<p style="text-align:justify"><span style="font-size:14px"><span style="color:#000000">There is a difference between an ideal cycle time calculated based on the decided speeds of a robot in a robotic cell; this difference occurs because of different time lags/delays termed as latency in robotic systems. This latency is spread throughout many parts of the cell; they are elaborated below:</span></span></p>

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<p style="text-align:justify"><span style="font-size:14px"><span style="color:#000000">Actuator Lag: Time required by the end-of-arm actuator</span></span></p>

<p style="margin-left:48px; text-align:justify"><span style="font-size:14px"><span style="color:#000000">In all actuators, the time difference between when the actuator is commanded to move and when the movement is completed always exists. For example, a pneumatic suction gripper may take 50-500 ms to generate a vacuum depending on the size of the suction cup. A mechanical finger-like gripper may take 10-500 ms depending on the load it carries.&nbsp;</span></span></p>

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<p style="text-align:justify"><span style="font-size:14px"><span style="color:#000000">Mechanical Lag: Movement of the robot</span></span></p>

<ul>
	<li style="list-style-type:disc; text-align:justify"><span style="font-size:14px"><span style="color:#000000">For any robot, there always exists a time difference between when the robot is commanded to move and when the movement is completed. This time is also due to the calculations required by the robot controller to execute inverse kinematics. This time delay, which can also be named mechanical time lag, depends on the design and size of the robot but generally lies in the range of 12-45ms in terms of response time and 10-150ms in terms of tracking time. If large robots with heavy payloads are used, it may even take several seconds to finish a given pick and place task.</span></span></li>
</ul>

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<p style="text-align:justify"><span style="font-size:14px"><span style="color:#000000">Computational Lag: PLC compute time</span></span></p>

<ul>
	<li style="list-style-type:disc; text-align:justify"><span style="font-size:14px"><span style="color:#000000">As explained above, the other factor that adds a delay to the task being carried out by the robot is the PLC compute delay. This is the time required for executing the logic inside the CPU of a PLC. This latency is very much dependent on the resources available within the CPU of the PLC and how complex the calculation is, but for an average task, this lag is in the range of 50&micro;s-250&micro;s for motion control logic, 100ms-1000ms for vision control logic and 1ms-500ms for process control logic.</span></span></li>
</ul>

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<p style="text-align:justify"><span style="font-size:14px"><span style="color:#000000">Sensing and communication delay</span></span></p>

<ul>
	<li style="list-style-type:disc; text-align:justify"><span style="font-size:14px"><span style="color:#000000">This delay is the difference between the time instance the sensor senses a physical quantity (e.g. temperature or pressure) and the instance when the digitized data reaches PLC. This is also known as transport or communication delay. These delays are directly proportional to the distance of communication and the type of communication protocol being used; it ranges from a few microseconds to a few seconds.</span></span></li>
</ul>

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