OverWatch - General - What is EQSS Overwatch and how does it work?
Principle of Operation
The OverWatch™ is an innovative system designed as an aid to the operator.
The system does not replace operator
training.
The system works on the premise of detecting the operator’s position and movements, with respect to the scissor
lift’s direction of movement in real time. This information is used to determine if a crushing or shearing event is about
to occur. This is determined by the physical movements and position of the operator’s body - with respect to the
platform control box.
The Overwatch system generates a cutout and emits an alarm when the lidar data indicates that the operator is outside
this safe operating envelope.
Outside safe operating envelope includes:
- The operator lurching forward or backward, indicating a possible collision
- The operator looking over the side, an unsafe practice
- The operator crouching, an unsafe practice (ie crouching to travelling through a doorway)
In these scenarios, the system generates an alarm and cutout, preventing the operation of the scissor lift in an
unsafe manner, or stopping the machine in the event of a collision to minimize operator crushing injury.
When the operator pushes the dead-man trigger, the system calibrates the position of the operator relative to the
control box. The system senses the machine’s mode of operation (Drive or Elevate) and determines the position of the
joystick. This initial calibration is done each time the dead-man trigger is pushed; therefore, the system calibrates for
each use session with the specific operator and environmental conditions at that point in time.
The system constantly measures the operator’s position, acceleration and velocity. The system will trigger and cut the
machine operation if the system detects movements above the threshold limits.
For example, if the machine is driving
forward and the operator moves forward to look over the front of the platform, the system will not trigger. If the
machine is driving backwards and the operator moves towards the platform controls quickly (with a high acceleration),
this may indicate a dangerous shearing event, and therefore, the system will trigger.
But how does the Overwatch do it?
The Overwatch sensor contains a LIDAR. The LIDAR is a time of flight distance sensor. It uses an inferred (850nm) laser to measure the distance from
the sensor to the target. In this application, the target is the operator of the scissor lift. This information
is used to determine if the operator moves forward or backward from the sensor (which is mounted at the
scissor lift joystick controls). The LIDAR is also used to measure the operator’s movement, speed and
acceleration relative to the joystick controls. When the operator presses the dead man switch on the
joystick, the LIDAR takes a measurement of the distance to the operator. This allows for a real time
base-line measurement to the operator (depending on the operator’s height and size).
More Technical description:
More articles and training:
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