###### Abstract
There is a list of reported accidents that includes fatality and non-fatality cases with injury and pain even using the full safety protocols and isolated work environments in developed countries such as China, Japan, the United States, and Germany, where robot use is popular in industry [14]. Environmental conditions, human error, and engineering error could be the reason for the accidents during HRC [15]. [PERSON] et al. reported thirty-two fatal and non-fatal accidents that occurred due to maintenance error and programming error [16]. [PERSON] et al. reported thirty-one cases in which workers were injured because of operators' error and maintenance errors, whereas eight cases were fatal injuries [17]. The Occupational Safety and Health Administration (OSHA) has also reported many fatal as well as non-fatal accidents occurring due to low-, medium-, and heavy-payload-capacity robots working in the non-collaborative environment since 1984. The human body regions that were affected during collisions between humans and robots were the arm, hand, shoulders, chest, neck, head, ribs, fingers, and knuckle [18]. The harm varies from minor injuries to fatal injuries. Therefore, safety issues are of prime importance for safe HRC to minimize the number of accidents. For appropriate safety standards in such systems, new regulations are established for the design and application to allow HRC in industrial environments [19]. Spanish UNE-EN 755, American ANSI/RIA R15.06, ISO 10218, and Technical Specification ISO/TS 15066:2016 are the national and international standards that incorporate robot-associated risks for safe human and robot interaction. In future manufacturing, HRC in the context of smart factories will involve heavy-payload-capacity robots that will increase the chances and magnitude of impacts due to several types of failures [20]. Therefore, for a safe collaborative environment in HRC, it is important to analyze the accidental impact on the human body either by estimating the pain tolerance or by quantifying the level of injury followed by impact. Several methods have been adopted by researchers to measure the tolerable pain level in case of impact in HRC. A pneumatic-cylinder-based actuator was used in one study to deliver impacts on twelve different regions of human volunteers for calculating the tolerable impact forces, but it was suggested to follow a simulations-based approach to include different surfaces of industrial robots [21]. A passive mechanical lower arm, which mimicked human characteristics, was used as an alternative to the human volunteers for evaluating pain level, as presented in [22]. Similarly, the Association for the Advancement of automotive Medicine (AAAM) has divided the human body into different regions for automobile crash-tests for the evaluation of injury level and has proposed standard injury scales such as the Abbreviated Injury Scale (AIS)and Maximum Abbreviated Injury Scale (MAIS) to assess the injury level after impact during HRC [23]  
In this work, we assessed the level of injury during human-robot accidental interaction. The Finite Element model of a human hand and a single index finger was selected to simulate the scenarios of human-robot accidents for the purpose of validation, reinforcement, and extension of the Technical Standard TS/15066 standard for Robots and Robotic devices [24]. Different cases of quasi-static and dynamic analysis were performed to estimate the level of damage expected in the case of accidents involving low-, medium-, and heavy-payload-capacity robots. No such analysis has previously been carried out for biomechanical modeling of accident scenarios for different-payload-capacity robots. This work offers insights into the impact of loading conditions and contact velocities on expected injury level, thus boosting confidence in the adoption of heavy-payload-robots in factories of the future.