Safe Robot Research Articles

Event-based tracking of human hands

Purpose This paper proposes a novel method for human hands tracking using data from an event camera. The event camera detects changes in brightness, measuring motion, with low latency, no motion blur, low power consumption and high dynamic range. Captured frames are analysed using lightweight algorithms reporting three-dimensional (3D) hand position data. The chosen pick-and-place scenario serves as an example input for collaborative human–robot interactions and in obstacle avoidance for human–robot safety applications. Design/methodology/approach Events data are pre-processed into intensity frames. The regions of interest (ROI) are defined through object edge event activity, reducing noise. ROI features are extracted for use in-depth perception. Findings Event-based tracking of human hand demonstrated feasible, in real time and at a low computational cost. The proposed ROI-finding method reduces noise from intensity images, achieving up to 89% of data reduction in relation to the original, while preserving the features. The depth estimation error in relation to ground truth (measured with wearables), measured using dynamic time warping and using a single event camera, is from 15 to 30 millimetres, depending on the plane it is measured. Originality/value Tracking of human hands in 3 D space using a single event camera data and lightweight algorithms to define ROI features (hands tracking in space).

Blower-Powered Soft Inflatable Joints for Physical Human-Robot Interaction.

Inflatables are safe and lightweight structures even at the human scale. Inflatable robots are expected to be applied to physical human-robot interaction (pHRI). Although active joint mechanisms are essential for developing inflatable robots, the existing mechanisms are complex in structure and it is difficult to integrate actuators, which diminish the advantages of inflatables. This study proposes blower-powered soft inflatable joints that are easy to fabricate and contain enough space for an actuation inside. The joints are driven by tendon wires pulled by linear actuators. We derived a theoretical model for both unilateral and bilateral joints and demonstrated a hugging robot with multiple joints as an application of the proposed joint mechanism. The novelty of the proposed joint mechanism and the inflatable robot is that rigid parts have been thoroughly eliminated and the tendons for actuation have been successfully hidden inside. Moreover, the active control of the internal pressure makes inflatables resistant to punctures. We expect that the contact safety of inflatable robots will facilitate advancement of the pHRI field.

Efficacy of a Novel Exoskeletal Robot for Locomotor Rehabilitation in Stroke Patients: A Multi-center, Non-inferiority, Randomized Controlled Trial.

Objective: To investigate the efficacy and safety of a novel lower-limb exoskeletal robot, BEAR-H1 (Shenzhen Milebot Robot Technology), in the locomotor function of subacute stroke patients.Methods: The present study was approved by the ethical committee of the First Affiliated Hospital of Nanjing Medical University (No. 2019-MD-43), and registration was recorded on the Chinese Clinical Trial Registry with a unique identifier: ChiCTR2100044475. A total of 130 patients within 6 months of stroke were randomly divided into two groups: the robot group and the control group. The control group received routine training for walking, while in the robot group, BEAR-H1 lower-limb exoskeletal robot was used for locomotor training. Both groups received two sessions daily, 5 days a week for 4 weeks consecutively. Each session lasted 30 min. Before treatment, after treatment for 2 weeks, and 4 weeks, the patients were assessed based on the 6-minute walking test (6MWT), functional ambulation scale (FAC), Fugl-Meyer assessment lower-limb subscale (FMA-LE), and Vicon gait analysis.Results: After a 4-week intervention, the results of 6MWT, FMA-LE, FAC, cadence, and gait cycle in the two groups significantly improved (P < 0.05), but there was no significant difference between the two groups (P > 0.05). The ratio of stance phase to that of swing phase, swing phase symmetry ratio (SPSR), and step length symmetry ratio (SLSR) was not significantly improved after 4 weeks of training in both the groups. Further analyses revealed that the robot group exhibited potential benefits, as the point estimates of 6MWT and Δ6MWT (post-pre) at 4 weeks were higher than those in the control group. Additionally, within-group comparison showed that patients in the robot group had a significant improvement in 6MWT earlier than their counterparts in the control group.Conclusions: The rehabilitation robot in this study could improve the locomotor function of stroke patients; however, its effect was no better than conventional locomotor training.

