HK1165380A - Automatic transmissions and methods therefor - Google Patents

Description

Automatic transmission and method therefor

Cross reference to related applications

This application protects the benefit of U.S. provisional patent application No.61/016,305, filed on 21/12/2007, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates generally to mechanical transmissions and, more particularly, to automatic transmissions and methods of controlling the same.

Background

Automatic transmissions are found in a variety of machines. However, in certain fields, manually operated transmissions are still common. For example, in the bicycle industry, most bicycles are configured to manually operate the transmission, which typically involves manually actuating a pull rod, cable and link (linkage) such that the chain moves from one rear sprocket to another. However, a need has arisen for a system and corresponding method that facilitates automatic control of a bicycle transmission.

The innovative embodiments disclosed herein address this need by providing a system and method of automatically controlling a transmission that is particularly suited in some instances for human powered vehicles such as bicycles.

Disclosure of Invention

The systems and methods described herein have several features, no single one of which is solely responsible for all desirable attributes. Without limiting the scope represented by the appended claims, the more prominent features of certain embodiments of the invention will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "detailed description of certain embodiments" one will understand how the features of the system and method provide several advantages over related conventional systems and methods.

In one aspect, the present invention is directed to a method of automatically controlling a ball-and-planet transmission of a bicycle. The method involves: receiving an input associated with a target user pedaling speed; determining a bicycle speed; and determining a target gear ratio based at least in part on the target user pedaling speed and the determined bicycle speed. The method may further include adjusting a gear ratio of the transmission to be substantially equal to the target gear ratio. In one embodiment, the method further comprises the step of determining an encoder position associated with the target user pedaling speed. In another embodiment, adjusting the gear ratio includes commanding the actuator to move to the determined encoder position. In yet another embodiment, adjusting the shift lever includes the step of rotating the shift lever about a longitudinal axis of the transmission.

In another aspect, the present invention is directed to a method of automatically controlling a ball-and-planet transmission of a bicycle. The method comprises the following steps: receiving an input associated with a target user pedaling speed; determining a bicycle speed; and adjusting a speed ratio of the bicycle based on the target user pedaling speed and the determined bicycle speed so as to maintain the user pedaling speed within a band of the target user pedaling speed. In some embodiments, the band is the target user pedaling speed plus or minus 10 revolutions per minute (rpm). In other embodiments, the band is in the range of +/-2rpm to about +/-5rpm of the target user pedaling speed. In one embodiment, adjusting the speed ratio of the bicycle comprises the step of determining an encoder position associated with the target user pedaling speed and the determined bicycle speed. In some embodiments, adjusting the speed ratio of the bicycle includes the step of commanding the actuator to move to the determined encoder position. In other embodiments, adjusting the speed ratio of the bicycle includes the step of adjusting a shift lever of the transmission. In other embodiments, adjusting the shift lever includes the step of rotating the shift lever about a longitudinal axis of the transmission.

Yet another aspect of the present invention relates to a method of automatically controlling a ball-and-planet transmission of a bicycle. The method involves: providing an input associated with a target user pedaling speed; determining a bicycle speed; and identifying a target encoder position associated with the bicycle speed. The method may further comprise actuating the servo system to obtain the target encoder position. In one embodiment, actuating the servo comprises the step of adjusting a shift lever of the transmission. In some implementations, identifying the target encoder position includes generating a data structure. In other embodiments, generating the data structure includes the step of recording the encoder position. In one embodiment, generating the data structure includes the steps of recording an input speed and recording an output speed. In some embodiments, the method includes the step of determining a speed ratio based at least in part on the input speed and the output speed. In other embodiments, the method includes the step of recording the velocity ratio.

