US20210268329A1

US20210268329A1 - Device for physical exercise

Info

Publication number: US20210268329A1
Application number: US17/261,238
Authority: US
Inventors: Mauro Fantin
Original assignee: TEXA SpA
Current assignee: TEXA SpA
Priority date: 2018-07-19
Filing date: 2019-07-11
Publication date: 2021-09-02
Also published as: IT201800007356A1; WO2020016712A1; EP3823733A1

Abstract

To improve the dynamic response, a method is described for managing a physical exercise device (10) comprising an endless belt (16) to create a track on which a user (U) can walk or run, and an electric motor (30) to slide the belt.The method has the steps of controlling the driving torque applied by the electric motor (30) to the belt (16) so that the driving torque is proportional to the force component (F), or to the torque, which the user imparts on the belt (16) to advance on the belt (16).

Description

The present invention relates to a device for physical exercise having an endless walkable surface, and more particularly to a treadmill having a motorized endless belt.
The most simple treadmills are usually motorized, with the speed of the belt being adjustable by the user.
Other more sophisticated motorized treadmills, which do not require the user to manually adjust the speed of the belt, can be classified into two types. The first type adjusts the belt speed as a function of the user's biological functions while the second type adjusts the belt speed as a function of the user's position relative to the treadmill.
The most common variety of the first type automatically controls the belt speed as a function of the user's heart rate, see e.g. U.S. Pat. No. 3,518,985.
The treadmills of the second type allow the user to adjust the speed of the belt simply by changing his pace, thereby more closely simulating natural conditions. See e.g. FR 1,565,617, U.S. Pat. Nos. 1,919,627 and 4,708,337.
In FR 1565617 there are sensors at the sides of the treadmill to detect the user's location. Each sensor consists of a photocell. U.S. Pat. No. 1,919,627 implements an automatic control based on the user's body position with respect to an electrostatic sensor attached to the treadmill. In U.S. Pat. No. 4,708,337 the belt is driven by a motor automatically controlled by the user's body position detected by an ultrasonic sensor mounted on the control panel.
However, all these models have the great disadvantage of only approximately simulating the stress of a real walk or run. It is a fact that the same distance travelled without a treadmill involves a much greater energy expense, because the treadmill facilitates too much the stride and the athlete must not shift his weight forward but only lift it temporarily.
The main object of the invention is to improve this state of the art.
Other main object of the invention is to provide a device for physical exercise having an endless walkable surface, more particularly a treadmill having a motorized endless belt, which simulates more closely the conditions of running or walking on the ground.
These and other objects are achieved by a device according to claim 4; other advantageous technical features are defined in the dependent claims.
A first aspect of the invention is a method for managing a physical exercise device comprising
an endless belt to create a track on which a user can walk or run,
an electric motor to slide the belt,
with the steps of
controlling the driving torque applied by the electric motor to the belt so that the driving torque is proportional to the force component, or to the torque, which the user imparts on the belt to advance on the belt.
Another aspect of the invention is a device for physical exercise comprising:

- an endless belt to create a track on which a user can walk or run,
- an electric motor to slide the belt,
- a sensor for generating an electrical signal indicative of the force component, or indicative of the torque, that the user imparts on the belt for advancing on the belt,
- an electronic circuit configured for
  - reading the sensor's signal, and
    - controlling the driving torque applied by the electric motor to the belt so that the driving torque is proportional to said component or said torque imparted by the user.

