Control device for electrical stimulation apparatus, electrical stimulation apparatus, and pedaling exercise system

A control device for an electrical stimulation apparatus according to the present disclosure includes a control section that adjusts an output of an electrode and communicates with an angular velocity detector, the electrode giving electrical stimulation to a predetermined part of a body doing a pedaling exercise by rotating a crank, the predetermined part being at least one of a leg and an arm, the angular velocity detector detecting an angular velocity of the predetermined part, the angular velocity being accompanied by an operation of the predetermined part during the pedaling exercise. The control section adjusts, according to a result of the detection in the angular velocity detector, an output timing of the electrical stimulation of the electrode such that the electrode gives electrical stimulation to the predetermined part when a state of the operation of the predetermined part during the pedaling exercise is a predetermined operation state.

BACKGROUND

1. Technical Field

The present disclosure relates to a control device for an electrical stimulation apparatus that electrically stimulates predetermined parts of a user's body while a user is doing pedaling exercise, to an electrical stimulation apparatus, and to a pedaling exercise system.

2. Description of the Related Art

Unexamined Japanese Patent Publication No. 2003-144556 discloses an electrical stimulation apparatus that helps a user do pedaling exercise or intensifies the pedaling exercise. More specifically, this electrical stimulation apparatus electrically stimulates the lower limbs, based on locations or rotation angles of the pedals.

SUMMARY

A relationship between a location or a rotation angle of a pedal and an angle of a knee joint of a lower limb may differ from a fundamentally desirable relationship due to various factors. This difference causes a concern that an electrical stimulation apparatus has difficulty in electrically stimulating the lower limb at an appropriate timing.

One embodiment of a control device for an electrical stimulation apparatus according to the present disclosure includes a control section that adjusts an output of an electrode and communicates with an angular velocity detector, the electrode giving electrical stimulation to a predetermined part of a body doing a pedaling exercise by rotating a crank, the predetermined part being at least one of a leg and an arm, the angular velocity detector detecting an angular velocity of the predetermined part, the angular velocity being accompanied by an operation of the predetermined part during the pedaling exercise. The control section adjusts, according to a result of the detection in the angular velocity detector, an output timing of the electrical stimulation of the electrode such that the electrode gives electrical stimulation to the predetermined part when a state of the operation of the predetermined part during the pedaling exercise is a predetermined operation state.

The control device for an electrical stimulation apparatus, the electrical stimulation apparatus, and the pedaling exercise system can electrically stimulate the predetermined part of a body doing pedaling exercise at an appropriate timing.

DETAILED DESCRIPTION

(One Example of Embodiments of Control Device for Electrical Stimulation Apparatus, Electrical Stimulation Apparatus, and Pedaling Exercise System)

One embodiment of a control device for an electrical stimulation apparatus according to the present disclosure includes a control section that adjusts an output of an electrode and communicates with an angular velocity detector, the electrode giving electrical stimulation to a predetermined part of a body doing a pedaling exercise by rotating a crank, the predetermined part being at least one of a leg and an arm, the angular velocity detector detecting an angular velocity of the predetermined part, the angular velocity being accompanied by an operation of the predetermined part during the pedaling exercise. The control section adjusts, according to a result of the detection in the angular velocity detector, an output timing of the electrical stimulation of the electrode such that the electrode gives electrical stimulation to the predetermined part when a state of the operation of the predetermined part during the pedaling exercise is a predetermined operation state.

Consequently, the angular velocity detector can directly detect the operation state of the predetermined part of the body that does the pedaling exercise. Hence, when the angular velocity detector is attached to, for example, a lower limb, even if a relationship between a location or a rotation angle of a pedal and an angle of a knee joint of the lower limb differs from a fundamentally desirable relationship, it is possible to accurately detect the operation of the lower limb. Consequently, it is possible to electrically stimulate a predetermined part of a body that does the pedaling exercise at an appropriate timing during the pedaling exercise. In this regard, the predetermined operation state refers to a state defined as an operation state suitable for electrical stimulation.

According to one example of the control device for an electrical stimulation apparatus, the control section adjusts the output timing of a current of the electrode according to the result of the detection in the angular velocity detector and delay of the result of the detection in the angular velocity detector in response to the angular velocity of the predetermined part.

Consequently, even when the measured operation of the predetermined part delays from an actual operation of the predetermined part, it is possible to electrically stimulate the predetermined part at an appropriate timing for the actual operation of the predetermined part.

According to one example of the control device for an electrical stimulation apparatus, the control section adjusts the output timing based on a rotation speed of the crank.

By setting a timing of electrical stimulation that reflects an influence of a rotation speed of the crank due to delay of a detection result of the angular velocity detector with respect to the angular speed of the predetermined part, it is possible to electrically stimulate the predetermined part at an appropriate timing even when the rotation speed of the crank changes.

According to one example of the control device for an electrical stimulation apparatus, the control section smooths the result of the detection in the angular velocity detector by using a first filter when a number of revolutions of the crank during the pedaling exercise is included in a first range, and smooths the result of the detection in the angular velocity detector by using a second filter having a more moderate frequency response than the first filter when the number of revolutions of the crank during the pedaling exercise is included in a second range higher than the first range.

According to one example of the control device for an electrical stimulation apparatus, the control section detects, based on a representative value of a peak or a bottom of an angular velocity during a first period, a peak or a bottom of an angular velocity during a second period, the first period being a period in which the number of revolutions of the crank during the pedaling exercise is equal to or less than a predetermined number of revolutions, the second period being a period after the number of revolutions of the crank exceeds the predetermined number of revolutions.

Instead of using a value set in advance as a representative value, a peak or a bottom of the angular velocity of an individual user is measured at a start of the pedaling exercise to calculate the representative value. Consequently, it is possible to prevent timings of the peak or the bottom of the angular velocity from varying due to a physical size of the user. Consequently, it is possible to electrically stimulate the predetermined part of the individual user at an appropriate timing even when physical sizes of users vary.

