This paper introduces a systematic constraint-based approach to specify complex tasks of general sensorbased robot systems consisting of rigid links and joints. The approach integrates both instantaneous task specification and estimation of geometric uncertainty in a unified framework. Major components are the use of feature coordinates, defined with respect to object and feature frames, which facilitate the task specification, and the introduction of uncertainty coordinates to model geometric uncertainty. While the focus of the paper is on task specification, an existing velocity based control scheme is reformulated in terms of these feature and uncertainty coordinates. This control scheme compensates for the effect of time varying uncertainty coordinates. Constraint weighting results in an invariant robot behavior in case of conflicting constraints with heterogeneous units.The approach applies to a large variety of robot systems (mobile robots, multiple robot systems, dynamic human-robot interaction, etc.), various sensor systems, and different robot tasks. Ample simulation and experimental results are presented.

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Aim This study aims to achieve an international expert consensus on joint patterns during gait for children with cerebral palsy (CP) by means of Delphi surveys. Method In Stage 1, seven local experts drafted a preliminary proposal of kinematic patterns for each lower limb joint in the sagittal, coronal, and transverse plane. In Stage 2, 13 experts from eight gait laboratories (four in the USA and four in Europe), participated in a Delphi consensus study. Consensus was defined by a pre‐set cut‐off point of 75% agreement among participants. Results After the first stage, 44 joint patterns were presented in a first survey and 29 patterns reached consensus. Consensus improved to 47 out of 48 patterns in the third survey. Only one pattern, ‘abnormal knee pattern during loading response’, did not reach consensus. The expert panel agreed to define six patterns for the knee during swing, most of them representing characteristics of a stiff knee pattern. Interpretation The defined joint patterns can support clinical reasoning for children with CP as joint patterns during gait might be linked to different treatment approaches. Automating the classification process and incorporating additional trunk, foot, and electromyography features should be prioritized for the near future.