<PAGE>   1
C&S 510 (8/93)

                                                                     EXHIBIT 3.1

  MICHIGAN DEPARTMENT OF COMMERCE - CORPORATION AND SECURITIES BUREAU
  Date Received                                      (FOR BUREAU USE ONLY)





   Name
   Warren, Price, Cameron, Faust & Asciutto, P.C.

   Address
   P.O. 26067

   City              State               Zip
   Lansing             MI               48909                    EFFECTIVE DATE:

   DOCUMENT WILL BE RETURNED TO NAME AND ADDRESS INDICATED ABOVE

                       RESTATED ARTICLES OF INCORPORATION
                    For use by Domestic Profit Corporations
            (Please read information and instructions on last page)

         Pursuant to the provisions of Act 284, Public Acts of 1972, the
undersigned corporation executes the following Articles:

  1.   The present name of the corporation is:    Medar, Inc.


  2.   The identification number assigned by the Bureau is: 105-593


  3.   All former names of the corporation are:    New Medar, Inc.


  4.   The date of filing the original Article of Incorporation was: January 6,
       1978


         The following Restated Articles of Incorporation supersede the
         Articles of Incorporation as amended and shall be the Articles of
         Incorporation for the corporation.

ARTICLE I
  The name of the corporation is:  Medar, Inc.


ARTICLE II
  The purpose or purposes for which the corporation is formed are: 
  To engage in any activity within the purposes for which corporations may be 
  organized under the Business Corporation Act of Michigan.
<PAGE>   2

ARTICLE III
  The total authorized shares:

       Common shares 15,000,000 

       Preferred shares 400,000 

  3.   A statement of all or any of the relative rights, preferences and
       limitations of the shares of each class is as follows:  See Attached
       Addendum 1



ARTICLE IV
  1.   The address of the current registered office is:

       38700 Grand River Avenue, Farmington Hills         MICHIGAN     48335
       ------------------------------------------------------------------------
       (Street Address)               (City)              (State)    (Zip Code) 

  2.   The mailing address of the registered office if different than above is:

                                                          MICHIGAN
       ------------------------------------------------------------------------
       (Street Address)                (City)             (State)     (Zip Code)
                
  3.   The name of the resident agent at the registered office is:  Max A. Coon


ARTICLE V (OPTIONAL.  DELETE IF NOT APPLICABLE.)

  Any action required or permitted by the Act to be taken at an annual or
  special meeting of shareholders may be taken without a meeting, without prior
  notice, and without a vote, if consents in writing, setting forth the action
  so taken, are signed by the holders of outstanding shares having not less
  than the minimum number of votes that would be necessary to authorize or take
  the action at a meeting at which all shares entitled to vote on the action
  were present and voted.  The written consents shall bear the date of
  signature of each shareholder who signs the consent.  No written consents
  shall be effective to take the corporate action referred to unless, within 60
  days after the record date for determining shareholders entitled to express
  consent to or to dissent from a proposal without a meeting, written consents
  signed by a sufficient number of shareholders to take the action are
  delivered to the corporation.  Delivery shall be to the corporation's
  registered office, its principal place of business, or an officer or agent of
  the corporation having custody of the minutes of the proceedings of its
  shareholders.  Delivery made to a corporation's registered office shall be by
  hand or by certified or registered mail, return receipt requested.

  Prompt notice of the taking of the corporate action without a meeting by less
  than unanimous written consent shall be given to shareholders who have not
  consented in writing.

ARTICLE VII (ADDITIONAL PROVISIONS, IF ANY, MAY BE INSERTED HERE; ATTACH
ADDITIONAL PAGES IF NEEDED.)

  See Attached Addendum 2
<PAGE>   3

5. COMPLETE SECTION (a) IF THE RESTATED ARTICLES WERE ADOPTED BY THE UNANIMOUS
   CONSENT OF THE INCORPORATORS BEFORE THE FIRST MEETING OF THE BOARD OF
   DIRECTORS; OTHERWISE, COMPLETE SECTION (b).  DO NOT COMPLETE BOTH.

   a. ___  These Restated Articles of Incorporation were duly adopted on the
           ___________ day of _________________, 19____, in accordance with the 
           provisions of Section 642 of the Act by the unanimous consent of the
           incorporators before the first meeting of the Board of Directors.