According to one example of the control device for an electrical stimulation apparatus, the control section determines the output timing of the electrical stimulation based on a predetermined reference point. The control section determines the predetermined reference point based on a reference point determination condition set based on a variation of a plurality of items of angular velocity data acquired in advance. Consequently, it is possible to improve adjustment accuracy of the output timing for electrical stimulation.

According to one example of the control device for an electrical stimulation apparatus, the control section executes control to electrically stimulate the predetermined part at a timing during a first period, the timing being different from the output timing of the electrical stimulation adjusted by the control section, the first period being a period in which a number of revolutions of the crank during the pedaling exercise is equal to or less than a predetermined number of revolutions. Consequently, it is possible to reduce user discomfort.

According to one example of the control device for an electrical stimulation apparatus, the control section executes control not to electrically stimulate the predetermined part during a first period being a period in which a number of revolutions of the crank during the pedaling exercise is equal to or less than a predetermined number of revolutions.

The above electrical stimulation apparatus according to one embodiment includes: the above control device for an electrical stimulation apparatus, the electrode, and the angular velocity detector.

The above pedaling exercise system according to one embodiment includes the above electrical stimulation apparatus, and a pedaling exercise machine.

First Exemplary Embodiment

As illustrated inFIG. 1, pedaling exercise system1includes electrical stimulation apparatus10, pedaling exercise machine30, and a seat40. Stimulation apparatus10is attached to user's lower limbs. The user does pedaling exercise using pedaling exercise machine30while sitting on seat40. The configuration of pedaling exercise system1may be modified appropriately. As a first example, pedaling exercise machine30is integrated with seat40. As a second example, pedaling exercise system1further includes a handle to be grabbed by the user's hand during the pedaling exercise. As a third example, seat40is provided with a mechanism that adjusts a height of seat40. With this mechanism, the height of seat40can be adjusted so that the user does the pedaling exercise easily.

Electrical stimulation apparatus10electrically stimulates his/her lower limbs in accordance with the user's pedaling exercise. Electrical stimulation apparatus10includes supporters11and controller20. Supporters11are attached to right and left lower limbs. Controller20is one example of a control device that controls electrical stimulation apparatus10.

Each supporter11is provided with two first electrodes12, two second electrodes13, and angular velocity detector14. First electrodes12and second electrodes13are disposed with a space being left therebetween. Two first electrodes12are disposed with a space being left therebetween. Two second electrodes13are disposed with a space being left therebetween. Angular velocity detector14is disposed closer to first electrodes12than second electrodes13. More specifically, angular velocity detector14is disposed between two first electrodes12, for example. In this case, each supporter11may have any number of first electrodes12and second electrodes13. As one example, each supporter11may have one or not less than three first electrodes12and/or second electrodes13.

When supporters11are attached to the lower limbs, first electrodes12are disposed at locations related to the quadriceps femorises of the lower limbs and second electrodes13are disposed at locations related to the biceps femorises of the lower limbs, for example. Angular velocity detectors14are disposed at locations related to the quadriceps femorises, for example. During the pedaling exercise, first electrodes12give electrical stimulation to the quadriceps femorises, second electrodes13give electrical stimulation to the biceps femorises, and angular velocity detectors14detect angular velocities of the quadriceps femorises. Angular velocity detectors14output detection signals according to the detected angular velocities to controller20.

Controller20is electrically connected to supporters11by wires so as to be electrically connected to first electrodes12, second electrodes13, and angular velocity detectors14. Controller20controls a mode of applying voltages to first electrodes12and second electrodes13, based on detection signals from angular velocity detectors14. Note that controller20may be wirelessly electrically connected to first electrodes12, second electrodes13, and angular velocity detectors14.

Pedaling exercise machine30includes main body31and crank32, for example. The main body31is installed on a floor, and crank32is provided with pedals35. Main body31is provided with an electric motor (not illustrated) that rotates crank32. Crank32includes crank shaft33and a pair of crank arms34. Crank shaft33penetrates main body31with axial both ends protruding from main body31. Crank arms34are connected to both ends of crank shaft33and extend perpendicularly to an axial direction of crank shaft33. Pedals35are mounted to ends of crank arms34.

Pedaling exercise machine30is provided with two operation modes including an automatic operation mode and a passive operation mode. In the automatic operation mode, crank32is rotated by the electric motor. In the passive operation mode, crank32is rotated by the pedaling exercise done by a user. During the passive operation mode, the electric motor stops, for example. Pedaling exercise machine30does not necessarily have to operate in the automatic operation mode. In this case, the electric motor is removed from pedaling exercise machine30.

With reference toFIG. 2, an electrical configuration of electrical stimulation apparatus10will be described.

Controller20includes control section21, storage section24, operation section25, operation display section26, and electrical stimulation circuits27.

Control section21executes predetermined control programs. Control section21includes a central processing unit (a CPU) or a micro processing unit (an MPU). Control section21outputs control signals to electrical stimulation circuits27in order to control electrical stimulation circuits27. Accordingly, control section21adjusts outputs from first electrodes12and second electrodes13that give electrical stimulation to lower limbs (legs) doing the pedaling exercise.

Storage section24stores information to be used for various control programs and control processes. Storage section24includes a random access memory (a RAM) and a read only memory (a ROM), for example. Storage section24may be incorporated into control section21.

Operation section25allows a user to set voltages to be applied to first electrodes12and second electrodes13via electrical stimulation circuits27, a period of the pedaling exercise during which the electrical stimulation is given, and an upper limit of a number of times that the electrical stimulation is given. Operation section25enables setting of voltages to be applied to first electrodes12and second electrodes13independently from each other. Hereinafter, the term “set voltage” refers to a voltage being strength of electrical stimulation set through operation section25among voltages applied to first and second electrodes12,13.

Operation display section26includes a liquid crystal panel, for example, and displays the contents set through operation section25and other information.

Electrical stimulation circuits27control the application of voltages to first electrodes12and second electrodes13in supporters11, based on control signals from control section21. Each electrical stimulation circuit27applies pulse voltages to first and second electrodes12,13. As a result, electric currents are output from first electrodes12and second electrodes13.

