Dual-motor differential drive with regenerative braking for exercise machine

Abstract

A system for an exercise machine comprises a differential (D) having a housing (6) connected on a first side to a first shaft (2) driven by a first motor (M2) and on a second side to a second shaft (4) driven by a second motor (M1). The first motor operates as a regenerative or braking motor and the second motor operates as a driving motor. The motors run in opposite rotational directions but generate torque in the same direction, so a combined output torque is provided at the differential housing. The system enables high output torque to be achieved at low speeds while maintaining both motors at or near their peak operational efficiency. The system may be incorporated into an exercise machine, such as a Pilates reformer machine, rowing machine, or exercise bike, to provide a digital or electrical spring resistance to a driving or driven member of the machine.

Description

DIGITAL RESISTANCE SPRING FOR EXERCISE MACHINECross-Reference to Related Application

[0001] This Patent Application claims priority to UK Patent Application No. 2504563.4, filed March 27, 2025, entitled “DIGITAL RESISTANCE SPRING FOR EXERCISE MACHINE,” assigned to the assignee hereof, and incorporated by reference in its entirety herein.Field of the Invention

[0002] The present invention relates to improved exercise machines, such as exercise bikes, rowing machines, weightlifting machines and, in particular, reformer machines. More specifically, the present invention relates to a dual motor and differential system for providing improved motor operational efficiency in exercise machines, and to a digital or electrical spring resistance system for use therein.Background

[0003] Many types of exercise machine utilise a motor to either drive components of the machine or apply resistance to components of the machine.

[0004] One example is described in the Applicant’s co-pending published WO Patent Application No. WO2023 / 194315 Al relating to a Pilates reformer exercise machine wherein movement of a belt or chain is controlled by a motor to apply resistance to movement of a carriage along a rail. Pilates exercises are carried out by pushing or pulling the carriage, or holding the carriage steady, during an exercise as it is pulled on by resistance imparted by the motor thereby enabling a wide range of exercises to be carried out to promote strength, flexibility, and balance.

[0005] Motors generate peak torque when stalled i.e. when stationary. However, when stationary or at low velocity, considerable energy is consumed, i.e. the motor is running highly inefficiently. Motors run at peak efficiency at appreciable speed. This is illustrated in the brushless motor torque / efficiency graph of Figure 1 showing that at maximum torque when stationary, the motor is highly inefficient. Furthermore, even where a driving or driven member is moving at low velocity rather than being held stationary, the same efficiency problem arises. That is, a single motor operating at low speed to provide high torque runs below its peakefficiency regardless of whether the load is stationary or moving slowly. There is therefore a tradeoff in single-motor systems between torque output and operational efficiency.

[0006] Thus, the application of a high or maximum torque to keep a belt stationary as required for operation of the aforementioned type of Pilates reformer machine results in the motor running highly inefficiently. It is desirable to be able to provide an arrangement where a load is held stationary or at low velocity but the motor is able to run at, or near to, peak efficiency. This type of arrangement would also be useful for other applications which require a driving or driven member, such as a belt, to be powered by a motor, such as rowing machines, bikes and weightlifting machines where high torques are required with low running speeds.

[0007] It is the aim of the present invention to provide an improved exercise machine, particularly but not exclusively a Pilates reformer machine, that overcomes, or at least alleviates, the abovementioned problems.Summary of the Invention

[0008] A first aspect of the present invention provides a resistance or generator, the resistance or generator comprising a dual motor and differential system, the system comprising a differential connected at each side to a shaft, each shaft being powered by a separate motor to rotate at a predetermined speed and torque, wherein the motor on one side of the differential serves as a regenerative or braking motor and the motor on the other side of the differential serves as a driving motor, whereby the motors run in opposite directions but generate torque in the same direction to provide a high output torque at lower speeds, the high output torque providing the resistance or generator.

[0009] The resistance or generator may be connected to a driving or driven member to impart resistance or motion thereto. Preferably, the differential is provided within a housing, the housing containing gears and the shafts extending from each side of the housing to their respective motor. Preferably, the outer surface of the housing acts as a mount for receiving or linking to the driving or driven member. When the driving or driven member is actively applying load then the system can capture energy and deliver it through the regenerative or braking motor. In some examples, the first motor and the second motor may each be operable to reverse function, such that the first motor may operate as a driving motor and the second motor may operate as a regenerative or braking motor, depending on the direction and nature of the load applied.

