Safe Robot Research Articles

Scaling Up Soft Robotics: A Meter-Scale, Modular, and Reconfigurable Soft Robotic System.

Today's use of large-scale industrial robots is enabling extraordinary achievement on the assembly line, but these robots remain isolated from the humans on the factory floor because they are very powerful, and thus dangerous to be around. In contrast, the soft robotics research community has proposed soft robots that are safe for human environments. The current state of the art enables the creation of small-scale soft robotic devices. In this article we address the gap between small-scale soft robots and the need for human-sized safe robots by introducing a new soft robotic module and multiple human-scale robot configurations based on this module. We tackle large-scale soft robots by presenting a modular and reconfigurable soft robotic platform that can be used to build fully functional and untethered meter-scale soft robots. These findings indicate that a new wave of human-scale soft robots can be an alternative to classic rigid-bodied robots in tasks and environments where humans and machines can work side by side with capabilities that include, but are not limited to, autonomous legged locomotion and grasping.

An Ultrasonic Proximity Sensing Skin for Robot Safety Control by Using Piezoelectric Micromachined Ultrasonic Transducers (PMUTs)

The safety issue of robot becomes a key challenge in modern manufacturing industry, especially in the scenario of frequent human-robot collaboration. This paper presents a flexible ultrasonic proximity sensing skin which can be integrated on the surface of robot arm to ensure the safe human-robot collaboration. The sensing skin is composed of three pieces of aluminum nitride based piezoelectric micromachined ultrasonic transducers (PMUTs) arrays at the resonance frequency of 115 kHz and chip size of 4 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 4$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times0.5$ </tex-math></inline-formula> mm. The three pieces of PMUTs arrays are evenly integrated on the flexible printed circuit board (FPCB) with a device size of 8.8 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times60$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.7$ </tex-math></inline-formula> mm. The proximity sensing skin can detect obstacles within 300 mm and 60 degrees in front, and shows a large sensing coverage in comparison with capacitive/infrared devices. Besides, it is capable of sensing transparent materials like glass. Finally, since the small size and good scalability of micro-electro-mechanical system (MEMS), the PMUTs are easy to install onto robots and to integrate with other ultrasonic transducers in the future. This PMUTs based sensing skin will greatly enhance the sensing capability of robots and human safety during collaborative work.

Safety Assessment of Rehabilitation Robots: A Review Identifying Safety Skills and Current Knowledge Gaps.

The assessment of rehabilitation robot safety is a vital aspect of the development process, which is often experienced as difficult. There are gaps in best practices and knowledge to ensure safe usage of rehabilitation robots. Currently, safety is commonly assessed by monitoring adverse events occurrence. The aim of this article is to explore how safety of rehabilitation robots can be assessed early in the development phase, before they are used with patients. We are suggesting a uniform approach for safety validation of robots closely interacting with humans, based on safety skills and validation protocols. Safety skills are an abstract representation of the ability of a robot to reduce a specific risk or deal with a specific hazard. They can be implemented in various ways, depending on the application requirements, which enables the use of a single safety skill across a wide range of applications and domains. Safety validation protocols have been developed that correspond to these skills and consider domain-specific conditions. This gives robot users and developers concise testing procedures to prove the mechanical safety of their robotic system, even when the applications are in domains with a lack of standards and best practices such as the healthcare domain. Based on knowledge about adverse events occurring in rehabilitation robot use, we identified multi-directional excessive forces on the soft tissue level and musculoskeletal level as most relevant hazards for rehabilitation robots and related them to four safety skills, providing a concrete starting point for safety assessment of rehabilitation robots. We further identified a number of gaps which need to be addressed in the future to pave the way for more comprehensive guidelines for rehabilitation robot safety assessments. Predominantly, besides new developments of safety by design features, there is a strong need for reliable measurement methods as well as acceptable limit values for human-robot interaction forces both on skin and joint level.

Image-guided robots for low dose rate prostate brachytherapy: Perspectives on safety in design and use.

