. This can be verified by analyzing the frequency spectrum of a helicopter during takeoff: there may be global and local maximas at the respective blade passing frequencies of each rotor blade. There may also be a very large distribution of acoustic power that sweeps over the higher frequencies, and this broadband noise may result from a combination of multiple noise mechanisms, including operation of the turbine, gearbox, and transmission. The present solution can address these noise sources by using a direct electric powertrain that relies on fewer interactions between mechanical components, and also by configuring rotor blades in a manner that reduces noise generation. As such, the present solution can reduce energy inefficiencies associated with noise generation, as well as nuisances associated with noise that make existing systems less viable for urban environment and personal use modes. 
     In some embodiments, the VTOL platform includes a rotor, a stator, a flight controller, and a motor controller. The rotor includes a plurality of rotor blades oriented about a rotor axis and radially spaced from the stator. Each rotor blade is coupled to a rotor arm such that rotation of the rotor arm causes the rotor blade to rotate about a rotor pitch axis. The rotor arm is coupled to a first rotor magnet spaced from a second rotor magnet. The stator includes a plurality of electromagnets. The flight controller is configured to receive a movement instruction, extract a desired movement from the movement instruction, and generate one or more flight commands configured to cause the rotor to generate at least one of thrust, moment of force about a yaw axis, moment of force about a platform pitch axis, or moment of force about a platform roll axis. The motor controller is configured to receive the one or more flight control commands and drive electrical signals through the electromagnets based on the one or more flight control commands. The plurality of electromagnets are configured to output electromagnetic fields corresponding to the electrical signals to drive the rotor magnets of the rotor to rotate the rotor about the rotor axis, rotate the rotor blade about the blade neutral pitch axis, and cause the rotor to generate the at least one of the thrust, the moment of force about the yaw axis, the moment of force about the platform pitch axis, or the moment of force about the platform roll axis. 
     Referring now to  FIGS.  1 - 2   , a VTOL platform  100  includes a stator  110  that drives a rotor  120 . The rotor  120  can extend from the stator  110  to a housing  130  (e.g., a nacelle). A support structure  140  can be mounted to the stator  110 , such as to provide a seat  142  for an operator  144  of the VTOL platform  100 . While  FIGS.  1 - 2    illustrate the stator  110  inward of the rotor  120 , the stator  110  may be outward from the rotor  120 . The rotor  120  can be supported by a levitation system (e.g., levitation system  360  described with reference to  FIG.  3   ) coupled to the stator  110  to rotate about the stator  110 . The stator  110  and rotor  120  can include various magnets (e.g., permanent magnets; electromagnetic coils; electromagnetic coils through which current can be driven to cause the electromagnetic coils to generate magnetic fields). 
     The stator  110  can use power from a power supply  112  to drive the rotor  120  by outputting electromagnetic fields to drive magnets of the rotor  120 , including to rotate the rotor  120  about a rotational axis  122 . For example, the stator  110  can drive the rotor  120  based on control signals received from a controller, as discussed further herein. The power supply  112  can include one or more batteries. The power supply  112  can be highly distributed and integrated into the support structure  140 , which can improve stiffness and reduce weight of the VTOL platform  100  as compared to existing systems. 
     The stator  110  can have increased efficiency relative to existing mechanical systems. Using an electromagnetic coupling between the stator  110  and rotor  120 , rather than mechanical connections, can improve operation relative to existing systems. In order to achieve a VTOL platform having similar performance parameters as can be enabled by the present solution in existing systems would require the engine to drive small gears spinning much faster than a large radius rotor, which could result in significant mechanical friction losses, and would weigh significantly more than a simple rotor mounted to a driven axle. In such existing systems, there could be large efficiency losses due to the extreme gear ratio, large inherent manufacturing difficulties from the large geared and/or toothed ring structures, loud mechanical interactions outweighing any aeroacoustic benefits of the annular rotor geometry, and/or large, heavy structures used for power transfer that could increase total weight significantly. The present solution can address such phenomena by using the stator  110  to drive the rotor  120 —in some embodiments, the present solution can produce a distributed torque through the use of a power dense, efficient and responsive electric synchronous motor, rather a gearbox or axle for torque transfer as the rotor-ring, and can simultaneously act as the electromechanical rotor, drive axle, and blade hub, thus lowering weight, efficiency losses, and mechanical complexity. 
     Further with respect to the stator  110  and rotor  120 , it has been found that motor power density increases linearly with hub radius, and decreases linearly with motor height. The present solution can implement such features to configure the stator  110  to have a relatively large radius and relatively low thickness to increase efficiency and power density, enabling the stator  110  to have less mass and/or greater power output relative to existing internal combustion-based systems. 
     The rotor  120  is shown as an annular rotor that can orbit about the stator  110  and support structure  140 . The rotor  120  includes a plurality of first blades  124  (coupled to respective magnets as discussed further herein). The plurality of first blades  124  can extend between the stator  110  and the housing  130 . In some embodiments, the stator  110  controls a pitch angle of each first blade  124 . The first blades  124  can be coupled with and transverse to (e.g., perpendicular to) sidewall  134 . As illustrated in  FIGS.  1  and  4   , each first blade  124  can extend from a first blade end (e.g., blade root)  444  coupled with the sidewall  134  (e.g., rotor segments  132  of sidewall  134 ) to a second blade end (e.g., blade tip)  448 , which can be coupled with the housing  130  or free from the housing  130 . The first blade  124  can define a blade axis  440  extending from the first blade end  444  to the second blade end, which can be perpendicular to the rotational axis  122 . 
     In some embodiments, the rotor  120  includes a plurality of second blades  126 , which can be similar to the first blades  124  and may rotate about the rotational axis  122  independently relatively to the plurality of first blades  124 . The second blades  126  can be spaced from the first blades  124 , such as being coupled with the sidewall  134  (e.g., rotor segments  132  of sidewall  134 ) below the first blades  124 , or coupled with a second sidewall  134  below the first blades  124 . 
     By rotating the first blades  124  and/or second blades  126 , the VTOL platform  100  can generate lift due to action of the first blades  124  and/or second blades  126  on air passing through the VTOL platform  100 . Similarly, the first blades  124  and/or second blades  126  can be driven in a manner to cause rotation about yaw, roll, and/or pitch axes. 
     The rotor blades  124 ,  126  can be individually feathered (e.g., blade surfaces aligned at a particular angle relative to direction of airflow) to maintain cyclic and collective pitch commands for guidance of the VTOL platform  100 . As compared to existing systems, in which a swashplate may be used to control operation of rotor blades, the present solution can individually control pitch of each rotor blade  124 ,  126  in a frictionless manner. 
     Systems and Methods for Controlling Lift Using Contra-Rotating Rotors 
     In some embodiments, the plurality of first blades  124  rotate in a first direction about the rotational axis  122 , while the plurality of second blades  126  rotate in a second direction about the rotational axis  122  opposite the first direction. As such, the plurality of first blades  124  and plurality of second blades  126  can be contra-rotating. For example, each second blade  126  can be coupled with respective rotor magnets  380  that are driven by the stator  110  in the second direction. As discussed further herein, the control circuit  310  can control operation of the plurality of first blades  124  by providing a first control signal to cause the plurality of first blades  124  to rotate about the rotational axis  122  in the first direction at a first angular rate, and control operation of the plurality of second blades  126  by providing a second control signal to cause the plurality of second blades  126  to rotate about the rotational axis  122  in the second direction at a second angular rate. The control circuit  310  can generate the first control signal and second control signal to generate a desired motion of the VTOL platform  100 . For example, to enable the VTOL platform  100  to operate in a hover mode, the control circuit  310  can generate the first control signal and second control signal so that the first angular rate and second angular rate are configured so that a force balance on the VTOL platform  100  is zero in at least a vertical direction (e.g., upward force generated by the plurality of first blades  124  counteracts gravity and downward force generated by the plurality of second blades  126 ). 
     Systems and Methods for Reducing Noise Based on Effective Rotor Area Relative to a Center of Rotation 
     In some embodiments, the rotor blades  124 ,  126  are configured to enable a relatively lower acoustic profile, such as to generated reduced noise while generating sufficient lift to support movement of the VTOL platform  100 . In the present solution, the number of rotor blades  124 ,  126  can be selected to be relatively high, with the blades having phase modulated spacing, to reduce noise while lift is maintained. Each blade  124 ,  126  may have a relatively large tip diameter. The rotor blades  124 ,  126  may be positioned and aligned relative to one another to operate incoherently. As such, noise resulting from interaction of the rotor  120  and surrounding fluid can be reduced. In some embodiments, the rotor blades  124 ,  126  have a maximum tip Mach number of 0.5, and a hover tip Mach number of 0.41. In some embodiments, the rotor blades  124 ,  126  are at least one of ducted or shrouded, which can increase lift generation, improve safety, and reduce noise radiated from the rotor blades  124 ,  126 . In some embodiments, the housing  130  is shaped to reflect noise upwards, and may also attenuate noise travelling outward from the rotor  120 . 