[0010] The motors, preferably being servo motors, enable precise control of the speed and torque generated, enabling the motors to run close to peak efficiency at higher speeds than is possible with a single motor. The two motors are driven at different speeds, close to their peak efficiency, to provide the output required. One motor is driven whilst the other acts as a generator.

[0011] In some implementations, the first aspect of the present invention provides resistance to serve as an electrical or digital spring. In this manner, the system acts as a digital or electrical spring wherein the resistance applied to the driving or driven member may be varied as a function of the position, speed, or direction of movement of a load connected to the differential housing, thereby simulating the behavior of a mechanical spring or other variable resistance profile without the use of physical springs or bands. The resistance profile may be user-defined or programmatically controlled.

[0012] A second aspect of the present invention provides an exercise machine incorporating at least one resistance or generator according to the first aspect of the present invention, wherein the exercise machine includes a driving or driven member and the resistance or generator imparts resistance or motion thereto.

[0013] The differential may comprise a conventional gear, epicyclic or planetary gear.Further reductions may be provided, for example by additional gearing, on either side of the differential.

[0014] The outer surface of the differential housing may be profiled to that it can drive or be driven by a toothed belt (no slip) or smooth belt (limited slip), thus enabling its incorporation into an exercise machine, for example to provide resistance or movement via a drive or driven belt or other type of drive or driven member. Alternatively, the profile could have a sprocket with a looped or straight chain arrangement.

[0015] In one embodiment of the second aspect, the exercise machine comprises a Pilates reformer machine wherein the dual motor and differential system of the first aspect provides resistance to a carriage moveable along a spine of the machine. Preferably, the outer housing of the differential receives a belt which extends around a pulley at an opposing end of the machine. A connector is attached to the belt for receiving the carriage. Preferably, the outer housing of thedifferential and the belt are both toothed. In this manner rotation of the belt by the pulley and shaft arrangement is assisted or impeded by the motors and differential. Movement of the belt may be controlled by feedback from the carriage to the motors, thereby controlling the resistance applied to the carriage by the belt.

[0016] It is to be appreciated that the machine may include various additional components as are known in the art for a Pilates reformer machine.

[0017] The control of the resistance in this manner allows for accurate control and fast, automatic adjustment. Additional features, such as position sensors and / or encoders, may be incorporated into the system to enable work rates and energy consumed to be measured and monitored. The combination of positional sensing, torque measurement, and motor speed monitoring enables the system to dynamically adjust the resistance profile in real time, providing precise and repeatable simulation of spring-like or other resistance characteristics.

[0018] Positional sensing of the carriage along the spine, measurement of torque and the resistance on the belt, together with speed of travel will enable an interface to be provided detailing performance, such as work rate and energy consumption. Preferably, a controller is provided to control and monitor the voltage and current supplied to the motors to control the at least one movable belt or other member to, in turn, control the resistance applied to movement of the carriage and / or cords. These electrical measurements combined with positional sensing of the motor, for example with an encoder, can be used to provide the performance data. Additionally, or alternatively, the load may be measured.

[0019] The dual motor and differential system according to the first aspect of the present invention may be incorporated into other types of exercise machine to effect movement or resistance to a driving or driven member. The driving or driven member may be provided in one or a variety of forms, such as but not limited to, smooth belts, toothed belts, bevel gears, gear trains and cords. In one embodiment, the system is incorporated into a rowing machine to impart resistance thereto. In another embodiment, the system may impart variable resistance to a belt affecting turning of pedals on an exercise bike. In a further embodiment, it may impart variable resistance to a weight-lifting exercise machine, enabling a variable load to be provided by varying the resistance. In weight-lifting exercise machine implementations, the dual motor and differential system may replace weight stacks or resistance bands, enabling a precisely controlledand electronically variable load to be applied to a lifting or pulling member, with the resistance profile adjustable in real time without any mechanical reconfiguration. However, the present disclosure is not limited thereto and may be provided in combination with any device which requires a generator or resistance for imparting motion or resistance to a driving or driven member.