Image-guided brachytherapy (BT) robots can be used to assist urologists during seed implantation, thereby improving therapeutic effects. However, safety issues must be considered in the design of such robots, including their structure, mechanical movements, function, materials and actuators. Previous reviews focused on image-guided prostate BT robot technology (e.g., imaging and robot navigation technology and robot system introduction); however, this review is the first time that safety issues have been investigated as part of a study on low-dose-rate (LDR) prostate BT robots. Multiple electronic databases were searched for LDR prostate BT robot articles published during the last 24 years (1996-2020), with a particular focus on two aspects of robots: safety in design and use. We retrieved a total of 26 LDR prostate BT robots. BT robots were divided into ultrasound, computed tomography, magnetic resonance imaging and fusion-guided systems. The conditions associated with each system were then analysed to develop a set of requirements for the safety of prostate BT robots. Recommendations are also provided for future BT robot development. The transrectal approach for prostate seed implantation is safer than the traditional transperineal approach. Research into the control of a steerable needle by the urologists and robot, the needle deflection model, and robotic automated needle changing and seed injection equipment should be pursued in a future study.

Motion planning approach for car-like robots in unstructured scenario

When a car-like robot travels in an unstructured scenario, real-time motion planning encounters the problem of unstable motion state in obstacle avoidance planning. This paper presents a hybrid motion planning approach based on the timed-elastic-band (TEB) approach and artificial potential field. Different potential fields in an unstructured scenario are established, and the real-time velocity of the car-like robot is planned by using the conversion function of the virtual potential energy of the superimposed potential field and the virtual kinetic energy of the robot. The optimized TEB approach plans the local optimal path and solves the problems related to the local minimum region and non-reachable targets. The safety area of the dynamic obstacle is constructed to realize turning or emergency stop obstacle avoidance, thereby effectively ensuring the safety of the car-like robot in emergency situations. The simulation experiments show that the proposed approach has superior kinematic characteristics and satisfactory obstacle avoidance planning effects and can improve the motion comfort and safety of the car-like robot. In the practical test, the car-like robot moves stably in a dynamic scenario, and the proposed approach satisfies the actual application requirements.

Collaborative Robot Safety for Human-Robot Interaction in Domestic Simulated Environments

Human-robot interactions carry several challenges, the most important being the risk of injury to the human. In industrial robotic systems, robots are mostly caged and isolated from humans in a safety guard environment. However, as time has passed, the use of domestic robots has emerged, leading to a high need in research on robot safety in domestic settings. Human-Robot collaboration is still in an initial stage; thus, safety assessments in domestic environments are critical in the field of collaborative robots or cobots, with simulations being the first stage of research. In this study, a preliminary investigation on the simulation of human’s safety throughout human-robot interactions in home surroundings with no safety fence is presented. A simulation model is designed and developed with Gazebo in the Robot Operating System, ROS-based, to simulate the human-robot interaction. In the robot trajectory, safety interaction can be simulated. In one example, the robot’s speed can be reduced before a collision with a human about to happen, and it can be minimized the risk of the collision or reduce the damage of the risk. After the successful simulation, this can be applied to the real robot in a domestic working environment.

Likert or Not? How Using Likert Rather Than Biposlar Ratings Reveal Individual Difference Scores Using the Godspeed Scales

We examined how a revised presentation method of The Godspeed Scales affected results accruing from such tests which concern user judgments of anthropomorphism, animacy, likability, perceived intelligence, and perceived safety of robots. Through the use of Likert-type scales, rather than the original semantic- or bipolar-scale structure, we correlated results in order to determine which word pairs in the original scales were truly opposite in their meanings, where true opposites were anticipated to possess a strongly negative correlation. Results showed that individual differences in each participant’s baseline tendency to choose a rating exerted the strongest relationship with their overall scores. When those differences were accounted for the majority of the word-pairs used in the Godspeed Scale had negative correlations. These findings indicate that individual differences, rather than features of the robot per se, played the largest part in predicting how people will perceive any particular robot.

