A Spring Loaded Double Pantograph (SLDP) mechanism is presented for safe balance training in elderly individuals practicing Tai Chi exercises. As people age, maintaining balance becomes increasingly critical, yet fear of falling often prevents effective exercise, creating a counterproductive cycle that increases fall risk. This natural hesitation to push physical limits during solo practice highlights the need for reliable safety systems. This paper presents a mechanism that provides variable assistance through spring-loaded actuation, so that support and freedom of movement can be balanced in a way that is both effective and unobtrusive. Here, it will be shown that, although support and unrestricted movement are traditionally considered contradictory goals, the two can be achieved simultaneously through mechanical design and the level of assistance can be automatically regulated. In this system, the support mechanism can a) detect falls rapidly, b) provide up to 98.0% body weight support when needed, and c) remain imperceptible during normal exercise. First, the mechanical design principles and kinematic analysis of the double-pantograph structure are presented. Methods for experimental validation with 13 human subjects will be addressed, demonstrating the system’s effectiveness through quantitative metrics of support forces, workspace utilization, and energy efficiency during simulated falls in Tai Chi movements.

In providing physical assistance to elderly people, ensuring cooperative behavior from the elderly persons is a critical requirement. In sit-to-stand assistance, for example, an older adult must lean forward, so that the body mass can shift towards the feet before a caregiver starts lifting the body. An experienced caregiver guides the older adult through verbal communications and physical interactions, so that the older adult may be cooperative throughout the process. This guidance is of paramount importance and is a major challenge in introducing a robotic aid to the eldercare environment. The wide-scope goal of the current work is to develop an in-telligent eldercare robot that can a) monitor the mental state of an older adult, and b) guide the older adult through an assisting procedure so that he/she can be cooperative in being assisted. The current work presents a basic modeling framework for describing a human's physical behaviors reflecting an internal mental state, and an algorithm for estimating the mental state through interactive observations. The sit-to-stand assistance problem is considered for the initial study. A simple Kalman Filter is constructed for estimating the level of cooperativeness in response to applied cues, with a thresholding scheme being used to make judgments on the cooperativeness state.

Optimization of gear ratios for dual-motor actuators is presented for the development of a walker-type assist robot. The robot is reconfigurable to provide an elderly user with multiple physical support functions; one is to assist sitto-stand transitions and the other is to serve as a walker to aid the user in walking. To avoid falling while walking, the robot must react quickly and reconfigure its footprint for supporting the user. This requires high speed actuators. In contrast, for assisting sit-to-stand transitions, high torque actuators are required. To meet the bimodal, conflicting load conditions, i.e. high-torque, low-speed v.s. high-speed, low-torque, this paper presents a dual-motor actuation solution, where two motors with diverse gear ratios are combined. The system is characterized with two key parameters: an internal gear ratio between a high-speed motor and a torque-booster, and an external gear ratio for connecting the dual motor actuator to the load. The internal and external gear ratios are optimized for performing both sit-to-stand assist and rapid foot reconfiguration.

Prior work has shown that children exhibit negative collaborative behaviors, such as blocking others' access to objects, when collaborating on interactive tabletop computers. We implemented previous design recommendations, namely separate physical territories and activity roles, which had been recommended to decrease these negative collaborative behaviors. We developed a multi-touch "I-Spy" picture searching application with separate territory partitions and activity roles. We conducted a deep qualitative analysis of how six pairs of children, ages 6 to 10, interacted with the application. Our analysis revealed that the collaboration styles differed for each pair, both in regards to the interaction with the task and with each other. Several pairs exhibited negative physical and verbal collaborative behaviors, such as nudging each other out of the way. Based on our analysis, we suggest that it is important for a collaborative task to offer equal opportunities for interaction, but it may not be necessary to strive for complete equity of collaboration. We examine the applicability of prior design guidelines and suggest open questions for future research to inform the design of tabletop applications to support collaboration for children.

Synchronous hybrid learning is a technology-rich approach to enacting comparable, shared, and collaborative learning experiences for face-to-face and online participants in real-time. The benefits of this approach are often realized through an iterative process of innovation, review, and revision. We present an instructive case in which we used robotic telepresence devices to bring greater individualization to online students in one particular synchronous hybrid course. Our goal was to see if increased individuation for online participants helped them feel more "present" with their face-to-face counterparts, and thereby foster rich interactions between the two groups. The context was a higher education course in which 12 robotic telepresence devices were used to build a synchronous hybrid learning models. This case presents how we came to use robotic telepresence devices in this course, what challenges we encountered, how we tried to solve those challenges, and the lessons we learned in the process. Of particular interest is the importance of pairing pedagogical strategies to the technologies that best suit them.

This paper develops an inductive theory of predictive common sense reasoning. The theory provides the basis for an integrated solution to the three traditional problems of reasoning about change; the frame, qualification, and ramification problems. The theory is also capable of representing non-deterministic events, and it provides a means for stating defeasible preferences over the outcomes of conflicting simultaneous events.