[0020] Further, while the dual motor and differential system is described herein in the context of example exercise machines, the system (two motors running in opposite rotational directions but generating torque in the same direction, mediated by a differential, to provide a combined output torque at near-peak motor efficiency) is applicable to any application involving high output torque at low speeds with improved operational efficiency.Brief Description of the Drawings

[0021] For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings in which:

[0022] Figure 1 is a brushless motor torque / efficiency graph illustrating peak efficiency at high rotational speeds;

[0023] Figure 2 is a schematic diagram illustrating the basic concept of the present invention wherein a differential is provided between a braking (regenerative) motor and a driving motor to provide improved operational efficiency;

[0024] Figure 3 A is a perspective view of a resistance belt and pulley arrangement for a reformer machine provided with a dual motor and differential system according to one embodiment of the present invention;

[0025] Figure 3B is an expanded top view of the dual motor and differential system provided at one end of the machine of Figure 3 A;

[0026] Figures 4 A to 4C are schematic diagrams of a reformer exercise machine bench, wherein in Figure 4 A the exterior of the bench is almost fully removed to show the internal dual motor and differential system with a belt and pulley arrangement carrying a carriage, Figure 4Bshows only a partial internal view of the components within the bench and Figure 4C shows the bench fully enclosing the internal components;

[0027] Figure 5 is a schematic diagram illustrating a dual motor and differential system with feedback according to one aspect of the present invention;

[0028] Figure 6 is a schematic diagram of a rowing machine incorporating a dual motor and differential system according to the present invention; and

[0029] Figure 7 is a schematic diagram of an exercise bike incorporating a dual motor and differential system according to the present invention.Detailed Description

[0030] The use of a motor to provide resistance, for example, in exercise machine applications requires high torque, but high torque with low speeds results in low operating efficiencies. Some products may tend to use one large motor to hold a load at stall but the efficiency of the motor is relatively low, as demonstrated in Figure 1 of the accompanying drawings. The present invention provides a novel dual motor and differential system wherein two motors run at near-peak efficiency and are separated by a differential gearbox, such as a conventional gearbox, epicyclic or planetary gear.

[0031] The dual motor and differential system of the present disclosure enables a load to be held stationary (for example, maintaining a carriage in a fixed position against a user’s applied force) while both motors continue to rotate at appreciable speed and thus operate at or near their peak efficiency. This is in contrast to single-motor arrangements, where holding a load stationary may involve the motor operating at or near stall, resulting in low efficiency as illustrated in Figure 1.

[0032] Figure 2 of the accompanying drawings illustrates the basic principle of the invention which increases the efficiency of a motor that may be used to provide resistance or movement via a drive or driven belt or other type of drive or driven member. A differential, such as a planetary gear box, is connected axially to two motors that can be precisely controlled to rotate at set speed and torque. One side of the differential D has a regenerative or braking motor Ml and the other has a driving motor M2. In this embodiment of the present invention, the differential D turns gears provided within a differential housing 6 connected to two axially aligned shafts 2, 4to allow work to be transferred at high efficiency through the system. The differential enables the two shafts to rotate in opposite directions at different speeds, enabling operating speeds and torques to be used that are closer to peak efficiency than is possible with prior art arrangements using a single motor.

[0033] The differential D mediates the angular velocity co and torque T of the different shafts 2, 4. The shafts rotate at the same or different speeds, close to maximum efficiency and the torque output, for example 2T generated is a combination of the applied torques, as illustrated in Figure 2. Alternative ratios may be provided to generate additional torques (eg 4T, 8T etc). It is to be appreciated that further reduction may be provided on one or both sides of the differential, between the differential and each motor, for example in the form of gearboxes (not shown).

[0034] As shown in Figure 2, when the output of the differential is stationary (2T Stationary), the angular velocities of the two shafts are equal and opposite (-coi = cm), while the torques are equal and act in the same direction (Ti = T2). This condition illustrates how the system achieves a high combined output torque at the differential housing whilst both motors continue to operate at appreciable rotational speeds, thereby maintaining near-peak efficiency.

[0035] The outer surface of the differential housing may be profiled to that it can drive or be driven by a toothed belt (no slip) or smooth belt (limited slip), thus enabling its incorporation into an exercise machine, for example to provide resistance or movement via a drive or driven belt or other type of drive or driven member. Alternatively, the profile could have a sprocket with a looped or straight chain arrangement.

