The slogan “robots will pervade our environment” has become a reality. Drones and ground robots are used for commercial purposes while semi-autonomous driving systems are standard accessories to traditional cars. However, while our eyes have been riveted on dangers and accidents arising from drones falling and autonomous cars’ crashing, much less attention has been ported to dangers arising from the imminent arrival of robots that share the floor with pedestrians and will mix with human crowds. These robots range from semi or autonomous mobile platforms designed for providing several kinds of service, such as assistant, patrolling, tour-guide, delivery, human transportation, etc. We highlight and discuss potential sources of injury emerging from contacts of robots with pedestrians through a set of case studies. We look specifically at dangers deriving from robots moving in dense crowds. In such situations, contact will not only be unavoidable, but may be desirable to ensure that the robot moves with the flow. As an outlook toward the future, we also offer some thoughts on the psychological risks, beyond the physical hazards, arising from the robot’s appearance and behaviour. We also advocate for new policies to regulate mobile robots traffic and enforce proper end user’s training.

This letter presents a physical human-robot interaction scenario in which a robot guides and performs the role of a teacher within a defined dance training framework. A combined cognitive and physical feedback of performance is proposed for assisting the skill learning process. Direct contact cooperation has been designed through an adaptive impedance-based controller that adjusts according to the partner's performance in the task. In measuring performance, a scoring system has been designed using the concept of progressive teaching (PT). The system adjusts the difficulty based on the user's number of practices and performance history. Using the proposed method and a baseline constant con-troller, comparative experiments have shown that the PT presents better performance in the initial stage of skill learning. An analysis of the subjects' perception of comfort, peace of mind, and robot performance has shown significant difference at the p <; 0.01 level, favoring the PT algorithm.

In this article, we present a personal mobility device for lower-body impaired users through a lightweight exoskeleton on wheels. On its core, a novel passive exoskeleton provides postural transition leveraging natural body postures with support to the trunk on sit-to-stand/stand-to-sit (STS) transitions by a single gas spring as an energy storage unit. We propose a direction-dependent coupling of knees and hip joints through a double-pulley wire system, transferring energy from the torso motion toward balancing the moment load at the knee joint actuator. Herewith, the exoskeleton maximizes energy transfer and the naturalness of the user’s movement. We introduce an embodied user interface for hands-free navigation through a torso pressure sensing with minimal trunk rotations, resulting on average $\text{19}^{\circ } \pm \text{13}^{\circ }$ on six unimpaired users. We evaluate the design for STS assistance on 11 unimpaired users observing motions and muscle activity during the transitions. Results comparing assisted and unassisted STS transitions validate a significant reduction (up to 68%, $p< \text{0.01}$ ) at the involved muscle groups. Moreover, we show its feasibility through natural torso leaning movements of $+\text{12}^{\circ }\pm \text{6.5}^{\circ }$ and $- \text{13.7}^{\circ } \pm \text{6.1}^{\circ }$ for standing and sitting, respectively. Passive postural transition assistance warrants further work on increasing its applicability and broadening the user population.

In this paper, we propose the design of an exoskeleton with support at the knee joint and lower torso for sit-to-stand and stand-to-sit (STS) posture transitions; devised for users with spinal cord injury and other complete lower-body impairments. The STS transitions assistance is achieved through a power transfer mechanism that synchronizes knees and lumbar motion through a cable-driven pulley system. We analyze the human body dynamics in the posture transition with a rigid link model and the interaction interface with the exoskeleton through an impedance model for producing a passive system voluntarily controlled by natural motions of the upper body. Therefore, allowing the potential users to achieve STS transitions with their body residual capabilities without an external power source. Instead, transferring power from their upper-body to lower-body, herewith, controlling a passive energy storage. A prototype was constructed and evaluated with seven healthy subjects observing the proposed motion and muscle activity during the STS transitions. The results show a significant reduction in the muscle activity evaluated, at the erector spinae, gluteus maximus and rectus femoris, with reductions between 30% to 50% at the p <; 0.01 level comparing STS transitions with and without the exoskeleton support. Concluding that the STS transitions support is feasible with the passive exoskeleton envisioned for applications in upright locomotion, STS training, and rehabilitation.

In this paper, we introduce a concept of passive knee exoskeleton for cycling assistance. Considering a knee moment and a knee angle varying with a pedal crank angle, the knee extension moment can be supported by a torsion spring storing energy from knee flexion in order to release it as the knee is extended. The reduction of knee extension effort is corresponding to the torsion spring stiffness and activation range. Exoskeleton prototypes were developed for the concept validation. A crossing four-bar mechanism was chosen for the knee joint to provide kinematic compatibility covering extreme knee flexion. Constant power cycling experiment was performed on a cycling trainer by a healthy subject wearing the exoskeletons on both legs. With the torsion spring support, the surface electromyography recorded from some major leg muscles shows the decrease of knee extensor muscle activity as the leg is moving around the pedal crank top dead center. Verifying the reduction of leg muscle fatigue over repetitive contractions in multiple subjects is our future plan of study.

This letter describes a novel method for non-holonomic robots of convex shape to avoid imminent collisions with moving obstacles. The method's purpose is to assist navigation in crowds by correcting steering from the robot's path planner or driver. We evaluate its performance using a custom simulator which replicates real crowd movements and corresponding metrics which quantify agents' efficiency and the robot's impact on the crowd and count collisions. We implement and evaluate the method on the standing wheelchair Qolo. In our experiments, it drives in autonomous mode using on-board sensing (LiDAR, RGB-D camera and a system to track pedestrians) and avoids collisions with up to five pedestrians and passes through a door.