Control section21includes state detector22and electrical stimulation control section23. State detector22detects states of lower limbs, and a number of revolutions and a rotation speed of crank32. Electrical stimulation control section23controls timings at which the voltages are applied to electrodes12,13in supporters11and levels of the applied voltages.

Angular-velocity calculator22A executes a filtering process on detection signals from each angular velocity detector14using a filter set by filter switch22F so as to remove noise from the detection signals to smooth the detection signals. Angular-velocity calculator22A calculates an angular velocity (referred below as “angular velocities AC”) smoothed in such a manner. One example of this filtering process is a moving-average filtering process.

The detection threshold calculator22B calculates a detection threshold which is used to detect a peak of angular velocity AC, based on angular velocity AC. For example, detection threshold calculator22B acquires a peak of angular velocity AC for each rotation of crank32(seeFIG. 1) within a first period. The first period is a period over which the number of revolutions of crank32is equal to or less than a predetermined number of revolutions RX. The peak of angular velocity AC is a maximum value of angular velocity AC within a range of transition from an increasing state to a decreasing state. Detection threshold calculator22B then sets peak threshold XP, which is used to detect the peak of angular velocity AC, based on a plurality of peaks of angular velocity AC. In one example, detection threshold calculator22B sets the average of the plurality of peak values to peak threshold XP.

Peak detector22C compares angular velocity AC and peak threshold XP. Then, based on the comparison result, peak detector22C detects a peak of angular velocity AC within a second period being a period that comes after the number of revolutions of crank32exceeds the predetermined number of revolutions RX.

Number-of-revolutions calculator22D calculates the number of revolutions of crank32, based on the number of peaks of angular velocity AC. Number-of-revolutions calculator22D resets the number of revolutions of crank32which has been accumulated, when a rotation speed of crank32becomes zero.

Rotation speed calculator22E calculates a rotation speed of crank32, based on angular velocity AC.

A correlation holds between an angular velocity of a lower limb and a rotation speed of crank32. Therefore, storage section24prestores information regarding the relationship between one cycle of angular velocity AC and a rotation speed of the crank32, for example in a function or map format. Based on the information regarding the relationship between one cycle of angular velocity AC and a rotation speed of the crank32, rotation speed calculator22E calculates a rotation speed of crank32from the angular velocity calculated by angular-velocity calculator22A. Note that, for example, rotation speed calculator22E calculates one cycle of angular velocity AC, based on neighboring peaks of angular velocity AC.

Filter switch22F includes a first filter and a second filter. A frequency response curve is steeper in the first filter than the second filter. The first filter provides a larger amount of reference data than the second filter. Each of the first and second filters is a low-pass filter. Note that each of the first and second filters may be a high-pass filter, a band-pass filter, or a resistor-capacitor (RC) filter.

Filter switch22F switches between the first and second filters, based on the number of revolutions of crank32. When the number of revolutions of crank32falls within a first range, filter switch22F switches over to the first filter. When the number of revolutions of crank32falls within a second range that is wider than the first range, filter switch22F switches over to the second filter. As one example, when the number of revolutions of crank32is equal to or less than the predetermined number of revolutions RX, filter switch22F switches over to the first filter. When the number of revolutions of crank32exceeds the predetermined number of revolutions RX, filter switch22F switches over to the second filter.

Immediately after a user starts doing the pedaling exercise, an exercise pace tends to be so unstable that noise is easily caused in a detection signal from each angular velocity detector14. Therefore, when the number of revolutions of crank32is equal to or less than the predetermined number of revolutions RX, angular-velocity calculator22A performs the filtering process using the first filter, thereby removing noise from the detection signal of angular velocity AC. Therefore, angular velocity AC is accurately calculated. After a considerable time has passed since a user has started doing the pedaling exercise, an exercise pace tends to be so stable that noise is hardly caused in a detection signal from each angular velocity detector14. Therefore, when the number of revolutions of crank32exceeds the predetermined number of revolutions RX, angular-velocity calculator22A performs the filtering process using the second filter. Performing this filtering process involves placing a lighter load on control section21than performing the filtering process using the first filter.

Voltage-application timing setting section23A adjusts output timings at which electrodes12,13give electrical stimulation, in accordance with angular velocity AC. Adjusting the timings in this manner enables legs, which are predetermined parts of a body of a user doing the pedaling exercise, to be electrically stimulated when the legs are in a predetermined motion state. In one example, voltage-application timing setting section23A applies a voltage to one of first and second electrodes12,13which is related to the antagonistic muscles. In this case, a load is placed on the antagonistic muscles during the pedaling exercise.

Applied-voltage setting section23B adjusts outputs of first electrodes12and second electrodes13so that the legs, which are predetermined parts of the body of the user doing the pedaling exercise, are electrically stimulated in relation to an exercise unit of the pedaling exercise. Applied-voltage setting section23B adjusts strength of electrical stimulation related to an exercise unit, in accordance with the amount of a physical activity during the pedaling exercise. One example of the amount of a physical activity is the number of revolutions of crank32. One example of an exercise unit is one revolution of crank32. One example of strength of electrical stimulation is magnitude of an applied voltage. Thus, applied-voltage setting section23B sets voltages applied to respective electrodes12,13, based on the number of revolutions of crank32. An applied voltage is set such that its magnitude gradually increases toward the set voltage, in accordance with increase in the number of revolutions of crank32. Note that the exercise unit may be a plurality of revolutions of crank32or a predetermined time of the pedaling exercise.

With reference t toFIGS. 1 and 2, the usage of pedaling exercise system1will be described.

A user sits on seat40and then starts doing the pedaling exercise with pedaling exercise machine30. In this case, the user preferably does the pedaling exercise so that crank32rotates within a recommended rotation speed range of crank32(for example, a range between 30 rpm and 60 rpm per minute, both inclusive). When the number of revolutions of crank32is equal to or less than the predetermined number of revolutions RX, electrical stimulation apparatus10does not apply a voltage to respective electrodes12,13. After the number of revolutions of crank32exceeds the predetermined number of revolutions RX, electrical stimulation apparatus10applies predetermined patterns of voltages to respective electrodes12,13at predetermined timings.