[0036] For example, in one embodiment of the present invention, this dual motor and differential system is incorporated into an exercise machine, such as a Pilates reformer machine, as illustrated in Figures 3A to 4C of the accompanying drawings. The machine does not rely on mechanical resistance springs or bands for the application of resistance to movement of parts of the machine, in particular the carriage and / or cords, but instead uses the dual motor and differential system of the present invention to provide resistance to the carriage akin to a digital or electrical spring. The motors Ml and M2 have shafts 2, 4 with the differential gear D, such as a planetary gear, between the two shafts. The outer housing 6 of the differential is toothed and receives a toothed belt 8 of the reformer machine which extends around a pulley 10 at the opposing end. A connector 12 is attached to the belt for receiving a platform (not shown). Theconnector 12 is attached to the belt drive and rotation of the belt by the pulley and shaft arrangement is assisted or impeded by the motors and differential.

[0037] The outer surface of the differential housing 6 may act as a mount, with the interior of the housing acting as a gear mechanically linked by other internal gears to the axially aligned shafts 2, 4, allowing work to be transferred at high efficiency through the system.

[0038] As shown in Figures 2, 3A, and 3B, the first motor M2, the differential D, and the second motor Ml are arranged in axial alignment, with the first shaft 2 and the second shaft 4 extending axially from opposing sides of the differential housing 6. This axial arrangement provides a compact and mechanically efficient configuration that is well-suited for incorporation into the elongate frame of an exercise machine such as a Pilates reformer machine.

[0039] As shown in Figure 3B, the first motor M2 and the second motor Ml are mounted on opposing sides of the differential D, with the first shaft 2 extending from the first motor M2 into the differential housing 6 and the second shaft 4 extending from the second motor Ml into the differential housing 6 on the opposing side. The toothed outer surface of the differential housing 6 engages the toothed belt 8, with the connector 12 attached to the belt 8 and positioned to carry the carriage or platform of the exercise machine.

[0040] Figures 4A to 4C illustrate how the arrangement shown in Figures 3A to 3B may be incorporated into a bench 20 of an exercise machine, such as a Pilates reformer machine. The connector 12 which may carry a platform, is slidable through an upper longitudinal slot 14 provided in an upper surface of the bench 20, with the belt 8, differential D housing 6 and pulley 10 (see Fig. 3 A) enclosed within the bench. The slot 14 allows a platform, once connected, to slide along the length of the bench with the amount of resistance applied being controlled by the dual motor and differential system of the invention. However other arrangements may be provided, such as a carriage which wraps around a longitudinal spine of the machine.

[0041] Thus, voltage applied can be used to control movement of the belt which in turn dictates the resistance applied to the carriage. In this manner, the Pilates reformer machine effectively employs a “digital” or “electrical” spring that can be carefully controlled and monitored.

[0042] It is to be appreciated that the machine would also have additional components known in the art for a Pilates reformer machine, many of which are omitted from the accompanying figures for the sake of simplicity. The bench 20 forms a frame having a central support spine extending between front support members or legs and rear support members or legs provided at the ends of the spine. The slidable connector 12 may support a flat platform (not shown), which may be padded for comfort. The machine may also include a foot bar (not shown) that may connect to the underside of the spine and may be selectively slidable along the length of the spine and each end of the bench may have support boards. Exercise cords may also be provided extending from the platform and around a pulley mechanism provided at the end support board and back to the user where the cord terminates in handles or cuffs. The platform and cords serve as resistance to perform movements directed at specific muscle groups.Movement is achieved by the application of certain force against the weight of the body and the resistance imposed by the drive belt.

[0043] The control of the resistance in this manner allows for accurate control and fast, automatic adjustment. Additional features, such as position sensors and / or encoders may be incorporated into the system to enable work rates and energy consumed to be measured and monitored. Feedback from the load may also be monitored to assess the performance of the differential, which in turn may be used to control the motors to provide the desired load.

[0044] Additional components may be included in a belt and pulley arrangement according to the invention to allow further control and monitoring of the resistance imparted by the machine.

[0045] Thus, with the present invention, the digital or electrical spring provided by the dual motor and differential system acting on the drive belt will (depending on the section of an oscillating cycle) have one motor Ml supplying power and the other M2 extracting it. The motors run in opposite directions but generate torque in the same direction such that the torque is the combination of the output of each motor (see Figures 2 and 5). The motion of the output can be adjusted by modifying the speed and torque at which the two motors Ml, M2 are running whilst keeping them both close to peak efficiency. This enables high torque to be achieved at slower speeds with higher efficiency.

