Expert Tips for Robot Collision Avoidance

From single robot usage to large-scale, multi-robot systems, a robot’s ability to perceive obstacles and avoid collisions is paramount to smooth and safe robotic operation. Whether through strategic path planning, proximity sensor detection or other means, collision avoidance is vital to ensuring application success. With that in mind, here are a few concepts to consider where collision avoidance is concerned:

Define Interference Zone
One of the easiest ways to prevent a collision is to make sure the robot knows which areas to avoid. By defining interference zones, you can restrict the robot to operate in a specific range, keeping it out of undesired areas. Note: it is important to add a tool interference file for each robot tool – as this allows the robot to consider the tooling for the interference zones and not just its own body.

Test Job in Teach Mode
Programming best practices involve testing each created job in teach mode. This allows the operator to check all positions a robot can go to during a job, helping to confirm collisions are avoided.

Utilize Sensor Technology
Adding sensors to track objects and machines that interact with the robot can be extremely beneficial. The robot will inevitably have to interact with objects or other machinery in the workcell to complete its designated tasks. Using sensors or other communication devices that inform the robot where an object might be at a given time, or what state a machine might be in, allows decisions to be made within the robot job. For example, proximity sensors can be used to confirm if an object exists at a pick and place location, or if a machine door is open or closed. This information can then be used in the robot job to determine if the robot should continue moving, wait for the status to change or flag an alarm to alert an operator.

Pay Attention to Speed
In play mode and teach mode, it is important to pay attention to the speed of the robot – as forgetting the robot is in high speed during the teaching process could result in colliding into an object unintentionally when creating the job. When in play mode, it is important to understand the speed of each motion and whether that could cause collisions with other moving parts within the workcell (based on timing).
 
Be “Coordinate System” Aware
In teach mode, always be aware of which coordinate mode you are teaching the robot in (i.e., joint, cartesian/world, tool, user frame). Otherwise, the robot could move in an unintended direction during the jogging process.

Maintain a Clear Operating Area
Always know what is allowed into the robot’s operation area. Clearly define the operation area by either putting up safety guarding or by marking the floor. Also, keep the operation area clean of objects or obstacles that are not taken into account by the robot’s programming.

Pay Attention to Cursor Placement
When the robot is running production and a fault or alarm occurs, be mindful of the cursor placement on the teach pendant’s job screen. If the cursor is moved while in teach mode, beware! Some of the worst crashes happen when restarting the robot in play mode after a fault or alarm – as the cursor may have been left in the wrong line or the operator may have restarted the Master Job from the beginning.

Offline Programming

To visually confirm a robot or robotic workcell configuration and test it with motion before it is installed on the production floor, the use of offline programming (OLP) software is highly suggested. From collision detection and path planning to conveyor tracking and more, OLP platforms provide fairly accurate 3D representation that visually demonstrates how a robot will move along a programmed path.

Overall, the flexibility provided by OLP software offers several perks and enables a higher mix of jobs with a simple transition from one job to the next. OLP allows detailed job programming for reduced robot downtime, and it helps larger companies with multiple locations and/or robotic workcells to reduce programming time and inconsistencies by distributing the programmed job from a central controlled source.

Yaskawa’s MotoSim® is a user-friendly, cost-effective software option that is ideal for a variety of programming and reach studies. Other third-party options, such as OCTOPUZ® and Delfoi, provide robust functionality, allowing task experts to program robots quickly with ease.

Training and Support

Often times, robot crashes reveal that more robot training may be needed. If you’re looking to upskill your current workforce, check out our upcoming classes available through Yaskawa Academy. And, as always, if you are a Yaskawa customer and need immediate assistance, don’t hesitate to call our 24/7 Yaskawa Support Services technical support hotline.