A multi-component force sensing system, capable of monitoring multiple components of force terms along x-, y-, and z-axis (F _x , F _y , and F _z ) and the moments terms about x-, y-, and z-axis (M _x , M _y , and M _z ) simultaneously, has been utilized in a huge variety of automation systems since 1970s. Fiber Bragg grating (FBG)-based sensing systems offer a significant viable with numerous competitive advantages over traditional force sensing systems such as immunity to electromagnetic interference, high sensitivity, larger sensing range, light weight, small size, intrinsically safe in the explosive environments, and multiplexing capabilities. Recently, a number of applications, such as robotic manipulation and robot-assisted surgery, have benefited from the developments in FBG-based force sensing systems. This paper presents a comprehensive review of different force transduction principles, state-of-the-art designs, and development methods, as well as their significances and limitations. Meanwhile, some of the significant developments in an FBG-based force sensing technology during the last few decades are surveyed, and current challenges in implementing the FBG-based force sensing technology is highlighted.

Collaborative robots equipped with multicomponent force-sensing systems at the human-robot-environment interaction interface provides competitive advantages, such as collaboration, flexibility, and reliability. Most wrist force sensors use the cross-beam structures with electrical strain gauge measurement technologies. This article proposes an approach to develop a new ultrathin three-axis fiber Bragg grating (FBG) force sensor. First, an appropriate elastomer with embedded floating beams in ultrathin dimensions to measure three-axis force is designed using a finite-element method (FEM). A temperature-compensated extreme learning machine (TC-ELM) network is proposed to achieve the characteristics of low coupling and temperature compensation (TC). Calibration and experiment on the UR5 robot are conducted, and results illustrate that the highest sensitivity of the sensor can reach 34.07 pm/N, the repetition error is less than 5%, and the maximum coupling error is less than 0.21%. The maximum temperature drift after compensation is less than 20 pm. The proposed sensor has identical output as a commercial sensor and performs well in dynamic loading and unloading operations. Finally, comparison results from commercial and academic alternatives demonstrate the interest of the proposed approach to develop high-performance and integrated force-sensing solutions.

This article presents a force/position detection model based on fiber Bragg grating (FBG), which has been further combined with the octagonal ring structure as a novel surgical jaw. Specifically, the upper jaw is force/position-jaw (FP-Jaw), which is used for position and force detection, and the lower jaw is utilized for temperature compensation. Then through Ansys finite-element simulation software, the structure optimization and harmonic response analysis of the clamp were carried out, and the operating frequency of the surgical clamp was determined to be about 0–640 Hz. Finally, temperature-compensation-force/position network (T-FPNet) for position/force decoupling is proposed, which can achieve temperature compensation as well. The experimental results clearly demonstrate that the proposed FP-Jaw can be well adapted to the forceps, with the measurement range, the maximum sensitivity, the measurement errors of force, and accuracy of the position being 0–5 N, 130.25 pm/N, 0.49%, and 99%, respectively.

The Hough transform has been widely used in image analysis and digital image processing due to its capability of transforming image space detection to parameter space accumulation. In this paper, we propose a novel Angle-Aided Circle Detection (AACD) algorithm based on the randomized Hough transform to reduce the computational complexity of the traditional Randomized Hough transform. The algorithm ameliorates the sampling method of random sampling points to reduce the invalid accumulation by using region proposals method, and thus significantly reduces the amount of computation. Compared with the traditional Hough transform, the proposed algorithm is robust and suitable for multiple circles detection under complex conditions with strong anti-interference capacity. Moreover, the algorithm has been successfully applied to the welding spot detection on automobile body, and the experimental results verifies the validity and accuracy of the algorithm.