**CERTIFICATION** **Exhibit 31.1**I, Robert J. Shillman, Chief Executive Officer and Chairman of the Board of Directors ofCognex Corporation, certify that: 1. I have reviewed this Annual Report on Form 10-K of Cognex Corporation;  2. Based on my knowledge, this report does not contain any untruestatement of a material fact or omit to state a material fact necessary to make thestatements made, in light of the circumstances under which such statements weremade, not misleading with respect to the period covered by this report;  3. Based on my knowledge, the financial statements, and other financialinformation included in this report, fairly present in all material respects thefinancial condition, results of operations, and cash flows of the registrant as of,and for, the periods presented in this report;  4. The registrant’s other certifying officer(s) and I are responsible forestablishing and maintaining disclosure controls and procedures (as defined inExchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financialreporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for theregistrant and have: (a) Designed such disclosure controls and procedures, or causedsuch disclosure controls and procedures to be designed under our supervision,to ensure that material information relating to the registrant, including itsconsolidated subsidiaries, is made known to us by others within those entities,particularly during the period in which this report is being prepared;  (b) Designed such internal control over financial reporting, orcaused such internal control over financial reporting to be designed under oursupervision, to provide reasonable assurance regarding the reliability offinancial reporting and the preparation of financial statements for externalpurposes in accordance with generally accepted accounting principles;  (c) Evaluated the effectiveness of the registrant’s disclosurecontrols and procedures and presented in this report our conclusions about theeffectiveness of the disclosure controls and procedures, as of the end of theperiod covered by this report based on such evaluation; and  (d) Disclosed in this report any change in the registrant’sinternal control over financial reporting that occurred during the registrant’smost recent fiscal quarter (the registrant’s fourth fiscal quarter in the caseof an annual report) that has materially affected, or is reasonably likely tomaterially affect, the registrant’s internal control over financial reporting;and 5. The registrant’s other certifying officer(s) and I have disclosed,based on our most recent evaluation of internal control over financial reporting,to the registrant’s auditors and the audit committee of the registrant’s board ofdirectors (or persons performing the equivalent functions): (a) All significant deficiencies and material weaknesses in thedesign or operation of internal control over financial reporting which arereasonably likely to adversely affect the registrant’s ability to record,process, summarize, and report financial information; and  (b) Any fraud, whether or not material, that involves management orother employees who have a significant role in the registrant’s internalcontrol over financial reporting.Date: February 28, 2007              /s/ Robert J. Shillman   Robert J. Shillman   Chief Executive Officer andChairman of the Board of Directors