[0046] In some examples, the resistance profile applied to the driving or driven member may be varied continuously and in real time by adjusting the relative speeds and torques of the first motor Ml and the second motor M2. In this manner, the system can simulate a wide range of resistance profiles, including spring-like resistance that increases with displacement, constant resistance, or user-defined variable resistance profiles, without any mechanical reconfiguration of the system.

[0047] Figure 5 of the accompanying drawings is a schematic diagram illustrating the incorporation of this type of dual motor and differential system into a reformer or other type of exercise machine to impart controlled and variable resistance to a carriage carried on a drive or driven belt. It is to be understood that the load could be otherwise connected to the differential such as a cord wrapped around a windlass. For example, a cord may be wrapped around a windlass connected to the differential housing, such that rotation of the housing winds or unwinds the cord to apply resistance or motion to a load attached to the cord. This arrangement may be particularly suitable for exercise machines where a pulling or pushing motion is performed against a cord, such as in cable-based resistance machines or rowing machines.

[0048] Similarly, there might not be a carriage included, the load might be more directly or indirectly connected to the differential arrangement. As illustrated a belt is provided around the differential which is provided between the motor and generator. A motor controller is provided which receives force feedback from the carriage for controlling the generator and / or driving motor (link to motor not shown). Alternatively, the load could be sensed less directly, for example via driving motor and generator torques and speeds. Additionally, a battery and power supply may be provided, together with a controller for the driving motor. The battery or energy store can provide energy to or receive energy from the motor or generator (such that they can reverse function). The controller could take various forms for example the generator controller, or energy extraction device, might be a rectifier feeding into a variable energy extraction circuit. Servo motors are preferably used as these allow for high precision control, having encoders within the motor for responding to the feedback from the carriage and other components.Feedback allows for the rotation speeds of the shafts to be altered independently to control the torque / load and speed using the dual motor and differential system of the invention.

[0049] As illustrated in Figure 5, the power supply may provide electrical power to the controller for the driving motor. The generator may produce regenerated power which is captured by the motor controller and directed to the battery or energy store. The battery may in turn supply power back to the driving motor via the power supply, thereby enabling energy recovery and reuse within the system. The combined output torque of 2T is provided at the differential, representing the sum of the individual torques Ti and T2 contributed by the motor and generator respectively, as labeled in Figure 5. The torque load applied through the carriage is transmitted to the differential, where it is sensed as force feedback and used to modulate the operating parameters of the motor and generator to maintain the desired resistance profile.

[0050] Embodiments of the invention may include reductions, such as additional gearboxes (not shown) on one or both sides of the differential to change the ratio and alter the torque provided to a driving or driven member.

[0051] The dual motor and differential system according to the present invention may be incorporated into other types of exercise machine to effect movement or resistance to a driving or driven member. The driving or driven member may be provided in one or a variety of forms, such as but not limited to, smooth belts, toothed belts, bevel gears, gear trains and cords. In some implementations, the system is incorporated into a rowing machine to impart resistance thereto, as shown in Figure 6. As shown in Figure 6, the dual motor and differential system is connected to the resistance mechanism of a rowing machine, such that the pulling motion of the user against the rowing handle or cord is resisted by the combined output torque of the system. The resistance may be varied dynamically to simulate different resistance profiles. In some implementations, the system may impart variable resistance to a belt effecting turning of pedals on an exercise bike, as illustrated in Figure 7 of the accompanying drawings. As shown in Figure 7, the dual motor and differential system is connected to the drivetrain of an exercise bike, such that the pedaling motion of the user is resisted by the combined output torque of the system. The resistance may be varied dynamically to simulate different cycling conditions or resistance profiles.

[0052] However, the invention is not limited thereto and may be provided in combination with any device which requires, for example the creation of a load that is stationary for resistance and strengthening purposes, such as weightlifting and strengthening machines. Thus, theinvention provides two motors running separately at near-peak efficiency, being connected by shafts to a differential gearbox, running in opposite directions but with increased torque generated in the same direction.

[0053] Further modifications to exercise machines incorporating the dual motor and differential system of the invention for providing a digital / electrical resistance or driving mechanism may be made without departing from the principles embodied in the examples described and illustrated herein.

