Sensorless control system for epicyclic pedal assist vehicle

Abstract

A human-electric hybrid powertrain controller for a continuously variable transmission achieved with the use of an epicyclic gear set. The controller (56) makes use of relationships between the ratio motor (26), assist motor (28) and rider input to eliminate the need for expensive and complex rider torque sensors and rider cadence / speed sensors. The control of the two electric motors (26, 28) can produce smooth mixed rider and electric power in a variety of control schemes to suit various pedal assist vehicle applications.

Description

SENSORLESS CONTROL SYSTEM FOR EPICYCLIC PEDAL ASSIST VEHICLE Cross-reference to related application

[0001] This application claims priority to and the benefit of the earlier filing of U.S. Provisional Application No.63 / 457,603, filed on April 6, 2023, which is incorporated by reference herein in its entirety. Field of the invention

[0002] The present invention relates generally to the control of an electric pedal assist vehicle transmission utilizing an epicyclic, continuously variable transmission. Background

[0003] An electric pedal assist vehicle powertrain is a type of hybrid drive where power provided by an electric motor and power provided by a human are combined in an additive fashion to mobilize a vehicle. To achieve this power combination, fixed-ratio, epicyclic gear sets are sometimes used to step the speed of the motor down to match rider cadence. Examples of these drives include U.S. Patent No. 8,985,254 and U.S. Patent No. 8,652,000. Recently, variable ratio epicyclic gear sets using two motors have been proposed to provide rider assist and to provide an infinitely variable final drive gear ratio. Typically, to achieve smooth control of such variable ratio, epicyclic, two motor pedal assist drivetrain, the torque and cadence of the rider’s pedal input must be measured. Some examples found in prior art include U.S. Pub. No. 2022 / 0258832, U.S. Pub. No. 2022 / 0048595, U.S. Patent No. 11,352,097 and International Application No. WO 2022 / 017859. While measuring the torque of the rider’s pedal input creates a more pleasant ride experience, it adds complexity and cost to the epicyclic, continuously variable transmission. Summary

[0004] The invention may in various aspects relate to a control system, a sensorless control system, an electrically assisted pedal bicycle, a method of controlling a motors of an electrical pedal assist powertrain, a control system for an electric pedal assistpowertrain and / or an electrical pedal assist power train according to the claims or otherwise described herein.

[0005] Described herein is an electric pedal assist powertrain controller for a hybrid, pedal and electric motor vehicle. More specifically, the embodiments provided herein allow for the control of the ratio motor and assist motor in a continuously variable transmission system with pedal assist. The controller can smoothly and responsively control the ratio motor that sets the effective gear ratio. The ratio motor is connected to the epicyclic gear set. The controller provides coordinated control of the assist motor connected to the epicyclic output to augment power to the wheels of the pedal assist vehicle either through a driveshaft, belt, or a chain driveline. The continuously variable nature of the transmission is achieved through a variable ratio epicyclic gear train. The embodiments described herein may be used in any human powered vehicle with an epicyclic, continuously variable transmission that can utilize power assistance from an electric motor. The most common of those applicable vehicles is a bicycle for either on or off-road use. However, a pedal assist vehicle may also be a tricycle, recumbent, delivery vehicle, paddle boat, cycle rickshaw or other configuration of vehicle using pedal-based input as part of the power used to propel the vehicle enhanced by an electric assist to provide additional motive power most typically in the form of a rotary electric motor.

[0006] The drivetrain control system described herein beneficially may operate over a wider range of rider input, be less expensive and require fewer parts than existing control systems.

[0007] In certain embodiments, the speeds of the three primary epicyclic gears may be controlled by an electronic control system. The three primary gears are typically referred to as the sun gear, planet carrier, and ring gear in a planar planetary epicyclic gear set as well as in bevel differential epicyclic gear sets. Those skilled in the art will understand that the sun gear and ring gear in a bevel planetary gear set happen to be symmetrical and lacking the tight correlation to the sun and ring metaphor from which their names derive. The rider may provide input to the control system through their application of power at the pedals and possibly through their input of control selections in the user interface.

[0008] According to certain embodiments, the controller may control motors in a torque control mode and / or in a speed control mode. In various embodiments, the ratio motor connection, pedal connection, and assist motor connection may be connected to various primary epicyclic gears as the function of the three primary gears can overlap. As non- limiting examples, in one embodiment, the pedals may connect to the planet carrier, and in another embodiment, the pedals might connect to the sun gear. Various configurations for connections of the pedals, ratio motor, and assist motor are possible, which may include ancillary mechanical connection items such as: spur gears, worm gears, belts, etc. These mechanical configuration details may be accounted for in the mathematics calculating the rider torque and rider cadence using the ratio motor and assist motor torques and speeds. Such alternate embodiments do not deviate from the invention.

[0009] In various embodiments, the control scheme may switch the assist motor into regenerative braking. This may allow the ratio motor to operate over a wider range, which may allow the control system to support a wider range of rider cadences, or rotational velocity at the pedal inputs, a wider range of torque inputs, and / or a wider range of desired control set points, such as but not limited to an assist level. Negative assist power may also be used in certain embodiments to enable rider braking and / or to adhere to regulations surrounding the speeds of electric vehicles, among other considerations. In some embodiments, being able to adjust the assist motor into negative power application may allow the control scheme to offset power provided by the ratio motor to keep a balanced level of assist power over a wide range of effective gear ratios.

[0010] Various other benefits and advantages may be realized with the devices and methods provided herein, and the aforementioned advantages should not be considered limiting.

[0011] In an embodiment, a control system for a pedal vehicle comprises an epicyclic, continuously variable transmission, a rider pedal input, an assist motor and a ratio motor. The rider pedal input is mechanically connected to a first of primary epicyclic gears of the transmission; the assist motor is mechanically coupled to a second of primary epicyclic gears of the transmission; the ratio motor is mechanically connected to a third of primary epicyclic gears of the transmission; and the first, second and third of primary epicyclic gears of the transmission are different. The control system comprising a motorcontroller arranged to provide an assist motor-controller-output-signal to control said assist motor, and a ratio motor-controller-output-signal to control said ratio motor. The motor controller further being arranged to calculate a rider pedal input torque; and at least one of said assist motor-controller-output-signal and said ratio motor-controller-output- signal is responsive to said calculated rider pedal input torque.

[0012] In an embodiment the torque of said rider pedal input is not directly sensed by the motor controller. In an embodiment, the control system comprises an assist motor driver being electrically connected to control the assist motor in response to said assist motor-controller-output-signal, and the control system comprising a ratio motor driver being electrically connected to control the ratio motor in response to said ratio motor- controller-output-signal. In an embodiment the assist motor-controller-output-signal is responsive to calculated or sensed rider cadence. In an embodiment the motor controller is arranged to control the assist motor to a desired torque or power set point. In an embodiment the motor controller is arranged to calculate a set point of the assist motor as a percentage of the calculated rider torque or a calculated rider power; wherein the calculated rider power is the product of a rider cadence and the calculated rider torque; and wherein a calculated assist motor power is a product of an assist motor speed and an assist motor torque. In an embodiment the motor controller is arranged to receive a desired assist level or a desired gear ratio from a rider, such as a desired percentage of the calculated rider torque or calculated rider power to be supplied by the assist motor. In an embodiment the motor controller is arranged to ramp down the assist motor-controller- output-signal when the vehicle approaches a maximum allowed electrically assisted velocity. In an embodiment the motor controller is arranged to provide the assist motor- controller-output-signal as a function of a rider heart rate. In an embodiment the torque and / or speed of the assist motor and / or ratio motor is read from the assist motor driver and / or ratio motor driver, respectively. In an embodiment the ratio motor-controller- output-signal is responsive to calculated or sensed rider cadence. In an embodiment the motor controller is arranged to hold an effective gear ratio controlled by the ratio motor- controller-output-signal constant. In an embodiment the motor controller is arranged to achieve a larger range of the ratio motor-controller-output-signal by controlling negativepower to the assist motor to allow the ratio motor to be controlled at a desired speed and / or torque given a current rider cadence and torque.

