System and method for load sensing

• US 5,488,872 A
• Filed: 06/17/1993
• Issued: 02/06/1996
• Est. Priority Date: 06/17/1993
• Status: Expired due to Fees

• Current Assignee: Delaware Capital Formation Incorporated (Dover Corporation)
• Original Assignee: EOA Systems, Incorporated (Dover Corporation)
• Inventors: McCormick, Peter
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): BIEGEL, RONALD L
• Application Number:
  US08/079,091
• Time in Patent Office: 964 Days
• Field of Search: 73/DIG. 4, 73/862.06, 73/862.041, 73/862.043, 73/862.68
• US Class Current: 73/862.68
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: G01L 5/226 to manipulators, e.g. the force due to gripping

Abstract

An intelligent load sensing system employs a piezoelectric sensor and digital processor for providing accurate sensing of loads, collisions, and vibrations.

Claims

1. A load sensing system comprising:

a piezoelectric sensor for generating a signal in response to an applied force;

amplifier means, coupled to the piezoelectric sensor, for conditioning the signal generated by the piezoelectric sensor;

processing means, coupled to the amplifier means, for interpreting the conditioned signal in accordance with a predetermined series of comparisons of the signal with threshold values, and for indicating results therefrom;

wherein the piezoelectric sensor comprises;

a first plate;

a length of piezoelectric cable in contact with the first plate;

a second plate disposed adjacent to the first plate and in contact with the piezoelectric cable so that the piezoelectric cable is compressed between the first and the second plates;

a charge amplifier having an input and an output, the input being coupled to the piezoelectric sensor; and

,

a gain amplifier having first and second inputs and an output, the first input coupled to the output of the charge amplifier, the second input coupled to the processing means for accepting an adjustable bias voltage, and the output of the gain amplifier coupled to the processing means for delivering a conditioned signal proportional to the piezoelectric signal.

2. The load sensing system as recited claim 1, wherein the processing means includes an analog to digital converter port coupled to the output of the gain amplifier for digitizing the conditioned signal.

3. A load sensing system comprising:

a piezoelectric sensor for generating a signal in response to an applied force;

amplifier means, coupled to the piezoelectric sensor, for conditioning the signal generated by the piezoelectric sensor;

processing means, coupled to the amplifier means, for interpreting the conditioned signal in accordance with a predetermined series of comparisons of the signal with threshold values, and for indicating results therefrom;

wherein the piezoelectric sensor comprises;

a first plate;

a length of piezoelectric cable in contact with the first plate;

a second plate disposed adjacent to the first plate and in contact with the piezoelectric cable so that the piezoelectric cable is compressed between the first and the second plates; and

,

wherein the processing means includes a pulse width modulation output coupled to the amplifier means, for providing a D.C. bias offset voltage.

4. A load sensing system comprising:

a piezoelectric sensor for generating a signal in response to an applied force;

amplifier means, coupled to the piezoelectric sensor, for conditioning the signal generated by the piezoelectric sensor;

processing means, coupled to the amplifier means, for interpreting the conditioned signal in accordance with a predetermined series of comparisons of the signal with threshold values, and for indicating results therefrom;

wherein the piezoelectric sensor comprises;

a first plate;

a length of piezoelectric cable in contact with the first plate;

a second plate disposed adjacent to the first plate and in contact with the piezoelectric cable so that the piezoelectric cable is compressed between the first and the second plates; and

,

further including a visual display coupled to the processing means, for displaying selected results from the series of comparisons of the signal with threshold values.

5. A load sensing system comprising:

a piezoelectric sensor for generating a signal in response to an applied force;

amplifier means, coupled to the piezoelectric sensor, for conditioning the signal generated by the piezoelectric sensor;

processing means, coupled to the amplifier means, for interpreting the conditioned signal in accordance with a predetermined series of comparisons of the signal with threshold values, and for indicating results therefrom;

wherein the piezoelectric sensor comprises;

a first plate;

a length of piezoelectric cable in contact with the first plate;

a second plate disposed adjacent to the first plate and in contact with the piezoelectric cable so that the piezoelectric cable is compressed between the first and the second plates; and

,

wherein the predetermined series of comparisons are performed at predetermined time intervals for masking out transitory changes in the piezoelectric sensor.

6. A load sensing system comprising:

a piezoelectric sensor for generating a signal in response to an applied force;

amplifier means, coupled to the piezoelectric sensor, for conditioning the signal generated by the piezoelectric sensor;

processing means, coupled to the amplifier means, for interpreting the conditioned signal in accordance with a predetermined series of comparisons of the signal with threshold values, and for indicating results therefrom;

wherein the piezoelectric sensor comprises;

a first plate;

a length of piezoelectric cable in contact with the first plate;

a second plate disposed adjacent to the first plate and in contact with the piezoelectric cable so that the piezoelectric cable is compressed between the first and the second plates; and

,

further comprising means for selecting one of the predetermined series of comparisons.

7. The load sensing system as recited in claim 6, wherein the means for selecting one of the predetermined series of comparisons is a set of configurable jumpers.