Restricting the IRB 6700 Working Range

A Practical Guide to Mechanical Stops and Software Settings

Learn how to define and restrict your ABB IRB 6700 robot's operational boundaries through mechanical stops and system parameters to prevent collisions and optimize performance.

Mechanical Stops Software Configuration

Industrial robots like the ABB IRB 6700 are powerful and versatile, but their extensive reach and speed necessitate careful planning within the workcell. One crucial aspect of safe and efficient robot integration is defining and restricting the robot's working range.

Why Restrict the Working Range?

The primary reason to limit a robot's movement envelope is safety and collision avoidance. An unrestricted robot could potentially collide with:

  • Expensive machinery or fixtures within the cell
  • Building structures like columns or walls
  • Safety fences or light curtains
  • Other robots or moving equipment

Beyond collision prevention, restricting the working range can also:

Optimize Cycle Times

Prevent the robot from making unnecessarily large movements outside its required operational area.

Define Safe Zones

Ensure the robot respects defined areas for human interaction or maintenance access.

Protect Equipment

Avoid forcing the robot into awkward positions or stressing its components unnecessarily.

Meet Safety Standards

Comply with regional or application-specific safety regulations that mandate defined operational limits.

Methods for Restricting the IRB 6700

Axis 1 (Rotation)

Can be restricted using a combination of hardware (mechanical stops) and software (system parameters).

Learn more

Axis 2 (Lower Arm)

Restricted via software (system parameters) without additional mechanical stops.

Learn more

Axis 3 (Upper Arm)

Restricted via software (system parameters) without additional mechanical stops.

Learn more

Deep Dive: Restricting Axis 1 Mechanically

Axis 1, controlling the robot's base rotation, often requires the most stringent physical limitations. While the robot has built-in end stops defining its maximum possible range (±170°), you can further reduce this using optional hardware for finer control.

Understanding the Hardware

The mechanical restriction for Axis 1 involves adding movable mechanical stops to the robot's base frame. These stops work in conjunction with the existing mechanical stop pin on the rotating part of the base.

  • Movable Mechanical Stop Set (Option 3HAC044287-001): This kit provides the necessary components to reduce the working range in 15° increments, typically between ±5° and ±125° in either direction from the zero position.
  • Installation Point: These stops are bolted directly onto designated mounting positions on the robot frame.

Components Diagram

Mechanical stop components diagram

A: Attachment screws M12x70 quality 12.9 Gleitmo 603 (2 pcs per stop)

B: Movable mechanical stop

C: Mechanical stop pin axis-1 (part of the standard robot)

Reference: xx1300001971

Required Tools and Documentation

  • Movable Mechanical Stop Set (3HAC044287-001): Includes the stop block(s) and required high-quality screws.
  • Standard Toolkit: Including torque wrenches and appropriate sockets/bits (Refer to section 7.6 Standard toolkit on page 559).
  • Crucially: Technical reference manual - System parameters (Document ID: 3HAC17076-1). Hardware installation is only half the process!

Installation Steps

Step 1: Safety First!

DANGER

Before entering the robot's working area, ensure all power sources are completely turned off.

Before proceeding, ensure the following power sources are disconnected:

  • Electric power supply to the robot and controller
  • Hydraulic pressure supply (if applicable)
  • Air pressure supply

Follow proper lock-out/tag-out procedures.

Step 2: Fit the Mechanical Stop

  1. 1
    Identify the correct mounting location on the robot frame based on the desired restriction angle. Consult the assembly drawing included with the stop set if needed.
  2. 2
    Position the Movable mechanical stop (B) onto the frame.
  3. 3
    Insert the two Attachment screws (A) M12x70 (quality 12.9 Gleitmo 603).
  4. 4
    Tighten the screws to the specified torque: 115 Nm. Use a calibrated torque wrench. Note: Gleitmo-treated screws have specific friction properties; use the correct torque.

Important: Always use a calibrated torque wrench and apply the specified 115 Nm torque to ensure the stop remains secure during robot operation.

Step 3: Software Configuration

CRITICAL STEP!

Fitting the hardware stop prevents physical over-travel, but the robot controller must be informed of this new limit to operate correctly and safely.

  1. 1
    Access the robot's system parameters via the FlexPendant or RobotStudio.
  2. 2
    Locate the parameters for Axis 1 motion range: Upper joint bound and Lower joint bound.
  3. 3
    Adjust these parameter values to precisely match the angle imposed by the newly installed mechanical stop. For example, if you install a stop at +90°, the Upper joint bound for Axis 1 must be set to 90 degrees or slightly less.
  4. 4
    Consult the Technical reference manual - System parameters for detailed instructions on modifying these parameters.

What happens if you skip this step?

Failure to correctly set these software limits can lead to:

  • • The robot attempting to move beyond the physical stop, resulting in errors or forceful impacts.
  • • Incorrect path planning and potential operational issues.
  • • Compromised safety functions.

Step 4: Post-Collision Check

WARNING

If the robot experiences a hard collision with a mechanical stop (either the standard pin or an additional stop), inspect the components immediately.

