Adaptive Vibration Control for Ski

• US 20140244071A1
• Filed: 10/28/2013
• Published: 08/28/2014
• Est. Priority Date: 03/04/2010
• Status: Active Grant

• Current Assignee: IPCOMM LLC
• Original Assignee: IPCOMM LLC
• Inventors: Czaja, Stanislaw, Afsar, Muhammad, Staszczuk, Grzegorz
• Granted Patent: US 9,020,782 B2
• Time in Patent Office: Days
• US Class Current: 701/2
• CPC Class Codes: A43B 1/0054 provided with magnets, magnetic parts or magnetic substances
• CPC Class Codes: A43B 3/34 with electrical or electronic arrangements
• CPC Class Codes: A43B 5/0415 Accessories A43B5/0403, A43B5/0413, A43B5/0494 take precedence
• CPC Class Codes: A63C 2203/18 Measuring a physical parameter, e.g. speed, distance
• CPC Class Codes: A63C 2203/22 Radio waves emitting or receiving, e.g. remote control, RFID
• CPC Class Codes: A63C 5/06 with special devices thereon, e.g. steering devices
• CPC Class Codes: A63C 9/00 Ski bindings
• CPC Class Codes: G05D 19/02 characterised by the use of electric means
• CPC Class Codes: Y10T 436/11 Automated chemical analysis

Abstract

A method and apparatus for controlling of ski vibration consisting an accelerator/actuator sub-system attached to the ski and a adaptive vibration control application residing in the user smart-phone and communicating with the accelerometer/actuator sub-system over Bluetooth radio interface is disclosed. The adaptive vibration control application extracts vibration frequencies and amplitudes from signal received from an accelerometer, separates such frequencies according to their types—bending or torsional, and after thresholding and scaling by the ski calibration parameters and by the user desired ski response, apply such signal to the control loop and consequently to the actuators to provide vibration dampening force. In one embodiment, such actuators are attached to the ski, while in another embodiment such actuators are embedded into the ski.

Claims

1. A system to actively control vibration of the ski or a snow board comprising:

an accelerometer assembly attached to the ski and consisting of at least a single accelerometer to provide measurements of the ski vibration;

a smart-phone based vibration analyzer, to analyze ski vibration and to generate control signals designed to cancel such vibrations;

an actuator assembly consisting of at least single MEMS actuator for transferring control signals generated by the vibration analyzer into a vibration dampening force; and

a radio interface for transferring measurements and control signals between sensor(s), and an actuator(s), and the smart-phone based adaptive vibration control,

wherein the estimation of ski vibration is provided through a frequency domain analysis of changes in acceleration vectors received form the accelerometer; and

wherein after such estimation is obtained, the vibration analyzer generates an inverse matrices of such frequencies, modifies such matrix by the equipment calibration information and the user information, then generates control signal with a frequency and gain identical to ski vibration but with opposite amplitude; and

wherein upon receiving such control signals the thermo-electrical MEMS actuator embedded in the actuator assembly produce a reactive force proportional does canceling selected vibration frequencies.

2. The method of claim 1, wherein the accelerometer assembly, consisting an accelerometer capable of measuring acceleration vectors with several degrees of freedom, and communicates such measurements to the smart-hone based vibration analyzer using Personal Area Network radio interface is attached to the ski equipment or embedded in said ski equipment.

3. The method of claim 1, wherein the actuator assembly, consisting one or several MEMS actuators capable of producing displacement at the frequency and force required to cancel ski vibration

4. The method of claim 3, wherein said actuator assembly is attached, or embedded in the ski equipment.

5. The method of claim 1, wherein the analysis of ski vibration consists of estimation of ski vibration frequencies, and wherein such vibration frequencies are classified as either fundamental or harmonics frequencies, and wherein all fundamental frequencies are retained while all harmonics frequencies are discarded.

6. The method of claim 1, wherein during such vibration analysis, the retained frequencies are further classified into one of three categories:

a) natural bending frequencies;

b) vibration bending frequencies;

c) torsional bending frequencies.

7. The method of claim 1, wherein during such vibration analysis all natural bending frequencies are discarded, while all the vibration bending frequencies and all torsional bending frequencies with the amplitudes above their respective destructive amplitude thresholds are retained.

8. The method of claim 7, wherein the retained frequencies are converted to time domain, scaled by:

the equipment calibration information; and

the user information, presented as a reference signal to the control loop generating control signals for the actuators.

9. The method of claim 7, wherein such control signal is transmitted to the actuator assembly over the personal area network radio interface, where is transformed into heat causing the thermo-electrical actuators to expand and/or contract, does in effect vibrating with the frequency of ski vibration but with the inverse amplitude and force proportional to the power of ski vibrations.