     In some embodiments, the rotor blades  124 ,  126  have a relatively short length relative to a radius of rotation of the second blade end  448 . For example, the rotor blades  124 ,  126  can define a rotor blade length from the first blade end  444  to the second blade end  448  along the blade axis  440  (e.g., from the blade root to the blade tip). The second blade end  448  can define a radius of rotation from the second blade end  448  to the rotational axis  122 . The rotor blades  124 ,  126  can define a ratio of the rotor blade length to the radius of rotation. In some embodiments, the ratio is less than or equal to 0.75. In some embodiments, the ratio is less than or equal to 0.6 and greater than or equal to 0.3. For example, as illustrated in  FIG.  2   , the rotor blades  124 ,  126  begin outward of the rotational axis  122 . In some embodiments, the efficiency of a rotor blade in generating lift as a function of distance from a center of rotation (e.g., from rotational axis  122 ) is generally higher towards the blade tip than the blade root. As such, the present solution can reduce noise with relatively less performance loss by selecting blades that operate primarily in the high efficiency region. 
     In some embodiments, the rotor blades  124 ,  126  have a relatively high blade effective area or blade solidity. The second blade end  448  can define a first perimeter (e.g., a perimeter swept by the second blade end  448  as the second blade end  448  rotates about the rotational axis  122 ). The sidewall  134  (or the first blade end  444 ) can define a second perimeter, which is inward of the first perimeter. The rotor blades  124  and/or  126  can also define a blade rotation area in a first plane between the first perimeter and the second perimeter (e.g., a first plane in which the first perimeter and second perimeter lie). The blade rotation area can represent the area swept by the first rotor blade  124  in the first plane as the first rotor blade  124  rotates about the rotational axis  122 . The rotor blades  124  and/or the rotor blades  126  can define a blade surface area in the first plane, which can represent a surface area of the rotor blades  124  and/or the rotor blades  126  that lies in the first plane (while the rotor blades  124  or the rotor blades  126  are steady or not moving). The plurality of first rotor blades  124  (or the plurality of second rotor blades  126 ) can define a blade effective area as a ratio of the blade surface area to the blade rotation area. In some embodiments, the blade effective area is greater than or equal to 0.4 (e.g., as compared to 0.2 in many existing systems). In some embodiments, the blade effective area is greater than or equal to 0.6. By having an increased blade effective area, the rotor blades  124 ,  126  can more efficiently generate lift at lower speeds and pitches; the VTOL platform  100  can achieve greater blade effective areas by using frictionless methods for driving rotation of the rotor  120 , which would otherwise not be possible using mechanical couplings, such as swashplates and gearboxes, to rotate the rotor  120  (or would result in increased mechanical noise that would offset noise reductions from increased blade effective area). 
     The VTOL platform  100  can include a plurality of beams  150  extending from the support structure  140  to the housing  130 . The beams  150  can be unidirectional carbon fiber spokes. The beams  150  can be swept and leaned to increase a number of incident wakes from the rotor blades  124 ,  126  acting on each beam  150 , spreading the phase angle of the wakes to achieve incoherence. The beams  150  can provide radial, vertical, and torsional stiffness to keep the housing  130  secure with respect to the support structure  140 . 
     Referring now to  FIGS.  3 - 5   , a VTOL system  300  includes a control circuit  310 , the stator  110 , and the rotor  120 . The VTOL system  300  can be implemented to control operation of the VTOL platform  100  described with reference to  FIGS.  1 - 2   . The control circuit  310  includes a processor  312  and memory  314 . The processor  312  may be implemented as a specific purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a group of processing components, or other suitable electronic processing components. The processor  312  may be a distributed computing system or a multi-core processor. The memory  314  is one or more devices (e.g., RAM, ROM, flash memory, hard disk storage) for storing data and computer code for completing and facilitating the various user or client processes, layers, and modules described in the present disclosure. The memory  314  may be or include volatile memory or non-volatile memory and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures of the inventive concepts disclosed herein. The memory  314  is communicably connected to the processor  312  and includes computer code or instruction modules for executing one or more processes described herein. The memory  314  can include various circuits, software engines, and/or modules that cause the processor to execute the systems and methods described herein. The memory may be distributed across disparate devices. 
     The memory  314  includes a flight controller  316  and a motor controller  318 . The flight controller  316  can use flight dynamics models, rotor state, and control laws to convert desired movement of the VTOL system  300  into flight control signals  320 , and transmit the flight control signals  320  to the motor controller  318 . The motor controller  318  can receive the flight control signals  320 , and generate motor control signals  322  based on the flight control signals  320  to control operation of the stator  110 , in order to cause the VTOL platform  100  to achieve the desired movement. 
     The VTOL system  300  can include a communications circuit  330 . The communications circuit  330  is configured to receive and transmit data. The communications circuit  330  can include receiver electronics and transmitter electronics. The communications circuit  330  can include a radio configured for radio frequency communication. The communications circuit  330  can include a datalink radio. The communications circuit  330  can receive and transmit navigation information from/to remote platforms. 
     The VTOL system  300  can include at least one sensor  334 . The at least one sensor  334  can provide sensor data to the control circuit  310 . The at least one sensor  334  can detect position, speed, acceleration, altitude, orientation, and other state parameters of VTOL system  300  (e.g., of the VTOL platform  100  implementing the VTOL system  300 ). The at least one sensor  334  can detect environmental parameters such as temperature, air pressure, and wind speed. The at least one sensor  334  may include at least one of an inertial measurement unit (which may include one or more gyroscopes and one or more accelerometers, such as three gyroscopes and three accelerometers), an air data sensor (e.g., sensor(s) configured to detect and output an indication of static pressure), or a magnetic compass. The at least one sensor  334  can include a global navigation satellite system (GNSS) receiver and/or a global positioning system (GPS) receiver. 
     The VTOL system  300  can include a user interface  340  including a display device  342  and a user input device  344 . The display device  342  can receive display data from control circuit  310  and present the received display data. The display device  342  can include various display components, including but not limited to CRT, LCD, organic LED, dot matrix display, and others. The display device  342  may include navigation displays, primary flight displays, electronic flight bag displays, tablets such as iPad® computers manufactured by Apple, Inc. or tablet computers, synthetic vision system displays, HUDs with or without a projector, head up guidance systems, wearable displays, watches, Google Glass® or other HWD systems. The display device  342  can present display data such as air traffic control data, weather data, navigation data (e.g., flight plans), and terrain information. 
     The user input device  344  may include, for example, dials, switches, buttons, touch screens, keyboards, a mouse, joysticks, cursor control devices (CCDs). The user input device  344  may include a touch interface provided by one or more components of the display device  342 . The user input device  344  may include an audio input device configured to receive audio information (e.g., spoken information from an operator) that the control circuit  310  can process. The user input device  344  may include an image capture device, such that the control circuit  310  can execute image processing functions such as gesture control, head-tracking, and/or eye-tracking, and generate control instructions based on the image processing. 
     The user interface  340  can receive a user input, and transmit an indication of the user input  346  to the flight controller  316 . The flight controller  316  can receive the indication of the user input  346 , extract an input command from the indication of the user input  346 , and determine a desired movement of the VTOL platform  100  based on the input command in order to generate the flight control signals  320 . 
     Improved Stator Assembly for Use with a Rotor 
     The stator  110  includes a stator housing  350  (e.g., an annular stator base) supporting a plurality of stator magnets  352  (e.g., propulsion magnets). The stator housing  350  can include a plurality of stator segments  351 , which can be contiguous, such as being integral or monolithic, or can be at least partially disconnected, such as by being separate members or being connected by extensions that are narrower than the adjacent stator segments  351 . The plurality of stator magnets  352  can each be driven by the motor control signals  322 . The plurality of stator magnets  352  can be electromagnets. For example, the plurality of stator magnets  352  can include electromagnetic coils that output electromagnetic fields based on electrical signals driven through the electromagnetic coils. The electromagnet coils may be made from various conductive materials, including aluminum or copper. In some embodiments, aluminum can be used based on being light weight, having high thermal conductivity, and having an electrical conductivity more than twice that of copper as a function of mass (e.g., aluminum can be selected that has 61 percent of the conductivity of copper but 30 percent of the mass of copper for a given volume, enabling mass savings offsetting the volume increase to achieve a same amp rating). The stator  110  can include a laminated iron core  504  adjacent to the stator magnets  352 , which can increase a magnitude of the magnetic field outputted by the stator magnets  352 . 