[0013] In an embodiment the ratio motor-controller-output-signal is responsive to the calculated rider torque. In an embodiment the motor controller is arranged to control the ratio motor driver to a desired speed set point. In an embodiment the motor controller is arranged to calculate the assist motor-controller-output-signal as a function of at least ratio motor speed, ratio motor torque and assist motor speed; and optionally further a function of time. In an embodiment the motor controller is arranged to calculate the ratio motor-controller-output-signal as a function of at least assist motor speed, assist motor torque, and ratio motor torque. In an embodiment the epicyclic, continuously variable transmission is a bevel planetary gearset. In an embodiment the motor controller is arranged to control the assist motor driver to apply negative assist motor torque for slowing of the pedal vehicle. In an embodiment the motor controller is arranged to control the assist motor driver to divert generated energy from the application of negative assist motor torque to charge the battery. In an embodiment a connection from the epicyclic, continuously variable transmission to a drive wheel of the pedal vehicle is through one or more of a drive shaft, a belt, a chain. In an embodiment the pedal vehicle is a bicycle type pedal vehicle.

[0014] In an embodiment is provided a sensorless control system for an epicyclic pedal assist vehicle. In an embodiment the sensorless control system comprises any of the above control system embodiments. In an embodiment an electrically assisted pedal bicycle comprises the control system of any of the above.

[0015] In an embodiment a method of controlling a ratio motor and an assist motor of an electric pedal assist powertrain comprises determining a rider pedal input torque based on a speed and / or torque of the ratio motor and assist motor; receiving or determining input about a desired assist level or a desired gear ratio; determining one or more of torque, power or speed set points for the ratio motor and the assist motor based on the determined rider pedal torque and the received input about the desired assist level or desired gear ratio; and controlling the ratio motor and assist motor to achieve the determined torque, power or speed set points.

[0016] In an embodiment the determining the rider pedal input torque is not based on a torque sensor. In an embodiment the method further comprises determining or sensing a rider cadence, and wherein the determining one or more of torque, power or speed set points for the ratio motor and the assist motor is further based on rider cadence. In an embodiment the assist motor is controlled to a desired torque or power set point, and / or wherein the ratio motor is controlled to a desired speed set point. In an embodiment a set point of the assist motor is calculated as a percentage of the calculated rider torque or a calculated rider power; wherein the calculated rider power is the product of a rider cadence and the calculated rider torque; and wherein a calculated assist motor power is a product of an assist motor speed and an assist motor torque. In an embodiment the assist motor set point is ramped down when the vehicle approaches a maximum allowed electrically assisted velocity. In an embodiment the assist motor is further controlled in response to a rider heart rate.

[0017] In an embodiment the ratio motor is controlled to hold an effective gear ratio constant. In an embodiment a larger range of ratio motor control is achieved by controlling negative power to the assist motor to allow the ratio motor to be controlled at a desired speed and / or torque given a current rider cadence and torque. In an embodiment the assist motor is controlled as a function of at least ratio motor speed, ratio motor torque and assist motor speed; and optionally further as a function of time. In an embodiment the ratio motor is controlled as a function of at least assist motor speed, assist motor torque, and ratio motor torque. In an embodiment the electric pedal assist powertrain comprises an epicyclic, continuously variable transmission, preferably being a bevel planetary gearset. In an embodiment the assist motor is controlled to apply negative assist motor torque for slowing of the pedal vehicle. In an embodiment generated energy from the application of negative assist motor torque is diverted to charge the battery. In an embodiment the pedal vehicle is a bicycle type pedal vehicle.Brief description of the drawings

[0018] The principles of the embodiments described herein show the structure and operation of several examples used to illustrate the disclosure. It should be understood that the drawings are diagrammatic and schematic representations of such example embodiments and, accordingly, are not limiting the scope of the present invention, nor are the drawings necessarily drawn to scale.

[0019] FIG.1 illustrates a typical bicycle frame and the location of electric components for rider assistance.

[0020] FIG. 2 illustrates an electric pedal assist powertrain consisting of motors, gears and a driveshaft.

[0021] FIG. 3 illustrates another perspective of an electric pedal assist powertrain to highlight internal details.

[0022] FIG.4 illustrates a bevel planetary gearset which allows for one embodiment of a continuously variable transmission.

[0023] FIGS. 5-6 illustrate alternate embodiments of motors and their corresponding drives for an electric pedal assist powertrain.

[0024] FIG.7 illustrates the functional blocks of the control system of an embodiment.

[0025] FIG.8 illustrates schematically the mechanical connections of the primary pieces of the control system of an embodiment.

[0026] FIGS. 9-10 illustrate the mechanical configuration of the system analyzed mathematically.Detailed description

[0027] FIG. 1 illustrates an example of an electric pedal assist bicycle 10 (hereinafter “bicycle 10”) that generally includes a frame 12 with a bottom bracket 13, seat tube 14, down tube 18, and rear hub 16 with a driving wheel 15. An assist motor (not illustrated in FIG. 1 for simplicity of the figure) may be provided in or on various portions of the frame 12, such as but not limited to the bottom bracket 13 or rear hub 16. The electric pedal assist bicycle 10 may also have gear change systems at various locations, such as but not limited to the bottom bracket 13 or rear hub 16. Batteries and auxiliary electronics (not illustrated) may be located within the down tube 18 and / or other locations as desired.

[0028] FIGS. 2-4 illustrate an example of a hybrid electric pedal assist powertrain 20 (hereinafter “hybrid powertrain 20”) for a bicycle, such as the bicycle 10, according to embodiments. The hybrid powertrain 20 generally includes a bicycle crank 22, a bevel planetary gearset 24, a first motor 26, a second motor 28, a bevel gear drive 30, and a driveshaft 32. A control system 46 may be used with the hybrid powertrain 20 in certain embodiments and as discussed in detail below. In use, the hybrid powertrain 20 delivers power to the rear hub 16 and driving wheel 15 via the driveshaft 32. In an alternative embodiment, power transfer from the bevel gearset to the driving wheel may, instead of driveshaft 32, be provided more traditionally by a chainring and chain or belt, possibly via an additional planetary gearset to reverse the chain ring direction.

[0029] The bicycle crank 22 includes a shaft 34. Pedals and / or other features or devices may be supported on the bicycle crank 22 for a rider to engage and thereby provide human power into the hybrid powertrain 20 as desired. The particular bicycle crank 22 illustrated should not be considered limiting.

[0030] The first motor 26 and the second motor 28 may be various types of framed or frameless motors as desired. In FIGS. 2-4, the motors 26, 28 illustrated are frameless motors. FIGS.5-6, discussed in detail below, illustrate examples of framed motors. The motors, as well as electronics, may be powered by a rechargeable battery, for example placed in or on the down tube, seat tube, luggage rack. In certain embodiments, the second motor 28 is an assist motor for providing additional output power to the system, and the first motor 26 is a ratio motor adjusting the gear ratio between the second, assist motor28 and the bicycle crank 22 so the rider can maintain a comfortable cadence. As non- limiting examples of motors, in FIGS. 2-4, the first motor 26 may be a direct drive brushless DC torque motor with a position sensor, and the second motor 28 may be a direct drive brushless DC torque motor. In another embodiment, the second motor 28 may be converted into a servo motor with a position feedback device. Examples of position feedback devices for direct drive motors include, but are not limited to, optical ring encoders, ring Hall-effect encoders, inductive encoders, combinations thereof, and / or other types of position feedback devices as desired. In further embodiments, the motors 26, and 28 are brushed and may or may not be frameless.