Musculoskeletal modeling and humanoid control of robots based on human gait data.

The emergence of exoskeleton rehabilitation training has brought good news to patients with limb dysfunction. Rehabilitation robots are used to assist patients with limb rehabilitation training and play an essential role in promoting the patient’s sports function with limb disease restoring to daily life. In order to improve the rehabilitation treatment, various studies based on human dynamics and motion mechanisms are still being conducted to create more effective rehabilitation training. In this paper, considering the human biological musculoskeletal dynamics model, a humanoid control of robots based on human gait data collected from normal human gait movements with OpenSim is investigated. First, the establishment of the musculoskeletal model in OpenSim, inverse kinematics, and inverse dynamics are introduced. Second, accurate human-like motion analysis on the three-dimensional motion data obtained in these processes is discussed. Finally, a classic PD control method combined with the characteristics of the human motion mechanism is proposed. The method takes the angle values calculated by the inverse kinematics of the musculoskeletal model as a benchmark, then uses MATLAB to verify the simulation of the lower extremity exoskeleton robot. The simulation results show that the flexibility and followability of the method improves the safety and effectiveness of the lower limb rehabilitation exoskeleton robot for rehabilitation training. The value of this paper is also to provide theoretical and data support for the anthropomorphic control of the rehabilitation exoskeleton robot in the future.

Assistive control of brain-control multiple robots

Brain-controlled robots have important application values in assisting persons with disabilities. However, few studies focus on brain-controlled multiple robots. This paper proposes an assistive controller based on model prediction with the leader-follower formation strategy for developing brain-controlled multiple robots. The controller is composed of a leader controller and a follower controller. The experimental results of brain-controlled multiple robots show that the proposed method can track the user’s lateral and longitudinal control intention and maintain the stability of the multi-robot formation while ensuring the safety of brain-controlled multiple robots. This work can advance the research and development of brain-controlled multiple robots.

On the Safety of Mobile Robots Serving in Public Spaces

Since 2014, a specific standard has been dedicated for the safety certification of personal care robots, which operate in close proximity to humans. These robots serve as information providers, object transporters, personal mobility carriers, and security patrollers. In this article, we point out the shortcomings concerning EN ISO 13482:2014, which encompasses guidelines regarding the safety and design of personal care robots. In particular, we argue that the current standard is not suitable for guaranteeing people's safety when these robots operate in public spaces. Specifically, the standard lacks requirements to protect pedestrians and bystanders. The guideline implicitly assumes that private spaces, such as households and offices, present the same hazards as in public spaces. We highlight the existence of at least three properties pertaining to robots’ use in public spaces. These properties include (1) crowds, (2) social norms and proxemics rules, and (3) people's misbehaviours. We discuss how these properties impact robots’ safety. This article aims to raise stakeholders’ awareness on individuals’ safety when robots are deployed in public spaces. This could be achieved by integrating the gaps present in EN ISO 13482:2014 or by creating a new dedicated standard.

A New Cam-follower Safety Joint Mechanism Design based on Variable-length Four-bar Linkage for Robot Safety

Abstract Humans come into physical contacts with various machines such as robots in daily life. This leads to the underlying issue of guaranteeing safety during such human-robot interactions. Thus, many devices and methods have been studied for impact damage reduction. A safety joint mechanism (SJM) using four-bar linkages has been highlighted as an impact cutoff device owing to its capabilities of nonlinear load transfer. This paper focuses on a new design and testing for a kinematic element of an SJM based on four-bar linkages to improve the impact cutoff performances. In the present work, a set of variable-length floating link designs is proposed, and the mechanism is implemented by mechanical contact surface profile shaping between the cams and followers. The performance of the cam-follower mechanism is evaluated depending on the variable length of the floating link, by using equivalent stiffness method, which successfully quantifies the performance of the proposed mechanism. Based on this design and analysis, two SJMs having symmetrical arrangements for four numbers of cam-follower mechanisms are fabricated: one SJM has fixed-length floating links and the other has variable-length floating links. The effect of the new kinematic elements on the performance improvement is verified by comparing the absorbed impact rates of the two SJMs by impact hammer-like drop tests. Consequently, it is confirmed that the rapid length change of the floating link is the core element for improving the performance of the safety mechanism.

