SOLID-STATE POSITION SENSOR FOR SENSING AN ADJUSTED POSITION OF A CONTROL ELEMENT

• US 3,576,302 A
• Filed: 07/10/1968
• Issued: 04/27/1971
• Est. Priority Date: 07/10/1968
• Status: Expired due to Term

• Current Assignee: Raymond D. Palfreyman
• Original Assignee: Raymond D. Palfreyman
• Inventors: Palfreyman, Raymond D.
• Application Number:
  US04/743,660
• Time in Patent Office: 1,021 Days
• US Class Current: 244/236
• CPC Class Codes: B64C 13/044 operated by feet, e.g. pedals
• CPC Class Codes: B64C 13/24 Transmitting means

Abstract

A solid-state position sensor for sensing an adjusted position of a control element for applying information corresponding to the sensed position of the control element to a system for controlling a surface of an aircraft and more particularly the disclosure relates to a solid-state rudder pedal position sensor including strain gages to provide signals corresponding to flexure of an associated spring member by the adjusted position of a rudder pedal to differentially unbalance an electrical bridge and provide an electrical output signal corresponding to the adjusted position of the rudder pedal and which output signal may effectively modify an automatic pilot control system for a control surface or rudder of an aircraft.

Claims

1. In an aircraft control system of a type including:

motor means for adjustably positioning a control surface of the aircraft;

a controller for the motor means;

means responsive to a flight condition of the aircraft to operate the controller in accordance with an operative setting thereof;

other means operable to override the operation of the controller by the flight condition responsive means so as to provide an independent operation of the controller of the motor means;

an improvement comprising;

operator-operative control means;

mechanical means for operatively connecting the operatoroperative control means to the controller of the motor means to effect said independent operation thereof;

means for sensing an adjusted position of the operatoroperative control means for modifying the operative setting of the aircraft flight condition responsive means; and

the position sensing means including;

a leaf spring affixed at one end portion to structure of sAid aircraft;

cam means;

the mechanical connecting means including means operatively connecting the operator-operative control means to said cam means;

the cam means bearing upon an opposite free end portion of the leaf spring and operable to variably flex the leaf spring about said fixed one end portion in accordance with the adjusted position of the operator-operative control means;

piezoresistive strain gauge means mounted on a side surface of the leaf spring;

said piezoresistive strain gauge means changing electrical resistance upon tensile and compressive forces being applied thereto;

an electrical bridge circuit means including the piezoresistive strain gauge means electrically connected therein and being arranged to electrically unbalance the bridge circuit means to provide electrical output signals of a polarity dependent upon the sense of the adjusted position of the operator-operative control means and of a magnitude corresponding to the adjusted position of the control means to modify the operative setting of the aircraft flight condition responsive means.

2. The improvement defined by claim 1 in which the operator-operative control means includes a pair of operator-operative pedals;

the mechanical connecting means includes a pair of shafts and differential gearing means for operatively connecting the pair of pedals to said controller;

at least one of said pair of shafts being operatively connected to said cam means so that the cam means may be adjustably positioned to variably flex the leaf spring in accordance with the adjusted position of the pair of pedals;

the piezoresistive strain gauge means includes multiple pairs of piezoresistive strain gauges;

one strain gauge of each pair of strain gauges being mounted on one side surface of the leaf spring;

another strain gauge of each pair of strain gauges being mounted on an opposite side surface of the leaf spring;

the mechanical connecting means being so arranged that a positioning of the operator-operative pedals within a predetermined limited range may cause the cam means to effect a stressing of the leaf spring and resultant change in the resistance of the strain gauges so as to provide at the bridge circuit means the electrical output signals to modify the operative setting of the aircraft flight condition responsive means and thereby effectively operate the controller in accordance therewith; and

the operator-operative pedals being directly connected through said pair of shafts and differential gearing means of said mechanical connecting means to the other means to override the operation of the controller by the flight condition responsive means and operable upon a positioning of said pedals in excess of said predetermined limited range so as to provide the independent operation of the controller of the motor means and thereby adjustably position the control surface of the aircraft in direct response to the adjusted positioning of said operator-operative pedals in excess of said predetermined limited range.