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Method of controlling motor for driving treadmill belt

Method of controlling motor for driving treadmill belt description/claims

1. Field of the Invention

The present invention relates generally to a method for controlling a treadmill and more specifically, to a method of controlling a motor that is used for driving a treadmill belt.

2. Description of the Related Art

A treadmill is a piece of indoors sporting equipment used to allow for the motions of running or walking without traveling any distance outdoors. Basically, a motor-driven treadmill comprises an endless belt on which the user runs or walks, and a motor for driving the endless belt.

The treadmill belt drive motor of a conventional treadmill can be an induction motor, AC motor, or DC motor. When running at a high speed, the treadmill belt drive motor of a conventional treadmill provides a high horsepower. The design of a conventional treadmill is based on the concept that the load from the user is assumed to be linear so that the treadmill belt drive motor drives the treadmill belt at a constant power. However, in actual practice, the load from the user is nonlinear. Every step from the user adds a load to the motor instantaneously. Because the treadmill belt drive motor of a conventional treadmill provides a constant output, the output of the treadmill belt drive motor becomes insufficient during the instant in which the load is changed, causing a sudden speed reduction or cogging of the treadmill, as shown in FIG. 1, and the user will feel unstable. Increasing the power of the treadmill belt drive motor can eliminate the sudden speed reduction or cogging problem. However, when the load from the user is reduced (for example, the user's step becomes light), the power of the treadmill belt drive motor becomes excessively high, and the user may slip and fall. In another word, a conventional treadmill belt drive motor has the drawback of difficult speed change control. High power consumption and high noise level are also the drawbacks of conventional treadmill belt drive motors. Further, increasing the output of the conventional treadmill belt drive motor of a treadmill will relatively increase the power consumption and electricity expense. Therefore, this is not an economic way. Further, the noises produced during operation of the treadmill belt drive motor of a conventional treadmill may bother the user.

To improve the aforesaid problems, an inverter may be installed to control the operation of the treadmill belt drive motor by means of open-loop control, allowing for speed change of the treadmill belt drive motor. However, an inverter for this purpose is expensive. The use of an inverter in a treadmill greatly increases the manufacturing cost. Further, when the frequency of the treadmill belt drive motor of a treadmill is converted to a low speed mode, the output torque of the treadmill belt drive motor is relatively reduced, and a speed reduction or cogging problem will occur at this time. Further, sound absorbing materials may be used in a treadmill and set around the treadmill belt drive motor to reduce the noise level. However, the installation of the sound absorbing materials affects heat dissipation of the treadmill belt drive motor. Accumulation of thermal energy may cause the treadmill belt drive motor to malfunction.

Therefore, it is desirable to provide a treadmill belt drive motor control method that eliminates the aforesaid problems.

The present invention has been accomplished under the circumstances in view. It is one objective of the present invention to provide a method of controlling a motor that is used for driving a treadmill belt, which can adjust the power and speed of the motor subject to the load and make compensation to an instantaneous load, providing the advantages of frequency conversion control and good power stabilization.

To achieve this objective of the present invention, the method of controlling a motor used for driving a treadmill belt comprises the steps of a) providing a micro controller unit having a proportional integral derivative controller and a load predictor; b) providing a driver controllable by the micro controller unit to drive the motor used for driving the treadmill belt; c) detecting a load and a speed of the motor and sending a load feedback signal and a speed feedback signal corresponding to the detections to the micro controller unit by a load meter and a speed meter respectively; d) running a procedure by the micro controller unit and outputting a control signal to the driver by means of computation of the proportional integral derivative controller and the load predictor; e) regulating the output status of the motor by the driver subject to the control signal received; and f) repeating step c) to step e) by the micro controller unit and the driver till end of the procedure.

By means of the aforesaid method, the invention regulates the power and speed of the treadmill belt drive motor subject to the load, and makes compensation to instantaneous load. When compared to conventional treadmill designs, a treadmill constructed according to the present invention has the advantages of frequency conversion control and good power stabilization. By means of the use of a DC brushless motor to substitute for a conventional treadmill belt drive motor, the invention has the advantages of low power consumption, low noise level, and low manufacturing cost.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a plot showing the relationships between user's steps and forces of motor, load and treadmill belt according to the prior art;

FIG. 2 is a flow chart of the method of controlling a motor that is use for driving a treadmill belt according to a preferred embodiment of the present invention;

FIG. 3 is a system block diagram of the preferred embodiment of the present invention;

FIG. 4 is a control block diagram of the preferred embodiment of the present invention;

FIG. 5 is a flow chart showing the operation of the micro controller unit (MCU) according to the preferred embodiment of the present invention; and

• Provisional Patent
• Utility Patent

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