     In response to receiving a particular motor control signal  322 , each stator magnet  352  can output a corresponding electromagnetic field  354 . Each stator magnet  352  can vary a magnitude of the outputted electromagnetic field  354  as a function of time depending on the received motor control signal  322 . For example, if the motor control signal  322  has varying values of parameters such as amplitude and frequency, amplitude and frequency of the electromagnetic field  354  can similarly vary. 
     As described further herein, the stator  110  can include magnets  362   a ,  362   b ,  364   a , and  364   b  of LGS  360  that can interact with rotor magnets  372 ,  374  to maintain respective spaces between the stator  110  and the rotor  120  and in turn receive lift from the rotor  120  to lift the stator  110 . For example, as the stator magnets  352  output electromagnetic fields  354 , lift generated by rotation of the rotor  120  can cause the rotor  120  to move upwards (e.g., closer to magnet  372  and further from magnet  374 ); as a result, the rotor  120  applies force via the magnets  372 ,  374  on the stator  110 , lifting the stator  110  as operation of the magnets  362   a ,  362   b ,  364   a , and  364   b  adjust to the forces applied by the rotor  120  and transfer the forces to the stator housing  350 . 
     Improved Rotor Assembly for Use with a Stator 
     The rotor  120  includes a rotor base  128 . The rotor base  128  can be annular, extending around the rotational axis  122  and defining a space between the rotor base  128  and the stator housing  350 . The rotor base  128  can include a plurality of rotor segments  132 . Each rotor segment  132  can include a sidewall  134  spaced from the rotational axis  122 . The rotor segments  132  can be contiguous, such as by each rotor segment  132  being connected with adjacent rotor segments  132  or being integral or monolithic. The rotor segments  132  can be at least partially disconnected, such as by being separate members or being connected by extensions that are narrower than the adjacent rotor segments  132  in a direction perpendicular to the rotational axis  122 . 
     The rotor  120  includes a plurality of rotor magnets  380  arranged around the rotor  120 . One or more rotor magnets  380  can be coupled with corresponding sidewalls  134 . Each rotor magnet  380  can be driven by corresponding electromagnetic fields outputted by the plurality of stator magnets  352 . The plurality of rotor magnets  380  can be permanent magnets, which may have a higher flux density than superconducting magnets for the form factors of the present solution. In some embodiments, the plurality of rotor magnets  380  (and, in some embodiments, the magnets  372  of the LGS  360  described below) include neodymium permanent magnets, which may have magnetic field strengths of up to 1 Tesla, and can be geometrically configured into Halbach arrays to increase the magnetic field strength up to 1.4 T. The time-varying nature of the electromagnetic fields  354  generated by the plurality of stator magnets  352 , along with the positioning of the stator magnets  352 , can drive the plurality of rotor magnets  380  to rotate about a rotor axis (e.g., rotational axis  122  shown in  FIG.  2   ). 
     Each rotor blade  124 ,  126  can be mechanically coupled to at least one rotor magnet  380 . In some embodiments, as the rotor magnets  380  rotate, the rotor magnets  380  can be differentially driven about the rotational axis  122  by propulsion  416  caused by the stator  110 , the rotor blades  124 ,  126  will rotate about a pitch axis. As shown in  FIG.  4   , as the rotor blades  124 ,  126  rotate, lift  402  can be generated. A castor wheel  508  (e.g., rubber, nylon castor wheel) can be positioned between the stator  110  and rotor  120  to enable the rotor  120  to be supported and continue to rotate relative to the stator  110  when the rotor  120  is at rotating below a speed threshold at which the rotor  120  generates sufficient lift that, when combined with levitation from the levitation system  360 , overcomes gravity to levitate the rotor  120 . The castor wheel  508  can extend between the stator  110  and the rotor  120  to separate the stator  110  and the rotor  120 . 
     The rotor blades  124 ,  126  can be made of a composite construction. The composite fiber skin of the blades  124 ,  126  can transfer the centrifugal and bending loads of the blades  124 ,  126  to an axle  418  (e.g., a feathering grip axle). In some embodiments, the axle  418  is resisted against the centrifugal and aerodynamic loads by a pair of thrust bearings  420 , which can include brass bushings to compensate for the primary bending and shear moments of the rotor blades  124 ,  126 . The rotor  120  can include a support ring  422 , which can be a modular assembly of a box hoop mounting the blade assemblies (e.g., each blade  124 ,  126  and corresponding axle  418  and bearings  420 ) and driving magnets  380 . The support ring  422  can include hollow disks end plates  424  to hold magnets  372 ,  374 . 
     B. Systems and Methods of Levitation and Guidance of a VTOL Platform 
     Referring further to  FIGS.  3 - 5    and now to  FIG.  6   , the VTOL system  300  includes a levitation and guidance system (LGS)  360 , which maintains a position (and orientation) of the rotor  120  relative to the stator  110 , including to enable the stator  110  to receive lift from the rotor  120  across an air gap between the rotor  120  and stator  110  in order to move the VTOL platform  100 . 
     Systems and Methods for Maintaining Levitation of a Rotor Relative to a Stator 
     The present solution can maintain levitation of a rotor (e.g., rotor  120 ) relative to a stator (e.g., stator  110 ). In implementations in which the stator drives a rotor, the rotor may be needed to be spaced apart from the stator (e.g., to limit friction, for instance). The implementations and embodiments described herein space apart the rotor from the stator even where the stator and rotor are levitating off the ground. 
     In some embodiments, a system includes a rotor and a stator. The rotor includes a sidewall and two rotor walls extending from the two ends of the sidewall such the two rotor walls are spaced apart from each other. The rotor includes a first and second rotor magnet coupled with the respective rotor walls. The stator includes a support structure extending between the rotor walls. The stator includes a stator magnet (e.g., a first stator magnet) coupled to a first surface of the support structure adjacent to one of the rotor magnets (e.g., the first rotor magnet). The first rotor magnet induces a current in the first stator magnet corresponding to a distance between the first stator magnet and the first rotor magnet. The stator includes another stator magnet (e.g., a second stator magnet) coupled to a second surface of the support structure adjacent to the second rotor magnet. The stator magnets are electrically coupled to one another such that the second stator magnet receives current from the first stator magnet. The second stator magnet outputs a magnetic field having a magnetic field strength based on the current from the first stator magnet. The magnetic field from the second stator magnet interacts with the second rotor magnet to control a distance between the at least one second stator magnet and the at least one second rotor magnet. 
     For example, referring still to  FIGS.  3 - 5  and  6   , the LGS  360  can maintain a position of the rotor  120  along the rotational axis  122  (e.g., vertically) relative to the stator  110 . For example, the LGS  360  can include a plurality of first magnets  362  and a plurality of second magnets  364  (also referred to herein as stator magnets) that are passive electromagnetic coils and electrically coupled, such that a total magnetic flux through the first magnets  362  and corresponding second magnets  364  is zero (e.g., the LGS  360  establishes a null flux condition). The magnets  362 ,  364  may be coupled with respective surfaces of a support structure  510  of the stator  110  which extends between rotor walls  512 ,  514  and adjacent a sidewall  516  of the rotor  120 . The magnets  362 ,  364  may be arranged along a stator axis. 
     As the rotor  120  rotates (e.g., due to the magnet  352  coupled to the support structure of the stator  110  driving the magnet  380  coupled to the sidewall  516  of the rotor  120 ), the blades  124 ,  126  generate lift  402 . The LGS  360  receives the lift via the first magnets  362  as the rotor  120  moves vertically along the rotor axis  122 , and transfers the lift to the stator housing  350 , causing the VTOL platform  100  to be lifted. The LGS  360  stabilizes the position of the rotor  120  in a direction perpendicular to the rotor axis  122 . For example, as a portion of the rotor  120  moves closer to or further from the stator  110 , the LGS  360  will pull or push the rotor  120  back to an equilibrium position. 
