Additive Manufactured Sensitive Gripper Jaw for Extended Gripping Force Ranges in Robotics

In this contribution, we present a novel additive manufactured sensitive gripper jaw based on strain gauge technology for extended gripping force ranges in robotics up to 40 N using fused layer manufacturing (FLM). The present sensor design is based on an arbitrary number of bending beams arranged one above the other, based on a single-point load cell. With this multiple-bending-beam structure, it is possible to individually reduce the mechanical stresses while maintaining the same deflection of the gripper jaw and enabling parallel gripping of parts. By varying the number of bending beams, it is also possible to adapt the measurement range accordingly. The investigations focus on the general sensor design, the fabrication process, and the sensor behavior in terms of zero-point deviation, characteristic value deviation, linearity behavior, repeatability, and viscoelastic behavior. The results show that higher gripping force measurement ranges are possible with good sensor linearity of 0.14% of full scale (FS). The arising viscoelastic behavior can be attributed to the properties of plastics. Nevertheless, this sensor is suitable for gripping force measurement in most industrial robot applications.