An Error Compensation Method for Surgical Robot Based on RCM Mechanism

Remote center of motion (RCM) mechanisms, which are widely used in surgical robots, use mechanical constraints to realize movement around the RCM point. Errors in processing and assembly cause deviation of the RCM point and position error of the end-effector, these deviations cause the robot to exert excessive force on the incision during movement, leading to adverse effects that reduce the safety and accuracy of surgical robots based on the RCM. Based on kinematic calibration, this paper proposes a solution of forward and inverse kinematics considering the RCM point deviation, and this solution can simultaneously reduce the positioning error of the end-effector and the deviation of the RCM point. First, a calibration method based on the combination of the model and neural network is used to improve the kinematic accuracy of the robot. Second, a forward and inverse kinematics solution applied to RCM mechanisms is proposed, and this solution reduces the RCM point deviation during surgery. Finally, experiments were performed with an established surgery robot, verifying that the proposed method can simultaneously reduce the deviation of the RCM point and the position error of the end-effector. The proposed method is found to be superior to other methods and can improve the safety and accuracy of surgical robots.

Indoor positioning, artificial intelligence and digital twins for enhanced robotics safety

Abstract Flexible robotics safety solutions allowing the implementation of fenceless robot cells are becoming a reality nowadays. Safety approved sensors such as light curtains, safety scanners, and safety cameras have been deployed already successfully in various industrial robotic solutions. Still, as these safety systems are installed in fixed locations, monitoring predefined regions, the systems can be rigid and inflexible. This paper introduces a novel hybrid safety solution. The solution comprises safety-approved sensors, additional sensors, and artificial intelligence analysis. The system increases flexibility, especially in cases where collaborating humans and robots need monitoring in larger areas. Typically, in such environments, work objects are large and heavy, introducing additional challenges. In addition, the proposed system includes a digital twin implementation that allows a connection between the real and virtual worlds. Already virtual models and robot simulation have been used for designing safe robot applications. However, the efficient use of digital twins in safety planning and safety monitoring is still uncommon.

Case-study on Ensuring Safety of Autonomous Mobile Robot

Case-study on Ensuring Safety of Autonomous Mobile Robot

AI safety and quality management method of autonomous mobile robots using deep reinforcement learning

AI safety and quality management method of autonomous mobile robots using deep reinforcement learning

Research on the Three‐Dimensional Power Frequency Electric Field Measurement System

It is of great significance to accurately provide electric field information for electric power operators and electric power inspection equipment to ensure the safety of live working robots and electric power workers. In this paper, the principle of parallel plate charge induction is used to detect electric field signals and the influence of the inherent capacitance of the parallel plate on the back‐end circuit is considered. An equipotential ring is used as the structure of the sensing unit to eliminate the uncertainty generated by the edge electric field. The parameters of the sensor probe are determined by the principle of differential‐integration, and its structure is analyzed and designed. The consistency of the designed sensor probe was analyzed, and the results show that the consistency of the sensor is better. We have measured the sensitivity coefficients of the six probes, and the average absolute deviation reached 0.031556. The fits were all above 0.9995. In addition, a three‐dimensional power frequency electric field measurement system that is easy to manufacture is designed using the hexahedral structure, which solves the problem of inaccurate electric field measurement caused by the parallel plate probe and the field source being not perpendicular, and the combined field strength formula of nonuniform electric field was obtained. In the laboratory environment, the three‐dimensional power frequency electric field measurement system produced in this paper is compared with the electric field simulated by an electric field simulation tool. The test results show that the deviation between the measurement system and simulation is within ±0.55%, the measurement range is 1 kV/m–200 kV/m, the resolution is ≥1 V/m, and the maximum electric field can be measured at 200 kV/m. The nonlinear error is 2.15%, and the sensitivity coefficient is 19.10 mV/(kV · m−1), which meets the measurement requirements of the power frequency electric field and can be applied to the actual power frequency electric field measurement.