     As the rotor  120  rotates and is lifted due to lift  402  generated by rotor blades  124 ,  126 , magnets  372 ,  374  (also referred to herein as rotor magnets) which are coupled with respective rotor walls  512 ,  514  of the rotor  120  will output magnetic fields  410 ,  412  that apply respective forces on the magnets  362 ,  364 . The magnets  372 ,  374  may be permanent magnets. The magnets  372 ,  374  may be arranged along a rotor axis extending parallel to the rotational axis of the rotor  120 . In some embodiments, magnet(s)  372  and magnet(s)  362  may be aligned, and magnet(s)  374  and magnet(s)  364  may be aligned. In some implementations, the rotor axis may be aligned with the stator axis such that each of magnets  362 ,  364 ,  372 ,  374  are aligned. 
     The magnitude of the force associated with magnetic field  410  will increase as third magnets  372  move closer to the plurality of first magnets  362 , while the magnitude of the magnetic field  412  will decrease as fourth magnets  374  move further from the second magnets  364  (or vice versa). The movement of the rotor  120  along the rotor axis  122  may occur due to various phenomena during operation of the VTOL system  300 , including but not limited to when rotation of the rotor  120  results in lift  402 . In particular, as rotation of the rotor  120  results in lift  402 , the rotor  120  will be driven vertically, applying a net vertical force on the stator  110 . In some embodiments, because the first magnets  362  are electrically coupled to the second magnets  364 , current induced in the first magnets  362  due to the magnetic field  410  increasing in magnitude will be driven to the second magnets  364  (e.g., due to the null flux condition), causing the magnitude of the magnetic field  412  to increase, in turn pulling the fourth magnets  374  closer to the second magnets  364  and thus maintaining a position of the rotor  120  relative to the stator  110  along the rotor axis  122 . The repulsive force associated with the stabilization implemented by the LGS  360  can be linear, which can facilitate the stabilization effect. 
     Systems and Methods for Improved Guidance of a Rotor Relative to a Stator 
     The present solution can enable improved guidance of a rotor relative to a stator (e.g., rotor  120 , stator  110 ), such as to maintain the rotor in an appropriate position along an axis perpendicular to the rotational axis  122  responsive to the rotor moving closer to or further from the stator. In implementations in which the stator drives a rotor, the rotor may have a tendency to laterally shift during rotation (e.g., due to centrifugal and centripetal forces). As a result of such lateral shifts, the rotor and stator may become misaligned, which may cause the system to malfunction or even become inoperable. The implementations and embodiments described herein maintain the position of the rotor with respect to the stator to prevent misalignment. 
     In some embodiments, a system includes a rotor and a stator. The rotor includes a sidewall and a rotor wall extending from an end of the sidewall. The rotor includes a rotor magnet coupled with the rotor wall. The stator includes a support structure adjacent the rotor wall. The stator includes a first stator magnet and a second stator magnet. The stator magnets are coupled with a surface of the support structure proximate to the rotor magnet. The stator magnets may be electrically coupled to one another. The rotor magnet may induce a current in the first stator magnet corresponding to a magnetic force between the first stator magnet and the rotor magnet. The second stator magnet may receive the current from the first stator magnet to control a magnetic force between the second stator magnet and the rotor magnet. 
     As shown in  FIGS.  4  and  6   , the first magnets  362  (e.g., stator magnets) include pairs of first magnets  362 , one first magnet  362   a  radially inward and one first magnet  362   b  radially outward. The second magnets  364  (e.g., stator magnets) similarly include an inward second magnet  364   a  and an outward second magnet  364   b . In some embodiments, the first magnet  362   a  is electrically coupled to the first magnet  362   b , and the second magnet  364   a  is electrically coupled to the second magnet  364   b , enabling a similar null flux condition as between corresponding magnets  362 ,  364 . At an equilibrium position, the magnets  362   a ,  364   a  are inward of the corresponding magnets  372 ,  374  (e.g., rotor magnets), and the magnets  362   b ,  364   b  are outward of the corresponding magnets  372 ,  374 . If the rotor  120  shifts towards the stator  110 , the magnitude of magnetic fields  376  will change to counteract the shift. For example, as the rotor  120 , and thus magnets  372 ,  374  shift closer towards the rotor axis  122 , the magnets  372 ,  374  will shift towards the magnets  362   a ,  364   a , and further from the magnets  362   b ,  364   b . As such, a distance between the magnets  372 ,  374  and magnets  362   a ,  364   a  increases. In turn, a magnitude of a first field  604   a  (e.g., a magnetic force of the first magnetic field  604   a ) between the magnet  372  and the magnet  362   a  will increase, while a magnitude of a second field  604   b  (e.g., a magnetic force of the second magnetic field  604   b ) between the magnet  372  and the magnet  362   b  will decrease (similarly for the magnet  374  and magnets  364   a ,  364   b ). As the magnitude of the field  604   a  increases, current is induced in the magnet  362   a . Because the magnets  362   a ,  362   b  are electrically coupled, changes in induced currents between the magnets  362   a ,  362   b  will counteract the movement of the magnet  372 , and thus move the rotor  120  back towards the equilibrium position. The induced current between the magnets  362   a ,  362   b ,  364   a ,  364   b  may control the magnetic force between the magnets  372 ,  374  and magnets  362   a ,  362   b ,  364   a ,  364   b  to move the rotor  120  back towards the equilibrium position. 
     C. Systems and Methods of Controlling a VTOL Platform 
     Referring now to  FIGS.  7 - 9   , a flight controller  700  is shown according to an embodiment of the present disclosure. The flight controller  700  can incorporate features of the flight controller  316  described with reference to  FIG.  3   , including to generate instructions for controlling motion of a VTOL platform (e.g., VTOL platform  100  described with reference to  FIGS.  1 - 3   ). For example, the flight controller  700  can generate commands to cause thrust, yaw, pitch, and roll movement of the VTOL platform (e.g., thrust, moment of force about yaw axis, moment of force about platform pitch axis, moment of force about platform roll axis). 
     Systems and Methods for Drive Control of a Magnetically Levitated Rotor 
     The present solution can be used to control operation of the rotor  120  to control movement of the VTOL platform  100 , such as to cause the rotor  120  to generate lift. In some embodiments, the flight controller  700  includes a flight dynamics model  702 . The flight dynamics model  702  can calculate variables associated with motion of the VTOL platform  100 . For example, the flight dynamics model  702  can model relationships between thrust, drag, and gravity acting on the VTOL platform  100 . The flight dynamics model  702  can calculate lift corresponding to forces acting on the VTOL platform  100 . The flight dynamics model  702  can include a function that computes a thrust generated by each rotor blade (e.g., rotor blades  124 ,  126 ) based on a pitch angle of each rotor blade; similarly, the flight dynamics model  702  can compute a total thrust generated by all of the rotor blades (e.g., a magnitude and direction of the total thrust) based on the pitch angle of all of the rotor blades. 
     The flight controller  700  includes a flight dynamics controller  704 . The flight dynamics controller  704  can include flight dynamics control laws used to generate control commands  708  to cause the VTOL platform  100  to perform desired movement, such as to selectively control (e.g., via motor controller  1000  and stator system  1100  as described below) the stator magnets  352  to produce respective magnetic fields that interact with rotor magnets  380  to rotate the rotor  120  about the rotational axis  122  to generate lift, and to control operation of the rotor blades  124 ,  126  to control an angle of the rotor blades  124 ,  126  about respective blade axes  440 . In particular, the flight dynamics controller  704  can generate a vertical command  708   a , a pitch command  708   b , a yaw command  708   c , and a roll command  708   d . The flight dynamics controller  704  can generate the commands  708   a ,  708   b ,  708   c ,  708   d  by mapping pitch angles of each rotor blade to corresponding thrust generated by each rotor blade, and mapping the thrust of each rotor blade to resulting thrust (e.g. total thrust), yaw, pitch, and roll. The flight dynamics controller  704  can generate the command  708   b  to a moment of force about the yaw axis, the command  708   c  to a moment of force about the pitch axis, and the command  708   d  to a moment of force about the roll axis. 
     The flight dynamics controller  704  can generate the vertical command  708   a  to indicate a desired vertical motion of the VTOL platform  100 . For example, the flight dynamics controller  704  can generate the vertical command  708   a  to indicate a desired lift to be achieved by the VTOL platform  100 . 