With reference toFIGS. 3 to 7, a method for setting timings of applying voltages to respective electrodes12,13will be described. InFIGS. 6 and 7, lengths of one cycle are equal to each other between angular velocity AC acquired when crank32rotates at a high speed and angular velocity AC acquired when crank32rotates at a low speed, for the purpose of easy understanding in relation to a difference in a phase delay amount of angular velocities AC.

In a graph ofFIG. 3, upper line L2represents a change in an angle of a right knee joint of a user while the user is doing the pedaling exercise. In the graph ofFIG. 3, lower line L1represents a change in an angular velocity detected by angular velocity detector14in supporter11. The angular velocity represented by line L1corresponds to angular velocity AC acquired as a result of the filtering process.

As can be understood from lines L1, L2, a phase difference between the angle of the right knee joint and angular velocity AC. More specifically, the phase of angular velocity AC is delayed from the phase of the angle of the right knee joint. The main cause of this phase delay of angular velocity AC is the filtering process.

In some cases, for example, wobbling of the crank and wobbling of the pedals with respect to the crank arm may cause noise to be superimposed on angular velocities detected by angular velocity detectors14. Further, when a distance between seat40and pedaling exercise machine30differs from a recommended distance, noise may be overlapped on angular velocities detected by angular velocity detectors14. The recommended distance is set so that the user can do the pedaling exercise easily. For these reasons, when calculating angular velocity AC, electrical stimulation apparatus10removes noise from an angular velocity detected by each angular velocity detector14using the first and second filters to smooth the angular velocity. Solid line LF drawn on a graph inFIG. 4shows one example of a frequency response of the second filter. Solid line LP drawn on a graph inFIG. 5shows one example of a phase characteristic of the second filter.

When angular velocity AC is calculated by the filtering process, the frequency response (phase characteristic) of the filter influences more strongly a phase delay of angular velocity AC with respect to an angle of the right knee joint as the rotation speed of crank32becomes higher. InFIG. 4, for example, at frequency GL, line LF indicates a decrease in the amplitude of angular velocity AC with respect to the angular velocity detected by each angular velocity detector14when crank32rotates at a low speed. InFIG. 5, at frequency PL, line LP indicates a phase delay of angular velocity AC with respect to the angular velocity detected by each angular velocity detector14when crank32rotates at a low speed. InFIG. 4, likewise, at frequency GH, line LF indicates a decrease in the amplitude of angular velocity AC with respect to the angular velocity detected by each angular velocity detector14when crank32rotates at a high speed. InFIG. 5, at frequency PH, line LP indicates a phase delay of angular velocity AC with respect to the angular velocity detected by each angular velocity detector14when crank32rotates at a high speed. As illustrated inFIG. 5, the phase delay of the second filter increases with an increase in a frequency. This causes the phase delay of angular velocity AC to increase with an increase in a rotation speed of crank32. As a result, as shown on graphs regarding temporal transition of angular velocity AC inFIGS. 6 and 7, the phase delay of angular velocity AC is smaller when crank32rotates at a low speed than when crank32rotates at a high speed. As can be understood fromFIGS. 6 and 7, ratio X for a high-speed rotation of crank32is lower than ratio X for a low-speed rotation of crank32, and ratio Y for a high-speed rotation of crank32is lower than ratio Y for a low-speed rotation of crank32. Details of the ratios X and Y will be described later.

Therefore, voltage-application timing setting section23A sets timings at which voltages are applied to respective electrodes12,13in accordance with a degree of the phase delay of angular velocity AC caused by the filtering process and a degree of the phase delay of angular velocity AC due to the rotation speed of crank32. More specifically, the relationship between an angular velocity of a lower limb and an angle of a knee joint is predetermined and is prestored in storage section24. Voltage-application timing setting section23A sets timings at which voltages are applied to respective electrodes12,13, based on the relationship between an angular velocity of a lower limb and an angle of a knee joint.

By simultaneously measuring an angular velocity of a lower limb and an angle of a knee joint, a phase difference between the angle of the knee joint and angular velocity AC can be acquired. Then, by simultaneously measuring angular velocities of lower limbs and angles of the knee joints at various rotation speeds of crank32, a degree of the phase difference between angular velocity AC and the angle of the knee joint due to a rotation speed of crank32can be acquired. In the graph ofFIG. 3, line L1represents one example of a measurement result of an angle of a knee joint, and line L2represents one example of a measurement result of an angular velocity of a lower limb. Line L2has a peak (a maximum value) when the knee joint is bent maximally, and has a bottom (a minimum value) when the knee joint stretches maximally.

Storage section24stores the phase differences between lines L1and L2at the peak and bottom of line L2, as the relationships between an angle of a knee joint and an angular velocity of a lower limb. Further, the phase difference between lines L1and L2at the bottom of line L2is stored as a ratio (referred to below as a “ratio X”) of a first phase difference related to one cycle of angular velocity AC. In the present exemplary embodiment, the phase difference between the peak of line L1and the bottom of line L2is stored as a ratio X of a first phase difference related to one cycle of angular velocity AC. The phase difference between lines L1and L2at the peak of line L2is stored as a ratio Y (referred to below as a “ratio Y”) of a second phase difference related to one cycle of angular velocity AC. In the present exemplary embodiment, the phase difference between the peak of line L1and the peak of line L2is stored as ratio Y of a second phase difference related to one cycle of angular velocity AC.

These ratios X, Y are stored in relation to various rotation speeds of crank32. In one example, storage section24stores map MPX and map MPY. Ratio X is related to the rotation speed of crank32in map MPX as illustrated inFIG. 8. The ratio Y is related to the rotation speed of crank32in map MPY as illustrated inFIG. 9. In one example, in map MPX, ratio X decreases with an increase in the rotation speed of crank32. In map MPY, ratio Y decreases with an increase in the rotation speed of crank32.

