Basic Sensors for Robot Grippers

Robot gripper with inductive proximity sensors mounted
Robot gripper with inductive proximity sensors mounted

Typically when we talk about end-of-arm tooling we are discussing how to make robot grippers smarter and more efficient. We addressed this topic in a previous blog post, 5 Tips on Making End-of-Arm Tooling Smarter. In this post, though, we are going to get back to the basics and talk about two options for robot grippers: magnetic field sensors, and inductive proximity sensors.

One of the basic differences is that detection method that each solution utilizes. Magnetic field sensors use an indirect method by monitoring the mechanism that moves the jaws, not the jaws themselves. Magnetic field sensors sense magnets internally mounted on the gripper mechanism to indicate the open or closed position. On the other hand, inductive proximity sensors use a direct method that monitors the jaws by detecting targets placed directly in the jaws. Proximity sensors sense tabs on moving the gripper jaw mechanism to indicate a fully open or closed position.

Robot gripper with magnetic field sensors mounted

Additionally, each solution offers its own advantages and disadvantages. Magnetic field sensors, for example, install directly into extruded slots on the outside of the cylinder, can detect an extremely short piston stroke, and offer wear-free position detection. On the other side of the coin, the disadvantages of magnetic field sensors for this application are the necessity of a magnet to be installed in the piston which also requires that the cylinder walls not be magnetic. Inductive proximity sensors allow the cylinder to be made of any material and do not require magnets to be installed. However, proximity sensors do require more installation space, longer setup time, and have other variables to consider.

Sensor Based Error Proofing – As easy as 1, 2, 3

Error proofing your manufacturing processes can be as easy as 1, 2, 3. You should be able to freely deploy error proofing in all appropriate locations in your plants without concerns regarding costs and long-term support or stability. It all starts by first identifying your trouble spots, then implementing a detection method, and finally establishing a process to handle the discrepancy. Let’s discuss the detection methods using sensors, as well as the process, for handling discrepancies.

By utilizing sensors as opposed to vision systems or other passive approaches, the cost of implementation and maintenance is reduced. With the new generation of low-cost lasers, sensors are now more affordable and easier to implement.  Radio Frequency Identification (RFID) brings new opportunities for handling non-conforming products. By tagging the individual part, assembly, or lot, products can be directed to the appropriate rework or scrap area.

These methods will allow you to implement more error proofing in your manufacturing lines to save thousand of dollars in scrap or rework and avoid the potential for costly containment.

Top 5 questions regarding error proofing…

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