[0054] Aspects of the present disclosure may be implemented according to any one or more of the following numbered clauses:

[0055] Clause 1 : A system comprising: a differential having a housing and connected on a first side to a first shaft and on a second side to a second shaft; a first motor connected to the first shaft and configured to operate as a regenerative or braking motor; and a second motor connected to the second shaft and configured to operate as a driving motor; wherein the first motor and the second motor are configured to run in opposite rotational directions and generate torque in a same direction.

[0056] Clause 2: The system of clause 1, wherein the differential comprises an epicyclic or planetary gear.

[0057] Clause 3: The system of any of clauses 1 or 2, wherein an outer surface of the housing of the differential is profiled to engage a toothed belt.

[0058] Clause 4: The system of any of clauses 1 or 2, wherein an outer surface of the housing of the differential is profiled to engage a smooth belt.

[0059] Clause 5: The system of any of clauses 1 or 2, wherein an outer surface of the housing of the differential is configured to engage a sprocket and chain arrangement.

[0060] Clause 6: The system of any of clauses 1 through 5, further comprising at least one additional gearbox disposed between the differential and at least one of the first motor or the second motor to alter a torque ratio provided to a driving or driven member.

[0061] Clause 7: The system of any of clauses 1 through 6, wherein the first motor and the second motor are servo motors each comprising an encoder.

[0062] Clause 8: The system of any of clauses 1 through 7, further comprising a controller configured to monitor and control voltage and current supplied to the first motor and the second motor to control an output torque of the system.

[0063] Clause 9: The system of clause 8, wherein the controller is configured to receive force feedback from a load connected to the housing of the differential and to independently adjust an operating speed and an operating torque of each of the first motor and the second motor in response thereto.

[0064] Clause 10: The system of any of clauses 1 through 9, further comprising an energy storage device configured to store energy regenerated by the first motor operating as the regenerative or braking motor.

[0065] Clause 11 : The system of any of clauses 1 through 10, further comprising a driving or driven member operatively connected to the housing of the differential to receive resistance or motion therefrom.

[0066] Clause 12: The system of clause 11, wherein: the system is incorporated into a Pilates reformer machine, the driving or driven member comprising a belt extending around the housing of the differential and around a pulley at an opposing end of the Pilates reformer machine, and a connector attached to the belt and configured to carry a carriage that is slidable along a length of the Pilates reformer machine; and the housing of the differential and the belt are both toothed, movement of the belt being controlled by feedback from the carriage to the first motor and the second motor to control the resistance applied to the carriage.

[0067] Clause 13: The system of clause 11, wherein the system is incorporated into one of: a rowing machine, an exercise bike, or a weightlifting machine.

[0068] Clause 14: The system of any of clauses 1 through 13, wherein the first motor and the second motor are configured to run in the opposite rotational directions and generate the torque in the same direction such that a combined output torque is provided at the housing of the differential at a torque level and operational efficiency greater than achievable with a single motor producing the combined output torque.

[0069] Clause 15: The system of any of clauses 1 through 14, wherein the system is incorporated into an exercise machine, and the driving or driven member is operatively connected to the housing of the differential to impart resistance or motion to a user of the exercise machine.

[0070] Clause 16: The system of any of clauses 1 through 15, wherein the driving or driven member comprises one or more of: a toothed belt, a smooth belt, a cord, a chain, a bevel gear, or a gear train.

[0071] Clause 17: The system of any of clauses 1 through 16, wherein the system is configured to simulate a digital or electrical spring by varying the output torque at the housing of the differential as a function of position, speed, or a user-defined resistance profile.

[0072] Clause 18: The system of clause 17, wherein the output torque is varied as a function of the position of a load connected to the housing of the differential.

[0073] Clause 19: The system of any of clauses 1 through 18, wherein the first motor and the second motor are each operable to reverse function, such that the first motor may operate as a driving motor and the second motor may operate as a regenerative or braking motor.

[0074] Clause 20: The system of any of clauses 1 through 19, wherein the differential mediates the angular velocity and torque of the first shaft and the second shaft such that the first shaft and the second shaft rotate at the same or different speeds.

[0075] Clause 21: A method comprising: connecting a differential on a first side to a first shaft driven by a first motor and on a second side to a second shaft driven by a second motor; operating the first motor as a regenerative or braking motor and the second motor as a driving motor such that the first motor and the second motor run in opposite rotational directions; generating torque from each of the first motor and the second motor in a same direction to produce a combined output torque at a housing of the differential; and applying the combined output torque to a driving or driven member to impart resistance or motion thereto.