Note that control section21may calculate ratios X, Y, based on a compensation equation, instead of based on map MPX ofFIG. 8and map MPY ofFIG. 9. Ratio X can be defined as the compensation equation: X=A1×R+B1, where R denotes a rotation speed, A1denotes gradient of the straight line in map MPX ofFIG. 8, and B1denotes an intercept of the straight line. Ratio Y can be defined as the compensation equation: Y=A2×R+B2, where A2denotes gradient of the straight line in map MPY ofFIG. 9, and B2denotes intercept of the straight line.

Voltage-application timing setting section23A sets a timing at which a voltage is applied to first electrodes12, based on map MPX ofFIG. 8and a current rotation speed of crank32. Likewise, voltage-application timing setting section23A sets a timing at which a voltage is applied to second electrodes13, based on map MPY ofFIG. 9and a current rotation speed of crank32. As a result, when a lower limb stretches maximally during the pedaling exercise, voltage-application timing setting section23A starts applying a voltage to the corresponding first electrodes12but stops applying a voltage to the corresponding second electrodes13. When a lower limb is bent maximally during the pedaling exercise, voltage-application timing setting section23A starts applying a voltage to the corresponding second electrodes13but stops applying a voltage to the corresponding first electrodes12. In this way, electrical stimulation apparatus10can electrically stimulate quadriceps and biceps femorises at appropriate timings during the pedaling exercise. Furthermore, electrical stimulation apparatus10sets ratios X, Y in accordance with a rotation speed of crank32. This can electrically stimulate quadriceps and biceps femorises at appropriate timings, in accordance with the pedaling exercise.

Further, over every first voltage-application period T1(seeFIG. 3), voltage-application timing setting section23A applies a voltage to first electrodes12but does not apply a voltage to second electrodes13. Over every second voltage-application period T2(seeFIG. 3), voltage-application timing setting section23A applies a voltage to second electrodes13but does not apply a voltage to first electrodes12. As illustrated inFIG. 3, first voltage-application period T1corresponds to a time length between the application of the voltage to first electrodes12and the application of the voltage to second electrodes13. Second voltage-application period T2corresponds to time length between the application of the voltage to second electrodes13and the application of the voltage to first electrodes12. Applying voltages in first application period T1and second application period T2in this manner enables a quadriceps femoris and biceps femoris to be electrically stimulated over the respective periods in which the quadriceps femoris and the biceps femoris stretch respectively.

A method for setting voltages applied to first and second electrodes12,13will be described.

Storage section24stores information regarding the relationship between the number of revolutions of crank32and the voltages applied to respective electrodes12,13. When the number of revolutions of crank32is equal to or less than the predetermined number of revolutions RX, no voltages are applied to first and second electrodes12,13. According to this information, when the number of revolutions of crank32exceeds the predetermined number of revolutions RX, voltages are applied to first and second electrodes12,13. When the number of revolutions of crank32becomes RX+1, an initial voltage lower than the set voltage is applied to first and second electrodes12,13. Then, as the number of revolutions of crank32increases, the applied voltage gradually increases toward the set voltage. In this way, a load on each leg gradually increases during the pedaling exercise, at the start of the rotation of pedals35. This suppresses the quadriceps and biceps femorises from bearing heavy loads suddenly. Consequently, user discomfort due to an increase in the load of the pedaling exercise can be suppressed.

FIG. 10illustrates one example of the above information. As can be understood fromFIG. 10, when the number of revolutions of crank32is equal to or less than five, no voltages are applied to respective electrodes12,13. When the number of revolutions of crank32exceeds six, a voltage is applied to respective electrodes12,13. Further, when the number of revolutions of crank32is six, a voltage lower than the set voltage is applied to respective electrodes12,13. In the voltage application pattern inFIG. 10, the initial voltage applied when the number of revolutions of crank32is six is about 50% of the set voltage. When the number of revolutions of crank32falls within a range between seven and eleven, every time the number of revolutions of crank32increases by one, the voltage applied to respective electrodes12,13increases by about 10%.

Storage section24prestores magnitude of the voltage applied to first electrodes12over first voltage-application period T1and magnitude of the voltage applied to second electrodes13over second voltage-application period T2.FIG. 11illustrates an example of these applied voltage values. As can be understood fromFIG. 11, voltages applied to respective electrodes12,13gradually increase during first half parts including start points of voltage-application periods T1, T2. Then, after the first half parts of voltage-application periods T1, T2have passed, the voltages applied to respective electrodes12,13are kept constant. Upper limit values of the voltages applied to electrodes12,13over voltage-application periods T1, T2are upper limit values of voltages illustrated inFIG. 10. Operation section25can change increasing rates of the voltages applied to respective electrodes12,13according to an increase in the number of revolutions of crank32, and increasing rates of the voltage applied to electrodes12,13over voltage-application periods T1, T2.

Applied-voltage setting section23B sets the voltages applied to respective electrodes12,13at each number of revolutions of crank32using the voltage-application pattern inFIG. 10. In addition, applied-voltage setting section23B sets voltages applied to electrodes12,13over first voltage-application period T1and second voltage-application period T2using the voltage-application patterns inFIG. 11.

In this way, the voltages applied to respective electrodes12,13are set low at the beginning of respective voltage-application periods T1, T2. Then, the voltages gradually increase with time. This further suppresses the quadriceps and biceps femorises from bearing heavy loads suddenly. Consequently, user discomfort due to an increase in the load can be further suppressed.

In this case, first voltage-application period T1and second voltage-application period T2are shorter when crank32rotates at a high speed than when crank32rotates at a low speed. However, the voltages applied to first electrodes12and second electrodes13have constant frequencies. Therefore, after the number of revolutions of crank32exceeds eleven, ratios in which the set voltage is applied to respective electrodes12,13are lower when crank32rotates at a high speed than when crank32rotates at a low speed. In this case, the ratio in which the voltage applied to first electrodes12is expressed by the equation: (a time when the set voltage is applied to first electrodes12during every first voltage-application period T1)/(first voltage-application period T1)×100. The ratio in which the voltage is applied to second electrodes13is expressed by the equation: (a time when the set voltage is applied to second electrodes13during second voltage-application period T2)/(second voltage-application period T2)×100.