[0031] The control system 46 includes a controller 56 and optionally includes an interface 58 and / or one or more sensors 60. The components of the control system 46 may be provided at various locations on the bicycle 10 as desired, and the particular locations illustrated should not be considered limiting. The controller 56 is operatively coupled through motor drivers to the motors 26, 28, and may be various types of controllers as desired. The controller 56 may include a processor and / or memory for controlling motors 26 and 28.

[0032] When included, the interface 58 may be on the controller 56 itself or may be a component separate and / or remote from the controller 56. The interface 58 may be various types of physical and / or virtual interfaces as desired for receiving input from the rider. The interface 58 may be provided at various locations as desired, and in one non- limiting example may be provided on or proximate to handlebars of the bicycle 10. There are many possible forms of physical user input control, including but not limited to, knobs, switches, levers, buttons, grip shifters, or dials. Such user control devices allow the user to set a desired control point or family of control points such as assist torque, rider heart rate, rider cadence, vehicle speed etc. In other embodiments, input may be provided to the controller 58 via various other techniques. As a non-limiting example, a user device, such as but not limited to phone, tablet, remote computing device, etc., may be communicatively coupled to the controller 56 (e.g., via wireless or wired communication), and the rider may provide input on the user device, which is in turn communicated to the controller 56.

[0033] In certain embodiments, the controller 56 is operatively coupled to the motors 26, 28, and may control one or both motors 26, 28 based on the input from the rider. In various embodiments, the controller 56 receives the input as data via wired or wireless signals from the interface 58 (or other source of input from the rider), and based on the received input, may modify and / or determine one or more set points for the motors 26, 28 and / or otherwise control the motors 26, 28. Such inputs may include, but are not limited to: actual heart rate, target heart rate, rider target power, rider target cadence, vehicle speed, percent assist level, and / or effective gear ratio, combinations thereof, and / or various other inputs as desired.

[0034] Optionally, the control system 46 includes one or more sensors 60. In such embodiments, the controller 56 may receive information from the sensors 60 via wired or wireless communication. In such embodiments, the controller 56 may control one or both motors 26, 28 based on the received information from the sensors (alone or in combination with the input from the rider). Non-limiting examples of sensors 60 include, but are not limited to, strain gauges, accelerometers, gyroscopes, motor speed, motor position, motor current, motor torque or combinations thereof, and / or other types of sensors or combinations of sensors for detecting or measuring other information related or relevant to operation of the hybrid powertrain 20.

[0035] In certain embodiments, the hybrid powertrain 20 with the control system 46 may determine, select, and / or otherwise control discrete gear ratios by utilizing the rider input and / or onboard sensors. The gear ratios can be customized by the rider, using the interface 58 or other suitable input device, prior to and / or during the use of the hybrid powertrain 20. The gear ratios may be selectable by the rider on the fly (e.g., in real time) utilizing the interface 58. The continuously variable transmission also provides the ability for the powertrain 20 to automatically change effective gear ratios to allow the rider to maintain a steady cadence regardless of the speed of the vehicle 10.

[0036] As illustrated in FIGS.3 and 4, the epicyclic bevel gear set 24 can include a bevel sun gear 36, one or more bevel planet gears 38, a planet carrier 40, and a bevel ring gear 42.

[0037] The bevel sun gear 36 may be centered on the bicycle crank 22 (e.g., on the shaft 34). In certain embodiments, a clutch 44 such as but not limited to a bearing (best illustrated in FIG. 3) acts as the mechanical linkage between the bevel sun gear 36 and the shaft 34. In one non-limiting embodiment, the clutch 44 is a one-way bearing clutch (e.g., configured to transmit torque between the sun gear 36 and the shaft 34 in one direction and allow free motion in the opposite direction), although in other embodiments, no clutch or other types of clutches may be utilized as desired. In various embodiments, the clutch 44 may beneficially disconnect the rider power at bicycle crank 22 from the bevel planetary gearset 24 to protect the rider in various situations. As a non-limiting example, the clutch 44 may disconnect the rider / bicycle crank 22 in the event the motors 26 and / or 28 cause the crank 22 to rotate faster than the rider cadence. Additionally, or alternatively, the clutch 44 beneficially may prevent the rider from back-driving the hybrid powertrain 20, which may confuse and / or otherwise cause issues with the control system 46.

[0038] The planet gears 38 of the bevel planetary gearset 24 are connected to the planet carrier 40 via mechanisms such as but not limited to pins 48. In the embodiment illustrated there are three planet gears 38. However, the number of planet gears 38 should not be limiting, and in other embodiments, any number of planet gears 38 may be used as desired, including less than three planet gears 38 or more than three planet gears 38. In various embodiments, the first motor 26 is attached and / or engaged with the planet carrier 40 (optionally affixed rigidly), although it need not be in other embodiments.

[0039] As best illustrated in FIGS. 3 and 4, similar to the bevel sun gear 36, the bevel ring gear 42 is connected to the crank 22. In certain embodiments, a bearing 50 (best illustrated in FIG.3) or other suitable devices or mechanisms connects the bevel ring gear 42 with the shaft 34. In one non-limiting embodiment, the bearing 50 is a ball bearing, although it need not be in other embodiments. The bevel ring gear 42 includes a first gear face 52 for engaging the planet gears 38 and a second gear face 54 for engaging the bevel gear drive 30. In certain embodiments, the bevel ring gear 42 is connected to the driveshaft 32 via the bevel gear drive 30, and as best illustrated in FIG.3, the bevel gear drive 30 engages the second gear face 54 of the bevel ring gear 42. In use, the planet carrier 40 rotates in the opposite direction of the sun gear 36, but in the same direction asthe bevel ring gear 42. Such rotation achieves the rotational direction of the driveshaft 32 required for the rear wheel to produce forward locomotion. The second motor 28 may be attached and / or engaged with the bevel ring gear 42.

[0040] The ratio motor 26 may modify the bevel planetary gearset 24 from a single speed gear train into a continuously variable transmission. The assist motor 28 may allow a steady state of output power to be provided to the rider. The ratio motor 26 may provide speed matching between the crank 22 and assist motor 28 so the rider can maintain a comfortable rider cadence and rider torque. If the speed of the ratio motor 26 is increased, the amount of assistance from the ratio motor increases, and the assist motor 28 may provide the difference.

[0041] In various embodiments, the epicyclic gear set can be the more common subtype, the planar planetary gear set, or of the bevel differential style, as well as others like stepped planet or meshed planet configurations. In certain embodiments, an “assist” for the pedal assist may be provided by an assist motor in the system to provide added power beyond what is added by the rider’s feet on the pedals, or hands in the case of hand cranked pedals, as the ratio motor alone may not provide a useful level of assist alone. In some embodiments, a “ratio” motor may be provided to set the effective gear ratio of the epicyclic gear set. The control system of this invention is largely concerned with the cooperative driving of these two motors to produce effective gear ratios between the pedals and the output wheel or drive wheel and the desired level of assist. The effective gear ratio being the ratio between the rider cadence rpm and drive wheel’s rpm as set by the ratio motor through the epicyclic gear set and any ancillary input and output gearing.