     The flight dynamics controller  704  can generate the vertical command  708   a  to execute collective rotor pitch control to generate vertical acceleration, such that the upper and lower rotor disks (e.g., upper disk corresponding to rotor blades  124 , lower disk corresponding to rotor blades  126 , as shown in  FIGS.  1 - 5   ) can increase or decrease thrust equally to negate yaw torque on a center of the VTOL platform  100 . The flight dynamics controller  704  can generate the vertical command  708   a  to control thrust by collectively changing a pitch angle of each of the rotor blades  124 ,  126 , independent of an angular position of each rotor blade  124 ,  126  relative to the rotational axis  122 . 
     For example, as shown in  FIG.  8   , the flight dynamics controller  704  can cause rotor blades  800  (e.g., illustrating an implementation of rotor blades  124  or rotor blades  126 ) to have a pitch angle resulting in individual thrusts  802  parallel to a rotor axis  806 , resulting in total thrust  804  parallel to rotor axis  806 .  FIG.  8    illustrates each rotor blade  800  having a same pitch angle about respective pitch axes, such as pitch axis  808  illustrated for one of the rotor blades  800 . 
     Systems And Methods for Independent Pitch Control of Rotor Blades of Rotor Assembly to Achieve Directional Control 
     The present solution can be used to independently control the pitch of each rotor blade  800 , enabling directional control of the VTOL platform (e.g., control thrust, pitch, yaw, roll). For example, the flight dynamics controller  704  can execute cyclic rotor pitch control to control pitch and roll of the VTOL platform  100 . For example, as shown in  FIG.  9   , the flight dynamics controller  704  can cause a first rotor blade  900  to have a pitch corresponding to a greater thrust  902   a  than the remaining rotor blades  900 , particularly than a lesser thrust  902   b  of the rotor blade  900  opposite the first rotor blade  900 , resulting in a total thrust  904  having a horizontal component relative to rotor axis  906 , the horizontal component corresponding to a greater amount of thrust being generated on a first side of the rotor axis  906  where the first rotor blade  900  is located. As will be described with reference to  FIGS.  11 - 12   , as the rotor blades  900  rotate about the rotor axis  906 , the flight dynamics controller  704  can selectively cause each rotor blade  900  to achieve a desired pitch angle as a function of the position of the rotor blade  900 . For example, to achieve the total thrust  904  illustrated in  FIG.  9    for a desired duration of time, the flight dynamics controller  704  can generate commands to cause each rotor blade  900  to change its pitch angle through the various pitch angles shown in  FIG.  9    as the rotor blades  900  rotate about the rotor axis  906 . As discussed further herein, the pitch angle of each rotor blade  900  can be controlled through various mechanisms, such as a motor coupled with the rotor blade  900  to rotate the rotor blade  900  or rotor magnets coupled with the rotor blade  900  that can be driven by stator magnets to rotate the rotor blade  900 . 
     In some embodiments, the flight dynamics controller  704  uses an operator input  706  (which may be received from user interface  340  described with reference to  FIG.  3   ) to generate the control commands  708 . For example, the flight dynamics controller  704  can extract movement instructions indicated by the operator input to generate the control commands  708 . In some embodiments, the flight dynamics controller  704  uses an autopilot to generate the control commands  708 . For example, the autopilot may provide a target destination to the flight dynamics controller  704 , such as a waypoint on a flight plan. The autopilot may provide a plurality of target destinations over time to defining a path for the VTOL platform  100  to follow (e.g., a path through a plurality of waypoints). 
     The flight dynamics controller  704  can use the flight dynamics model  702  to generate the control commands  708 . For example, the flight dynamics controller  704  can use the flight dynamics model  702  to calculate a lift expected to be generated by the rotor  120  given pitch angles of the rotor blades. The flight dynamics controller  704  can execute the flight dynamics control laws to convert instructions indicative of desired movement (e.g., instructions extracted via operator input indicating desired movement to a higher altitude at a particular vertical speed and airspeed), and use the flight dynamics model  702  to determine how to control operation of the rotor blades  900  to generate the lift, yaw, pitch, and/or roll expected to achieve the desired movement. 
     The flight dynamics controller  704  outputs the control commands  708  to a first network  710 . The first network  710  can be a communication bus, such as a controller area network (CAN) bus, a local interconnect network (LIN) bus, or a padded jittering operative network (PJON) network. The first network  710  can operate using a micro control stack network stack protocol. 
     Referring now to  FIG.  10   , a motor controller  1000  is shown according to an embodiment of the present disclosure. The motor controller  1000  can incorporate features of the motor controller  318  described with reference to  FIG.  3   , including to generate electronic instructions for controlling operation of a stator of a VTOL platform (e.g., stator  110  and VTOL platform  100  described with reference to  FIGS.  1 - 3   ). 
     The motor controller  1000  includes at least one motor control circuit  1002 . For example, as shown in  FIG.  10   , the motor controller  1000  includes a first motor control circuit  1002   a , a second motor control circuit  1002   b , and a third motor control circuit  1002   c . The at least one motor control circuit  1002  can receive control commands from the first network  710  (e.g., control commands  708  as described with reference to  FIG.  7   ), and generate motor control signals  1004  to be outputted to the stator  110  via second network  1006 . The second network  1006  can be similar to the first network  710 . 
     For example, as shown in  FIG.  10   , the first motor control circuit  1002   a  can output first motor control signal  1004   a , the second motor control circuit  1002   b  can output second motor control signal  1004   b , and the third motor control circuit  1002   c  can output third motor control signal  1004   c . In some embodiments, the number of motor control circuits  1002  corresponds to the number of phases of operation of magnets of the stator  110 ; for example, the motor controller  1000  shown in  FIG.  10    can be configured for three-phase operation. The motor controller  1000  can execute synchronous control of the stator  110 , and can maintain a constant speed of rotation of the rotor  120  by maintaining a source frequency of the motor control signals  1004 , including for any load condition that is less than a rated maximum load. 
     As will be described with further reference to  FIG.  11   , the at least one motor control circuit  1002  can generate the motor control signals  1004  to cause specific waveforms to be applied to electromagnets of the stator  110  in order to cause resulting motion of magnets of the rotor  120 . The motor controller  1000  includes a position encoder  1004  that receives a position signal  1010  from a third network  1008 . The third network  1008  can be similar to the first network  710  and second network  1006 . 
     The position signal  1010  indicates positions of magnets of the rotor  120 , which the position encoder  1004  can convert into position data that the at least one motor control circuit  1002  can use to determine which electromagnets of the stator  110  to control (and thus how to generate the waveforms to be applied to the electromagnets of the stator  110 ). 
     Systems and Methods for Dynamically Triggering Independent Stator Coils to Control Rotational Velocity of Rotor 
     Referring now to  FIG.  11   , a stator system  1100  is shown according to an embodiment of the present disclosure. The stator system  1100  can incorporate features of the stator  110  described with reference to  FIGS.  1 - 5   . The stator system  1100  includes at least one magnet controller  1102 , such as magnet controllers  1102   a ,  1102   b , and  1102   c , which can each execute one phase of a three-phase control scheme. The at least one magnet controller  1102  receives motor control signals  1004  from the second network  1006 . For example, as depicted in  FIG.  11   , the first magnet controller  1102   a  receives the first motor control signal  1004   a , the second magnet controller  1102   b  receives the second motor control signal  1004   b , and the third magnet controller receives the third motor control signal  1004   c . The stator system  1100  can be used to independently trigger electromagnets of the stator  110  (e.g., stator coils) or groups of electromagnets to output magnetic fields that can be used to rotate the rotor  110  at desired rotation rates about the rotational axis  122 . 
     The stator system  1100  includes a plurality of electromagnets (e.g., electromagnetic coils).  FIG.  11    illustrates nine pairs of electromagnets  1110 ,  1112 ;  1114 ,  1116 ;  1118 ,  1120 ;  1122 ,  1124 ;  1126 ,  1128 ;  1130 ,  1132 ;  1134 ,  1136 ;  1138 ,  1140 . An electromagnet of each pair can be provided in a corresponding stator rail  404  or  408  as shown in  FIG.  4   . For example, electromagnets  1110 ,  1114 ,  1118 ,  1122 ,  1126 ,  1130 ,  1134 ,  1138 , and  1142  can be provided in the stator rail  404 , and electromagnets  1112 ,  1116 ,  1120 ,  1124 ,  1128 ,  1132 ,  1136 ,  1140 , and  1144  can be provided in the stator rail  408 . While  FIG.  11    illustrates the stator system  1100  including nine pairs of electromagnets controlled by the three magnet controllers  1102   a ,  1102   b , and  1102   c , it will be understood that the stator system  1100  can include additional such modules of magnet controllers and electromagnets—for example, the stator system  1100  can include a circumferential ring of magnet controllers and electromagnets to enable the stator system  1100  to drive the rotor  120  from all around the rotational axis  122 . 