           Signed this _____________ day of ____________________, 19 _________

           _________________________________  ________________________________


           _________________________________  ________________________________
        (Signatures of Incorporators; type or print name under each signature)


b. X    These Restated Articles of Incorporation were duly adopted on 27th
        day of March, 1996, in accordance with the provisions of 
        Section 642 of the Act and: (check one of the following)

        X    were duly adopted by the Board of Directors without a vote of the
             shareholders.  These Restated Articles of Incorporation only 
             restate and integrate and do not further amend the provisions of 
             the Articles of  Incorporation as heretofore amended and there is
             no material discrepancy between those provisions and the 
             provisions of these Restated Articles.

       __    were duly adopted by the shareholders.  The necessary number of 
             shares as required by statute were voted in favor of these 
             Restated Articles.

       __    were duly adopted by the written consent of the shareholders 
             having not less than the minimum number of votes required by 
             statute in accordance with Section 407(1) of the Act.  Written 
             notice to shareholders who have not consented in writing has been
             given. (Note:  Written consent by less than all of the 
             shareholders is permitted only if such provision appears in the 
             Articles of Incorporation.)

       __    were duly adopted by the written consent of all the shareholders 
             entitled to vote in accordance with Section 407(2) of the Act.



                                      Signed this 27th  day of March, 1996

                                      By: _____________________________________
                                                      (Signature)

                                      Charles J. Drake, President
                                      _________________________________________
                                              (Type or Print Name and Title)
<PAGE>   4

C&S 510
<TABLE>
<CAPTION>

   Name of Person or Organization                                 Preparer's Name and Business
   Remitting Fees:                                                Telephone Number:
<S>                                                         <C>
   Warren, Price, Cameron, Faust & Asciutto, P.C.                 Josephine L. Cameron                         
                                                                                     (517) 349-8600                               

</TABLE>

                          INFORMATION AND INSTRUCTIONS
  1.    The articles of incorporation cannot be restated until this form, or a
        comparable document, is submitted.

  2.    Submit one original copy of this document.  Upon filing, the document
        will be added to the records of the Corporation and Securities Bureau.
        The original copy will be returned to the address appearing in the box
        on front as evidence of filing.

        Since this document will be maintained on optical disk media, it is
        important that the filing be legible.  Documents with poor black and
        white contrast, or otherwise illegible, will be rejected.

  3.    This document is to be used pursuant to sections 641 through 643 of the
        Act for the purpose of restating the articles of incorporation of a
        domestic profit corporation.  Restated articles of incorporation area
        an integration into a single instrument of the current provisions of
        the corporation's articles of incorporation, along with any desired
        amendments to those articles.

  4.    Restated articles of incorporation which do not amend the articles of
        incorporation may be adopted by the board of directors without a vote
        of the shareholders.  Restated articles of incorporation which amend
        the articles of incorporation require adoption by the shareholders.
        Restated articles of incorporation submitted before the first meeting
        of the board of directors require adoption by all of the incorporators.

  5.    Item 2 - Enter the identification number previously assigned by the
        Bureau.  If this number is unknown, leave it blank.

  6.    The duration of the corporation should be stated in the restated
        articles of incorporation only if it is not perpetual.

  7.    This document is effective on the date endorsed "filed" by the Bureau.
        A later effective date, no more than 90 days after the date of
        delivery, may be stated as an additional article.

  8.    If the restated articles are adopted before the first meeting of the
        board of directors, item 5(a) must be signed in ink by all of the
        incorporators.  Other restated articles must be signed by the
        president, vice-president, chairperson or vice-chairperson.

  9.    FEES:  Make remittance payable to the State of Michigan.  Include
        corporation name and identification number on check or money order.