[0042] Cooperatively controlling and driving the ratio and assist motor also produces an appropriate amount of assist power with the assist motor. Typically, to provide power from the assist motor and to set the cadence with the ratio motor appropriately, the cadence or rotational speed of the rider at the pedals and the torque the rider provides need to be taken into account along with the rotational velocity of the drive wheel. See the sample calculations and control scheme examples for further explanation.

[0043] The drive wheel in a two, three or four wheeled pedal assist vehicle motion may provide motile power. For instance, the rear wheel on a bicycle would typically be thedrive wheel. However, the “drive wheel” may also be a propeller in a water based pedal assist vehicle. A tricycle or vehicle with more wheels, such as a pedal based delivery vehicle with four or more wheels, may have multiple drive wheels. So, in some embodiments “drive wheel” would refer to multiple wheels that provide motile power.

[0044] In certain embodiments, to provide assist power, it may be advantageous to know if the rider is pedaling and / or how hard they are pedaling. Rather than instrumenting the pedals or crank for torque sensing, the systems described herein may utilize the speed and torque of the ratio and assist motors to back calculate the speed and torque provided by the rider. Because the torque of a motor is highly correlated to the current draw of a motor, and because the speed of an electric motor is typically proportional to the voltage applied to a motor, inexpensive and simple instrumentation at the motor or motor driver, in conjunction with some mathematical calculations can be used in place of a sensor for the rider’s torque and rotational speed at the pedals.

[0045] In a traditional flat or planar planetary epicyclic gear set the three primary gear connections would be the sun gear, the planet gear carrier and the ring gear. In a bevel differential style epicyclic gear set, the primary gear connections would be the bevel sun gear, the bevel planetary gear, and the bevel ring gear. As such, the term “ring gear” can apply to epicyclic planar ring gears or epicyclic bevel ring gears. The term “sun gear” can apply to epicyclic planar sun gears or epicyclic bevel sun gears. The term “planet gear” or “planet gear carrier” can apply to epicyclic planar planet gears or epicyclic bevel planet gears. There are multiple ways to configure the planet gear or gears in an epicyclic gear set, some involving a carrier and some not. As such, the term planet gear and planet gear carrier may be interchangeable depending on the configuration of the planets and their carrier or lack thereof.

[0046] Various additional gears may be added or reconfigured around the primary epicyclic gear set, such as spur gears to better match motor properties or worm gears to handle shear forces. Such changes would alter constants in the mathematical analysis of an example embodiment presented here, but are details of matching the control system to the details of the mechanical layout and do not fall outside the spirit of the invention.

[0047] Embodiments with the hybrid powertrain 20 with the bevel planetary gearset 24 may provide an opportunity to optimize the gear ratio between the input and output of the driveshaft 32 for a bicycle, and / or for example allow it to comfortably fit in or be supported at the limited available space in the bottom bracket 13 area, but as mentioned, the disclosure herein also apply to other powertrain embodiments.

[0048] There are many international, national, and regional regulations surrounding the speed electric assist bicycles are allowed to transit at. In such cases, the hybrid powertrain 20 described herein may achieve a wide range of gear ratios without exceeding the speed limits imposed by regulations surrounding electric assist bicycles. To this end, in certain embodiments the control scheme described herein optionally may include a maximum allowed assist-able velocity which is the vehicle speed above which assist power from the assist motor may no longer be provided, such as for regulatory and / or safety concerns. In such optional examples, the vehicle may be operated above this speed using rider applied pedal power only. The assist motor may also apply negative output power to place a hard cap on overall vehicle speed. Negative power may be diverted to recharge the battery.

[0049] As non-limiting examples, the assist motor 28 of the hybrid powertrain 20 may not only provide additional assistance, but when the ratio motor 26 is providing too much power to achieve a certain gear ratio (and therefore a transit speed that is too high), the assist motor 28 may be used as a regenerative motor. In such an example, utilizing the assist motor 28 as a regenerative motor allows the hybrid powertrain 20 to achieve a wide range of gear ratios without exceeding the speed limits imposed by regulations surrounding electric assist bicycles.

[0050] FIGS.5 and 6 illustrate additional embodiments of a hybrid powertrain 520 that is substantially similar to the hybrid powertrain 20 except that the hybrid powertrain 520 includes framed motors 526 and 528 in place of frameless motors 26, 28. As best illustrated in FIG. 5, spur gears 562, 564 are used to transmit the motor power to the planet carrier 40 and bevel ring gear 42, respectively. As best illustrated in FIG. 6, replacing the spur gears 562, 564 with bevel gears 566 may allow a different orientation of the motors 526, 528. In further embodiments, chains and sprockets, belts and pulleys, and / or other features or mechanisms are used to transmit motor power to the planet carrier40 and / or the bevel ring gear 42. Framed motors might be used for either the ratio motor 526, assist motor 528, or both. These embodiments may be advantageous for the use of motors of lower torque and power to achieve the same bicycle speeds. The embodiments with framed motors may be combined with any of the configurations described herein relating to frameless motors, in particular with respect to configurations of power transfer from the bevel gearset to the driving wheel being driveshaft, chain or belt, and / or with respect to where the first motor is engaged being the planet carrier or the sun gear, and / or whether or not a secondary planetary gearset is provided between the bevel ring gear and the power transfer to the driving wheel.

[0051] The improvement of this patent applies to the control system of the pedal assist vehicle. In order to smoothly blend the power provided by the rider ^^^and the power provided by the assist motor ^^, traditionally a torque sensor, and often a rider pedal cadence sensor, are used. The torque sensor especially adds cost and complexity to the drivetrain of the pedal assist vehicle.

[0052] To avoid this added expense, one may use the motor controller driver’s position / speed sensing for the assist and ratio motors to compute the rider pedaling speed. In turn, use the desired gear ratio and the rider pedaling speed to compute a new target ratio motor speed. Use the target ratio motor speed as the input to a control loop, such as a PID control loop, to drive the ratio motor controller to achieve the new target speed.

[0053] The ratio motor input current is proportional to the load on the motor or the torque being supplied by the motor. Motor controllers, especially brushless motor controllers, have different ways to compute or measure the motor input current, either directly or inferred from quantities like the PWM duty cycle, the motor impedance, etc. The ratio motor input current may be used to approximate the ratio motor output torque. In epicyclic gear sets, the ratio motor torque is directly related to the rider pedaling torque in the non- limiting example calculation by the formula ^^^= −2^^^. The system then controls the assist motor torque based on the rider pedaling torque and the desired assist level and the current gear ratio. This may be implemented as direct torque assistance or by computing the rider pedaling power as torque multiplied by rider pedaling cadence (revolutions per second), and then providing power assistance.

[0054] Within the discipline of control theory, there are many possible ways to set up control of the process variables, assist motor torque, and ratio motor speed against their desired setpoints. These approaches include, but are not limited to: proportional integral (PI), proportional integral differential (PID), field oriented control (FOC), feed forward, Kalman, or even a predictive artificial intelligence (AI) model, are outside the scope of the invention. Regardless of the control approach used, rider torque and cadence may be utilized as inputs to these control schemes in order to update the set points for the assist motor torque control algorithm and ratio motor speed control algorithm. This invention discloses how to add these inputs into any of the aforementioned control schemes without the need for the complexity of a torque sensor on the rider pedal input or a speed sensor on the rider pedal input. The invention allows the replacement of the traditionally sensed rider torque and rider cadence which are directly sensed with costly dedicated sensors to provide the rider cadence and rider torque directly back to the motor controller, with calculated rider torque and calculated rider cadence which allows to indirectly but more cost effectively control the ratio and assist motors. By using calculated rider cadence and calculated rider torque derived from the assist motor and ratio motor speeds and torques, the complexity and cost of rider torque sensing and rider cadence sensing can be saved.