In one aspect, the present invention is directed to a system for automatically switching a ball-planetary bicycle transmission. The system comprises: a speed sensor configured to detect a speed of the bicycle; a processor configured to receive input from a speed sensor; and a data input interface configured to provide cadence data to the processor, the cadence data being indicative of a desired constant input pedaling speed. The system may additionally have a memory in communication with the processor having one or more maps storing thereon a bicycle speed to a speed ratio. In one embodiment, the system includes a logic module in communication with the processor, the logic module configured to cooperate with the processor to determine a target speed ratio from the map based on the bicycle speed and a desired constant input pedaling speed. In some embodiments, the system has an actuator in communication with the processor, the actuator configured to adjust a speed ratio of the transmission to be substantially equal to the determined target speed ratio. In one embodiment, the control unit includes at least one of a processor, an application specific integrated circuit, or a programmable logic array. The actuator is operably coupled to a shift lever of the transmission that is configured to adjust a speed ratio of the transmission. The data input interface may include a display and at least one button. The system may include a position sensor configured to provide an indication of the position of the actuator. The data structures may include a speed ratio data structure and a bicycle speed data structure. The system may have a power source configured to provide power to the actuator. In one embodiment, the power source is a generator. In some embodiments, the actuator is operably coupled to a shift lever of the transmission.

Another aspect of the present invention is directed to a bicycle having a ball-and-planet transmission and a system for automatically shifting the ball-and-planet transmission. In one embodiment, the system has a speed sensor configured to detect a speed of the bicycle. The system has a processor configured to receive input from the speed sensor. In some embodiments, the system includes a data input interface configured to provide cadence data to the processor. Cadence data indicates a desired constant input pedaling speed. The system may include a memory in communication with the processor. In one embodiment, one or more maps associating bicycle speed with speed ratio are stored in the memory. The system includes a logic module in communication with a processor. The logic module is configured to cooperate with the processor to determine a target speed ratio from the map based on a bicycle speed and a desired constant input pedaling speed. The system may also include an actuator in communication with the processor. The actuator is configured to adjust a speed ratio of the transmission to be substantially equal to the determined target speed ratio. In one embodiment, the data input interface includes a display and at least one button. In some embodiments, the data input interface is mounted to a handlebar of the bicycle. The bicycle may include a position sensor configured to provide an indication of the position of the actuator. In some embodiments, the data structure has a speed ratio data structure and a bicycle speed data structure. In other embodiments, the ball-and-planet transmission includes a shift lever operably coupled to the actuator.

Yet another aspect of the present invention is directed to an automatic shifting bicycle system having a ball-and-planetary transmission with a shift lever. In one embodiment, the system has an actuator operably coupled to a shift lever. The system includes a processor in communication with the actuator. The system also includes a memory in communication with the processor. In some embodiments, the memory has at least one table that associates actuator positions with gear ratios. The processor is configured to determine a target speed ratio of the transmission. The system may include a speed sensor configured to detect a speed of the transmission, the speed sensor in communication with the processor. The actuator is adapted to adjust the gear ratio based at least in part on the target gear ratio. In one embodiment, the actuator is configured to rotate a shift lever in order to adjust the gear ratio. The system may include a user interface in communication with the processor. The user interface is configured to receive a command from an operator, the command indicating a desired operating condition. In one embodiment, the user interface includes at least one button. In some implementations, the user interface can include a display. In other embodiments, the desired operating condition is a desired cadence level. The system may also include an encoder in communication with the processor. The encoder is configured to indicate a position of the shift lever. In one embodiment, the table contains data associating shift lever positions with gear ratios. In other embodiments, the table contains data associating shift lever positions with cadence levels.

These and other modifications will become apparent to those skilled in the art upon reading the following detailed description and viewing the included drawings.

Drawings

FIG. 1 is a block diagram of a transmission control system employing the inventive embodiments described herein.

FIG. 2 is a block diagram of yet another transmission control system incorporating the inventive embodiments described herein.

FIG. 3 is a block diagram of an automatic bicycle transmission shifting system in accordance with an innovative embodiment described herein.

FIG. 4 is a process flow diagram of a method that may be used to generate data structures that may be used with the inventive embodiments of the transmission control methods and systems described herein.

FIG. 5A is an example data structure that may be used with the inventive embodiments of the transmission control methods and systems described herein.

FIG. 5B is yet another example data structure that may be used with the inventive embodiments of the transmission control methods and systems described herein.

FIG. 6 is a process flow diagram of an automatic transmission control method in accordance with an inventive embodiment described herein.

