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Prosthetic hands introduce an artificial sensorimotor interface between the prosthesiswearer and the environment that is prone to perturbations. We analyze theoretically and evaluate psychophysically the performance in stable grip control in conditions of physical grasps perturbation, such as object slip. Simulation results suggest that user-centered stable grasp control depends on two primal user parameters: reaction time to slip and grip force intensity. Experiments with human users indicate that a user's response time can be controlled by relaying information about the speed of the slipping object, while minimal grip force intensity can be adjusted with information about grip force at the onset of the slip. Based on our theoretical and experimental findings, we propose a stable grasp control method for prosthetic hands. [ABSTRACT FROM AUTHOR]

In quadruped animals, spinal movements contribute to locomotion in terms of controlling body posture and integrating limb and trunk actions. In this paper, we develop quadruped models with different numbers of spinal joints to demonstrate the spine-driven locomotion. Actuated spinal joint(s) are exclusively employed to these models with a minimalistic control strategy. We choose some typical individuals from two models and analyze them on gait properties. Results show that employing the spine morphology with two joints can greatly enhance the stability and speed of locomotion by readjusting the center of mass, increasing the stride length, and generating double flight phases similar to running cheetahs’ gait, which makes significant difference in the speed and the gait. Furthermore, we explore and compare models with more spinal joints. Results show that all gaits emerged from them can be categorized into three types (bounding, bounding with double flight phase, and stotting gaits). Overall, bounding gait with double flight phases is a more biologically inspired locomotive behavior; model with two spinal joints could be sufficient to emulate biological spine-driven locomotive behaviors. [ABSTRACT FROM AUTHOR]