Self-protective motion planning for mobile manipulators in a dynamic door-closing workspace

PurposeMany work conditions require manipulators to open cabinet doors and then gain access to the desired workspace. However, after opening, the unlocked doors can easily close, interrupt a task and potentially break the operating end-effectors. This paper aims to address a manipulator's behavior planning problem for responding to a dynamic workspace released by door opening.Design/methodology/approachA dynamic model of the restricted workspace released by an unlocked door is established. As a whole system to treat, the interactions between the workspace and robot are analyzed by using a partially observable Markov decision process. A self-protective policy decision executed as a belief tree is proposed. To respond to the policy, this study has designed three types of actions: stay on guard in the workspace, using an elbow joint to defense the door and linear escape out of the workspace for self-protection by observing collision risk levels to trigger them. Finally, this study proposes self-protective motion controllers based on risk time optimization to act to the planned actions.FindingsThe elbow defense could balance robotic safety and work efficiency by interrupting the end-effector's work and using the elbow joint to prevent the door-closing in an active collision way. Compared with the stay and escape action, the advantage of the elbow defense is having a predictable performance to quick callback the interrupted work after the risk was relieved.Originality/valueThis work provides guidance for the safe operation of a class of robot operations and the upgrade of motion planning.

Towards a balancing safety against performance approach in human–robot co-manipulation for door-closing emergencies

Telemanipulation in power stations commonly require robots first to open doors and then gain access to a new workspace. However, the opened doors can easily close by disturbances, interrupt the operations, and potentially lead to collision damages. Although existing telemanipulation is a highly efficient master–slave work pattern due to human-in-the-loop control, it is not trivial for a user to specify the optimal measures to guarantee safety. This paper investigates the safety-critical motion planning and control problem to balance robotic safety against manipulation performance during work emergencies. Based on a dynamic workspace released by door-closing, the interactions between the workspace and robot are analyzed using a partially observable Markov decision process, thereby making the balance mechanism executed as belief tree planning. To act the planning, apart from telemanipulation actions, we clarify other three safety-guaranteed actions: on guard, defense and escape for self-protection by estimating collision risk levels to trigger them. Besides, our experiments show that the proposed method is capable of determining multiple solutions for balancing robotic safety and work efficiency during telemanipulation tasks.

The concept of spatial motion restriction zones in a robot-assisted surgical system.

The development of robotics and medicine in recent years leads to increasing mutual integration of these two disciplines. The use of specialized robotic solutions in medicine poses new challenges, including the issue of safety. The paper analyzes existing solutions aimed at improving safety in medical robotics. The concept of spatial motion restriction zones-areas of space affecting the process of robot-assisted surgery and designed to minimize risks for the patient is proposed. Various applications of such zones are considered, such as: creating an optimal medical tool path when planning an operation, an adaptive movement restriction during manual manipulator control, including limiting maximum velocity. An approach to adaptively changing the parameters of motion restriction zones is presented, and possible data sources for this change are considered. A technique is introduced for using a hybrid motion restriction zone, combining several zones into a single complex system with various types of interaction. Approaches to manual control of a collaborative robot, including the use of force-torque sensors, are considered.

ILLEGAL USE OF MEDICAL ROBOTS: CRIMINAL LAW ASSESSMENT AND CRIMINOLOGICAL RISKS

In the article, the author, on the positive side, assessing the capabilities of robotic medicine, states that today there is no comprehensive study of the safety of medical robots. In this regard, the possibility of risks and threats in the conduct of robotic surgical care cannot be denied. These actions can lead to serious legal consequences for the surgeon, medical institution and manufacturer of the medical robot. The author draws attention to the fact that there is no definition of the concept of "medical robot" in domestic regulatory legal acts. However, the Federal Law of November 21, 2011 No. 323-FZ "On the basics of protecting the health of citizens in the Russian Federation" establishes the concept of "medical product," which is quite capacious and may include the concept of "medical robot."It is necessary to distinguish the concept of "medical robot" as one of the types of medical devices, indicating it in the text of the order of the Ministry of Health of the Russian Federation. The author concludes that it should be understood as a "medical robot," and also attempts to classify the criminological risks arising from its use, depending on the contact of the medical robot with humans. In addition, the publication raises issues of qualifying the actions of attackers who, in the process of illegal access, illegally receive patient data, which forms part of the crime under Art. 137 of the Criminal Code.

