Human–robot collaborative disassembly is an approach designed to mitigate the effects of uncertainties associated with the condition of end-of-life products returned for remanufacturing. This flexible semi-autonomous approach can also handle unpredictability in the frequency and numbers of such returns as well as variance in the remanufacturing process. This article focusses on disassembly, which is the first and arguably the most critical step in remanufacturing. The article presents a new method for disassembling press-fitted components using human–robot collaboration based on the active compliance provided by a collaborative robot. The article first introduces the concepts of human–robot collaborative disassembly and outlines the method of active compliance control. It then details a case study designed to demonstrate the proposed method. The study involved the disassembly of an automotive water pump by a collaborative industrial robot working with a human operator to take apart components that had been press-fitted together. The results show the feasibility of the proposed method.

Disassembly is a core procedure in remanufacturing. Disassembly is currently carried out mainly by human operators. It is important to reduce the labor content of disassembly through automation, to make remanufacturing more economically attractive. Threaded fastener removal is one of the most difficult disassembly tasks to be fully automated. This article presents a new method developed for automating the unfastening of screws. An electric nutrunner spindle with a geared offset adapter was fitted to the end of a collaborative robot. The position of a hexagonal headed screw in a fitted stage was known only approximately, and its orientation in the hole was unknown. The robot was programed to perform a spiral search motion to engage the tool onto the screw. A control strategy combining torque and position monitoring with active compliance was implemented. An existing robot cell was modified and utilized to demonstrate the concept and to assess the feasibility of the solution using a turbocharger as a disassembly case study. Note to Practitioners-Remanufacturing is known to generate substantial economic, social, and environmental benefits. Disassembly is the first operation in a remanufacturing process chain. Unfastening threaded parts (“unscrewing”) is a common disassembly task accounting for approximately 40% of all disassembly activity. Like other disassembly tasks, often, unscrewing has to be carried out manually in remanufacturing due to difficulties caused by the variable and unpredictable condition of the end-of-life (EoL) products to be remanufactured. Automating unscrewing operations should reduce the labor content of disassembly, thus lowering remanufacturing costs and promoting the adoption of remanufacturing. This article proposes the use of a collaborative robot to perform autonomous unfastening of hexagonal headed screws. Collaborative robots have built-in force sensors and can be programed to carry out operations involving not only position but also active force and compliance control. They can work safely alongside human operators, enabling the latter to focus on jobs requiring high cognitive or manipulation abilities. The article presents a novel spiral search technique developed to improve the rate of successful engagement between the robot end effector and the screw heads despite uncertainties in the location of the screws. The technique was successfully demonstrated on the dismantling of a turbocharger but can readily be applied to other EoL products with hexagonal headed screws. It can also be used with other kinds of screws (e.g., Phillips screws and slotted-head screws) simply by changing the tool and tuning the robot control parameters. A limitation of the proposed technique is that it can only deal reliably with undamaged screws. In our future research, we will consider screws that are in imperfect conditions through usage and develop appropriate solutions for their removal by robots.

Real-time cutting force measurement is significant important to monitor tool condition and machining process. Although commercial dynamometers are available for a range of machining applications, there is a lack of multi-point and low-cost measuring methods suitable for detecting cutting forces in harsh machining environments. In this paper, a smart cutting tool integrated with optical fibre sensors is firstly presented for cutting force measurements in turning. Fibre Bragg grating (FBG) sensors are employed to acquire cutting force information on cutting tools. Compared with electrical and piezoelectric sensors, the proposed smart cutting tool has unique advantages such as electromagnetic interference immunity, explosion proof, ability to measure multiple cutting forces in the same and simplified data acquisition device with a long-distance signal transmission, enabling it to work in harsh machining environments. In addition, the proposed smart tool brings little effect on the structure and characteristics of machine tools due to FBG’ small size and lightweight. This paper investigates the operating principle of the sensory cutting tool theoretically and validates it using finite element simulations. A prototype of the proposed device was developed and tested. Static calibration, dynamic identification experiment and comparative cutting tests were conducted to evaluate its performances. Experimental results have shown that the cutting forces acquired by the developed smart tool are in good agreements with the results obtained by the reference commercial dynamometer. The proposed smart cutting tool has the potential to provide a new solution to the real-time measurement and monitoring of multi-point cutting forces in turning processes.

Using humans and robots working together to disassemble end-of-life (EoL) products so that they can be remanufactured enables catering for the effects of uncertainties in the condition of those products and unpredictability in remanufacturing operations. Collaborative robots are one of the key elements of Industry 4.0. This paper presents a strategy for human-robot collaborative disassembly that exploits the active compliance control capability of collaborative robots. The paper outlines the proposed human-robot collaboration strategy and active compliance control. It then presents a case study of robotic disassembly designed to show a practical implementation of the proposed strategy to take products apart. The study involved the dismantling of an automotive water pump by a collaborative industrial robot working with a human operator and by two collaborative robots and a human operator. Active compliance control was implemented to separate press-fitted components from the water pump. The results demonstrate the feasibility of the strategy and its effectiveness at increasing flexibility and adaptability by reducing setup efforts.

Vibration fatigue failure is a critical problem of hydraulic pipes under severe working conditions. Strain modal testing of small and light pipes is a good option for dynamic characteristic evaluation, structural health monitoring and damage identification. Unique features such as small size, light weight, and high multiplexing capability enable Fibre Bragg Grating (FBG) sensors to measure structural dynamic responses where sensor size and placement are critical. In this paper, experimental strain modal analysis of pipes using distributed FBG sensors ispresented. Strain modal analysis and parameter identification methods are introduced. Experimental strain modal testing and finite element analysis for a cantilever pipe have been carried out. The analysis results indicate that the natural frequencies and strain mode shapes of the tested pipe acquired by FBG sensors are in good agreement with the results obtained by a reference accelerometer and simulation outputs. The strain modal parameters of a hydraulic pipe were obtained by the proposed strain modal testing method. FBG sensors have been shown to be useful in the experimental strain modal analysis of small and light pipes in mechanical, aeronautic and aerospace applications.