A deformed stop pin (C), movable stop (B), or attachment screws (A) must be replaced. A damaged stop compromises the integrity of the working range restriction and poses a safety risk.

Restricting Other Axes (Axes 2 & 3)

As mentioned, restricting the working range for Axis 2 (lower arm) and Axis 3 (upper arm) is achieved purely through software configuration. There are no standard mechanical stops for these axes.

  • Similar to Axis 1, you will need to adjust the Upper joint bound and Lower joint bound system parameters for Axis 2 and Axis 3 respectively.
  • Refer to the Technical reference manual - System parameters for the specific parameter names and procedures.

The Process Visualized

This flowchart illustrates the critical relationship between hardware installation and software configuration when restricting the IRB 6700's working range:

flowchart TD A[Start: Decide Working Range Limits] --> B{Need to Restrict Axis 1?} B -->|Yes| C[Procure Mechanical Stop Kit\n3HAC044287-001] C --> D[Install Physical Stop at\nDesired Angular Position\n±5° to ±125° in 15° increments] D --> E[Torque Screws to 115 Nm] E --> F[Configure Software Parameters\nUpper/Lower Joint Bounds] B -->|No| F F --> G{Need to Restrict\nAxes 2 & 3?} G -->|Yes| H[Configure Software Parameters\nfor Axis 2 and/or Axis 3] G -->|No| I[Test Robot Movement\nVerify Boundaries] H --> I I --> J[Document Changes\nfor Future Reference] J --> K[End: Safely Restricted\nWorking Range] style D fill:#f0f7ff,stroke:#0e72c0,stroke-width:2px style F fill:#f0f7ff,stroke:#0e72c0,stroke-width:2px style E fill:#fef8ee,stroke:#f59e0b,stroke-width:2px

This visualization emphasizes the critical relationship between physical stops and software parameters, and the need for both to be properly configured for safe operation.

Key Takeaways and Best Practices

Hardware + Software = Safety

Always remember that mechanical stops must be mirrored by corresponding software limits in the system parameters.

Torque Matters

Use a calibrated torque wrench and the specified 115 Nm for the M12 stop screws.

Verify Parameters

After installation and configuration, double-check the system parameters to ensure they accurately reflect the physical limits. Test robot movement carefully near the new boundaries.

Inspect Regularly

Periodically check mechanical stops for any signs of damage, deformation, or loosening, especially in demanding applications.

Document Changes

Keep records of any working range modifications for future reference and maintenance.

Beyond Mechanical Stops: Advanced Considerations

Calibration Accuracy Impact

Accurate robot calibration is fundamental to the reliable functioning of software-defined working range limits. If calibration is off, the robot might either stop short unnecessarily, or worse, overshoot and potentially collide with obstacles.

Always ensure the robot is accurately calibrated before setting and relying on tight working range limits.

DressPack and Cabling Considerations

The robot's cabling solution introduces practical constraints on the working range. Cables have minimum bend radii, and forcing the robot into extreme postures might over-bend them, leading to premature wear.

When defining working ranges, inspect the cable routing throughout the intended motion envelope to ensure sufficient clearance.

TCP and Tooling: The Bigger Picture

Joint limits restrict the movement of the robot's arm structure, but the most likely part to collide is the End-of-Arm Tooling (EOAT), defined by the Tool Center Point (TCP).

Consider the TCP's position and the tool's geometry when designing the cell layout. Joint limits alone are not sufficient for tool safety.

Documentation and Handoff

Maintain a log detailing which mechanical stops are installed, at what positions, and the corresponding software parameter values. This documentation helps maintenance personnel troubleshoot issues or engineers modifying the cell layout.

Consider placing clear labels on the robot controller indicating any non-standard restrictions.

Integration with the Wider Safety Ecosystem

It's vital to understand that restricting the robot's working range using mechanical stops and system parameters is just one layer of a comprehensive workcell safety strategy. These basic restrictions work alongside:

Physical Guarding

Safety fences that physically prevent personnel from entering the robot's maximum possible reach area.

Presence Sensing Devices

Light curtains, laser scanners, or safety mats that detect intrusion into specific zones and trigger appropriate stops.

ABB SafeMove (Optional)

Advanced safety zoning allowing for configuration of complex 3D safety zones, axis range supervision, and speed restrictions.

Emergency Stop Systems

E-stops and protective stop circuits that can immediately halt robot motion in case of detected hazards.

Think of the basic working range restrictions (mechanical/parameter-based) as defining the "walls" of the robot's maximum possible operating room, while other safety devices and systems manage access and specific hazardous areas within that room.

Conclusion

Restricting the working range of the ABB IRB 6700 is a fundamental step in ensuring a safe, reliable, and efficient robot installation. By correctly installing mechanical stops for Axis 1 and meticulously configuring the corresponding system parameters for all relevant axes, you create defined operational boundaries that protect your equipment, personnel, and the robot itself.

Always prioritize safety, follow the manual's procedures accurately, and consult the specific ABB documentation, especially the Technical reference manual - System parameters, for detailed configuration steps.