[0076] Clause 22: The method of clause 21, wherein the differential comprises an epicyclic or planetary gear.

[0077] Clause 23: The method of any of clauses 21 or 22, wherein applying the combined output torque comprises engaging a toothed belt with an outer surface of the housing of the differential.

[0078] Clause 24: The method of any of clauses 21 or 22, wherein applying the combined output torque comprises engaging a smooth belt with an outer surface of the housing of the differential.

[0079] Clause 25: The method of any of clauses 21 or 22, wherein applying the combined output torque comprises engaging a sprocket and chain arrangement with an outer surface of the housing of the differential.

[0080] Clause 26: The method of any of clauses 21 through 25, further comprising altering a torque ratio provided to the driving or driven member using at least one additional gearbox disposed between the differential and at least one of the first motor or the second motor.

[0081] Clause 27: The method of any of clauses 21 through 26, wherein the first motor and the second motor are servo motors each comprising an encoder, and wherein the method further comprises using the encoder of each motor to monitor rotational position and speed.

[0082] Clause 28: The method of any of clauses 21 through 27, further comprising monitoring and controlling voltage and current supplied to the first motor and the second motor using a controller to control the combined output torque.

[0083] Clause 29: The method of clause 28, further comprising receiving force feedback from a load connected to the housing of the differential and independently adjusting an operating speed and an operating torque of each of the first motor and the second motor in response thereto.

[0084] Clause 30: The method of any of clauses 21 through 29, further comprising storing energy regenerated by the first motor operating as the regenerative or braking motor in an energy storage device.

[0085] Clause 31: The method of any of clauses 21 through 30, wherein the driving or driven member is operatively connected to the housing of the differential to receive resistance or motion therefrom.

[0086] Clause 32: The method of clause 31, wherein: the method is performed in a Pilates reformer machine, the driving or driven member comprising a belt extending around the housing of the differential and around a pulley at an opposing end of the Pilates reformer machine, and a connector attached to the belt and configured to carry a carriage that is slidable along a length of the Pilates reformer machine; and the housing of the differential and the belt are both toothed, movement of the belt being controlled by feedback from the carriage to the first motor and the second motor to control the resistance applied to the carriage.

[0087] Clause 33: The method of clause 31, wherein the method is performed in one of: a rowing machine, an exercise bike, or a weightlifting machine.

[0088] Clause 34: The method of any of clauses 21 through 33, wherein the first motor and the second motor are operated such that the combined output torque is provided at the housing of the differential at a torque level and operational efficiency greater than achievable with a single motor producing the combined output torque.

[0089] Clause 35: The method of any of clauses 21 through 34, wherein the method is performed in an exercise machine, and the driving or driven member imparts resistance or motion to a user of the exercise machine.

[0090] Clause 36: The method of any of clauses 21 through 35, wherein the driving or driven member comprises one or more of: a toothed belt, a smooth belt, a cord, a chain, a bevel gear, or a gear train.

[0091] Clause 37: The method of any of clauses 21 through 36, further comprising varying the combined output torque at the housing of the differential as a function of position, speed, or a user-defined resistance profile to simulate a digital or electrical spring.

[0092] Clause 38: The method of clause 37, wherein the combined output torque is varied as a function of the position of a load connected to the housing of the differential.

[0093] Clause 39: The method of any of clauses 21 through 38, further comprising reversing the function of the first motor and the second motor such that the first motor operates as a driving motor and the second motor operates as a regenerative or braking motor.

[0094] Clause 40: The method of any of clauses 21 through 39, wherein the differential mediates the angular velocity and torque of the first shaft and the second shaft such that the first shaft and the second shaft rotate at the same or different speeds.

[0095] As described herein, being “configured to,” being “configurable to,” and being “operable to” may be used interchangeably and may be associated with a capability, when executing code (such as processor-executable code, instructions) stored in memory circuitry (such as a non-transitory computer-readable medium, of the memory circuitry, storing code for wireless communication that is executable by a processing system) or otherwise, to perform one or more of the functions described herein.

[0096] It should be noted that methods described herein describe possible implementations. Other implementations in accordance with the described techniques are possible, including implementations in which operations are rearranged or otherwise modified relative to the described methods. Further, aspects from two or more of the described methods may be combined.