Framed and non-framed robotics in neurosurgery: A 10-year single-center experience.

Safety, efficacy and efficiency of neurosurgical robots are defined by their design (i.e., framed and non-framed) and procedural workflow (PW) (from image to surgery). The present study describes the quality indicators of three different robots in brain and spine surgery. This single-centre study enrolled 252 patients over a 10-year period. Safety (complication rate) and efficacy (diagnostic yield, pedicle screw placement) were determined. Predictors of workflow efficiency (e.g., skin-to-skin) were evaluated and compared to conventional techniques (neuronavigation, stereotaxy). All robots showed excellent reliability (97.5%-100%) with low complication rates (4.5%-5.3%) and high efficacy (94.7%-97.7%). Robotics demonstrated a better time-efficiency than neuronavigation. However, there was no shortening of surgery time compared to conventional stereotaxy. Time-efficiency differed significantly between framed and non-framed workflows. While all neurosurgical robots were reliable, safe and efficacious, there were significant differences in time-efficiency. PWs should be improved to increase the acceptance of robotics in neurosurgery.

Design and Passive Training Control of Elbow Rehabilitation Robot

In this paper, a rehabilitation robot driven by multifilament muscles is designed based on the rehabilitation robot motion model and a system elbow joint model. The passive training mode of rehabilitation robots were researched, and active disturbance rejection control (ADRC) leveraged to improve the tracking angle of robot joints. In the no-load motion simulation of rehabilitation robots, disturbances are added to the control variables to complete the ADRC and Proportional Integral Differential (PID) position control simulation. The simulation results indicate that the auto disturbance rejection control can quickly keep up the expected signal without overshoot, solve the contradiction between the system rapidity and overshoot. Moreover, it can better suppress the interference even if the external load changes. The upper limbs of the human body are used as the load on the robot body to complete the simulation of ADRC and PID position control objects of different weights. Finally, a passive rehabilitation training experiment was conducted to verify the safety of the rehabilitation robot, the rationality, comfort, and robustness of the mechanism design, and the effectiveness and feasibility of the ADRC.

Energy budgets for coordinate invariant robot control in physical human–robot interaction

In this work we consider the current certification process of applications with physical human–robot interaction (pHRI). Two major hazards are collisions and clamping scenarios. The implementation of safety measures in pHRI applications typically depends strongly on coordinates, e.g., to monitor the robot velocity or to predict external forces. We show that the current certification process does not, in general, guarantee a safe robot behavior. In particular, in unstructured environments it is not possible to predict all risks in advance. We therefore propose to control the energy of the robot, which is a coordinate invariant entity. For an impedance controlled robot, the total energy consists of potential energy and kinetic energy. The energy flow from task description to physical interaction follows a strict causality. We assign a safe energy budget for the robot. With this energy budget, the presented controller auto-tunes its parameters to limit the exchanged kinetic energy during a collision and the potential energy during clamping scenarios. In contact, the robot behaves compliantly and therefore eliminates clamping danger. After contact, the robot automatically continues to follow the desired trajectory. With this approach the number of safety-related parameters to be determined can be reduced to one energy value, which has the potential to significantly speed up the commissioning of pHRI applications. The proposed technique is validated by experiments.

