Robotic force sensors are on the fast track to joining robot vision systems as a mainstream robotic technology. While force sensor technology has been around for years, recent improvements have led to the rise of their use since they can expand manufacturing capabilities with robots. Providing industrial robots with the sense of touch has been proven to be widely beneficial for many applications, especially those in the material removal and material handling categories. A FANUC M-701ic/50 is able to accurately and efficiently polish parts with force sensing feedback producing even and uniform product finishes. While a Motoman HP20 integrated with force sensors is better equipped to determine the correct amount of pressure and torque to apply while assembling parts with tight tolerances.
There are many different types of robotic force sensors available on the market for users to choose from. Below is a breakdown of the three most common types used when automating with industrial robots.
Pressure Sensors
The development of force sensing technology actually began with pressure sensors. These are the most basic type of force sensor and because of this they tend to be the most affordable. Also known as force sensitive resistors, they can detect force applied to a single axis in one direction. Because of their simplicity they are best suited for detecting if force was applied or not. They cannot be utilized for measuring amounts of force or for complex robotic applications since they have a higher margin of error.
Strain Gauge Force Sensors
Strain gauge sensors are the most common force sensor type integrated with today’s industrial robots. They feature a thin conductor composed of either a metal foil or silicon as is the case with newer models. The conductor is arranged in a wheel shaped pattern and when force is applied it becomes deformed resulting in a longer and thinner shape. The resistance change of the conductor is measured with an analog circuit. The circuit converts the resistance change measurement into an analog voltage to be recorded electronically. There are two types of strain gauge sensors; single-axis load cells and multi-axis force sensors. Single-axis load cell sensors are not typically deployed with industrial robots since they can only detect force form one axis. Multi-axis force sensors, however, are the most popular type for robots since they consist of several strain gauges to measure the forces applied to all six robot axes.
Integrating strain gauge force sensors to the wrist of a FANUC R-2000ib provides it with touch sensory feedback for more accurate and precise movements allowing for the proper handling and assembly of parts. These sensors have become popular amongst the electronic industry where providing sensory information is key for successful automation of small part assemblies that are common in the industry.
Capacitive Force Torque Sensors
Capacitive force torque sensors are designed to measure the force applied to all six robot axes digitally instead of through an analog signal. These sensors feature a metal block placed in-between two metal plates that each contain capacitive sensors. When force is applied, the metal block will become deformed and the capacitive sensors measure the movement of the plates to determine the amount of force. These sensors are not impaired by loud noise and tend to be more accurate than other types.
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