<TABLE>
<S>                                                                                                       <C>
        NON-REFUNDABLE FEE.......................................................................                   $10.00
        TOTAL MINIMUM FEE........................................................................                   $10.00
        ADDITIONAL FEES DUE FOR INCREASED AUTHORIZED SHARES ARE:
          each additional 20,000 authorized shares or portion thereof ...................................    $30.00
             maximum fee for first 10,000,000 authorized shares ..........................................$5,000.00
             each additional 20,000 authorized shares or portion thereof in excess of 10,000,000 shares      $30.00
             maximum fee per filing for authorized shares in excess of 10,000,000 shares                $200,000.00
</TABLE>
  10.   Mail form and fee to:                  The office is located at:

        Michigan Department of Commerce        6546 Mercantile Way
        Corporation and Securities Bureau      Lansing, MI  48910
        Corporation Division
        P.O. Box 30054                         Telephone: (517) 334-6302
        Lansing, Michigan  48909-7554
                                     
<PAGE>   5


               ADDENDUM 1 ATTACHED TO AND MADE A PART OF CERTIFICATE OF
               AMENDMENT TO THE ARTICLES OF INCORPORATION OF MEDAR, INC.

         (a)  Shares of preferred stock may be issued from time to time in one
or more series, each such series to have such distinctive designation or title
and to include such number of shares as may be fixed and determined by the
Board of Directors prior to the issuance of any shares thereof.  Each such
series may differ from every other series already outstanding, as may be
determined from time to time by the Board of Directors prior to the issuance of
any shares thereof, in any or all of the following respects:

                 (i)  The rate of dividend which the preferred stock of any
such series shall be entitled to receive and whether such series shall be
entitled to receive a dividend and whether such dividend shall be cumulative or
non-cumulative.

                 (ii)  The amount per share which the preferred stock of any
such series shall be entitled to receive in case of the redemption thereof or
in case of a voluntary liquidation distribution or sale of assets, dissolution
or winding up of the Corporation, or in case of the involuntary liquidation,
distribution or sale of assets, dissolution or winding up of the Corporation;

                 (iii)  The relative rights, if any, of the holders of
preferred stock of any such series to vote the same, and the extent, terms and
conditions of such voting rights.

                 (iv)  The right, if any, of the holders of preferred stock of
any such series to convert the same into other classes of stock, and the terms
and conditions of such conversion.

                 (v)  The terms of the sinking fund or redemption of purchase
account, if any, to be provided for the preferred stock of any such series.

         The description and terms of the preferred stock of each series shall
be fixed and determined by the Board of Directors by appropriate resolution or
resolutions at or prior to the time of the authorization of the issue of the
original shares of each such series, shall be summarized in the certificates
therefor, and a Certificate containing the resolution of the Board establishing
and designating the series and prescribing the relative rights and preferences
thereof shall be filed with the Corporations and Securities Bureau, Michigan
Department of commerce, and when filed shall constitute an amendment to the
Articles of Incorporation.  All shares of preferred stock shall be of equal
rank, and shall be identical in all respects except in respect of the
particulars that may be fixed by the Board of Directors.



<PAGE>   6


         ADDENDUM 2 ATTACHED TO AND MADE A PART OF CERTIFICATE OF
         AMENDMENT TO THE ARTICLES OF INCORPORATION OF MEDAR, INC.


         To the full extent that the laws of the State of Michigan, as they
exist on the date hereof or as they may hereafter be amended, permit the
limitation or elimination of the liability of Directors or Officers, no
Director or Officer of the Corporation shall be personally liable to the
Corporation or its stockholders for damages for breach of any duty owed to the
Corporation or its stockholders.  Neither the amendment or repeal of this
Article nor the adoption of any provision of the Articles of Incorporation
which is inconsistent with this Article shall apply to or have any effect on
the liability or alleged liability of any Director or Officer of the
Corporation for or with respect to any act or omission of such Director or
Officer occurring prior to such amendment, repeal or adoption.