10. The method of claim 1, wherein the equipment calibration information consist of:

a ski or snowboard design parameters, which among the others includes such information as;

total length, effective length, turning radius, logitudal and torsional stiffness; and

a ski calibration parameters, which among the others includes such information as;

natural deflection due to standard load, natural vibration frequencies and their amplitudes, and natural damping coefficient.

11. The method of claim 1, wherein the user information consist of:

the user physical characteristics, such as;

weight, height;

the user skiing level, for example—

beginner, advanced, and ski response preference parameters, for example—

soft, racing, etc.; and

the slope snow conditions, for example—

hard, ice, powder.

12. The method of claim 10, wherein the ski natural deflection of the ski is obtained by placing the ski on support located at ¼

distance from each end of the ski effective length and applying a load of N₁ [kg] to the point located at ½

of the ski effective length, while recording the ski center deflection; and

wherein, the natural deflection of the ski tip is obtained by placing the support of at the ½

point of the ski effective length and another at the tip-end of the ski effective length, then applying a standard load of N₂ [kg] at the ½

distance between the ½

point of the ski effective length and the tip-end of the ski effective length, while recording deflection of ski tip section.

13. The method of claim 10, wherein the center ski natural vibration frequencies and their amplitudes are obtained by placing the ski on support located at ¼

distance from each end of the ski effective length, then applying and instantaneously releasing load of N₁ [kg] to the point located at ½

of the ski effective length, while recording ski center vibration frequencies and amplitudes; and

wherein, the ski tip natural vibration frequencies and their amplitudes are obtained by placing the support of at the ½

point of the ski effective length and another at the tip-end of the ski effective length, then applying and instantaneously releasing load of N₂ [kg] at the ½

distance between the ½

point of the ski effective length and the tip-end of the ski effective length, while recording ski tip vibration frequencies and amplitudes.

14. An apparatus to control ski vibration consisting of:

a multi-axes accelerometer attached to the ski providing measurements of magnitude and direction of acceleration of the ski surface;

means for wirelessly receiving magnitude and direction of the acceleration from an accelerometer;

means estimate ski vibration frequencies and their amplitudes, and to generate control signal intended for cancellation of such vibration;

means for wirelessly transmitting control signals to the actuators attached to the ski equipment; and

an actuator subsystem consisting of a single or multiplicity of thermo-electrical actuators,

wherein, the acceleration vectors received from accelerometer are translated to the frequency domain, and after extraction of fundamental vibration frequencies and appropriate thresholding of the vibration amplitudes, the residual frequencies are converted to the time domain, scaled by the ski calibration information and the user information, then applied to the control loop for the generation of the control signal intended to cancel ski vibration; and

wherein upon reception of the control signal, the thermo-electrical actuators provide linear expansion does producing force for the extension cores coupled to the actuators does canceling ski vibration.

15. The method of claim 14, wherein the number and orientation of actuator/extension core assemblies inside the actuator subsystem may be logitudal for canceling only the bending vibrations or longitudinal and transversal, or longitudinal and transversal, or any combination thereof, for canceling of both the bending and the torsional vibrations.

16. The method of claim 14, wherein the actuator subsystem is attached to the ski or embedded into the ski core.

17. The method of claim 14, wherein the ski vibration damping coefficient is scaled by the ski calibration information and the user information before it is applied as a reference to produce the vibration control signal.

18. A computer accessible memory medium for storing program instruction for operating a ski vibration control, wherein the program instructions are executable to:

retrieve magnitudes and amplitudes of acceleration form multi-axes accelerometer using short-range wireless link;

perform analysis of such acceleration vector in order to estimate ski vibration;

scaling of the residual vibration estimates by the;

first, second and third information, then applying such result as a reference signal for the actuator control loop; and

transmitting the resulting control signal to the actuators,

wherein the first information consist of ski design parameters, wherein the second information consists of ski calibration parameters, and wherein the third information consists of user physical and preference parameters.

19. The memory medium of 18, wherein the vibration analysis consists of:

performing of an DFT (Discrete Fourier Transform) of the time domain samples received form an multi-axes accelerometer to estimate vibration frequencies and their respective amplitudes;

retaining all fundamental frequencies while discarding all harmonic frequencies;

storing the bending frequencies, and the torsional frequencies in their respective frequency bins;

applying bending and torsional thresholds to the respective frequency bins and discarding all frequencies with amplitudes falling below the respective thresholds;

adding the remaining frequency matrixes and generate the time domain representation of the result through the IDFT (Inverse Discrete Fourier Transform).

20. The memory medium of 18, wherein the scaled estimates of the is applied to a 2^nd order control loop as a reference to control loop generating control signals canceling such residual vibration.