Detailed Description

Preferred embodiments of the present invention will now be described with reference to the drawings, wherein like reference numerals refer to like elements throughout. The inventive systems and methods described herein may be used with transmissions and transmissions disclosed in U.S. Pat. nos. 6,241,636, 6,419,608, 6,689,012, and 7,011,600 in general. As such, the innovative systems and methods disclosed herein relate to the transmission, controller, user interface, and vehicle or technical applications described in U.S. patent applications 11/243,484, 11/543,311, 60/887,767, 60/895,713, and 60/914,633. The entire disclosure of each of these patents and patent applications is incorporated herein by reference.

Referring to FIG. 1, a transmission control system 100 for maintaining a constant speed input will now be described. In one embodiment, the system 100 includes an input shaft 102 and an output shaft 104 coupled to a transmission 106, wherein the transmission 106 is coupled to a transmission controller 108. The input shaft 102 has an input speed w_iAnd the output shaft 104 has an output speed w_o. The Speed Ratio (SR) of the transmission is defined as the output speed w_oDivided by the input speed w_i(or, equivalently, w)_i＝w_o/SR). During operation of the control system 100, inIn some embodiments, when the speed w is output_oUpon change, the transmission controller 108 adjusts SR to set the input speed w_iAt a substantially constant value, or at the input speed w_iIn a predetermined band. Thus, in one embodiment, a desired constant input speed w is given_iAnd the output speed w detected during operation_oThe controller 108 adjusts the transmission 104 to correspond to the sensed output speed w_oThe associated predetermined SR runs.

The transmission 106 may be a conventional range box (range box), a gearbox, a planetary-based transmission, a traction-based transmission (e.g., a toroidal transmission, a ball-and-planetary transmission, or any other continuously variable or infinitely variable transmission), or any combination thereof. The transmission controller 108 may include various integrated circuits, computer processors, logic modules, input and output interfaces, data structures, digital memory, power supplies, actuators, sensors, encoders, servos, and the like. Preferably, in one embodiment, the transmission controller 108 includes a controller that adjusts the vehicle output speed w_oA data structure associated with data related to the SR of the transmission 106.

Turning now to fig. 2, an automatic transmission control system 200 includes a speed sensor 202 coupled to a digital processor 204. A digital memory 206 is disposed in communication with the digital processor 204. The output speed w associated with SR is stored in the digital memory 206_oOr tables or maps (hereinafter "tables 208"). In some cases, the logic module 209 is disposed in communication with the digital processor 204; the logic module 209 is suitably programmed and/or algorithmic to cooperate with the digital processor 204 to process inputs and provide outputs, for example, based on sensed output speed w_oAnd a desired constant input speed w_iThe associated data input determines the SR. In one embodiment, the system 200 includes a processor coupled to the digital processor 204 to provide a desired constant input speed target w to the digital processor 204_cAssociationThe input device 210 for data input. In some embodiments of the system 200, the actuator 212 (or ratio adjuster mechanism) is coupled to the digital processor 204, whereby the digital processor 204 can control the actuator 212 to adjust the SR of the transmission 107, in one case, the transmission 107 can be a Continuously Variable Transmission (CVT).

During operation, the speed sensor 202 provides an output speed w to the digital processor 204_oIs indicated. The input device 210 provides a target input speed w to the digital processor 204_c. In cooperation with the logic 209 and/or the table 208, the digital processor 204 determines the indicated output speed w_oAnd a target input speed w_cAn associated SR. The digital processor 204 then commands the actuator 212 to adjust the operating speed ratio of the transmission 107 to the determined SR. In some embodiments, the target input speed w_cCan be at the output speed w_oThe range is substantially constant so that the rider pedals at a substantially constant cadence. In one embodiment, the input device 210 provides and outputs a speed w_oValue-dependent predetermined input speed w_cThe mapping of values may alternatively indicate the selection of such a mapping.

