An Admittance-controlled Force-scaling Dexterous Assistive Robotic System

Abstract

<jats:p> Play has a vital role in a child’s development; it can affect everything from social and language to cognitive and perceptual skills. However, if a child has a physical disability, the fundamental limitations of their disability may prevent them from participating in all forms of play. Construction and block play is an example of play that may be difficult for children who have reduced upper body strength and are, therefore, unable to manipulate heavier objects in space. In this paper, we propose a novel 6 degree-of-freedom admittance-controlled, force-scaling robot that will allow for children to lift heavier objects than they would normally be able to, while still retaining the full range of motion of their upper body. This assistive system is designed to retain the user’s haptic perception, allowing the user to still partially feel the weight of the objects that they are manipulating. Two user studies are done to evaluate the usability of the system. First, to ensure that the force scaling of the system does not negatively affect a user’s haptic perception, 10 able-bodied individuals were asked to order a series of buckets with identical appearances but different masses from lightest to heaviest with three different force-scaling factors. It was shown that the force amplification ability of the system does not significantly detract from users’ ability to discriminate masses. Second, to evaluate the precision and the usefulness of the force scaling of the system, users were asked to perform a challenging peg-in-hole insertion task. Results indicate that the system has a positive effect on the ability of a user to perform the task when the assistance is necessary. However, increasing amounts of assistance, past those required for participants to complete the task without issues, do not have any significant effect. The effect of a modular reacher bar that can augment the workspace of users is investigated through a similar peg-in-hole insertion task. For the trials with the modular reacher bar attached, it is shown that the system’s force amplification has a very positive effect in assisting users in completing the task. It should be noted that although the target population for this paper is children with disabilities, there can also be uses for this system as a general assistive technology for adults with upper-body weakness in their daily lives. </jats:p>

Robotic Ultrasound Scanning With Real-Time Image-Based Force Adjustment: Quick Response for Enabling Physical Distancing During the COVID-19 Pandemic

“…Authors in Carriere et al ( 2019 ) use admittance control to ensure compliance in a co-manipulated US scanning system controlling the force applied to the tissue and reducing exerted force from the sonographer. The method proposed in Piwowarczyk et al ( 2020 ) uses an admittance controller to scale the force applied by the user on the robot in relation to force applied to the environment. The stability of admittance-controlled robots and their ability to cope with different environmental forces have been investigated in Ferraguti et al ( 2019 ).…”

“…The matrix of K has only one non-zero parameter (in the z direction) that controls the US force applied to the tissue. The values of M and K are based on Piwowarczyk et al ( 2020 ), and they were chosen empirically as a trade-off between sluggishness and control of the system. We calculated the value for B to have a critically damped response in the z direction.…”

An Adaptive Control Method and Learning Strategy for Ultrasound-Guided Puncture Robot

“…Furthermore, many studies have attempted to control robot-assisted US-scanning using force feedback. The most common control methods for this task include hybrid forceposition control [15], impedance control [16], and admittance control [17,18]. Kurnicki et al [11] developed the ReMeDi US-scanning system, which consists of a 7-degree-offreedom robotic arm and a torque sensor controlled by an STM32 microcontroller to replicate complex procedures performed by surgeons in real time.…”