overwatch how it works

OverWatch - General - What is EQSS Overwatch and how does it work?

Principle of Operation
Notes
The OverWatch™ is an innovative system designed as a safety aid to the operator, but it does not replace operator training.
The system works by emitting a low power invisible LASER light. Then in real time, it detects the operator’s position and movements from the LASER light reflection. 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:
  1. The operator lurching forward or backward, indicating a possible collision
  2. The operator looking over the side; yes we know that this is what you've always done but it's an unsafe practice
  3. The operator crouching (crouching to travelling through a doorway); another unsafe practice that's resulted in at least one death in Australia
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 establishes 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. Then the system will trigger and cut the machine operation if the system detects movements outside the threshold limits.

For example, if the machine is being driven 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 human 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).
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