[0055] A non-limiting embodiment of the invention is provided below for illustrative purposes and to demonstrate sample calculations of rider torque and rider cadence. This embodiment should not be considered limiting. The configuration of the variable planetary bevel drive embodiment of the sample calculations below is: rider input pedal power / cranks connected to the middle planet / carrier, ratio motor connected to the non- drive side sun gear, assist motor connected to the drive side ring, and chainring output to the wheel connected to the drive side ring or ring gear output. See FIG.3, FIG.5, FIG.7 and FIG. 10. An example of mathematics to generate the calculated rider torque and a calculated rider cadence follow.Power relationships

[0056] Regarding the relationship between power at various positions in a configuration of an embodiment of the disclosure herein, the following may be defined: PRD = Rider Power (always positive) PRM = Ratio Motor Power (generally positive, but may be negative for gear ratios < 2.0) PO = Output Power Total (net of Assist Motor Power and Driveshaft Power) PA = Assist Motor Power (may be positive or negative) PCH= Chain Power (negative unless regenerative braking is added)

[0057] With the above, PRM + PRD + PO = 0 Eq.1

[0058] Further, PO = PA + PCH Eq.2

[0059] Combined, PRM + PRD + PA + PCH = 0 Eq.3

[0060] Further, in the form of Rotational Velocity ω and Torque τ, using the equation for power, ^ = ^^ Eq.4

[0061] Using the following definitions: ωRM = Ratio Motor Output Ring Rotational Velocity (negative = gear ratio > 2) ωRD= Rider Planet Carrier Rotational Velocity (positive = forward rider pedaling) ωO = Output Ring Rotational Velocity also Assist motor rotational velocity ωA (positive = forward vehicle motion) τRM = Ratio Motor Ring Torque τRD= Rider Planet Carrier Torque τO = Output Ring Torque τA= Assist Torque (at the output ring)τCH= Chain Torque (at the output ring) with all rotational velocities ω being positive when rotating clockwise when viewed from the right side of FIG.1.

[0062] The power equations may be transformed into:orSign relationships

[0063] The following relationships may exist between the signs of the torque and velocity parameters:Overall torque relationship

[0064] Regarding the overall torque relationships may be considered:

[0065] The sum of all torques equals zero:^^= −(^^^+ ^^^+ ^^^) Eq.10Power relationship between rider and output

[0066] Given: A = Assist (0 = none, 1 = 100%, 2 = 200%, etc.)

[0067] The target chain power is the negative of the input rider power times (1+A).Speed relationships

[0068] Given: GR= Gear ratio from rider ring to output ring

[0069] Defining theωRDas positive andωOas positive. TheωRMmay be zero forGRof 2.0, negative for GR> 2, positive for GR< 2.

[0070] Or

[0071] The output ring speed is the rider speed multiplied by the gear ratio:Eq.15

[0072] Using Eqs.13 and 15, is obtained:

[0074] Substituting Eq.13 and solving yields:

[0075] Below is a table with some sample values.Torque relationships

[0076] Starting from Eq.11 and rewriting it with respect to torques:^^^^^= −^^^^^^(1 + ^)

[0077] Substitute for ωOusing Eq.15. ^^^^^^^^= −^^^^^^(1 + ^)

[0078] Divide both sides by ωR.

[0079] Solve for τCH. ^^^ ^^^= −^^^^^Eq.17

[0080] Based on a free body analysis:

[0081] Or

[0082] Using the above result and Eq.7 yields the following: ^^^+ ^^^+ ^^= 0 Eq.7 (repeated)

[0083] The following steps compute the assist torque from the speed motor torque. ^^^+ ^^^+ ^^+ ^^^= 0 Eq.9 (repeated)

[0084] Substitute Eq.17 ^^^ ^^^+ ^^^+ ^^− ^^^^^= 0 Eq.20

[0085] Simplify and combine terms:

[0086] Substitute ^^^for ^^^from Eq.18

[0087] Simplify

[0088] Solve for ^^:

[0089] Below is a table with some sample values. The power values use ^^^= 1.0.

[0090]

[0091] As the assist motor or rider load (i.e., incline or other outside loading) changes, this change directly affects the rider load. The feedback between the rider load and the output and is represented by ^^^= −2^^^, and may be the direct feedback to the control motor. In certain embodiments, a sudden output load application may cause both the rider ring and the control motor to slow down. ^^= ^^+ ^^^Eq.8 (repeated)

[0092] In some embodiments, to have a responsive set point for the control system responding to the calculated rider torque, the set point may be dynamic. However, it is not necessary that both set points within the control scheme be dynamic. As an example,the target ratio motor speed and / or the target assist motor torque motor-controller-output- signal may be held constant by applying a user input through a control interface while the other motor-controller-output-signal may be dynamic and responsive to calculated rider torque. In certain embodiments, when an effective gear ratio set point is used as the target of the ratio motor-controller-output-signal by a value in firmware or a value set by user input, the effective gear ratio may be held constant and remain fixed over the full range of rider input cadences and torques to give a constant effective gear ratio as the vehicle speed changes. To be responsive to rider generated torque or cadence means the rider torque and / or cadence affects the ratio motor-controller-output-signal and or assist motor- controller-output-signal.

[0093] In various embodiments, when a constant multiplier of rider assist power or torque is selected the ratio of the pedal input power or torque may be held constant by the assist motor-controller-output-signal over the full range of rider torques and rider cadences. These control schemes may have the ratio or assist motor-controller-output- signal or both motor-controller-output-signals responsive to rider torque as a ratio is held constant against rider input torque, power, or cadence. The calculated rider torque and rider cadence values may be used in a variety of ways to provide input into assist motor and ratio motor control.

[0094] In some embodiments, the torque of the assist motor, ^^, may be controlled to follow the torque provided to the system by the rider, ^^, multiplied by a simple gain factor, A, for determining the level of assist as a percentage of the rider torque. ^^= ^^*A. This type of ‘percentage assist’ may allow for the assist power to be in sync with the rider’s natural, and variable, pedaling torque.

[0095] The ratio motor-controller-output-signal then might not be a function of calculated rider torque because the assist motor torque is a function of the calculated rider torque. In this case, the effective gear ratio experienced by the rider may be set by the vehicle speed: GR = S * m + f, where ^^is gear ratio, S = vehicle speed, m = slope, and f = offset. Time-domain filtering may be added for a smooth response. In this way, when the vehicle speeds up, the gear ratio increases.

[0096] Or, one can control the gear ratio by the rider pedaling torque: ^^= ^^* m + f, where ^^is gear ratio, ^^= rider torque, m = slope, and f = offset. Again time-domain filtering may be added for a smooth response. As the rider pedals harder (as in climbing a hill or trying to accelerate), the gear ratio is reduced.

[0097] In another embodiment, the gear ratio ^^may be set by the rider cadence ^^^: ^^= ^^^* m + f, where ^^is gear ratio, ^^^: = rider pedaling cadence, m = slope, and f = offset. Time-domain filtering can be added for a smoother response. In this embodiment of the control scheme, as the cadence increases, the gear ratio increases.

[0098] Another control scheme may set the gear ratio by the rider cadence by using a control loop (PID or other) to try to maintain a steady cadence at the rider’s desired preset value.

