An apparatus for guiding a piece of equipment along a predetermined path and, upon sensing variations in the path in either a two-way or a one-way sensing mode, for correspondingly controlling the movement of such a piece of equipment, comprising:
- (a) a sensor assembly for sensing variations in the path by traveling in a predetermined direction therealong together with the guided piece, the sensor assembly comprising:
- (1) a hollow elongated body;
- (2) an arm disposed within the body and supported intermediate its ends for pivotal movement in any direction, one end of the arm extending out of the body for sensing engagement with the path;
- (3) a first, second, a third and a fourth fixed contact mounted within the body adjacent the other end of the arm and disposed at constant angular spacings of 90 degrees about the axis of the body;
- (4) a movable contact of substantially circular shape fixedly mounted on said other end of the arm and having a diameter greater than the distance between any two adjacent ones of the fixed contacts, whereby the movable contact is selectively engageable with any one of two adjacent ones of the fixed contacts depending upon a direction in which the arm is pivoted relative to the body by a variation in the path;
- and,
- (5) means on the body biasing said other end of the arm in such a direction that the movable contact thereon is normally held engaged with the first and second fixed contacts which are disposed adjacent to each other;
- (b) means for adjustably varying the angular position of the sensor assembly about its axis relative to work defining the path, the sensor assembly being held in such an angular position when the apparatus is in a two-way sensing mode that the direction in which said other end of the arm is biased is substantially opposite to the predetermined traveling direction of the sensor assembly along the path, the sensor assembly being further held when the apparatus is in first and second one-way sensing modes, in respective angular positions spaced 45 degrees in opposite directions from its angular position in the two-way sensing mode;
- (c) first drive means for moving the sensor assembly and the guided piece in the opposite transverse directions of the path, the first drive means including a first electrically controlled actuator;
- (d) second drive means for moving the sensor assembly and the guided piece in opposite vertical directions with respect to the path, the second drive means including a second electrically controlled actuator;
- (e) two-way sensing circuit means adapted to be connected between the four fixed contacts and the first and second actuators, the two-way sensing circuit means being effective to cause the first and second drive means to move the sensor assembly and the guided piece;
- (1) downward when the movable contact is engaged with both first and second fixed contacts;
- (2) upward when the movable contact is engaged with both third and fourth fixed contacts;
- (3) in one transverse direction when the movable contact is engaged with both second and third fixed contacts;
- (4) in the opposite transverse direction when the movable contact is engaged with both first and fourth fixed contacts;
- (5) in both downward and said opposite transverse directions when the movable contact is engaged with only the first fixed contact;
- (6) in both downward and said one transverse directions when the movable contact is engaged with only the second fixed contact;
- (7) in both upward and said one transverse directions when the movable contact is engaged with only the third fixed contact;
- and,
- (8) in both upward and said opposite transverse directions when the movable contact is engaged with only the fourth fixed contact;
- (f) first one-way sensing circuit means adapted to be connected between the four fixed contacts and the first and second actuators, the first one-way sensing circuit means being effective to cause the first and the second drive means to move the sensor assembly and the guided piece;
- (1) downward when the movable contact is engaged with only the first fixed contact;
- (2) in said one transverse direction when the movable contact is engaged with only the second fixed contact;
- (3) upward when the movable contact is engaged with only the third fixed conatct;
- and,
- (4) in said opposite transverse direction when the movable contact is engaged with only the fourth fixed contact;
- (5) whereby when the movable contact is engaged with both first and second fixed contacts, for example, the sensor assembly and the guided piece are moved in both downward and said one transverse directions;
- (g) second one-way sensing circuit means adapted to be connected between the four fixed contacts and the first and second actuators, the second one-way sensing circuit means being effective to cause the first and the second drive means to move the sensor assembly and the guided piece:
- (1) in said opposite transverse direction when the movable contact is engaged with only the first fixed contact;
- (2) downward when the movable contact is engaged with only the second fixed contact;
- (3) in said one transverse direction when the movable contact is engaged with only the third fixed contact;
- and,
- (4) upward when the movable contact is engaged with only the fourth fixed contact;
- (5) whereby, when the movable contact is engaged with both first and second fixed contacts, for example, the sensor assembly and the guided piece are moved in both said opposite transverse and downward directions;
- and,
- (h) switch means for selectively connecting the two-way, the first one-way and the second one-way sensing circuit means between the four fixed contacts and the first and second actuators.