Referring now to fig. 3, an automatic switching bicycle system 300 is configured to maintain the cadence of the rider within a narrow band of a cadence level selected by the rider. As used herein, the term "cadence" refers to the pedaling speed of the rider (which is equivalent to the rotational speed of the bicycle cranks). In one embodiment, the bicycle system 300 includes a control unit 302 in communication with a speed sensor 304, an encoder position sensor 306, a user interface 308, a power source 310, and a reversible motor 312. In some cases, a gear reduction set 314 is coupled between the reversible electric motor 312 and a transmission 316. A bicycle wheel 318 and an input drive 320 are operatively coupled to the transmission 316. In some embodiments, the encoder position sensor 306 is coupled to the gear reduction set 314, and the speed sensor 304 is operatively coupled to the cycle wheel 318 or to any rotating component associated therewith. The input drive 320 may be, or be operatively coupled to, a rear sprocket, a chain, a front sprocket, a one-way clutch, a freewheel, or the like. The power supply 310 may be coupled to or integrated with any of the control unit 302, the user interface 308, and the motor 312. The power source 310 may be, for example, a battery, a generator, or any other suitable power generation or energy storage device.

In some embodiments, the control unit 302 includes a digital processor 322 in communication with a memory 324 and a logic module 326. The control unit 302 may additionally include a motor controller 328 in communication with the digital processor 322. It should be noted that the digital processor 322, memory 324, logic module 326, and motor controller 328 need not all be integrated into one device or placed in a common housing. That is, in some embodiments, any one of the digital processor 322, memory 324, logic module 326, and motor controller 328 may be located remotely from any one of the other devices; the communication between them (or among them) may be wired or wireless. The memory 324 preferably has one or more tables 330, wherein the tables 330 have a desired output speed w_oIs associated with the value of SR. In one embodiment, as shown in FIG. 3, the value of SR is represented by a value associated with the encoder position; that is, the encoder position represents at least one SR state of the actuator 316. As used herein, the term "encoder position" refers to a state of a detector and/or sensor that represents a position of a component of the actuator 316 or a position of an internal or external component coupled to such a component of the actuator 316. For example, in one instance, the encoder position indicates the angular position of a gear coupled to a shift lever of the transmission 316, such that the encoder position indicates the angular or axial position of the shift lever.

In one embodiment, the user interface 308 includes a display 332 and one or more operating button switches 334. Display 332 may be any suitable screen or the like for presenting a variety of graphical and/or alphanumeric information. The operating switches 334 may include one or more buttons or manipulators configured to enable an operator to, for example, input data, make selections, or change values. In some embodiments, operating the switch 334 enables the rider to select between operating modes (e.g., automatic continuous ratio adjustment, automatic stepped ratio adjustment, manual, etc.). The operating switch 334 may be configured to enable the rider to command different cadence levels in an automatic mode, or to request SR adjustments in a manual mode.

Still referring to fig. 3, during operation of the automatic switching bicycle system 300, a user can use the user interface 308 to adjust a desired cadence level while operating the bicycle in a daily ride. The control unit 302 receives the tempo input, queries the memory 324 and cooperates with the logic module 326 to select a correspondence table 330 associated with the tempo input. Thus, in normal operation of the bicycle, the user may select from a predetermined cadence level map (i.e., table 330) by indicating a desired cadence value. The speed sensor 304 detects the speed of the bicycle wheel 318, which in some cases involves detecting the rotational speed of some other rotating component (e.g., a spoke of the bicycle wheel 318) that rotates at a speed indicative of the rotational speed of the bicycle wheel 318. Based on the indicated cadence value and the detected speed of the bicycle wheel 318, the control unit 302 identifies an SR or encoder position from the table 330 that is associated with the sensed speed of the bicycle wheel 318. In cooperation with the motor controller 328, the control unit 302 actuates the reversible electric motor 312 to adjust the transmission 316 to achieve a speed ratio that substantially matches the SR identified from the table 330. When the control unit 302 adjusts SR in response to a change in the speed of the bicycle wheel 318, the rider's cadence is controlled to stay within a band of the rider's desired cadence level. For example, in some cases, the actual cadence level of the rider during steady-state operation may be maintained at the desired cadence level plus or minus 10 revolutions per minute (rpm), or +/-5rpm, or less than +/-2 rpm. In some embodiments, the auto-switching bicycle system 300 can be configured to have multiple automatic modes. The pattern may be predetermined to control the cadence of the rider in any desired manner over a range of output speeds. For example, in one such mode, table 330 may have tempo values, output tempo values, and associated SR values such that over a first output tempo range the tempo is controlled to a certain tempo value or a particular range of tempo values, and over a second output tempo range the tempo is controlled to another tempo value or another particular range of tempo values.