[0099] A different embodiment may control the gear ratio and or the assist power based on the rider’s heart rate. This would not be used alone but in combination with one or more of the other mechanisms such as torque. For instance, the ratio motor may continue to upshift the gear ratio once a target cadence set point had been reached, until a target heart rate is reached. If the target heart rate is exceeded, the effective gear ratio may be reduced. Additionally, the assist motor torque may be ramped up from a nominal multiple of the rider provided torque, to a higher multiple of rider provided torque as the target heart rate was approached until the maximum allowed assist-able velocity for vehicles under electric assist were approached. At which point the assist level would taper down just before reaching the maximum allowed assist-able velocity.

[0100] The control system may also be set to operate between a pair of inter-related assist motor torque and ratio motor speed set points. The set point pair may be adjusted between a casual and sport end of a selection range. The target cadence can be based on the rider’s input torque or power. For low input torque or power, a low target cadence set point may be used (relaxed ride). For higher rider torque or power input, the control system would select a higher target cadence set point for a sport workout.

[0101] The control system scheme may maintain a fixed gear ratio over vehicle speed and a fixed percent of rider torque assist which tapers off as the maximum assist-able velocity is reached. In this embodiment the motor-control-output-signal sent through themotor driver to the assist motor to set the torque set point might be set as ^^= 2^^^if the rider torque ^^^has not changed more than 20% in the last three seconds and the vehicle velocity is less than 0.9*(maximum assist-able velocity). If the rider torque has changed more than 20% in the last three seconds, the control scheme would not change the torque setpoint for the assist motor controller algorithm. If the vehicle velocity V is greater than ninety percent of the maximum assist-able velocity, ^^^, it could be considered to taper the assist using the equation ^^= 10 ∗ (^^^− ^) ∗ 2^^^unless V is greater than ^^^in which case ^^would be set to zero.

[0102] In this way, the assist level, set at twice the rider input torque does not fluctuate unless the new rider torque has been relatively constant for three seconds. The level of the assist stays at a fixed percentage, 200%, of the rider torque until the vehicle gets close to the maximum assist-able speed at which point the assist tapers down to zero.

[0103] The speed of the ratio motor may maintain a fixed effective gear ratio ^^by causing the speed of the ratio motor ^^^to be controlled by the ratio motor control algorithm using the formula ^^^= ^^^(2 − ^^). For an effective gear ratio constant of say, 0.5 the set point for the ratio motor speed would be computed as ^^^= 1.5^^^.

[0104] Other control schemes such as one in which heart rate is used as a target and assist is only added as the rider gets closer to the heart rate target may also be used.

[0105] In other embodiments, an offset term, multiplier, or other adjustment based on the user control may be added. For example, if the user selects a lower gear ratio, the control scheme may do one or more of the following: 1. Change the slope or offset of any of the equations to make it easier to pedal (lower ratio) given the same inputs. 2. Adjust the target rider cadence to a higher value. 3. Adjust the target heart rate to a lower value. 4. Modify the motor-controller-output-signal for torque control so that it only affects the gear ratio if the rider provided torque exceeds a preset level.

[0106] The control scheme may use the opposites of the above actions to provide a higher effective gear ratio. Any of the above approaches may be modified to include logicthat prevents lowering the gear ratio if the pedaling cadence is already high. This may be a hard limit or a factor that phases in gradually as the cadence approaches an upper acceptable limit.

[0107] The specific control system of this invention can be viewed in multiple parts. See FIGS. 7 and 8. The possible control scheme logic described herein is run on a motor controller, but may be implemented on various other processing devices and / or controllers as desired. The motor controller has at least one microprocessor capable of calculating the calculated rider torque and applying that calculated rider torque as an input to influence the control algorithms. The control algorithms control around the set points prescribed by the motor controller operating within the overall control scheme.

[0108] The microprocessor may then generate motor-controller-output-signals that are sent from the motor controller to the various motor drivers. At least two of the motor drivers may control around the set point of the assist motor and the ratio motor. These signals may be digital or analog. The motor-controller-output-signals can include signals and commands in addition to those required to set the desired torque or speed set point. The motor drivers under the control of the motor controller receive these motor- controller-output-signals and respond by electrically driving the motors by altering the voltages, currents, duty cycles, and / or frequency of the electrical power to the motors. The motor-controller-output-signals may also specify the direction of motor rotation and the domain of the motor such as speed based control or torque based control.

[0109] The motor controller may dictate higher level commands such as speed or torque set points to the motor driver, or the motor controller may dictate lower level commands such as certain currents, voltages or PWM duty cycles or frequencies. The microprocessor of the motor controller may use algorithms such as: field oriented control (FOC), proportional integral derivative (PID), proportional integral (PI), Kalman, or feed forward in the overall control scheme. Because practicing the invention involves control of at least two motors in concert, it may be advantageous to use different algorithms for the set- point of each motor within the overall control scheme. Additional motors optionally may be used in parallel where the more common and simpler single ratio motor and single assist motor embodiments are described. Current control - controls the motor current (ideally only the component of current that provides torque) to the motor andconsequently the torque, it provides torque control (force) but does not limit or attempt to control the speed. Duty cycle control - controls the duty cycle (voltage) to the motor and consequently the speed, it gives rough speed control (velocity) but does not control the current (the maximum set motor current may be used to accelerate or decelerate the motor to the commanded duty cycle). The motor driver may not increase the duty cycle to maintain the same speed when under heavy load. Different control schemes may generate set points and different control algorithms can control around those set points as such techniques are known in the art. These techniques may be used alongside the novel improvement of using calculated rider torque or calculated rider cadence in the generation of these target set points or desired set points which the control scheme adjusts for the various control algorithms to take as target set point.

[0110] The power electronics in the motor drivers which supply the dynamic electrical drive to the motors may be transistors arranged into an H-Bridge, although they need not be in other embodiments. Other methods may be used in the motor driver to electrically drive the motor. The power connections between the motors and motor drivers are in contrast to the signal level connections between the motor controller microprocessor and the motor drivers. Additionally the motor drivers may contain within their circuitry a method to sense the motor current, such as a burden resistor or a hall effect sensor so that motor current, which corresponds to motor torque, can be reported back to the motor controller.

[0111] In this way the torque and or speed of the motor can be read from the motor driver. The torque or speed of either motor can also be assumed. If a target is set, often one may assume the desired set point is reached. However, even if it is assumed the ratio motor speed set point has been reached, the torque value that corresponds to getting the ratio motor up to the set point speed may need to be read out. The desired speed set point for the ratio motor and desired torque set point for the assist motor may change in response to changing rider torque and cadence and potentially other variables such as heart rate or user interface control parameter adjustments depending on the overall control scheme.

[0112] It may be necessary to read back the speed achieved when the assist motor is set to a certain torque set point even if the torque value is assumed and not read back. Torqueand speed of the assist and ratio motors may be assumed, read back, or sensed with a sensor. A sensor may be mounted on the motor driver, or on the motor itself.

[0113] Rider cadence and rider torque are calculated from the speed and torque values of the ratio motor and assist motor. Sample calculations on one embodiment allow to determine rider cadence as ^^^= (^^^+ ^^) / 2 and rider torque from ^^^= −2^^^. The speed and torque of the ratio motor and assist motor may be read back from the motor drivers under the assumption that the desired speed or torque was met by the motor when commanded by the motor driver, or a separate speed and or torque sensor can be used to read the speed and or torque of the ratio motor and assist motor. It is easier and less expensive to instrument the motors used on the drivetrain, than it is to instrument the pedals or crankshaft that provide work input from the rider into the epicyclic drive.

