Neural Network Learning of Robot Arm Impedance in Operational Space

lmpedance control is one of the most effective controlmethods for the manipulators in contact with their environments.The characteristics of force and motion control, however, isdetermined by a desired impedance parameter of a manipulator'send-effector that should be carefully designed according to agiven task and an environment. The present paper proposesa new method to regulate the impedance parameter of theend-effector through learning of neural networks. Three kindsof the feed-forward networks are prepared corresponding toposition, velocity and force control loops of the end-effector beforelearning. First, the neural networks for position and velocitycontrol are trained using iterative learning of the manipulatorduring free movements. Then, the neural network for forcecontrol is trained for contact movements. During learning ofcontact movements, a virtual trajectory is also modified to reducecontrol error. The method can regulate not only stiffness andviscosity but also inertia and virtual trajectory of the end-effector.Computer simulations show that a smooth transition from freeto contact movements can be realized by regulating impedanceparameters before a contact

Impedance adaptation for optimal robot–environment interaction

In this paper, impedance adaptation is investigated for robots interacting with unknown environments. Impedance control is employed for the physical interaction between robots and environments, subject to unknown and uncertain environments dynamics. The unknown environments are described as linear systems with unknown dynamics, based on which the desired impedance model is obtained. A cost function that measures the tracking error and interaction force is defined, and the critical impedance parameters are found to minimize it. Without requiring the information of the environments dynamics, the proposed impedance adaptation is feasible in a large number of applications where robots physically interact with unknown environments. The validity of the proposed method is verified through simulation studies

Design and development of the ‘POD Adventures’ smartphone game: a blended problem-solving intervention for adolescent mental health in India

Introduction: Digital technology platforms offer unparalleled opportunities to reach vulnerable adolescents at scale and overcome many barriers that exist around conventional service provision. This paper describes the design and development of POD Adventures, a blended problem-solving game-based intervention for adolescents with or at risk of anxiety, depression and conduct difficulties in India. This intervention was developed as part of the PRemIum for ADolEscents (PRIDE) research programme, which aims to establish a suite of transdiagnostic psychological interventions organised around a stepped care system in Indian secondary schools. Methods and materials: Intervention development followed a person-centered approach consisting of four iterative activities: (i) review of recent context-specific evidence on mental health needs and preferences for the target population of school-going Indian adolescents, including a multiple stakeholder analysis of school counselling priorities and pilot studies of a brief problem-solving intervention; (ii) new focus group discussions with N=46 student participants and N=8 service providers; (iii) co-design workshops with N=22 student participants and N=8 service providers; and (iv) user-testing with N=50 student participants. Participants were aged 12-17 years and recruited from local schools in New Delhi and Goa, including a subgroup with self-identified mental health needs (N=6). Results: Formative data from existing primary sources, new focus groups and co-design workshops supported a blended format for delivering a brief problem-solving intervention, with counsellors supporting use of a game-based app on ‘offline’ smartphones. User-testing with prototypes identified a need for simplification of language, use of concrete examples of concepts and practice elements to enhance engagement. There were also indications that participants most valued relatability and interactivity within real-world stories with judicious support from an in-app guide. The final prototype comprised a set of interactive and gamified vignettes and a structured set of problem-solving questions to consolidate and generalise learning while encouraging real-world application. Discussion: Findings shaped the design of POD Adventures and its delivery as an open-access blended intervention for secondary school students with a felt need for psychological support, consistent with an early intervention paradigm. A randomised controlled trial is planned to evaluate processes and impacts of POD Adventures when delivered for help-seeking students in low-resource school settings

Noncontact Impedance Control for Redundant Manipulators

This paper proposes an impedance control methodthat can regulate a virtual impedance between a robot manipulatorand external objects using visual information. Theconventional impedance control method is not useful in somecases where no interaction force between the arm and its environmentexists, although it is one of the most effective controlmethods for manipulators in contact with the environment. Usingthe proposed method, we can control the manipulator motionbased on the virtual impedance before contact with the objects.The validity of the proposed method is verified through computersimulations and experiments using a direct-drive robot