     The first magnet controller  1102   a  can control operation of electromagnets  1110 ,  1112 ;  1122 ,  1124 ; and  1134 ,  1136 . For example, the first magnet controller  1102   a  can transmit individual magnet control signals to each of the electromagnets  1110 ,  1112 ;  1122 ,  1124 ; and  1134 ,  1136 . In some embodiments, the stator system  1100  includes a first actuator  1142  coupled to the electromagnet  1110  and a second actuator  1144  coupled to the electromagnet  1112 . The first actuator  1142  and second actuator  1144  can be implement using a switch circuit, such as a metal oxide semiconductor field effect transistor (MOSFET). The stator system  1100  can include an actuator coupled to each electromagnet (as depicted in  FIG.  11   ). 
     The at least one magnet controller  1102  can transmit magnet control signals to control operation of the electromagnets, such as by executing pulse-width modulation (PWM) based on the received motor control signals  1004  to control at least one of a current or a voltage of the outputted magnet control signal based on the received motor control signals  1004 . For example, by increasing a duty cycle of the control signals using PWM, the at least one magnet controller  1102  can cause the electromagnets to output magnetic fields having relatively greater field strengths. The first magnet controller  1102   a  can transmit a first magnet control signal to cause the first actuator  1142  to drive a first electrical signal through the electromagnet  1110 , causing the electromagnet  1110  to output a corresponding first magnetic field, and can transmit a second magnet control signal to cause the second actuator  1142  to drive a second electrical signal through the electromagnet  1112  to output a corresponding second magnetic field. As the magnet controllers  1102  control the electromagnets (e.g., based on the magnetic force output from the electromagnets, based on a switching rate between the electromagnets outputting magnetic fields, and so forth), the magnet controller  1102  can control the rotational velocity of the rotor  120  relative to the stator  110 . The switching rate can correspond to a rate of current being driven through respective electromagnets, or a rate of pulse output by the at least one magnet controller  1102 . The magnet controllers  1102  may modify the switching rate by changing a rate by which the electromagnets are sequentially excited to produce a respective magnetic field. The magnet controllers  1102  may modify the magnetic force (e.g., based on magnitude of magnetic field strength of the respective magnetic field) by increasing the current, increasing the duty cycle, and so forth. For instance, the magnetic controller  1102  can increase the magnetic force to increase the rotational velocity, increase the switching rate to increase the rotational velocity, and so forth. By increasing the rotational velocity, the rotor blades  124 ,  126  can produce more lift. In some embodiments, the magnet controller  1102   a  can control the electromagnets  1110 ,  1112 ;  1122 ,  1124 ; and  1134 ,  1136  at a first switching rate, and the second magnet controller  1102   b  can control the electromagnets  1114 ,  1116 ;  1126 ,  1128 ; and  1138 ,  1140  at a second switch rate different than the first switching rate. 
     The second magnet controller  1102   b  can control operation of electromagnets  1114 ,  1116 ;  1126 ,  1128 ; and  1138 ,  1140 . For example, the second magnet controller  1102   b  can transmit individual magnet control signals to each of the electromagnets  1114 ,  1116 ;  1126 ,  1128 ; and  1138 ,  1140 . The third magnet controller  1102   c  can control operation of electromagnets  1118 ,  1120 ;  1130 ,  1132 ; and  1142 ,  1144 . For example, the third magnet controller  1102   c  can transmit individual magnet control signals to each of the electromagnets  1118 ,  1120 ;  1130 ,  1132 ; and  1142 ,  1144 . As the magnet controllers  1102  control the electromagnets (e.g., based on the magnetic force output from the electromagnets, based on the switching rate between the electromagnets outputting magnetic fields, and so forth), the magnet controller  1102  can control the rotational velocity of the rotor  120  relative to the stator  110 . The magnet controllers  1102  may modify the switching rate by changing a rate by which the electromagnets are sequentially excited to produce a respective magnetic field. For instance, the magnetic controller  1102  can increase the magnetic force to increase the rotational velocity, increase the switching rate to increase the velocity, and so forth. By increasing the velocity, the rotor blades  124 ,  126  can produce more lift. 
     Systems and Methods for Dynamically Triggering Independent Stator Coils to Control Pitch of Rotor Blade 
     The present solution can be used to control pitch angles of rotor blades  1164  by independently triggering and controlling operation of electromagnets or groups of electromagnets of the stator system  1100 , in turn controlling the respective magnetic fields outputted by the electromagnets that interact with the rotor  120  and magnets thereof. For example, the magnet controllers  1102  can output control signals having duty cycles, magnitudes, switching rates, or other parameters that selectively control the electromagnets of the stator system  1100  to output desired magnetic fields. In the configuration depicted in  FIG.  11   , the third magnet controller  1102   c  has outputted a magnet control signal to cause electromagnet  1120  to output an electromagnetic field  1152 . The third magnet controller  1102   c  configures the electromagnetic field  1152  to repulse a first rotor magnet  1160  (e.g., a lower rotor magnet of the two rotor magnets  380  interacting with rotor blade  124  as shown in  FIGS.  4 - 5   ), such as by timing a magnitude and polarity of the electromagnetic field  1152  to repulse a corresponding lagging-side pole of the first rotor magnet  1160 . The second magnet controller  1102   b  has outputted a magnet control signal to cause electromagnet  1128  to output an electromagnetic field  1154 , which is configured to attract the first rotor magnet  1160 , such as by timing a magnitude and polarity of the electromagnetic field  1154  to attract a corresponding leading-side pole of the first rotor magnet  1160 . As such, the stator system  1100  can drive the first rotor magnet  1160  at a desired speed along the direction  1170  by controlling the timing, magnitude, and/or polarity of the outputted magnetic fields. Similarly, in the configuration depicted in  FIG.  11   , the first magnet controller  1102   a  has outputted a magnet control signal to cause electromagnet  1122  to output an electromagnetic field  1156  to repulse a lagging-side pole of a second rotor magnet  1162 , and the third magnet controller  1102   c  has outputted a magnet control signal to cause electromagnet  1130  to output an electromagnetic field  1158  to attract a leading-side pole of the second rotor magnet  1162 , thus driving the second rotor magnet  1162  at a desired speed (which can be different than the speed at which the first rotor magnet  1160  is driven) along the direction  1170 . 
     The rotor blade  1164  is coupled to the first and second rotor magnets  1160 ,  1162 , and thus can be driven along the direction  1170  by movement of the first and second rotor magnets  1160 ,  1162 . As such, the stator system  1100  can generate desired lift based on the speed at which the rotor blade  1164  is driven, as well as the pitch angle at which the rotor blade  1164  is oriented. As will be described with further reference to  FIG.  12   , the stator system  1100  can selectively lag and lead the first and second rotor magnets  1162 ,  1164  relative to one another (based on the motor control signals  1004  received from the motor controller  1000 ) to adjust the pitch angle of the rotor blade  1164 , enabling lift, yaw, pitch, and roll control. In addition, the stator system  1100  can maintain synchronicity with the rotor magnets  1160 ,  1162  due to the combined attraction and repulsion applied to each pair of rotor magnets  1160 ,  1162 . 
     As the rotor magnets  1160 ,  1162  are driven along the direction  1170 , the at least one magnet controller  1102  can continue to use received motor control signals  1004  to selectively activate electromagnets (including the depicted electromagnets  1110 ,  1112 ;  1114 ,  1116 ;  1118 ,  1120 ;  1122 ,  1124 ;  1126 ,  1128 ;  1130 ,  1132 ;  1134 ,  1136 ;  1138 ,  1140 ), and thus drive the rotor magnets  1160 ,  1162  throughout a full rotation about the stator system  1100 . 
     The stator system  1100  includes a position encoder  1104 . The position encoder  1104  can transmit a position signal indicating a position of each rotor blade (e.g., rotor blade  1164 ) via the third network  1008  to the position encoder  1004  of the motor controller  1000 , so that the motor controller  1000  can use the position of each rotor blade to generate appropriate motor control signals  1004  to transmit to the stator system  1100 . The position encoder  1004  can be distributed throughout the stator  110  in a similar manner as the configuration of the stator system  1100  shown in  FIG.  11    can be distributed throughout the stator  110  to enable full circumferential operation. 
