Crafting an Affordable DIY Collision Detection Sensor for Industrial Robot Tools: Exploring Effective and Low-Cost Solutions

What is your tool? For educational purposes I've seen people use a cardboard box as the working surface so if it hits it, it just dents the box.

Maybe a rubber vibration mount. I wouldn't use it for anything super precise.

You could also mount a limit switch or prox sensor to see if it was bumped out of place.

Here are some on McMaster.

IMHO I think that you are going to discover that there is no solution that meets the requirements of

1. inexpensive
2. easy to implement
3. does not restrict working volume or access to workpieces
4. is simple and fast to build a DIY system

In my teaching episodes, I finally and reluctantly acknowledged that students will be students: clumsy, underskilled, impatient, refuse to read instructions, entitled to believe there are no consequences to their reckless actions, and they already know everything. They also think every machine should have the same ease-of-use and speed of reaction as an iPhone.

My teaching method guides the students into the realization that robotic programming is a game of diligence, discipline, and patience. My teaching rigs all have surfaces of home-store semi-rigid foam insulation boards for the inevitable crashes and scrapes. My fundamentals teaching methodology is delivered in progressive steps using a flat table surface and a simple pointer tool:

1. Rigorous skills development of motion mode and pendant fundamentals with practicum before proceeding to simple programming. Students must pass this 100% before moving on to demonstrate competency.
2. Simple joint mode teaching of a path. The printed path contains linear & circular paths, but the first exercise is strictly non-oriented point-to-point joint moves. Tool-Z is not aligned perpendicular to the surface and this enhances understanding of coordinate systems and limits of joint mode teaching.
3. Same path, but this time introduce Tool-Z perpendicular to surface for ease of teaching. Base mode and tool mode teaching used.
4. Same path, but Tool-X (or Tool-Y) must now change orientation and follow the tangent of the path.
5. Same path, but now linear & circular interpolation is introduced.
6. Same path, but now variable speeds and variable tool tilt orientations are introduced.
7. Same path, but now variable point accuracy is introduced (which is manifested in a zig-zag path segment).

By the time the students get to Step 3 they are usually very competent and don't crash the robot. Usually. After Step 3, the remaining steps progress very rapidly. But crashes still occur in the foam board, so no damage is done.

After students complete this sequence, we move on to more advanced 3D paths with integrated gripper & sensor tasks. Home-built fixtures and teaching objects are clamped on the foam board.

If you are committed to a crash sensor, then here are a few ideas for DIY devices to ponder:

• investigate "3D printed flexure robot gripper" for images of ideas of things already done
• flexible strip resistors attached to flexible elements, then measure the voltage through the resistors to sense defection. I had a student develop this idea for sensing the bending position of a finger inside a glove. This would require electrical integration & programming.
• 3D printed hacked copies of commercially available breakaway devices...maybe could be done. Maybe.
• Tool-Z collision devices may be sufficient with spring-loaded designs.
• Depending on how sophisticated your robot of choice is, there may be an opportunity to monitor the current of the wrist joint motors. Too much current = crash or collision. But this is a tricky software solution.