Vehicle restraint with bi-directional sensor

Abstract

A vehicle restraint restricts the movement of a vehicle at a loading dock by engaging the vehicle's RIG (rear impact guard). The vehicle restraint includes a barrier carried by a vertically translatable track follower, the barrier being driven by a motor or some other type of power unit. A RIG sensor detects the RIG's horizontal position relative to the barrier and can periodically energize the motor to maintain the barrier in generally continuous contact with the RIG, even if the RIG moves horizontally away from the barrier. Detection of such horizontal movement of the RIG triggers the barrier to move accordingly to reduce a horizontal gap that may have formed between the RIG and the barrier.

1 . A method of operating a vehicle restraint disposed adjacent to a loading dock face, wherein the vehicle restraint includes a movable barrier adapted to prevent movement of a RIG (rear impact guard) of a vehicle in a direction opposite the loading dock face, wherein the RIG includes a front surface and a rear surface, the rear surface being closer to the loading dock face than the front surface, the method comprising:
 moving the barrier to a first operative position wherein the barrier is horizontally adjacent the front surface of the RIG;   holding the barrier substantially stationary in the first operative position; and   sensing that the front surface is no longer horizontally adjacent the barrier.   
   
   
       2 . The method of  claim 1 , further comprising moving the barrier at least horizontally toward the dock face to a second operative position, wherein the barrier is again horizontally adjacent the front surface, in response to sensing that the front surface is no longer horizontally adjacent the barrier. 
   
   
       3 . The method of  claim 1 , further comprising illuminating a light in response to sensing that the front surface is no longer horizontally adjacent the barrier. 
   
   
       4 . The method of  claim 1 , further comprising sounding an audible alarm in response to sensing that the front surface is no longer horizontally adjacent the barrier. 
   
   
       5 . The method of  claim 1 , wherein moving the barrier to the first operative position comprises moving the barrier in an upward direction and in a horizontal direction toward the loading dock face. 
   
   
       6 . The method of  claim 1 , wherein moving the barrier to the first operative position comprises rotating the barrier. 
   
   
       7 . A method of operating a vehicle restraint disposed adjacent to a loading dock face, wherein the vehicle restraint includes a rotatable barrier with a distal end, and the rotatable barrier can be used for restricting a RIG (rear impact guard) of a vehicle, the method comprising:
 raising the distal end after the RIG has passed thereover;   after raising the distal end, holding the distal end substantially stationary relative to the RIG; and   sensing horizontal movement of the RIG away from the distal end.   
   
   
       8 . The method of  claim 7 , further comprising moving the distal end vertically and horizontally in response to sensing horizontal movement of the RIG. 
   
   
       9 . The method of  claim 7 , wherein the raising of the distal end after the RIG has passed thereover is carried out by motorized rotation of the rotatable barrier. 
   
   
       10 . The method of  claim 7 , further comprising illuminating a light in response to sensing horizontal movement of the RIG. 
   
   
       11 . The method of  claim 7 , further comprising sounding an audible alarm in response to sensing horizontal movement of the RIG. 
   
   
       12 . A vehicle restraint mountable near a loading dock for engaging a RIG (rear impact guard) of a vehicle, the vehicle restraint comprising:
 a barrier that is movable relative to the loading dock;   a powered drive unit coupled to the barrier such that the powered drive unit can move the barrier; and   a RIG sensor coupled to the barrier and providing a signal in response to the RIG's horizontal position relative to the barrier, such that the powered drive unit moves the barrier toward the RIG until it receives the signal from the RIG sensor indicating that the barrier is horizontally adjacent the RIG, upon receiving the signal, the powered drive unit is de-energized, and after the powered drive unit is de-energized, the signal triggers the powered drive unit to be re-energized to further move the barrier toward the RIG to minimize a gap between the barrier and the RIG.   
   
   
       13 . The vehicle restraint of  claim 12 , wherein the barrier comprises a rotating hook. 
   
   
       14 . The vehicle restraint of  claim 12 , wherein the barrier comprises a vertically elongate member. 
   
   
       15 . The vehicle restraint of  claim 12 , wherein the powered drive unit is an electric motor. 
   
