Abstract-This paper investigates the effect of maximum indentation force and depth on people's ability to accurately discriminate compliance using indirect visual information only. Participants took part in two psychophysical experiments in which they were asked to choose the 'softest' sample out of a series of presented sample pairs. In the experiments, participants observed a computer-actuated tip indent the sample pairs to one of two conditions; maximum depth (10mm) or maximum force (4N). This indentation process simulates tool operated palpation in laparoscopic surgery. Results were used to plot psychometric functions as a measure of accuracy of compliance discriminability. A comparison indicated that participants performed best in the task where they judged samples being indented to a pre-set maximum force relying solely on visual cues, which demonstrates the effect of visual information on compliance discrimination. Results also show that indentation cues such as force and deformation depth have different effects on our ability to visually discriminate compliance. These findings will inform future work on designing a haptic feedback system capable of augmenting visual and haptic information independently for optimal compliance discrimination performance.

This paper describes a psychophysical experiment which investigates the effect of the source of vision on the perception of compliance with a specific focus on palpation; a basic surgical task. Twelve participants were asked to complete four forced-choice compliance discrimination tasks representing different modes of surgery when assessing soft human tissue. These tasks were compliance discrimination using direct vision; indirect vision on a computer monitor; only haptic information; and only indirect visual information. In the first 3 tasks, the subjects actively indented pairs of silicone stimuli covering a range of compliances simulating soft human tissue using a tool and were asked to choose which stimulus within each pair felt harder. In the fourth task, participants watched video recordings of the stimuli being indented on a monitor without touching the stimuli themselves. As a control task, participants performed discriminations using their index finger without any visual cues present. The results were used to determine psychometric functions of group behaviour for all conditions. These functions suggest that participants performed best during the control task followed by that involving a combination of touch using tool and direct vision. The latter task presented higher compliance discriminability than the three remaining tasks. Moreover, the task using only indirect vision without any haptic information presented similar compliance discriminability to that using only touch through a tool without any visual information. We conclude that while compliance discrimination via a tool is achievable under direct visual conditions, it remains significantly more challenging than through direct cutaneous information. The research shows the importance of visual cues for the discrimination of compliance as well as a cross-modal integration of visual and haptic sensory information in compliance discrimination, with key implications for the development of new surgical tools and training systems.--

Driven by the aim of realizing functional robotic systems at the milli- and submillimetre scale for biomedical applications, the area of magnetically driven soft devices has received significant recent attention. This has resulted in a new generation of magnetically controlled soft robots with patterns of embedded, programmable domains throughout their structures. This type of programmable magnetic profiling equips magnetic soft robots with shape programmable memory and can be achieved through the distribution of discrete domains (voxels) with variable magnetic densities and magnetization directions. This approach has produced highly compliant, and often bio-inspired structures that are well suited to biomedical applications at small scales, including microfluidic transport and shape-forming surgical catheters. However, to unlock the full potential of magnetic soft robots with improved designs and control, significant challenges remain in their compositional optimization and fabrication. This review considers recent advances and challenges in the interlinked optimization and fabrication aspects of programmable domains within magnetic soft robots. Through a combination of improvements in the computational capacity of novel optimization methods with advances in the resolution, material selection and automation of existing and novel fabrication methods, significant further developments in programmable magnetic soft robots may be realized.

This is a repository copy of The impact of visual cues on haptic compliance discrimination using a pseudo-haptic robotic system.