Referring now to FIG. 4, a process 400 for generating a data structure that may be used with table 330 is described. In one embodiment, the example transmission 316 is a ball-and-planet, traction CVT type, hybrid variable planetary gear (CVP). An example of such a device is NuVinci^TMAnd a transmission device. In such a transmission 316, the speed ratio between the speed of the input traction ring and the speed of the output traction ring is determined at least in part by the position of the shift lever. Thus, the position of the encoder of the servo may be correlated to the position of the shift lever, which effectively means that the position of the encoder is correlated to the speed ratio of the transmission 316. The process 400 begins at state 402 after a servo with an encoder is coupled to the actuator 316. At state 404, the position of the encoder is recorded (and, for example, preferably stored in a data structure that will be part of table 330). Moving to state 406, the input speed of the actuator 316 is recorded, and the output speed of the actuator 316 is recorded at state 408. Transition to state 410 by outputting speed w_oDivided by the input speed w_iThe SR is calculated. At state 412, the SR is recorded (and preferably stored in a data structure that will be part of table 330).

Process 400 then moves to decision state 414, where it is determined whether the end of the range of actuator 316 has been reached. For the present purposes, it is assumed that the range of encoder positions can be coextensive with the range of speed ratios of the transmission 316. When transmission 316 is a continuously variable transmission, there are an infinite number of transmission speed ratios within a given range; however, in practice, each of the encoder position and the speed ratio of the transmission 316 will be a finite set. If the end of the range of the actuator 316 has been reached, the process 400 continues to state 416 where the encoder moves to the next encoder position. The process 400 then returns to state 404 and records the new encoder position. Process 400 then repeats until it is determined at decision state 414 that the end of the range of actuator 316 has been reached, in which case process 400 ends at state 418.

Thus, the result of process 400 is a data structure that correlates encoder position to an empirically determined speed ratio of transmission 316. For one type of infinitely variable transmission, the speed ratio and encoder position data can be fitted to a curve generally described by SR ═ a exp (B × p), where a and B are constants or parametric characteristics of a single device and p is the encoder position. For example, for example CVP, a-0.4844 and B-0.0026. The data table 330 may incorporate encoder position and velocity ratio data generated by the process 400.

Turning to FIG. 5A, an example table 330 is shown and will now be discussed. The table 330 may include a vehicle speed data structure 502 having data associated with a vehicle speed. The table 330 may additionally include an encoder position data structure 504 having data associated with encoder positions. The vehicle speed data structure 502 and the encoder position data structure 504 correspond to each other when forming the columns and rows of the table 330. Given a target constant input speed, a corresponding SR may be determined and tabulated as a data structure 506 of the requested SR. However, in some cases, the requested SR is not available because, for example, such SR is below the lowest SR that transmission 316 may provide. In this case, the data structure 506 of the requested SR is used to generate a data structure 508 of possible SRs. In the example shown in FIG. 5, the lowest possible SR that can be obtained from the transmission 316 is 0.5; therefore, all values of the data structure of the requested SR below 0.5 are represented as 0.5 in the data structure 508 of the possible SR. The corresponding lowest encoder position is then associated with the lowest possible SR ratio value in table 330. Similarly, in some cases, the requested SR is higher than the highest possible SR of the transmission 316; thus, items in the data structure 506 of the requested SR that are higher than the highest possible SR of the actuator 316 are all represented by the highest SR (1.615 in the illustrative example) of the actuator 316.

Of course, those values in the data structure 506 of the requested SR that fall within the possible range of speed ratios for the transmission 316 correspond to the same items in the data structure 508 of possible SRs. It should be noted that in addition to values below and above the 6 possible ranges of the actuator 31, in table 330 there is a unique encoder position value in the encoder position data structure 505 that corresponds to a unique SR value in the data structure 508 of possible SRs. However, a range of speeds (rather than a unique speed) corresponds to a given encoder position. Thus, for wheel speeds of 58-rpm and less than 60-rpm in the vehicle speed data structure 502, only one encoder position value (i.e., 24) and one possible speed ratio value (i.e., 0.52) correspond. The illustrative table 330 includes a table having an AND (using expression w)_i＝w_oSR) calculated tempo data structure 510 of data associated with the tempo. Cadence data structure 510 need not be part of table 330; however, the inclusion of cadence data structure 510 in illustrative chart 330 facilitates demonstrating how the cadence may be held constant over a range of possible speed ratios for transmission 316 (as indicated by constant value 50 in cadence data structure 510).