SIMULATION OF MOBILE ROBOT CLAMPING MAGNETS BY CIRCLE-FIELD METHOD

Abstract There are a list of complicated tasks need to be solved to increase the working productivity and decrease working cost in modern shipbuilding and ship repair. Good results in solving those problems are shown whether automation with varied robots implementation. The mobile robots able to move and perform given technological operations on different-spaced ferromagnetic surfaces are equipped with own control systems, movers and clamping devices. Usually, reliability and safety of such robots are in direct dependence on designers’ adequate representation of their behavior that is described by mathematical description of separate parts or the robot in the whole to correct control problem solving. The article amply considers the process of the climbing mobile robot clamping electromagnet simulation model building using the improved circle-field method on the example of BR-65/30 clamping electromagnet. The model is built on the basis of interpolated dependences of flux coupling and electromagnetic force on the magnetomotive force and the value of the air gap obtained by numerical calculations of the magnetic field. The dynamic properties of the electromagnet are investigated and a family of its traction characteristics is obtained by the developed model, which can be used for automatic control of the robot clamping device. References 25, figures 5, tables 3.

Use of Human Motion Data to Train Wearable Robots

Development of wearable robots is accelerating. Walking robots mimic human behavior and must operate without accidents. Human motion data are needed to train these robots. We developed a system for extracting human motion data and displaying them graphically.We extracted motion data using a Perception Neuron motion capture system and used the Unity engine for the simulation. Several experiments were performed to demonstrate the accuracy of the extracted motion data.Of the various methods used to collect human motion data, markerless motion capture is highly inaccurate, while optical motion capture is very expensive, requiring several high-resolution cameras and a large number of markers. Motion capture using a magnetic field sensor is subject to environmental interference. Therefore, we used an inertial motion capture system. Each movement sequence involved four and was repeated 10 times. The data were stored and standardized. The motions of three individuals were compared to those of a reference person; the similarity exceeded 90% in all cases.&#x0D; Our rehabilitation robot accurately simulated human movements: individually tailored wearable robots could be designed based on our data. Safe and stable robot operation can be verified in advance via simulation. Walking stability can be increased using walking robots trained via machine learning algorithms.

Effectiveness and Safety of Moxibustion Robots on Primary Dysmenorrhea: A Randomized Controlled Pilot Trial.

To conduct a pilot trial to explore the effectiveness and safety of moxibustion robots in treating primary dysmenorrhea (PD) and evaluate its feasibility in clinic. A total of 70 participants with PD were allocated to either moxibustion robot (MR) group (35 cases) or manual moxibustion (MM) group (35 cases) using computer-generated randomization. One acupoint Guanyuan (CV 4) was selected to receive moxa heat stimulation. Two groups of participants were given 3 menstrual cycles of MM and MR treatment respectively (once a day, 5 days a session) and received another 3 menstrual cycles follow-up. The degree of pain was evaluated by short-form McGill pain questionnaire (SF-MPQ) and the symptoms of dysmenorrhea were evaluated by Cox Menstrual Symptom Scale (CMSS). The safety was measured by the occurrence rate of adverse events (AEs), including burns (blisters, red and swollen), itching, bowel changes, menstrual cycle disorder, menorrhagia and fatigue, etc. RESULTS: A total of 62 patients completed the trial, 32 in MR group and 30 in MM group. Compared with baseline, scores of SF-MPQ and CMSS significantly decreased in both groups (P<0.05), and no significant difference was observed between the two groups in the 3rd and 6th menstrual cycles (P>0.05). The total occurrence rate of AEs in MR group was 2.1%, which was significantly lower than MM group (7.2%, P<0.05). MR has the same effect as MM at SF-MPQ and CMSS in patients with PD. However, MR is safer than MM (Trial registration No. ChiCTR1800018236).

The Zap-X Radiosurgical System in the Treatment of Intracranial Tumors: A Technical Case Report.

