Stopping distance after triggering an emergency stop for ABB robots

When an ABB robot triggers the emergency stop, the stopping distance is a crucial factor. It is affected by multiple elements such as the robot’s speed, load, and motion mode at the moment of activation.

Generally, in normal operating conditions with a relatively low speed and light load, the stopping distance is relatively short. However, if the robot is moving at a high speed or carrying a heavy load, it may require a longer distance to come to a complete halt. Advanced control systems in ABB robots are designed to minimize this distance and ensure safety.
I. Overview

1. For ABB articulated robots and SCARA robots, all measurements and calculations of stopping distances and times are performed according to ISO 10218-1 with single-axis movements on axes 1, 2 and 3. If the movement uses multiple axes, the stopping distances and times may be longer. Normal delays in hardware and software are taken into account.
2. For ABB gantry robots, these values ​​are based on the movement of all axes, as these axes always move together. Only the stop times are shown.
3. For ABB positioners, these values ​​are based on single-axis movements. Stop categories 0 and 1 comply with IEC 60204-1.
   II. Definitions
4. Category 0 stops:    Stop distances and times for Category 0 stops are measured using maximum speed, maximum payload and the arm extended to its maximum reach.
5. Category 1 stops:    Stop category 1 data is based on calculations in worst-case scenario simulations. The data for stop category 1 is verified by measurements. The simulation and validation were performed using the default value (100%) of the system parameter AccSet. Changing this value will affect the stopping distance and time (only for robots running versions prior to RobotWare 6.01). 3. Robot
   For the robot, stopping distances and times for category 1 stops are provided for three arm extensions and three payloads. These variables are 100%, 66%, and 33% of the robot maximum, respectively. The speed and zone data in the simulation are based on TCP0.
   4. Positioner
   For the positioner, stopping distances and times are provided for three payloads. No extension zones are applied. The payloads are 100%, 66%, and 33% of the positioner maximum, respectively.
   5. Load
   The loads used represent the rated loads, with the rated inertia, maximum cog z, and zero cog x and cog y in the load diagram. No arm loads are used. The load diagrams are also found in the corresponding product specifications. At 66% and 33% load, the mass and inertia are reduced to 66% and 33%, respectively, but cog z is the same as at 100% load.
   6. Extended zones for articulated manipulators
   The extended zones for stop category 1 are based on the wrist center point (WCP). The extended zone limits describe the size of each zone. The radius R is measured from the center of axis 1.
   (1). Zone 0 (Z0): The radius (R) is 0-33% of the maximum reach of the wrist center point (WCP).
   (2). Zone 1 (Z1): The radius (R) is 33-66% of the maximum reach of the wrist center point (WCP).
   (3).Zone 2 (Z2): The radius (R) is 66-100% of the maximum reach of the wrist center point (WCP).
   7. Speed
   For robots, the TCP0 speed is measured in meters per second when the stop is triggered.
   For positioners, the speed is the angular velocity in radians per second. 8. Stop distance:
   The stop distance is in degrees.
   9. Stop time:
   The stop time is in seconds.
6. Limitations
   The stopping distance can vary depending on the additional load on the robot. The braking distance of a category 0 brake may vary depending on the individual brakes and their friction.
   III. Measuring the stopping distance and stopping time
   Preparation for measurement
   For the measurement and calculation of the overall stopping performance of the system, see ISO 13855:2010.
   The measurements should be performed for the selected stop category. The emergency stop button on the robot controller is configured for stop category 0 on delivery. A risk assessment may deduce the necessity of another stop category. The stop category can be changed via the system parameter “Function” (topic “Controller”, type “Safety Run Chain”). If deviations occur from the default configuration for stop category 0, this is detailed in the product specification of the respective manipulator.
   Measurement with TuneMaster
   The TuneMaster software can be used to measure the stopping distance and time of ABB robots. The steps are as follows:
7. Download TuneMaster from www.abb.com/robotics.
8. Install TuneMaster on your computer. Start the TuneMaster application and select Log Signals.
9. Connect to the robot controller.
10. Define the I/O stop signal for measurement, e.g. ES1 for emergency stop.
11. Define the signal number for measurement, 1298 for axis position. The value is in radians.
12. Start logging in TuneMaster.
13. Start the test program on the controller.
14. When the axis reaches maximum speed, press the emergency stop button.
15. In TuneMaster, measure the stopping distance and time.
16. Repeat the above steps for all installed emergency stop buttons until the identified hazard has been verified for the stopping distance and time of the axis.