FIG. 5B shows another example of a map or table 331 of output speed versus SR that produces a predetermined rider cadence. In one embodiment, table 331 includes a vehicle speed data structure 503 having data associated with an output or vehicle speed. Table 331 additionally includes an encoder position data structure 505 having data associated with encoder positions. The vehicle speed data structure 503 and the encoder position data structure 505 correspond to each other when forming the columns and rows of the table 331. Given the desired predetermined mapping for the target input speed, a data structure 509 of possible SRs is generated. The cadence data structure 511, which need not be part of table 331, illustrates how the cadence is controlled over a range of vehicle speeds associated with the vehicle speed data structure 503. As can be seen in FIG. 5B, when the output speed is varied from 0 to 100-rpm, the cadence is allowed to rise to a first level (i.e., 74.7-rpm), with SR adjusting from 0.6 to 0.9. The cadence drops to 51.1-rpm and is allowed to rise again to 74.7-rpm before the output speed of 153-rpm, SR is adjusted from 0.9 to 1.4, and the cadence drops to 48.8 at an output speed of 153-rpm. When the output speed increased to 200-rpm, the cadence rose to 64-rpm, and the SR remained constant at 1.4. This is an example of an automatically controlled transmission such that cadence is controlled relative to a three-speed ratio shift scheme. Of course, similar mapping may be provided for other automatic modes (e.g., 4-speed, 5-speed, 6-speed, 8-speed, or 9-speed). Furthermore, the cadence range may be adjusted by shifting the event by means of a map, for example, for a given vehicle speed or vehicle speed range, replacing 50-rpm to 75-rpm with a range of 65-rpm to 90-rpm. In some implementations, the mapping can have any desired relationship (e.g., linear, exponential, reciprocal, etc.) between output speed and cadence.

Turning to FIG. 6, a process 600 for controlling the transmission 316 so that the rider's cadence is controlled within a band of cadence levels selected by the rider will now be described. The process 600 begins at state 602 after, for example, the bicycle automatic shifting system 300 has been started and initialized. Process 600 continues to state 604 and receives an indication of a target constant tempo level. In one embodiment, the rider uses the user interface 308 to provide a target constant cadence level. The process 600 next moves to state 606 where the bicycle speed is determined. In one embodiment, the speed sensor 304 detects the speed of the bicycle wheel 318. However, in other embodiments, the bicycle speed may be determined by measuring and/or sensing other features or components of the bicycle, such as by detecting a voltage, resistance, or current level on a generator (not shown) coupled to the bicycle wheel 318. Process 600 then continues to state 608 where an encoder position associated with the bicycle speed and the target cadence is determined or identified. In one embodiment, the digital processor 322 cooperates with the memory 324 and the logic module 326 to look up the table 330 and thereby select the encoder position associated with the bicycle speed and the target cadence. At state 610 of process 600, the actuator is commanded to move to a position associated with the selected encoder position of state 608. In some implementations, at decision state 612 of process 600, it is determined whether process 600 should exit and end at state 614 or loop back to state 604 in order to receive the target tempo input. At state 604, process 600 may query whether the rider has commanded a new cadence level; if not, process 600 continues with the initial input cadence level. In one embodiment, the rider does not initially set a cadence level, but rather the control unit 302 is configured to use a default cadence level, such as 70-rpm. In other embodiments, a mapping of tempo to output speed (rather than a particular tempo value) may be provided to the process at state 604. As discussed previously, such a mapping may include any type of mapping that associates a tempo, an output speed, and a corresponding SR. At state 614 of process 600, the decision to exit may be based on a power down condition, a mode change command, and the like. For example, if the rider changes mode from automatic to manual, the process 600 detects a new condition and exits at state 614.