Therefore, applied-voltage setting section23B adjusts increasing rates of the voltages applied to respective electrodes12,13during voltage-application periods T1, T2in accordance with the rotation speed of crank32. More specifically, applied-voltage setting section23B increases the increasing rates of the voltages applied to respective electrodes12,13with an increase in the rotation speed of crank32. Storage section24stores information regarding the relationship between the rotation speed of crank32and the increasing rates of the voltages applied to respective second electrodes12,13. This information may be stored in storage section24in a map format as illustrated inFIG. 12or in a function format. In this exemplary embodiment, the increasing rate of the voltage applied to first electrodes12over first voltage-application period T1is equal to the increasing rate of the voltage applied to second electrodes13over second voltage-application period T2. Thus, a single common map illustrated inFIG. 12is used in the relationship between the rotation speed of crank32and the increasing rates of the voltages applied to respective electrodes12,13. Applied-voltage setting section23B sets, using the map, for example as illustrated inFIG. 12, the increasing rates of the voltages applied to respective electrodes12,13in accordance with the rotation speed of crank32. This setting can reduce or reduce to zero the difference in ratio between the set voltage applied to respective electrodes12,13when crank32rotates at a high speed and when crank32rotates at a low speed.

Various processes performed by control section21will be described below with reference toFIGS. 13 to 15.

Control section21performs a first process, a second process, and a third process. In the first process, control section21detects peaks of angular velocity AC within the period between a time when the pedaling exercise is started by a user and when the number of revolutions of crank32becomes the predetermined number of revolutions RX. In the second process that follows the first process, control section21sets timings at which voltages are applied to respective electrodes12,13. In the third process that follows the first process, control section21sets magnitude of voltages applied to respective electrodes12,13. The second process and the third process are simultaneously performed.

FIG. 13illustrates steps of the first process. Control section21acquires a peak of angular velocity AC at step S11. The peak of angular velocity AC is stored in storage section24. Control section21determines at step S12whether the number of revolutions of crank32reaches the predetermined number of revolutions RX. When determining that the number of revolutions of crank32does not yet reach the predetermined number of revolutions RX, control section21returns this process to step S11. When determining that the number of revolutions of crank32reaches the predetermined number of revolutions RX, control section21calculates peak threshold XP from the plurality of peaks of angular velocity AC at step S13, and terminates the first process. In this process, after acquiring peaks of angular velocity AC when the number of revolutions of crank32reaches the predetermined number of revolutions RX, control section21calculates peak threshold XP.

FIG. 14illustrates steps of the second process. The second process for a right lower limb will be described with reference toFIG. 14. Note that the similar steps are applied to the second process for a left lower limb.

Control section21acquires a rotation speed of crank32at step S21. At step S22, control section21calculates ratios X, Y from the rotation speed of crank32, using maps MPX, MPY. Accordingly, timings at which voltages are applied to respective electrodes12,13are set. Control section21determines at step S23whether the timing at which the voltage is applied to first electrodes12comes. When determining that the timing at which the voltage is applied to first electrodes12comes, the control section21outputs a control signal for applying the voltage to first electrodes12to electrical stimulation circuit27at step S24. However, the control section21does not output a control signal for applying the voltage to second electrodes13to electrical stimulation circuit27. As a result, first electrodes12start giving electrical stimulation to the quadriceps femoris. When the number of revolutions of crank32is RX+1, second electrodes13do not start giving electrical stimulation to the biceps femoris. When the number of revolutions of crank32exceeds RX+2, namely, after the voltage is started being applied to second electrodes13, second electrodes13stops giving electrical stimulation to the biceps femoris.

When determining that the timing at which a voltage is applied to first electrodes12does not yet come, control section21determines at step S25whether the timing at which the voltage is applied to second electrodes13comes. When determining that the timing at which the voltage is applied to second electrodes13comes, at step S26control section21outputs the control signal for applying the voltage to second electrodes13to electrical stimulation circuit27. However, the control section21does not output the control signal for applying the voltage to first electrodes12to electrical stimulation circuit27. As a result, second electrodes13starts giving electrical stimulation to the biceps femoris, whereas first electrodes12stop giving electrical stimulation to the quadriceps femoris.

When determining at step S25that the timing at which the voltage is applied to second electrodes13does not yet come, at step S27control section21maintains a control state of the voltages to first and second electrodes12,13.

Control section21determines at step S28whether the pedaling exercise is terminated. Control section21makes the determination at step S28, based on the period of the pedaling exercise which has been set by operation section25. When determining that the pedaling exercise is not terminated, the control section21returns this process return to step S21. When determining that the pedaling exercise is terminated, the control section21terminates the second process.

FIG. 15illustrates steps of the third process. Control section21determines at step S31whether either of the timings at which the voltages are applied to electrodes12,13comes. When determining that either of the timings at which the voltages are applied to respective electrodes12,13comes, at step S32control section21calculates the number of revolutions of crank32at this time. At step S33, control section21sets magnitude of a voltage applied to first electrodes12or second electrodes13, whose voltage application timing comes, based on the number of revolutions of crank32.

At step S34, control section21calculates a rotation speed of crank32. At step S35, control section21calculates an increasing rate of the voltage applied to ones of first electrodes12or second electrodes13, whose voltage application timing comes, based on the rotation speed of crank32. At step S36, control section21sets magnitude of the voltage applied to first electrodes12or second electrodes13, whose voltage application timing comes, based on the increasing rate calculated at step S35.

Control section21determines at step S37whether the pedaling exercise is terminated. When determining that the pedaling exercise is not terminated, control section21returns this process to S31. When determining that the pedaling exercise is terminated, control section21terminates the third process.