   
       16 . A vehicle restraint mountable near a loading dock for engaging a RIG (rear impact guard) of a vehicle, wherein the RIG includes an upper surface, a lower surface, a left lateral surface, and a right lateral surface that is closer to the loading dock than the left lateral surface, the vehicle restraint comprising:
 a barrier assembly vertically movable relative to the loading dock;   a RIG sensor coupled to the barrier assembly, the RIG sensor providing a signal in response to the RIG being in a preferred capture area relative to the barrier assembly; and   a powered drive unit coupled to the barrier assembly such that the powered drive unit can move the barrier assembly relative to the loading dock, the powered drive unit being responsive to the signal such that:
 a) the powered drive unit moves the barrier assembly toward the RIG until it receives the signal from the RIG sensor indicating that the RIG is positioned in the preferred capture area, 
 b) after receiving the signal, the powered drive unit is de-energized, and 
 c) after the powered drive unit is de-energized, the signal triggers the powered drive unit to be re-energized to further move the barrier assembly toward the RIG until the RIG is in the preferred capture area. 
   
   
   
       17 . The vehicle restraint of  claim 16 , wherein the preferred capture area is an area in which at least a portion of the barrier assembly is below the lower surface, above the upper surface, and further from the dock face than the left lateral surface. 
   
   
       18 . The vehicle restraint of  claim 16 , wherein the barrier assembly comprises a rotating hook. 
   
   
       19 . The vehicle restraint of  claim 16 , wherein the barrier assembly comprises a vertical elongate member with an upper tip that extends horizontally toward the loading dock. 
   
   
       20 . The vehicle restraint of  claim 16 , wherein the powered drive unit is an electric motor. 
   
   
       21 . A vehicle restraint mountable to a loading dock for engaging a RIG (rear impact guard) of a vehicle, wherein the vehicle restraint includes a track mountable to the loading dock and a track follower vertically movable along the track upon interaction with the RIG, the vehicle restraint comprising:
 a barrier rotatably coupled to the track follower, wherein the barrier helps define a RIG-receiving throat area in which the RIG may be positioned and the barrier includes a distal end and further defines a variable horizontal distance between the distal end and the track;   a RIG sensor coupled to at least one of the track follower and the barrier, the RIG sensor providing a signal in response to the RIG's position relative to the RIG-receiving throat area; and   a powered drive unit coupled to the barrier such that the powered drive unit can rotate the barrier relative to the track follower between a blocking position and a stored position, the powered drive unit being responsive to the signal such that:
 a) the powered drive unit rotates the barrier toward the RIG after the RIG forces the track follower downward, 
 b) after rotating the barrier toward the RIG, the powered drive unit is de-energized, and 
 c) after the powered drive unit is de-energized, the signal triggers the powered drive unit to be re-energized to further rotate the barrier upward, thereby reducing the variable horizontal distance between the track and the distal end of the barrier. 
   
   
   
       22 . The vehicle restraint of  claim 21 , further comprising a resilient member coupled to the track follower, wherein the resilient member urges the track follower upward. 
   
   
       23 . The vehicle restraint of  claim 21 , further comprising a ramp disposed on the track follower and being engageable by the RIG such that the RIG can force the track follower downward as the vehicle backs the RIG over the ramp. 
   
   
       24 . The vehicle restraint of  claim 21 , wherein the barrier comprises a first plate and a second plate that define a space therebetween, and the RIG sensor is movable within that space. 
   
   
       25 . The vehicle restraint of  claim 21 , wherein the powered drive unit is an electric motor. 
   
   
       26 . The vehicle restraint of  claim 21 , further comprising a barrier sensor in addition to the RIG sensor, the barrier sensor is coupled to at least one of the track follower and the barrier, the barrier sensor provides a stored-signal that triggers the powered drive unit to stop lowering the barrier when the barrier reaches the stored position. 
   
   
       27 . The vehicle restraint of  claim 21 , wherein the RIG sensor includes a sensing arm pivotally coupled to the barrier such that the sensing arm can pivot into the RIG-receiving throat area. 
   
   
       28 . The vehicle restraint of  claim 21 , wherein the RIG sensor includes an optical beam that helps define the RIG-receiving throat area. 
   
   
       29 . The vehicle restraint of  claim 21 , wherein the signal has a first state and a second state, the first state triggers the motor to be energized, and the second state triggers the motor to be de-energized. 
   
   
       30 . The vehicle restraint of  claim 21 , wherein when the RIG is captured by the barrier within the RIG-receiving throat area, and the RIG subsequently moves, the barrier responds by:
 translating upward under the impetus of the resilient member when the RIG moves upward, and   rotates upward under the impetus of the powered drive unit when the RIG moves horizontally toward the track.