Ensuring Area Coverage and Safety of a Reconfigurable Staircase Cleaning Robot

Multistorey buildings are rapidly constructing with the current world development. Cleaning of these buildings is a major concern due to several issues such as scarcity of labor. Cleaning robots are developed to cope with these issues. Among these cleaning robots, staircase cleaning robots play a vital role in a multistorey building. Therefore, this paper proposes a control strategy for a reconfigurable staircase cleaning robot to ensure area coverage and safety. A staircase cleaning robot should particularly maintain its orientation parallel to the riser while maintaining a proper clearance with the riser when performing the sideways movement on a thread to ensure safety and coverage. Two Fuzzy Logic Systems (FLSs) have been developed to correct the heading and the clearance distance during sideways movements. Precise measurements on heading error and clearance distance are essential for the decision-making process of the proposed control strategy. Thus, a vision-based perception mechanism has been developed to accurately perceives these essential measurements. The proposal of the control strategy to correct the heading and the clearance distance, and the development of the vision-based perception mechanism are the major contributions of the work. Experiments were conducted by deploying the developed robot in a typical staircase considering different conditions. The experiment results validate that the proposed method can ensure coverage and safety by properly maintaining the heading and clearance of the robot with respect to a riser.

Multi-layer cyber-physical control method for mobile robot safety systems

Multi-layer cyber-physical control method for mobile robot safety systems

Structure-Controlled Variable Stiffness Robotic Joint Based on Multiple Rotary Flexure Hinges

Variable stiffness actuator (VSA) plays an important role for achieving safety and robustness for robots to physically interact with environments. This article proposes a structure-controlled approach in developing a new variable stiffness robotic joint with the merits of compactness, high stiffness, and high displacement-to-stiffness ratio. Unlike the common methods of using antagonist springs and lever concept, the structure-controlled approach achieves stiffness variation through the adjustment of mechanical structure configuration inside the actuator. Specifically, the stiffness variation is realized by changing the effective second moment of area through rotating a combination of leaf flexure hinges arranged in a radial configuration. A range of configurations are studied and the configuration we identified has the advantages of minimum unbalanced twists in the mechanism while providing high transmission torque, large stiffness, range and minimum lateral buckling effects. The performance characteristics are accomplished through a novel variable stiffness mechanism and a position-based control strategy for both position and torque control modes. A prototype system was implemented to verify the characteristic and performance of the design concept. It demonstrated that the new VSA system is effective for realising independent joint-stiffness and joint-position control of robot joints.

Constrained Model Predictive Control for dynamic path tracking of a bi-steerable rover on slippery grounds

The research works carried out in this paper deal with the control of a fast double-steering off-road mobile robot. Such kind of robots requires very high stable and accurate controllers because their mobility is particularly influenced by wheel–ground interactions. Hence, the vehicle dynamics should be incorporated in the control circuit to take into account these issues, which is developed based on the road geometry parameters and the slippage-friction conditions at the wheel–ground contacts. Relying on this dynamic model, we present in this paper the design and application of a constrained Model Predictive Control (MPC). It is based on the minimization of a cost function (optimizing the deviation from the reference trajectory, and the variation of the control input) along a finite prediction horizon, however, the prediction horizon is variable according to the forward speed of the robot. On the other hand, this approach incorporates several constraints, essentially important for the stability and safety of an off-road mobile robot moving at the high velocity, namely : saturation and maximum variations of the vehicle’s actuators (i.e. steering joints and their speeds limits) as well as the tire adhesion zone bounds (allowing to validate the assumption of a linear tire model). The full optimization problem is formulated as a Linearly Constrained Quadratic Programming (QP) to compute at each time-step the optimal and dynamically-consistent front and rear steering angles that are required to reach the desired path, with respect to all these constraints. The capabilities of our proposed controller are compared with another control law which does not apply any physical or intrinsic constraints. The latter is simply a feedback controller based on the same dynamic model and LQR theory (Linear Quadratic Regulator). Both of them have been investigated through several tests on simulations via ROS/GAZEBO and experiments on a real off-road vehicle for different kinds of trajectories and velocity levels.