When determining at step S31that neither of the timings at which the voltage is applied to first electrodes12and at which the voltage is applied to second electrodes13comes, control section21maintains the present patterns of the voltages applied to respective electrodes12,13at step S38so as to proceed to the determination at step S37.

Second Exemplary Embodiment

Electrical stimulation apparatus100according to the second exemplary embodiment differs from electrical stimulation apparatus10according to the first exemplary embodiment in setting reference points of ratio X of a first phase difference and ratio Y of a second phase difference. In other respects, electrical stimulation apparatus100according to the second exemplary embodiment employs a substantially same configuration as the configuration of electrical stimulation apparatus10according to the first exemplary embodiment. Here, the components common to the components of electrical stimulation apparatus10according to the first exemplary embodiment will be assigned the same reference numerals to describe electrical stimulation apparatus100according to the second exemplary embodiment. Description of the common components will be partially or entirely omitted.

Electrical stimulation apparatus100according to the present exemplary embodiment will be described below, focusing on the difference from the first exemplary embodiment.

As illustrated inFIG. 3, electrical stimulation apparatus10according to the first exemplary embodiment sets reference point Z1of the ratio (ratio X) of the first phase difference and the ratio (ratio Y) of the second phase difference to a peak of line L1. Electrical stimulation apparatus100according to the present exemplary embodiment sets reference point Z2of the ratio (ratio X) of the first phase difference and the ratio (ratio Y) of the second phase difference to a point different from peak Z1of line L1.

A method for setting reference point Z2of the ratio (ratio X) of the first phase difference and the ratio (ratio Y) of the second phase difference according to the present exemplary embodiment will be described below.

FIG. 16illustrates a change in one cycle of an angular velocity of users1to7(seven people) when crank32rotates forward. A vertical axis indicates a normalized amplitude, and a horizontal axis indicates a lapse of time. As illustrated inFIG. 16, near a peak of an angular velocity waveform (area A) and before a peak (area B), the angular velocity waveform significantly varies between the users. When angular velocities corresponding to area A and area B in which the angular velocity waveform significantly varies are set to reference point Z2of the ratio (ratio X) of the first phase difference and the ratio (ratio Y) of the second phase difference, adjustment accuracy of an electrical stimulation output timing is likely to deteriorate.

In area C which is an area in which the angular velocity waveform lowers from a peak to a bottom, the angular velocity waveform varies little between the users. When angular velocities corresponding to area C in which the angular velocity waveform varies little are set to reference point Z2of the ratio (ratio X) of the first phase difference and the ratio (ratio Y) of the second phase difference, adjustment accuracy of an electrical stimulation output timing improves.

In this regard, control section21stores in advance a reference point determination condition (e.g., an angular velocity corresponding to 0.8 of a normalized amplitude) of the reference point of the ratio (ratio X) of the first phase difference and the ratio (ratio (ratio Y) of the second phase difference. Further, control section21determines whether or not a value of the measured angular velocity satisfies the reference point determination condition during pedaling exercise, and determines a point that satisfies the determination condition as the reference point. In this regard, the reference point determination condition stored in advance in control section21is determined according to the following method, for example. The degree of variation of the angular velocity waveform in each area is measured by using a standard deviation of a value of a time of each user corresponding to a predetermined amplitude. Further, the angular velocity of an area of a small degree of variation of the angular velocity waveform is determined according to the determination condition of reference point Z2of the ratio (ratio X) of the first phase difference and the ratio (ratio Y) of the second phase difference.

FIG. 17illustrates a change in one cycle of an angular velocity of users1to7(seven people) when crank32rotates backward. A vertical axis indicates a normalized amplitude, and a horizontal axis indicates a lapse of time. As illustrated inFIG. 17, near a peak of an angular velocity waveform (area A) and after a peak (area C), the angular velocity waveform significantly varies between the users. By contrast with this, before the peak (area B), the angular velocity waveform varies little between the users. Hence, during backward rotation of crank32, the angular velocity corresponding to area B may be set to reference point Z3of the ratio (ratio X) of the first phase difference and the ratio (ratio Y) of the second phase difference. Thus, control section21may change the reference point according to a rotation direction of crank32.

In this regard, as illustrated inFIGS. 16 and 17, in an area that is shifted by a predetermined value from the peak and the bottom of the angular velocity waveform, the angular velocity waveform varies little between the users. This is a case where a joint angle of a lower limb is a maximum stretch or a maximum bend, and relates to a small degree of variation.

As described above, the reference point determination condition is determined based on the variation of the change in the angular velocity between a plurality of users. However, the present disclosure is not limited to this. The reference point determination condition can be determined based on the variation of the change in the angular velocity according to a pedal type and a displacement condition. That is, control section21stores the reference point determination condition set based on the variation of a plurality of items of angular velocity data acquired in advance.

Third Exemplary Embodiment

Electrical stimulation apparatus1000according to the third exemplary embodiment differs from electrical stimulation apparatus10according to the first exemplary embodiment in applying a voltage to each of electrodes12,13during a period in which a number of revolutions of crank32is equal to or less than a predetermined number of revolutions RX. In other respects, electrical stimulation apparatus1000according to the third exemplary embodiment includes a substantially same configuration as the configuration of electrical stimulation apparatus10according to the first exemplary embodiment. Here, components common to components of electrical stimulation apparatus10according to the first exemplary embodiment will be assigned the same reference numerals to describe electrical stimulation apparatus1000according to the third exemplary embodiment, and description of the common components will be partially or entirely omitted.

Electrical stimulation apparatus1000according to the present exemplary embodiment will be described below, focusing on the difference from the first exemplary embodiment.

As described above, electrical stimulation apparatus10according to the first exemplary embodiment does not apply the voltage to each of electrodes12,13during a first period in which the number of revolutions of crank32is equal to or less than the predetermined number of revolutions RX. In this case, a user does not feel electrical stimulation while doing pedaling exercise. This may cause the user discomfort.