Those of skill would appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein, including with reference to the automatic switching bicycle system 300, can be implemented as electronic hardware, software stored on a computer readable medium and executed by a processor, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. For example, the various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. The software associated with such a module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other suitable form of storage medium known in the art. An example storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. For example, in one embodiment, the control unit 302 includes a processor (not shown). The processor of the control unit 302 may also be configured to perform the functions described herein with reference to one or both of the motor controller 328 and the user interface 308.

The foregoing description details certain preferred embodiments of the invention and describes the best mode contemplated. It will be appreciated, however, that no matter how detailed the foregoing appears literally, the invention can be practiced in many ways. Accordingly, the scope of the invention should be construed solely in accordance with the appended claims and any equivalents thereof.

Claims (20)

1. A method of automatically controlling a transmission of a bicycle, the method comprising the steps of:

receiving an input associated with a target user pedaling speed;

determining a bicycle speed;

determining a target gear ratio based at least in part on the target user pedaling speed and the determined bicycle speed; and

the gear ratio of the transmission is adjusted to be substantially equal to the target gear ratio.

2. The method of claim 1, wherein adjusting the gear ratio of the transmission comprises the step of adjusting a shift lever of the transmission.

3. The method of claim 1, further comprising the step of determining an encoder position associated with the target user pedaling speed.

4. The method of claim 3, wherein adjusting the gear ratio comprises commanding the actuator to move to the determined encoder position.

5. The method of claim 2, wherein adjusting the shift lever comprises the step of rotating the shift lever about a longitudinal axis of the transmission.

6. A method of automatically controlling a transmission of a bicycle, the method comprising the steps of:

receiving an input associated with a target user pedaling speed;

determining a bicycle speed; and

based on the target user pedaling speed and the determined bicycle speed, adjusting a speed ratio of the bicycle so as to maintain the user pedaling speed within a band of the target user pedaling speed.

7. The method of claim 6, wherein the band comprises the target user pedaling speed plus or minus 10 revolutions per minute (rpm).

8. The method of claim 6, wherein the band comprises a range of +/-2rpm to about +/-5rpm of the target user pedaling speed.

9. The method of claim 6, wherein adjusting a speed ratio of a bicycle comprises the step of determining an encoder position associated with the target user pedaling speed and the determined bicycle speed.

10. The method of claim 6, wherein adjusting the speed ratio of the bicycle comprises the step of commanding the actuator to move to the determined encoder position.

11. The method of claim 6, wherein adjusting the speed ratio of the bicycle comprises the step of adjusting a shift lever of the transmission.

12. A method of automatically controlling a ball-and-planet transmission of a bicycle, the method comprising the steps of:

providing an input associated with a target user pedaling speed;

determining a bicycle speed;

identifying a target encoder position associated with a bicycle speed; and

the servo system is actuated to obtain a target encoder position.

13. The method of claim 12, wherein actuating the servo comprises the step of adjusting a shift lever of the transmission.

14. The method of claim 13, wherein identifying a target encoder position comprises generating a data structure.

15. The method of claim 14, wherein generating the data structure comprises the step of recording an encoder position.

16. The method of claim 15, wherein generating the data structure comprises the step of recording an input speed and recording an output speed.

17. A system for automatically shifting a bicycle transmission, the system comprising:

a speed sensor configured to detect a bicycle speed;

a control unit configured to receive input from a speed sensor;

a data input interface configured to provide cadence data to a control unit, the cadence data being indicative of a desired constant input pedaling speed;

a memory in communication with the control unit, in which one or more data structures relating bicycle speed to speed ratio are stored;

wherein the control unit is configured to determine a target speed ratio from the data structure based on bicycle speed and cadence data, an

An actuator configured to selectively tilt a power transmitting ball of the transmission, the actuator in communication with the control unit and configured to adjust a speed ratio of the transmission to be substantially equal to the determined target speed ratio.

18. The system of claim 17, wherein the control unit comprises at least one of a processor, an application specific integrated circuit, or a programmable logic array.

19. The system of claim 20, wherein the actuator is operably coupled to a shift lever of the transmission, the shift lever configured to adjust a speed ratio of the transmission.

20. The system of claim 17, wherein the data input interface comprises a display and at least one button.