[0114] The motor controller and motor driver discussed in this invention are functional blocks and may exist on separate circuit boards or on the same circuit board and may share the same microprocessor for their intelligence or use separate microprocessors. The above-described aspects are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Many variations and modifications may be made to the above-described embodiments without departing substantially from the spirit and principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure. Moreover, although specific terms are employed herein, as well as in the claims that follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described embodiments, nor the claims that follow.

[0115] Example 1: A control system for a continuously variable transmission, which obviates the need for direct sensing of rider torque, comprising: a motor controller providing motor-controller-output-signals to an assist motor driver and to a ratio motor driver within an epicyclic, continuously variable transmission of a pedal vehicle; a rider pedal input mechanically connected to one of the primary epicyclic gears, said primary gear not being connected to the ratio or assist motors, the torque of said rider pedal input being not directly sensed by the motor controller; a ratio motor driver electricallyconnected to a ratio motor, the ratio motor driver being under the control of the motor controller; a ratio motor electrically driven by the ratio motor driver, said ratio motor being mechanically coupled to one of the three primary epicyclic gears of the epicyclic gear set exclusive of the primary epicyclic gears connected to the assist motor and rider pedal input; an assist motor driver electrically connected to an assist motor, the assist motor driver being under the control of the motor controller; an assist motor electrically driven by the assist motor driver, said assist motor being mechanically coupled to one of the three primary epicyclic gears of the epicyclic gear set exclusive of the epicyclic gears connected to the ratio motor and rider pedal input; and a motor-controller-output-signal controlling an assist motor through an assist motor driver and a motor-controller-output- signal controlling a ratio motor through a ratio motor driver where at least one of the said motor-controller-output-signals is responsive to calculated rider torque.

[0116] Example 2: Example 1 wherein the assist motor-controller-output-signal is responsive to calculated rider cadence. Example 3: Example 1 wherein the assist motor- controller-output-signal is responsive to sensed rider cadence.

[0117] Example 4: Example 1 wherein the assist motor driver is controlled to a desired torque or power set point. Example 5: Example 4 wherein the set point of the assist motor is calculated as a percentage of calculated rider torque or power, calculated rider power being the product of calculated rider cadence and calculated rider torque and calculated assist motor power being the product of the assist motor speed and assist motor torque. Example 6: Example 5 wherein the percentage of calculated rider power to be supplied by the assist motor is selected by a user input control.

[0118] Example 7: Example 4 wherein the assist motor-controller-output-signal ramps down as the vehicle approaches the maximum allowed assist-able velocity. Example 8: Example 4 wherein the assist motor-controller-output-signal is a function of rider heart rate. Example 9: Example 4 wherein the torque and or speed of the assist motor is read from the assist motor driver. Example 10: Example 4 wherein the torque and or speed of the ratio motor is read from the ratio motor driver.

[0119] Example 11: Example 1 wherein the ratio motor-controller-output-signal is responsive to calculated rider cadence. Example 12: Example 11 wherein the effectivegear ratio set by the ratio motor-controller-output-signal is held constant. Example 13: Example 11 wherein a larger range of the ratio motor-controller-output-signal is achieved by applying negative power to the assist motor to allow the ratio motor to be controlled at the desired speed and torque given the current rider cadence / speed and torque.

[0120] Example 14: Example 1 wherein the ratio motor-controller-output-signal is responsive to calculated rider torque. Example 15: Example 1 wherein the ratio motor- controller-output-signal is responsive to sensed rider cadence. Example 16: Example 1 wherein the ratio motor driver is controlled to a desired speed set point. Example 17: Example 1 wherein the assist motor-controller-output-signal is calculated as a function of at least ratio motor speed, ratio motor torque and assist motor speed. Example 18: Example 17 wherein the assist motor-controller-output-signal is also a function of time.

[0121] Example 19: Example 1 wherein the ratio motor-controller-output-signal is calculated as a function of at least assist motor speed, assist motor torque, and ratio motor torque. Example 20: Example 1 wherein the epicyclic, continuously variable transmission is a bevel planetary gearset. Example 21: Example 1 wherein the assist motor controller can control the assist motor driver to apply negative assist motor torque for slowing of the pedal vehicle. Example 22: Example 21 wherein the assist motor driver can divert generated energy from the application of negative assist motor torque to charge the battery. Example 23: Example 1 wherein the connection to the drive wheel is through a shaft. Example 24: Example 1 wherein the connection to the drive wheel is through a belt. Example 25: Example 1 wherein the connection to the drive wheel is through a chain. Example 26: Example 1 applied to a bicycle type pedal vehicle. Example 27: A sensorless control system for an epicyclic pedal assist vehicle.

[0122] Example 28: A method of controlling ratio and assist motors of an electric pedal assist powertrain, the method comprising: a) determining an input speed and / or torque provided by a rider based on a speed and / or torque of the ratio and assist motors; b) receiving (or determining) input about a desired assist level (or gear ratio); c) determining a target speed for the ratio and assist motors based on the determined input speed and / or torque provided by the rider and the received input about the desired assist level; and d) controlling the ratio and assist motors to achieve the target speed.

[0123] Example 29: A control system for an electric pedal assist powertrain, the control system comprising: a) a processor adapted to receive input information from a rider about a desired assist level and adapted to receive information about speed and / or torque of ratio and assist motors; and b) a memory coupled by the processor, the memory comprising instructions executable by the processor to: i) determine an input speed and / or torque provided by the rider based on the received information about speed and / or torque of ratio and assist motors; ii) determine a target speed for the ratio and assist motors based on (1) the determined input speed and / or torque and (2) input information about desired assist level from the rider; and iii) generate a control signal based on the determined target speed for controlling the ratio and assist motors.

[0124] Example 30: An electric pedal assist powertrain comprising: a) a ratio motor; b) an assist motor; and c) a controller, the controller configured to: i) receive (or determine) input about a desired assist level (or gear ratio) and receive (or determine) a speed and / or torque of the ratio assist motors; ii) determine an input speed and / or torque provided by a rider based on the speed and / or torque of the ratio and assist motors; iii) determine a target speed for the ratio and assist motors based on the determined input speed and / or torque provided by the rider and the received input about the desired assist level; and iv) control the ratio and assist motors to achieve the target speed.

[0125] The subject matter of embodiments is described herein with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described. Directional references such as “up,” “down,” “top,” “bottom,” “left,” “right,” “front,” and “back,” among others, are intended to refer to the orientation as illustrated and described in the figure (or figures) to which the components and directions are referencing. All ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, allsubranges beginning with a minimum value of 1 or more, e.g.1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10.

[0126] The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, or gradients thereof, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention, and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0127] The above-described aspects are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Many variations and modifications can be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure. Moreover, although specific terms are employed herein, as well as in the claims that follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described embodiments, nor the claims that follow.Reference numbers 10, 12 Bicycle, Frame 13, 14 Bottom bracket, Seat tube 15, 16 Driving wheel, Rear hub 18 Down tube 20 Hybrid powertrain 22 Crank 24 Bevel planetary gearset 26 First motor, ratio motor 28 Second motor, assist motor 30 Bevel gear drive of driveshaft 32 32 Driveshaft 34 Crank shaft of crank 22 36 Bevel sun gear of gearset 24 38 Bevel planetary gears of gearset 24 40 Planet carrier of gearset 24 42 Bevel ring gear of gearset 24 44 Clutch 46 Control system 48 Pins connecting planets 38 to carrier 40 50 Bearing for ring gear 42 52 First gear face of ring gear 42 54 Second gear face of ring gear 42 56, 58, 60 Controller, Interface, Sensors 520 Hybrid powertrain 526 First framed motor, ratio motor 528 Second framed motor, assist motor 562, 564 Spur gears 566 Bevel gears

Claims

Claims 1. A control system for a pedal vehicle comprising an epicyclic, continuously variable transmission, a rider pedal input, an assist motor and a ratio motor; wherein the rider pedal input is mechanically connected to a first of primary epicyclic gears of the transmission; wherein the assist motor is mechanically coupled to a second of primary epicyclic gears of the transmission; wherein the ratio motor is mechanically connected to a third of primary epicyclic gears of the transmission; and wherein the first, second and third of primary epicyclic gears of the transmission are different; the control system comprising a motor controller arranged to provide an assist motor-controller-output-signal to control said assist motor, and a ratio motor-controller-output-signal to control said ratio motor; the motor controller further being arranged to calculate a rider pedal input torque; wherein at least one of said assist motor-controller-output-signal and said ratio motor-controller-output-signal is responsive to said calculated rider pedal input torque.