BACKGROUND AND IMPORTANCEThe Zap-X system (Zap Surgical Systems Inc, San Carlos, California) is a radically new surgical robot designed for brain and head and neck radiosurgery. It represents the first new dedicated brain stereotactic radiosurgery platform in almost half a century optimizing the goals of safety, speed, and accuracy. The Zap-X system was used in a required Chinese National Medical Products Administration clinical study. In early January 2020, 2 patients were treated with the Zap-X robot prior to a national COVID-19 lockdown. Both were closely followed via clinical exam and magnetic resonance imaging (MRI) imaging. Prospectively collected data were used to generate this report.CLINICAL PRESENTATIONTwo female patients, each harboring either a trigeminal schwannoma or petroclival meningioma, were treated with the Zap-X robot. Respective tumor volumes were 2.60 and 4.02 cm3. A radiation dose of 13 Gy was prescribed to the 50% isodose line. At 8 mo of follow-up, preoperative symptoms were either resolved or stable and MRI imaging demonstrated a 31% and 56% reduction in lesion volume, respectively. In both patients, symptoms improved, and tumor volumes decreased, whereas no major complication was observed.CONCLUSIONGiven only 2 patients and short-term follow-up, any conclusions about the safety and efficacy of the Zap-X radiosurgery robot are preliminary. However, in the absence of any other published outcomes to date, this small case series may be of interest to many radiosurgical specialists.

RMPflow: A Geometric Framework for Generation of Multitask Motion Policies

Generating robot motion for multiple tasks in dynamic environments is challenging, requiring an algorithm to respond reactively while accounting for complex nonlinear relationships between tasks. In this article, we develop a novel policy synthesis algorithm, Riemannian motion policy (RMP)flow, based on geometrically consistent transformations of RMPs. RMPs are a class of reactive motion policies that parameterize non-Euclidean behaviors as dynamical systems in intrinsically nonlinear task spaces. Given a set of RMPs designed for individual tasks, RMPflow can combine these policies to generate an expressive global policy, while simultaneously exploiting sparse structure for computational efficiency. We study the geometric properties of RMPflow and provide sufficient conditions for stability. Finally, we experimentally demonstrate that accounting for the natural Riemannian geometry of task policies can simplify classically difficult problems, such as planning through the clutter on high-degree-of-freedom manipulation systems. Note to Practitioners —Requirements on safety and responsiveness for collaborative robots have driven a need for new ideas in control design that bridge between standard objectives in low-level control (such as trajectory tracking) and high-level behavioral objectives (such as collision avoidance) often relegated to planning systems. Modern results from geometric control, which promise stable controllers that can smoothly and safely transition between many behavioral tasks, therefore, become highly relevant. However, for years, this field has remained inaccessible due to its mathematical complexity. This article aims to: 1) make those ideas accessible to robotics and control experts by recasting them in a concrete algorithmic framework amenable to controller design and 2) to additionally generalize them to better satisfy the specific needs of robotic behavior generation. Our experiments demonstrate that the resulting controllers can engender natural behavior that adapts instantaneously to changing surroundings with zero planning while performing manipulation tasks. The framework is gaining traction within the robotics community, finding increasing application in areas, such as autonomous navigation, tactile servoing, and multi-agent systems. Future research will address learning these controllers from data to simplify that process of design and tuning, which at present can require experience.

Concept and Realization of a Novel Test Method Using a Dynamic Test Stand for Detecting Persons by Sensor Systems on Autonomous Agricultural Robotics.

As an essential part for the development of autonomous agricultural robotics, the functional safety of autonomous agricultural machines is largely based on the functionality and robustness of non-contact sensor systems for human protection. This article presents a new step in the development of autonomous agricultural machine with a concept and the realization of a novel test method using a dynamic test stand on an agricultural farm in outdoor areas. With this test method, commercially available sensor systems are tested in a long-term test around the clock for 365 days a year and 24 h a day on a dynamic test stand in continuous outdoor use. A test over a longer period of time is needed to test as much as possible all occurring environmental conditions. This test is determined by the naturally occurring environmental conditions. This fact corresponds to the reality of unpredictable/determinable environmental conditions in the field and makes the test method and test stand so unique. The focus of the developed test methods is on creating own real environment detection areas (REDAs) for each sensor system, which can be used to compare and evaluate the autonomous human detection of the sensor systems for the functional safety of autonomous agricultural robots with a humanoid test target. Sensor manufacturers from industry and the automotive sector provide their sensor systems to have their sensors tested in cooperation with the TÜV.