A Simple Yet Effective Whole-Body Locomotion Framework for Quadruped Robots.

In the context of legged robotics, many criteria based on the control of the Center of Mass (CoM) have been developed to ensure a stable and safe robot locomotion. Defining a whole-body framework with the control of the CoM requires a planning strategy, often based on a specific type of gait and a reliable state-estimation. In a whole-body control approach, if the CoM task is not specified, the consequent redundancy can still be resolved by specifying a postural task that set references for all the joints. Therefore, the postural task can be exploited to keep a well-behaved, stable kinematic configuration. In this work, we propose a generic locomotion framework which is able to generate different kind of gaits, ranging from very dynamic gaits, such as the trot, to more static gaits like the crawl, without the need to plan the CoM trajectory. Consequently, the whole-body controller becomes planner-free and it does not require the estimation of the floating base state, which is often prone to drift. The framework is composed of a priority-based whole-body controller that works in synergy with a walking pattern generator. We show the effectiveness of the framework by presenting simulations on different types of simulated terrains, including rough terrain, using different quadruped platforms.

Development of an IoT-Based Solution Incorporating Biofeedback and Fuzzy Logic Control for Elbow Rehabilitation

The last few years have seen significant advances in neuromotor rehabilitation technologies, such as robotics and virtual reality. Rehabilitation robotics primarily focuses on devices, control strategies, scenarios and protocols aimed at recovering sensory, motor and cognitive impairments often experienced by stroke victims. Remote rehabilitation can be adopted to relieve stress in healthcare facilities by limiting the movement of patients to clinics, mainly in the current COVID-19 pandemic. In this context, we have developed a remote controlled intelligent robot for elbow rehabilitation. The proposed system offers real-time monitoring and ultimately provides an electronic health record (EHR). Rehabilitation is an area of medical practice that treats patients with pain. However, this pain can prevent a person from positively interacting with therapy. To cope with this matter, the proposed solution incorporates a cascading fuzzy decision system to estimate patient pain. Indeed, as a safety measure, when the pain exceeds a certain threshold, the robot must stop the action even if the desired angle has not yet been reached. A fusion of sensors incorporating an electromyography (EMG) signal, feedback from the current sensor and feedback from the position encoder provides the fuzzy controller with the data needed to estimate pain. This measured pain is fed back into the control loop and processed to generate safe robot actions. The main contribution was to integrate vision-based gesture control, a cascade fuzzy logic-based decision system and IoT (Internet of Things) to help therapists remotely take care of patients efficiently and reliably. Tests carried out on three different subjects showed encouraging results.

Comparison of Safety, Efficacy and Outcomes of Robot Assisted Laparoscopic Pyeloplasty vs Conventional Laparoscopy.

Pyeloplasty is considered the gold standard for the management of ureteropelvic junction obstruction in cases of flank pain, recurrent stone formation or infection, and deteriorating renal function. Over the last two decades, minimally invasive techniques such as robotic (RALP) and laparoscopic pyeloplasty (LP) have become increasingly popular and have been moderately replacing the open approach. This paper aims to provide a comprehensive up-to-date review on safety, efficacy and outcomes regarding robotic repair of UPJO compared to the conventional laparoscopic procedure. RALP represents a viable and innovative alternative to conventional LP with a comparable success and complication rate both in adult and in paediatric fields. The robotic approach seems to add further technical advantages when compared to conventional LP but sustains a higher costs. Currently, the choice to adopt one of the different minimally invasive approaches depends on the surgeon’s preference or experience, and on institutional availability.

Cybersecurity Analysis of Intelligent IIOT Robots

This paper studies the possible threats to the damaged robots. By analyzing the security problems of intelligent robots, the purpose is to strengthen the safety of robots and prevent the possible serious damage to enterprises, consumers and their surrounding environment after the vulnerabilities are maliciously exploited by attackers. ()