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In the dynamic and unstructured environment of human–robot symbiosis, companion robots require natural human–robot interaction and autonomous intelligence through multimodal information fusion to achieve effective collaboration. Nevertheless, the control precision and coordination of the accompanying actions are not satisfactory in practical applications. This is primarily attributed to the difficulties in the motion coordination between the accompanying target and the mobile robot. This paper proposes a companion control strategy based on the Linear Quadratic Regulator (LQR) to enhance the coordination and precision of robot companion tasks. This method enables the robot to adapt to sudden changes in the companion target’s motion. Besides, the robot could smoothly avoid obstacles during the companion process. Firstly, a human–robot companion interaction model based on nonholonomic constraints is developed to determine the relative position and orientation between the robot and the companion target. Then, an LQR-based companion controller incorporating behavioral dynamics is introduced to simultaneously avoid obstacles and track the companion target’s direction and velocity. Finally, various simulations and real-world human–robot companion experiments are conducted to regulate the relative position, orientation, and velocity between the target object and the robot platform. Experimental results demonstrate the superiority of this approach over conventional control algorithms in terms of control distance and directional errors throughout system operation. The proposed LQR-based control strategy ensures coordinated and consistent motion with target persons in social companion scenarios.

Earthquake and other disasters nowadays still threat people’s lives and property due to their destructiveness and unpredictability. The past decades have seen the booming development of search and rescue robots due to their potential for increasing rescue capacity as well as reducing personnel safety risk at disaster sites. In this work, we propose a spider-inspired wheeled compliant leg to further improve the environmental adaptability of search mobile robots. Different from the traditional fully-actuated method with independent motor joint control, this leg employs an under-actuated compliant mechanism design with overall semi-tendon-driven control, which enables the passive and active terrain adaptation, system simplification and lightweight of the realized search robot. We have generalized the theoretical model and design methodology for this type of compliant leg, and implement it in a parametric program to improve the design efficiency. In addition, preliminary load capacity and leg-lifting experiments are carried out on a one-leg prototype to evaluate its mechanical performance. A four-legged robot platform is also fabricated for the locomotion tests. The preliminary experimental results have verified the feasibility of the proposed design methodology, and also show possibilities for improvements. In future work, structural optimization and stronger actuation elements should be introduced to further improve the mechanical performance of the fabricated wheeled leg mechanism and robot platform.

Abstract Robotic legs are an important component of the quadruped robot for achieving different motion gaits. Although the conventional rigid-link-based legs can generally perform robust motions, they still have the issues with poor sealing when operating in complex and liquid terrains. To cope with this problem, fully compliant legs with monolithic structure have been introduced in recent years to improve the system compactness and structural compliance of quadruped robots. In this article, we present a topology-optimization-based method to achieve efficient design of compliant robotic legs. In order to balance the structural stiffness and bending flexibility of the realized leg, a multi-objective optimization algorithm is utilized. A series of design cases are presented to illustrate the design principle and analytical procedure of the proposed method. In addition, experimental evaluation is also performed, and the results have demonstrated that, a quadruped robot with the optimized legs can successfully achieve stable and continuous straight-line walking motions.

Aquatic unmanned aerial vehicles (AquaUAV) have aroused much attention from researchers, though no fully-featured aerial-aquatic UAV exists so far. The assistance of webbed foot hydroplaning can accomplish rapid take-off of a cormorant. A significant impact force and moment can be generated due to the webbed foot propulsion in the water-to-air transition. However, the change law of force and moment experienced by the cormorant during take-off has not been captured. Based on previous achievements in the biological investigation, we developed a biomimetic prototype with curve fitting model and parameter optimization to attain specific movements to imitate cormorant's hydroplaning strategy. The bionic webbed foot considers the elastic mechanics, and the forepart is regarded as flexible material for fluid-structure interaction (FSI). Dynamic process of rapid take-off in the aspects of flow characteristics and mechanical properties can be estimated by computational fluid dynamics (CFD) in our proposed FSI model, which establishes a foundation for further applications in the design of the assisted propulsion system of aerial-aquatic UAV.

Background and study aims A major drawback of endoscopic en-bloc resection technique is its inability to perform bimanual tasks. Although endoscopic platforms that enable bimanual tasks are commercially available, they are neither approved for various locations nor adaptable to specific patients and indications. Methods Based on evolution of an adaptive 3D-printable platform concept, system variants with different characteristic properties were evaluated for ESD scenarios, ex-vivo in two locations in the stomach and colorectum. Results In total 28 ESDs were performed (7 antrum, 7 corpus in inversion, 7 cecum, 7 rectum) in a porcine ex-vivo setup. ESD was feasible in 21 cases. Investigated manipulator variants are differently well suited for performing ESD within the varying interventions scenarios. Dual-arm manipulators allowed autonomous ESD, while single-arm flexible manipulators could be used more universally due to their compact design, especially for lesions difficult to access. Pediatric scopes were too frail to guide the overtube-manipulators in extremely angled positions. Working in the rectum was impaired using long-sized manipulator arms. Conclusions The presented endoscopic platform based on 3D-printable and customizable manipulator structures might be a promising approach for future improvement of ESD procedure. With regard to localization, especially flexible manipulators attached to standard endoscopes appear to be most promising for further application of specific and individualised manipulator systems.

Accurate evaluation of bradykinesia plays a crucial role in the diagnosis and therapy effect of Parkinson's disease. However, the subjective assessment shows low consistency among different evaluators, and the objective sensor-based methods cannot accurately distinguish patients with different grades of the 5-point clinical bradykinesia ratings. In this paper, an objective scoring method based on axis-angle representation and multi-class support vector machine (SVM) classifier was employed to estimate the bradykinesia severity. To reduce the dimension of attitude data for the better statistical analysis, the axis-angle representation approach was employed to obtain the 1D combined orientation angle to express the 3-D hand-grasping assessment task. The significant bradykinesia features extracted from the 1-D combined orientation angle were used to train the SVM classification algorithm to acquire an objective score on the bradykinesia severity. Clinical experiments with 78 patients and 18 age-matched healthy subjects showed that the classification accuracy of the proposed method was 95.349%, which was superior to other related reports. Hence, the proposed objective scoring method can provide a 5-point bradykinesia score in realtime, and matches the clinical assessment approach of neurologists. Moreover, this method improves both the inter-rater reliability and intra-rater reliability of the bradykinesia assessment.

Quantitative assessment of parkinsonian tremor based on inertial sensors can provide reliable feedback on the effect of medication. In this regard, the features of parkinsonian tremor and its unique properties such as motor fluctuations and dyskinesia are taken into account. Least-square-estimation models are used to assess the severities of rest, postural, and action tremors. In addition, a time-frequency signal analysis algorithm for tremor state detection was also included in the tremor assessment method. This inertial sensor-based method was verified through comparison with an electromagnetic motion tracking system. Seven Parkinson’s disease (PD) patients were tested using this tremor assessment system. The measured tremor amplitudes correlated well with the judgments of a neurologist (r = 0.98). The systematic analysis of sensor-based tremor quantification and the corresponding experiments could be of great help in monitoring the severity of parkinsonian tremor.