The motor is preferably controlled only as a function of the force component or torque alone, discharged by the user on the belt, which is responsible for the forward motion for walking or running (the weight force is e.g. neglected because orthogonal to the motion).
To evaluate the torque or force applied by the user e.g. the vector component of the force that the user imparts on the belt is measured, component of which—in particular—the weight is only a part. The dynamic force generated by the muscles of the legs is added to the weight and thus the total thrust vector is determined.
The user's weight force is preferably measured to evaluate only, or also, the physical stress and/or the actual calories consumed.
To evaluate the torque imparted by the user on the belt, preferably the torque imparted on a roller or on an axle that supports the belt is measured, by means of e.g. a rotating torsiometer or a generic torque sensor.
A variant provides to control the motor by measuring only the weight of the person, that is, the force exerted on the belt and directed downwards. Since between weight and force of tangential thrust there is enough proportionality, the force or torque imparted on the belt can be calculated or indirectly estimated from the weight.
The motor's torque, being proportional to said force or torque impressed by the user, returns to the belt (and to the foot) a force proportional to that imparted by the user.
The control of driving torque applied by the electric motor to the belt is open to many variations, all included in the general inventive concept of the method or device.
According to a first preferred variant, the driving torque is regulated for transmitting to the belt a force or torque in the same direction to said force or torque generated by the user. In this way, the motor assists the stride, which is facilitated (useful condition e.g. for elderly or disabled people during recovery therapies of the lower limbs).
According to a second preferred variant, the driving torque is adjusted to transmit to the belt a force or torque having a direction opposite to that of said force or torque generated by the user. In this way the motor opposes the stride, and simulates e.g. an uphill or the actual response of a ground. Preferably in these variants the electronic circuit is configured to, or the microprocessor is programmed to, execute the motor control according to the above logic.
To simplify the detection, there is detected a force imparted by the user along a direction parallel to the sliding direction of the belt and/or a direction parallel to that of the supporting surface on which the device is placed.
E.g. said force is detected at a point located between the device and the floor, and/or
on and/or under the surface of the belt, and/or
on the user's shoes.
Preferably, the electric motor is an axial-flux motor.
The sensor can be realized in many ways. E.g. with
one or more load cells placed between the device and the floor, and/or
one or more load cells placed on and/or under the belt, and/or
one or more load cells placed in the user's shoes and communicating with the electronic circuit e.g. by wireless radio means.
Each load cell may be replaced e.g. even by a strain gauge or a pressure sensor.
The electronic circuit is preferably a microprocessor, but it is also possible to implement it with a discrete-component circuit board. The microprocessor is programmable and allows great freedom to implement intelligent functions.
Preferably the device comprises a low-pass filter for filtering the signal generated by the sensor before sending it to the electronic circuit. The sensor is likely to emit a pulse signal with peaks at the instants when the foot leans, while the signal will be smaller or zero when the user is “in flight” over the belt. The filter is configured e.g. to level the signal and/or to extract the average thereof or however to restrict the signal to less fluctuating values. E.g. a peak detector can also be used.
The filter may be implemented in the digital domain by programming the microprocessor.
Preferably the device comprises a user interface, such as e.g. a touch-screen or a keyboard, configured to detect a user selection directed to adjust the value of a constant of proportionality between the torque transmitted to the belt and the force generated by the user. The electronic circuit may detect the user's selection and in accordance with the proportionality constant regulates the driving torque of the motor transmitted to the belt. As mentioned, the proportionality constant can be positive or negative.
Another aspect of the invention is a program that, when loaded into a processor, performs one or each activity or method step as defined above.

Further advantages will become apparent from the following description, which refers to a preferred embodiment in which:

FIG. 1 shows a diagram of a treadmill.