As illustrated inFIGS. 18 and 19, in electrical stimulation apparatus1000according to the present exemplary embodiment, control section21executes first control of applying the voltage to each of electrodes12,13even during the first period in which the number of revolutions of crank32is equal to or less than the predetermined number of revolutions RX (five rotations in the present exemplary embodiment). Consequently, it is possible to reduce user discomfort. In this regard, control executed by control section21to set a timing of voltage application to each of electrodes12,13by reflecting a degree of phase delay of angular velocity AC due to a rotation speed of crank32described in the first exemplary embodiment will be referred to as second control.

As described below, according to the first control, the voltage is applied to each of electrodes12,13at a timing different from the timing of voltage application to each of electrodes12,13(second control) that reflects the degree of phase delay of angular velocity AC due to the rotation speed of crank32.

A description will now be given of the timing of voltage application to each of electrodes12,13, a magnitude of an applied voltage, and an application period when the number of revolutions of crank32is equal to or less than the predetermined number of revolutions RX (the five rotations in the present exemplary embodiment).

As illustrated inFIGS. 18 and 19, in the present exemplary embodiment, when angular velocity detector14detects a peak value of an angular velocity, the voltage is applied to first electrode12. When angular velocity detector14detects a bottom value of the angular velocity, the voltage is applied to second electrode13. The present disclosure is not limited to this, and an application timing can be freely set.

<Magnitude of Applied Voltage>

The magnitude of the applied voltage may gradually increase as the number of revolutions of crank32increases or may be fixed. Further, the magnitude of the applied voltage may gradually increase in a first half period of the application period and may be fixed after the first half period of the application period passes.

The application period may extend as the number of revolutions of crank32increases as illustrated inFIG. 19or may be fixed irrespectively of the number of revolutions of crank32as illustrated inFIG. 18.

Further, as illustrated inFIGS. 18 and 19, electrical stimulation apparatus1000according to the present exemplary embodiment adjusts an output timing of electrical stimulation according to the degree of phase delay of angular velocity AC and electrically stimulates a predetermined part, as described in the first exemplary embodiment during the second period in which the number of revolutions of crank32is larger than the predetermined number of revolutions RX (the five rotations in the present exemplary embodiment).

Modification

The foregoing exemplary embodiment has provided examples of embodiments of a control device for an electrical stimulation apparatus, an electrical stimulation apparatus, and a pedaling exercise system in the present disclosure, and therefore is not intended to limit the present disclosure. A control device for an electrical stimulation apparatus, an electrical stimulation apparatus, and a pedaling exercise system in the present disclosure may employ embodiments of some modifications of the foregoing exemplary embodiment which will be described below or combinations of two or more of these modifications which are not mutually contradictory.In the foregoing exemplary embodiment, control section21may calculate the number of revolutions and rotation speed of crank32, based on a detection signal from a crank sensor. Moreover, control section21may set voltages applied to respective electrodes12,13, based on the detection signal from the crank sensor.In the foregoing exemplary embodiment, control section21may be provided inside pedaling exercise machine30. In this case, pedaling exercise machine30is electrically connected to first electrodes12, second electrodes13, and angular velocity detectors14in supporters11. Furthermore, controller20and pedaling exercise machine30may be integrated with each other.In the foregoing exemplary embodiment, only one angular velocity detector14may be provided in either of supporters11.In the foregoing exemplary embodiment, state detector22may include a bottom detector that detects a bottom of a detection signal from each angular velocity detector14. Control section21may calculate an amplitude of angular velocity AC from the peak and bottom of angular velocity AC.In the foregoing modification, voltage-application timing setting section23A may set the timings at which the voltages are applied to respective electrodes12,13, based on ratios X, Y preset for the amplitude of angular velocity AC.In the foregoing modification, when the bottom detector is provided to state detector22, peak detector22C do not necessarily have to be provided to state detector22. In this case, control section21calculates one cycle of angular velocity AC, and the number of revolutions and rotation speed of crank32, based on the bottom detected by the bottom detector.In the foregoing exemplary embodiment, control section21may calculate one cycle of angular velocity AC, based on zero crossing points of angular velocity AC, instead of based on neighboring peaks of angular velocity AC.In the foregoing exemplary embodiment, filter switch22F may further include a third filter whose frequency response differs from frequency response of the first filter and the second filter. In this case, filter switch22F may switch between filters, at least once, to smooth an angular velocity detected by angular velocity detector14over the period between the start and the termination of the pedaling exercise done by a user.In the foregoing exemplary embodiment, control section21may compensate for the increasing rates of the voltages applied to respective electrodes12,13which are related to an increase in the number of revolutions of crank32, based on a rotation speed of crank32. Applied-voltage setting section23B makes this compensation so that the increasing rates of the voltages applied to respective electrodes12,13increase with an increase in the rotation speed of crank32. With this compensation, when crank32rotates at a high speed, voltages applied to respective electrodes12,13at a small number of revolutions of crank32are set as their set voltages.In the foregoing exemplary embodiment, applied-voltage setting section23B may set the maximum values of voltages applied to respective electrodes12,13in a variable manner, in accordance with the number of revolutions of crank32. For example, after the set voltages have been applied to respective electrodes12,13, applied-voltage setting section23B may gradually decrease the maximum values of the voltages applied to respective electrodes12,13from the set voltages according as the number of revolutions of crank32increases. Alternatively, applied-voltage setting section23B may vary the maximum values of the voltages applied to respective electrodes12,13, in accordance with the number of revolutions of the crank32.In the foregoing exemplary embodiment, a user may do the pedaling exercise with both arms. In this case, supporters11are attached to the right and left upper arms respectively. In this case, first electrodes12is disposed at a location related to the biceps brachii muscles, for example, whereas second electrodes13is disposed at a location related to the triceps brachii muscles, for example. In addition, angular velocity detector14is disposed at a location related to the biceps brachii muscles, for example.

The electrical stimulation apparatus and the pedaling exercise system of the present disclosure may be applied to any electrical stimulation apparatus and any pedaling exercise system for household use, professional use, or any other uses.