2. The control system of claim 1, wherein the torque of said rider pedal input is not directly sensed by the motor controller.

3. The control system of claim 1 or 2, comprising an assist motor driver being electrically connected to control the assist motor in response to said assist motor-controller-output- signal, and the control system comprising a ratio motor driver being electrically connected to control the ratio motor in response to said ratio motor-controller-output- signal.

4. The control system of any one of claims 1 to 3, wherein the assist motor-controller- output-signal is responsive to calculated or sensed rider cadence.

5. The control system of any one of claims 1 to 4, wherein the motor controller is arranged to control the assist motor to a desired torque or power set point.

6. The control system of any one of claims 1 to 5, wherein the motor controller is arranged to calculate a set point of the assist motor as a percentage of the calculated rider torque or a calculated rider power; wherein the calculated rider power is the product of a ridercadence and the calculated rider torque; and wherein a calculated assist motor power is a product of an assist motor speed and an assist motor torque.

7. The control system of any one of the claims 1 to 6, wherein the motor controller is arranged to receive a desired assist level or a desired gear ratio from a rider, such as a desired percentage of the calculated rider torque or calculated rider power to be supplied by the assist motor.

8. The control system of any one of the claims 1 to 7, wherein the motor controller is arranged to ramp down the assist motor-controller-output-signal when the vehicle approaches a maximum allowed electrically assisted velocity.

9. The control system of any one of the claims 1 to 8, wherein the motor controller is arranged to provide the assist motor-controller-output-signal as a function of a rider heart rate.

10. The control system of any one of the claims 1 to 9, wherein the torque and / or speed of the assist motor and / or ratio motor is read from the assist motor driver and / or ratio motor driver, respectively.

11. The control system of any one of the claims 1 to 10, wherein the ratio motor- controller-output-signal is responsive to calculated or sensed rider cadence.

12. The control system of any one of the claims 1 to 11, wherein the motor controller is arranged to hold an effective gear ratio controlled by the ratio motor-controller-output- signal constant.

13. The control system of any one of the claims 1 to 12, wherein the motor controller is arranged to achieve a larger range of the ratio motor-controller-output-signal by controlling negative power to the assist motor to allow the ratio motor to be controlled at a desired speed and / or torque given a current rider cadence and torque.

14. The control system of any one of the claims 1 to 13, wherein the ratio motor- controller-output-signal is responsive to the calculated rider torque.

15. The control system of any one of the claims 1 to 14, wherein the motor controller is arranged to control the ratio motor driver to a desired speed set point.

16. The control system of any one of the claims 1 to 15, wherein the motor controller is arranged to calculate the assist motor-controller-output-signal as a function of at least ratio motor speed, ratio motor torque and assist motor speed; and optionally further a function of time.

17. The control system of any one of the claims 1 to 16, wherein the motor controller is arranged to calculate the ratio motor-controller-output-signal as a function of at least assist motor speed, assist motor torque, and ratio motor torque.

18. The control system of any one of the claims 1 to 17, wherein the epicyclic, continuously variable transmission is a bevel planetary gearset.

19. The control system of any one of the claims 1 to 18, wherein the motor controller is arranged to control the assist motor driver to apply negative assist motor torque for slowing of the pedal vehicle.

20. The control system of any one of the claims 1 to 19, wherein the motor controller is arranged to control the assist motor driver to divert generated energy from the application of negative assist motor torque to charge the battery.

21. The control system of any one of the claims 1 to 20, wherein a connection from the epicyclic, continuously variable transmission to a drive wheel of the pedal vehicle is through one or more of a drive shaft, a belt, a chain.

22. The control system of any one of the claims 1 to 21, wherein the pedal vehicle is a bicycle type pedal vehicle.

23. A sensorless control system for an epicyclic pedal assist vehicle.

24. The sensorless control system of claim 23, comprising the control system of any of the claims 1 to 22.

25. An electrically assisted pedal bicycle comprising the control system of any of the claims 1 to 24.

26. A method of controlling a ratio motor and an assist motor of an electric pedal assist powertrain, the method comprising: determining a rider pedal input torque based on a speed and / or torque of the ratio motor and assist motor; receiving or determining input about a desired assist level or a desired gear ratio; determining one or more of torque, power or speed set points for the ratio motor and the assist motor based on the determined rider pedal torque and the received input about the desired assist level or desired gear ratio; and controlling the ratio motor and assist motor to achieve the determined torque, power or speed set points.

27. The method of claim 26, wherein the determining the rider pedal input torque is not based on a torque sensor.

28. The method of claim 26 or 27, wherein the method further comprises determining or sensing a rider cadence, and wherein the determining one or more of torque, power or speed set points for the ratio motor and the assist motor is further based on rider cadence.

29. The method of any one of claims 26 to 28, wherein the assist motor is controlled to a desired torque or power set point, and / or wherein the ratio motor is controlled to a desired speed set point.

30. The method of any one of claims 26 to 29, wherein a set point of the assist motor is calculated as a percentage of the calculated rider torque or a calculated rider power; wherein the calculated rider power is the product of a rider cadence and the calculated rider torque; and wherein a calculated assist motor power is a product of an assist motor speed and an assist motor torque.

31. The method of any one of claims 26 to 30, wherein the assist motor set point is ramped down when the vehicle approaches a maximum allowed electrically assisted velocity.

32. The method of any one of claims 26 to 31, wherein the assist motor is further controlled in response to a rider heart rate.

33. The method of any one of claims 26 to 32, wherein the ratio motor is controlled to hold an effective gear ratio constant.

34. The method of any one of claims 26 to 33, wherein a larger range of ratio motor control is achieved by controlling negative power to the assist motor to allow the ratio motor to be controlled at a desired speed and / or torque given a current rider cadence and torque.

35. The method of any one of claims 26 to 34, wherein the assist motor is controlled as a function of at least ratio motor speed, ratio motor torque and assist motor speed; and optionally further as a function of time.

36. The method of any one of claims 26 to 35, wherein the ratio motor is controlled as a function of at least assist motor speed, assist motor torque, and ratio motor torque.

37. The method of any one of claims 26 to 36, wherein the electric pedal assist powertrain comprises an epicyclic, continuously variable transmission, preferably being a bevel planetary gearset.

38. The method of any one of claims 26 to 37, wherein the assist motor is controlled to apply negative assist motor torque for slowing of the pedal vehicle.

39. The method of any one of claims 26 to 38, wherein generated energy from the application of negative assist motor torque is diverted to charge the battery.

40. The method of any one of claims 26 to 39, wherein the pedal vehicle is a bicycle type pedal vehicle.

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