A treadmill 10 is illustrated schematically in FIG. 1, and comprises a base frame 14 on which are mounted two rollers 12 which support a well-known endless belt 16 on which a user U can place his feet P in the act of walking or running on the spot.
The base frame 14 rests on a floor T through feet 18, on or in or under which are mounted one or more load cells 22.
At least one of the two rollers 12 is coupled with an electric motor 30 for receiving rotary motion and move the belt 16.
The electric motor 30 is controlled by a microprocessor 40 through known power electronics stages (not shown), e.g. an inverter. The arrows in FIG. 1 indicate signal lines.
The microprocessor 40 is also connected to the load cells 22, to read the emitted signals therefrom, and to an (optional) data input user interface 50, e.g. a touchscreen. Through the user interface 50 the user can program a proportionality constant, useful for adjusting the operation of the treadmill 10.
The cells 22 are installed so as to emit a signal indicative of the force that a foot P of a user U exerts onto the belt 16 during the exercise. From the measured force the weight of the user U is disregarded, while only the component F parallel to the surface of the belt 16 and/or to the surface of the floor T is considered. One may also measure a different force or at different points, and extract or calculate therefrom the component F parallel to the belt surface 16 and/or to the floor T's surface.
The cells 22 may be replaced by any sensor capable of generating an electrical signal proportional to or indicative of the component of the thrust generated by the foot P which, on the floor T and without the treadmill 10, would move the user U's body forward. To this force, as explained below, the device reacts by generating a proportional force or torque on the belt 16.
In the microprocessor 40 the signal generated by the cells 22 is compared in a circuit 42 with a signal which expresses the proportionality constant entered with the user interface 50. The comparison is e.g. a subtraction to generate an error term.
The result of the circuit 42 is processed by a gain stage 44 which emits control signals for the electric motor 30 so that the latter develops a certain torque and imposes a force to the endless belt 16 in dependence of the signal emitted by the circuit 42.
Preferably, for greater accuracy, the electric motor 30 is also feedback controlled thanks to a signal line 32 which returns to the stage 44 a feedback signal from the electric motor 30.
As it can be seen, the microprocessor 40 implements a feedback control in which the proportionality constant entered with the user interface 50 becomes a reference signal for adjusting the torque imparted by the electric motor 30 to the endless belt 16. Then, according to the value of this proportionality constant, the electric motor 30 can impart to the endless belt 16 a force opposite to that imparted by a foot P (resistance to the stride), or a force in the same direction (assistance to the stride).
In another exemplary embodiment, the circuit 42 is a multiplication block, in which the signal coming from the cells 22 is multiplied by the constant of proportionality. The result of the multiplication is input to the stage 44 as a torque reference for the motor 30. The stage 44 then acts on the motor 30 for making it develop a torque which tracks the reference.
Since the cells 22 generate a pulse signal, with peaks having cadence of the stride, it is preferable to filter it with a low pass filter 52, e.g. a digital filter implemented numerically in the microprocessor 40. Thus, the torque reference for the motor 30 has a less oscillatory trend.

Claims

1. Method for managing a physical exercise device (10) comprising an endless belt (16) to create a track on which a user (U) can walk or run, and an electric motor (30) to slide the belt,

with the steps of

controlling the driving torque applied by the electric motor (30) to the belt (16) so that the driving torque is proportional to the force component (F), or to the torque, which the user imparts on the belt (16) to advance on the belt (16).

2. Method according to claim 1, wherein the driving torque is regulated to transmit to the belt a force or torque that has equal direction as said force or torque generated by the user.

3. Method according to claim 1, wherein the driving torque is regulated to transmit to the belt a force or torque having opposite direction to that of said force or torque generated by the user.

4. Physical exercise device (10) comprising:

an endless belt (16) to create a track on which a user (U) can walk or run,

an electric motor (30) to slide the belt,

a sensor (22) for generating an electrical signal indicative of the force component, or indicative of the torque, that the user imparts on the belt for advancing on the belt,

an electronic circuit (40) configured for

reading the sensor's signal, and

controlling the driving torque applied by the electric motor (30) to the belt (16) so that the driving torque is proportional to said component or said torque imparted by the user.

5. Device according to claim 4, wherein the electronic circuit (40) is configured to regulate the driving torque so as to transmit to the belt (16) a force or torque that has same direction as said force or torque generated by the user.

6. Device according to claim 4, wherein the electronic circuit (40) is configured to regulate the driving torque so as to transmit to the belt (16) a force or torque having opposite direction to that of said force or torque generated by the user.

7. Device according to claim 4, wherein the sensor (22) is configured to detect a force imparted by the user along a direction (F) parallel to the sliding direction of the belt and/or a direction parallel to that of the supporting surface (T) on which the device is placed.

8. Device according to claim 4, wherein the sensor (22) is placed at a point located between the device and the supporting surface (T), and/or on and/or below the surface of the belt, and/or on the user's shoes.

9. Device according to claim 4, wherein the sensor (22) is a load cell, or a strain gauge or a pressure sensor.

10. Device according to claim 4, comprising a low-pass filter for filtering the signal generated by the sensor before sending it to the electronic circuit.