     The position encoder  1104  can include a back electromotive force (EMF) encoder that measures a back EMF of each electromagnet of the stator system  1100 , and determines the positions of rotor magnets  1160 ,  1162 , and thus rotor blades  1164 , based on the measured back EMF. For example, at each motor control state, the position encoder  1104  can detect a back EMF of a distributed selection of unpowered electromagnets of the stator system  1100 ; the zero crossing of the voltage signal in each of the electromagnets can indicate the passing of the corresponding rotor magnets  1160 ,  1162  over the center of the electromagnet coil. The position encoder  1104  and/or the position encoder  1004  of the motor controller  1000  can use a high resolution of rotor magnet positions, combined with a Kalman filter to produce a high speed measurement and prediction of blade position/pitch for a large number of blades, in order to generate motor control signals  1004  with highly precise timing. 
     Systems and Methods for Variable Blade Pitch Control 
     The present solution can enable various solutions for independent, variable blade pitch control of the pitch of rotor blades (e.g., rotor blades  124 ,  126 ,  1164 ), allowing for directional control of the VTOL platform  100  based on the individual and collective pitches (e.g., pitch angle) of the rotor blades. In implementations in which the VTOL platform  100  is used as a vehicle, it may be desirable to move the VTOL platform  100  in different directions. The systems and methods described herein may modify the pitch angle of the rotor blades to achieve an overall desired movement of the rotor and, thus, the VTOL platform  100 . 
     In some embodiments, the system includes a rotor and a stator. The rotor includes a first rotor magnetic component aligned with one or more first stator coils. The rotor includes a second rotor magnetic component aligned with one or more second stator coils and adjacent to the first rotor magnetic component. The rotor includes an arm connecting the first rotor magnetic component and the second rotor magnetic component. A first arm end of the arm is coupled with the first rotor magnetic component and a second arm end of the arm coupled with the second rotor magnetic component which together define an arm angle which changes based on a first magnetic force applied to the first rotor magnetic component relative to a second magnetic force applied to the second rotor magnetic component. The rotor includes a first rotor blade fixed to the arm, the first rotor blade extending from the arm along a blade pitch axis. The first rotor blade defines a blade pitch angle relative to the blade pitch axis with the blade pitch angle corresponding to the arm angle. The stator includes a plurality of electromagnets configured to output at least a first magnetic field that drives the first rotor magnetic component and a second magnetic field that drives the second rotor magnetic component responsive to control signal(s). The control signal(s) cause the first magnetic field to apply the first magnetic force on the first rotor magnetic component and the second magnetic field to apply the second magnetic force on the second magnetic component to control the blade pitch angle. 
     In some embodiments, the system includes a rotor and a stator which rotates the rotor about a rotational axis. The rotor includes an annular rotor base defining the rotational axis and including a plurality of rotor segments arranged around the stator. Each rotor segment includes a first rotor blade configured to be rotated about a blade pitch axis perpendicular to the rotational axis. The rotor segments include a power receiver circuit. The rotor segments include a motor that rotates using power received via the power receiver circuit for rotating the first rotor blade about the blade pitch axis. The rotor segments include a motor controller that provides a motor signal to the motor for rotating the first rotor blade about the blade pitch axis responsive to a control signal. The rotor segments include a first wireless transceiver that receives the control signal and provides the control signal to the motor controller. The stator includes a second wireless transceiver that receives a control command and wirelessly transmits the control signal to the first wireless transceiver based on the control command. The stator includes a power transmitter circuit that outputs a magnetic field that interacts with the power receiver circuit to provide power to the power receiver circuit. 
     Referring now to  FIG.  12   , a rotor control system  1200  is shown according to an embodiment of the present disclosure. The rotor control system  1200  can enable frictionless blade pitch control, and can avoid difficulties that may arise from applying traditional pitch control approaches to the form factors achieved by the present solution. For example, existing systems typically use a swashplate to transfer directional control inputs into rotor pitch control. However, when applied to a larger radius rotating at a comparable rotation rate, the radial velocity of the hub of the ring may be significantly larger, which can result much larger friction losses, require more material to support cyclic loads in fatigue strength resulting in larger more heavily reinforced bearing solutions, may require intricate cooling methods, may result in large amounts of wear and more maintenance, and may increase of mechanical noise from cyclic loading of high speed bearings that could mitigate improved noise performance that could otherwise be achieved by the annular and electric motor configuration. The rotor control system  1200  can avoid these difficulties by driving rotor blade rotation using controlled electromagnetic fields across an air gap. 
     As shown in  FIG.  12   , the rotor control system  1200  includes a first (e.g., upper) magnet member  1202  supporting the first rotor magnet  1160 , and a second (e.g., lower) magnet member  1204  supporting the second rotor magnet  1162 . The first magnet member  1202  is coupled to the second magnet member  1204  by an arm  1206 . A rotor blade (e.g., rotor blade  1164  described with reference to  FIG.  11   ) is fixed to the arm  1206 , such that as the arm  1206  rotates about a pitch axis (extending into the view shown in  FIG.  12   ) perpendicular to a direction of movement  1208  of the magnet members  1202 ,  1204  (the direction of movement  1208  being about a rotor axis (e.g., rotational axis  122  shown in  FIG.  2   )), a pitch angle  1210  of the rotor blade will vary. 
     An electromagnet of the upper stator rail  404  outputs a first electromagnetic field that applies a first force on the first motor magnet  1160 , causing the first magnet member  1202  to be driven forward in direction  1211 . The first force will depend on the electrical current driven through the electromagnet of the upper stator rail  404  (as described with reference to  FIG.  11   ) as well as a spatial relationship between the upper stator rail  404  and first motor magnet  1160 . Similarly, an electromagnet of the lower stator rail  408  outputs a second electromagnetic field that applies a second force on the second rotor magnet  1162  to drive the second magnet member  1204  forward in direction  1212 . Based on the initial positions of the magnet members  1202 ,  1204 , and the magnitudes of the first and second forces, the magnet members  1202 ,  1204  will move to positions resulting in a lag/lead distance  1218  between the magnet members  1202 ,  1204  (e.g., as measured from planes  1214 ,  1216  at ends of the magnet members  1202 ,  1204 ). The lag/lead distance  1218  corresponds to the pitch angle  1210 , as the arm  1206  is fixed to the magnet members  1202 ,  1204 , and will rotate as the lag/lead distance  1218  changes. 
     In various embodiments, the synchronizing force of the electromagnetic fields that the stator (e.g., stator  110 , stator system  1100 ) applies to the rotor magnets  1160 ,  1162  may be approximately the same in magnitude as a maximum driving force of the stator. As such, the rotor control system  1200  can be configured such that the stator and corresponding magnet members  1202 ,  1204  (e.g., rotor magnets  1160 ,  1162 ) are sized to produce a moving electromagnetic field across an air gap between the stator rails  404 ,  408  and magnet members  1202 ,  1204  which is large enough that a minimum linear driving force of the stator to an individual magnet member  1202 ,  1204 , between phases, is larger than a maximum combination of the following forces: the peak blade drag on the rotor blade (e.g., rotor blade  1164 ), a reactionary force of a peak aerodynamic pitching moment about a ¼ cord of the rotor blade, and a reactionary force of a maximum blade rotational inertia about a feathering axis of the rotor blade at a maximum cyclic pitch setting in overspeed operation. In various such embodiments, the number of rotor blades can be selected based on such factors, as too few blades may lead to large magnet arrays mounted to each rotor blade hub, and too many rotor blades may lead to and increased weight. 
     Referring now to  FIG.  13   , a method  1300  for controlling operation of a VTOL platform is shown according to an embodiment of the present disclosure. The method  1300  can be implemented using various systems and components disclosed herein, including the VTOL platform  100 , the VTOL system  300 , the flight controller  700 , the motor controller  1000 , the stator system  1100 , and the rotor control system  1200 . 
     At  1305 , a flight controller of a VTOL platform receives a movement instruction indicating a desired movement of the VTOL platform. The operation instruction can be received from a user interface configured to receive a user input. The operation instruction can be received from an autopilot; for example, the desired movement can be indicated to be movement towards a waypoint of a flight plan. 