[0097] As used herein, a phrase referring to “at least one of’ or “one or more of’ a list of items refers to any combination of those items, including single members. For example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c. Additionally, as used herein, a phrase referring to “a” or “an” element refers to one or more of such elements acting individually or collectively to perform the recited function(s). Thus, the terms “a,” “at least one,” “one or more,” and “at least one of one or more” may be interchangeable. For instance, for a claim that refers to “a” component performing one or more functions, each of the individual functions may be performed by a single component or by any combination of multiple components, and subsequent reference to a component introduced with the article “a” using the term “the” may refer to any or all of the single or multiple components. Thus, a component introduced with the article “a” may be understood to mean “one or more” components, and referring to “the” component subsequently in the claims may be understood to be equivalent to referring to “at least one of the one or more” components. Additionally, as used herein, a “set” can refer to one or more items, and a “subset” can refer to a whole set or less than the whole set, but not an empty set. Additionally, as used herein, the term “or” is intended to be interpreted in the inclusive sense, such as when referring to a series, and may be used interchangeably with theterm “and / or,” unless otherwise explicitly indicated (for example, if used in conjunction with “either” or “only one of’). For example, “a or b” may include a only, b only, or a combination of a and b.

[0098] The disclosure is provided to enable a person having ordinary skill in the art to implement the described techniques. Modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the techniques disclosed herein may be applied with other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

ClaimsWhat is claimed is:

1. A system for an exercise machine, comprising:a differential having a housing and connected on a first side to a first shaft and on a second side to a second shaft;a first motor connected to the first shaft and configured to operate as a regenerative or braking motor; anda second motor connected to the second shaft and configured to operate as a driving motor;wherein the first motor and the second motor are configured to run in opposite rotational directions and generate torque in a same direction.

2. The system of claim 1, wherein the differential comprises an epicyclic or planetary gear.

3. The system of any of claims 1 or 2, wherein an outer surface of the housing of the differential is profiled to engage a toothed belt.

4. The system of any of claims 1 or 2, wherein an outer surface of the housing of the differential is profiled to engage a smooth belt.

5. The system of any of claims 1 or 2, wherein an outer surface of the housing of the differential is configured to engage a sprocket and chain arrangement.

6. The system of any of claims 1 through 5, further comprising at least one additional gearbox disposed between the differential and at least one of the first motor or the second motor to alter a torque ratio provided to a driving or driven member.

7. The system of any of claims 1 through 6, wherein the first motor and the second motor are servo motors each comprising an encoder.

8. The system of any of claims 1 through 7, further comprising a controller configured to monitor and control voltage and current supplied to the first motor and the second motor to control an output torque of the system.

9. The system of claim 8, wherein the controller is configured to receive force feedback from a load connected to the housing of the differential and to adjust an operating speed and an operating torque of each of the first motor and the second motor in response thereto.

10. The system of any of claims 1 through 9, further comprising an energy storage device configured to store energy regenerated by the first motor operating as the regenerative or braking motor.

11. The system of any of claims 1 through 10, further comprising a driving or driven member operatively connected to the housing of the differential to receive resistance or motion therefrom.

12. The system of claim 11, wherein:the system is incorporated into a Pilates reformer machine, the driving or driven member comprising a belt extending around the housing of the differential and around a pulley at an opposing end of the Pilates reformer machine, and a connector attached to the belt and configured to carry a carriage that is slidable along a length of the Pilates reformer machine; and the housing of the differential and the belt are both toothed, movement of the belt being controlled by feedback from the carriage to the first motor and the second motor to control the resistance applied to the carriage.

13. The system of claim 11, wherein the system is incorporated into one of: a rowing machine, an exercise bike, or a weightlifting machine.

14. The system of any of claims 1 through 13, wherein the first motor and the second motor are configured to run in opposite rotational directions and generate torque in the same direction such that a combined output torque is provided at the housing of the differential at a torque level and operational efficiency greater than achievable with a single motor producing the combined output torque.

15. A method of providing resistance or drive in an exercise machine, comprising: connecting a differential on a first side to a first shaft driven by a first motor and on a second side to a second shaft driven by a second motor;operating the first motor as a regenerative or braking motor and the second motor as a driving motor such that the first motor and the second motor run in opposite rotational directions;generating torque from each of the first motor and the second motor in a same direction to produce a combined output torque at a housing of the differential; andapplying the combined output torque to a driving or driven member of the exercise machine to impart resistance or motion thereto.

Images