     At  1310 , the flight controller generates one or more flight control commands based on the desired movement. The flight controller can use a flight dynamics model to generate the one or more flight control commands. For example, the flight dynamics controller can use the flight dynamics model to calculate a lift expected to be generated by a rotor of the VTOL platform, given pitch angles of rotor blades of the VTOL platform. The flight dynamics controller can execute flight dynamics control laws to convert instructions indicative of desired movement (e.g., instructions extracted via operator input indicating desired movement to a higher altitude at a particular vertical speed and airspeed), and use the flight dynamics model to determine how to control operation of the rotor blades to generate lift, yaw, pitch, and/or roll expected to achieve the desired movement. In some embodiments, the flight controller generates the one or more flight control commands to execute collective pitch control to cause the VTOL platform to generate lift. In some embodiments, the flight controller generates the one or more flight control commands to execute cyclic pitch control to cause the VTOL platform to generate movement about pitch and/or roll angles. 
     At  1315 , a motor controller generates one or more motor control signals based on the flight control command(s). The motor controller can generate the motor control signals to cause specific waveforms to be applied to electromagnets of a stator of the VTOL platform, in order to cause the electromagnets to output electromagnetic fields expected to cause the VTOL platform to execute the desired movement indicated by the movement instruction. In some embodiments, the motor controller receives a position signal indicating positions of rotor blades of the rotor, which the motor controller can use to generate the motor control signals to individually control operation of each rotor blade. The motor controller can generate the motor control signals and provide the motor control signals, via one or more transceivers, to control operation of motors coupled with the rotor blades to rotate the rotor blades to desired pitch angles. 
     At  1320 , the stator drives the electromagnets of the stator based on the motor control signals. For example, the stator can use a plurality of magnet controllers to drive electrical signals at desired current and/or voltage to each electromagnet based on the motor control signals. The magnet controllers can execute PWM to drive electrical signals through each electromagnet. In some embodiments, the magnet controllers operate switch circuits, such as MOSFET circuits, to selectively drive electrical signals through each electromagnet based on the motor control signals. In some embodiments, levitation/guidance magnets of the stator output magnetic fields that interact with corresponding magnets of the rotor to rotate the rotor. 
     At  1325 , the electromagnets output electromagnetic fields corresponding to the electrical signals driven through each electromagnet. Magnets of the rotor are in turn moved by the electromagnetic fields. In some embodiments, the rotor includes a plurality of rotor blades, each coupled to a pair of magnets via a rotor arm, such that selective movement of the magnets can vary a pitch angle of the rotor blade, resulting in desired lift, yaw, pitch, and/or roll. In some embodiments, motors of the rotor receive power via the electromagnetic fields and use the power to rotate respective rotor blades. 
     Referring now to  FIGS.  14 A and  14 B , a rotor control system  1400  is shown according to an embodiment of the present disclosure. Various elements and components shown in the embodiment depicted in  FIGS.  14 A and  14 B  are similar to those elements and components described above with reference to  FIG.  1 - 13   . Therefore, the same reference numerals are used to indicate similar features. The rotor control system  1400  is shown to include a blade controller  1402 . The blade controller  1402  may be any element, device, component, script, etc. designed or implemented to control movement of rotor blades  124 ,  126  to produce or achieve a desired movement. The blade controller  1402  may be similar in some aspects to the flight controller  700  described above. In some implementations, the blade controller  1402  may be embodied on or a component of the flight controller  700 . The blade controller  1402  may be configured to determine a desired pitch angle for the rotor blade(s)  124 ,  126  (e.g., a blade pitch angle). The blade controller  1402  may determine (e.g., based on a maintained ledger of commands, based on data from an encoder coupled directly or indirectly to the rotor blade  124 ,  126 , etc.) a current position of the rotor blade(s)  124 ,  126 . The blade controller  1402  may be configured to modify the pitch angle for the rotor blade(s)  124 ,  126  to achieve the desired pitch angle to result in a desired movement. As described in greater detail below, the blade controller  1402  may be configured to generate motor control signals to a motor  1404  coupled to the rotor blade(s)  124 ,  126  to move the rotor blade(s)  124 ,  126  to the desired pitch angle. 
     The blade controller  1402  may be configured to generate motor control signals for communicating to the motor  1404  to move the motor  1404 . In some implementations, the blade controller  1402  may generate a Pulse Width Modulated (PWM) signal for the motor  1404 . The PWM signal may have a duty cycle which moves the motor a certain number of steps or rotational angle. The blade controller  1402  may communicate the motor control signals to the motor through the stator  110 . In some implementations, each rotor blade  124 ,  126  may correspond to a dedicated blade controller  1402 . In other implementations, a plurality of rotor blades  124 ,  126  may be controlled by a common blade controller  1402 . 
     The blade controller  1402  is shown to be coupled to a transceiver  1406  of the stator  110 , which is communicably coupled to a transceiver  1408  of the rotor  120 . The transceivers  1406 ,  1408  may be any device(s), component(s), element(s), circuit(s), etc. designed or implemented to wirelessly transmit data over a distance. The transceivers  1406 ,  1408  may be configured to communicate according to various protocols. For instance, the transceivers  1406 ,  1408  may be configured to communicate via a ZigBee (e.g., high frequency) data transmission protocol. In still other embodiments, the transceivers  1406 ,  1408  may be configured to communicate via a Near-Field Communication (NFC) protocol, a Radio Frequency Identification (RFID) protocol, an Infrared (IR) or other free-space optical communication transmission protocol, etc. 
     The stator  110  is shown to include a power transmission circuit  1410 . The power transmission circuit  1410  may be any device(s), component(s), element(s), or circuit(s) designed or implemented to transmit power over a distance. The rotor  120  may correspondingly include a power receiving circuit  1412 . The power receiving circuit  1412  may be any device(s), component(s), element(s), or circuit(s) designed or implemented to receive power over a distance. The power transmission circuit  1410  and power receiving circuit  1412  may be coupled to each other such that the power transmission circuit  1410  wirelessly transmits power to the power receiving circuit  1412 . In some implementations, the power transmission circuit  1410  and power receiving circuit  1412  may be coupled to each other via magnetodynamic coupling. In other implementations, the power transmission circuit  1410  and power receiving circuit  1412  may be coupled to one other via inductive coupling (e.g., Qi or some other form of inductive coupling), resonant inductive coupling, laser coupling, and so forth. The power receiving circuit  1412  may be configured to transfer power received from the power transmission circuit  1410  to the transceiver  1408  of the rotor  120  and to the motor  1404 . Thus, the transceiver  1408  and motor  1404  may be wirelessly powered. In some implementations, the power receiver circuit  1412  may include a rectification circuit (e.g., via sets of diodes) to rectify an AC supply to drive a DC load as needed. In some implementations, the power receiver circuit  1412  may include a step-up or step-down circuit for stepping up (or stepping down) a voltage/current/power to drive a particular load or device (such as the motor  1404  or transceiver  1408  of the rotor  120 ). 
     The transceiver  1408  of the rotor  120  may be configured to wirelessly receive motor control signals from the transceiver  1406  of the stator  110 . The transceiver  1408  may be configured to provide the motor control signals to the motor  1404 . The motor  1404  may be configured to drive the rotor blade(s)  124 ,  126 . The motor  1404  may be or include various types of motor  1404  designed or implemented to control the position of the rotor blade(s)  124 ,  126  For instance, the motor  1404  may be an Air-Core BM-BLDC motor. In other embodiments, the motor  1404  may be a stepper motor, a gear tooth servo actuator (e.g., remote controlled (RC)) motor, an Iron-Core PM-BLDC, or other type of motor. The motor  1404  may be configured to receive the motor control signals from the blade controller  1402  via the transceivers  1406 ,  1408 . The rotor  120  may include an encoder coupled to the motor  1404  and/or rotor blade(s)  124 ,  126  configured to detect a position of the motor  1404  and/or rotor blade(s)  124 ,  126 . The encoder may be configured to provide data corresponding to the position of the motor  1404 /rotor blade(s)  124 ,  126  to the blade controller  1402 , which the blade controller  1402  uses as feedback for adjusting the position of the rotor blade(s)  124 ,  126 . 
     References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms. References to at least one of a conjunctive list of terms may be construed as an inclusive OR to indicate any of a single, more than one, and all of the described terms. For example, a reference to “at least one of ‘A’ and ‘B’” can include only ‘A’, only ‘B’, as well as both ‘A’ and ‘B’. Such references used in conjunction with “comprising” or other open terminology can include additional items. 
     The construction and arrangement of the systems and methods as shown in the various exemplary embodiments are illustrative only. Although only example embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements can be reversed or otherwise varied and the nature or number of discrete elements or positions can be altered or varied. Accordingly, such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps can be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present disclosure. 
     The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions. 
     Although the figures show a specific order of method steps, the order of the steps may differ from what is depicted. Also two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.