Tiffany L. Chen

Robots for humanity: using assistive robotics to empower people with disabilities

Assistive mobile manipulators (AMMs) have the potential to one day serve as surrogates and helpers for people with disabilities, giving them the freedom to perform tasks such as scratching an itch, picking up a cup, or socializing with their families.

Towards an assistive robot that autonomously performs bed baths for patient hygiene

This paper describes the design and implementation of a behavior that allows a robot with a compliant arm to perform wiping motions that are involved in bed baths. A laser-based operator-selection interface enables an operator to select an area to clean, and the robot autonomously performs a wiping motion using equilibrium point control. We evaluated the performance of the system by measuring the ability of the robot to remove an area of debris on human skin. We tested the performance of the behavior algorithm by commanding the robot to wipe off a 1-inch square area of debris placed on the surface of the upper arm, forearm, thigh, and shank of a human subject. Using image processing, we determined the hue content of the debris and used this representation to determine the percentage of debris that remained on the arm after the robot completed the task. In our experiments, the robot removed most of the debris (>96%) on four parts of the limbs. In addition, the robot performed the wiping task using relatively low force (<3 N).

Touched by a robot: an investigation of subjective responses to robot-initiated touch

By initiating physical contact with people, robots can be more useful. For example, a robotic caregiver might make contact to provide physical assistance or facilitate communication. So as to better understand how people respond to robot-initiated touch, we conducted a 2x2 between-subjects experiment with 56 people in which a robotic nurse autonomously touched and wiped the subjects forearm. Our independent variables were whether or not the robot verbally warned the person before contact, and whether the robot verbally indicated that the touch was intended to clean the persons skin (instrumental touch) or to provide comfort (affective touch). On average, regardless of the treatment, participants had a generally positive subjective response. However, with instrumental touch people responded significantly more favorably. Since the physical behavior of the robot was the same for all trials, our results demonstrate that the perceived intent of the robot can significantly influence a persons subjective response to robot-initiated touch. Our results suggest that roboticists should consider this factor in addition to the mechanics of physical interaction. Unexpectedly, we found that participants tended to respond more favorably without a verbal warning. Although inconclusive, our results suggest that verbal warnings prior to contact should be carefully designed, if used at all.

A Direct Physical Interface for Navigation and Positioning of a Robotic Nursing Assistant

People often use direct physical contact to guide a person to a desired location (e.g., leading a child by the hand) or to adjust a persons posture for a task (e.g., a dance instructor working with a dancer). When a user is in close proximity to a robot, physical contact becomes a potentially valuable channel for communication. We define a direct physical interface (DPI) as an interface that enables a user to influence a robots behavior by making contact with its body. We evaluated a DPI in a controlled laboratory setting with 18 nurses and compared its performance with that of a comparable gamepad interface. The DPI significantly outperformed the gamepad according to several objective and subjective measures. Nurses also tended to exert more force at the robots end-effectors and command higher velocities when using the DPI to perform a navigation task compared with using the DPI to perform a positioning task. Based on user surveys, we identify various nursing tasks where robotic assistance may be useful and provide design recommendations specifically in the area of healthcare.

An investigation of responses to robot-initiated touch in a nursing context

Physical human-robot interaction has the potential to be useful in a number of domains, but this will depend on how people respond to the robot’s actions. For some domains, such as healthcare, a robot is likely to initiate physical contact with a person’s body. In order to investigate how people respond to this type of interaction, we conducted an experiment with 56 people in which a robotic nurse autonomously touched and wiped each participant’s forearm. On average, participants had a favorable response to the first time the robot touched them. However, we found that the perceived intent of the robot significantly influenced people’s responses. If people believed that the robot intended to clean their arms, the participants tended to respond more favorably than if they believed the robot intended to comfort them, even though the robot’s manipulation behavior was the same. Our results suggest that roboticists should consider this social factor in addition to the mechanics of physical interaction. Surprisingly, we found that participants in our study responded less favorably when given a verbal warning prior to the robot’s actions. In addition to these main results, we present post-hoc analyses of participants’ galvanic skin responses (GSR), open-ended responses, attitudes towards robots, and responses to a second trial.

Hand it over or set it down: A user study of object delivery with an assistive mobile manipulator

Delivering an object to a user would be a generally useful capability for service robots. Within this paper, we look at this capability in the context of assistive object retrieval for motor-impaired users. We first describe a behavior-based system that enables our mobile robot EL-E to autonomously deliver an object to a motor-impaired user. We then present our evaluation of this system with 8 motor-impaired patients from the Emory ALS Center. As part of this study, we compared handing the object to the user (direct delivery) with placing the object on a nearby table (indirect delivery). We tested the robot delivering a cordless phone, a medicine bottle, and a TV remote, which were ranked as three of the top four most important objects for robotic delivery by ALS patients in a previous study. Overall, the robot successfully delivered these objects in 126 out of 144 trials (88%) with a success rate of 97% for indirect delivery and 78% for direct delivery. In an accompanying survey, participants showed high satisfaction with the robot with 4 people preferring direct delivery and 4 people preferring indirect delivery. Our results indicate that indirect delivery to a surface can be a robust and reliable delivery method with high user satisfaction, and that robust direct delivery will require methods that handle diverse postures and body types.

A list of household objects for robotic retrieval prioritized by people with ALS

Studies have consistently shown that object retrieval would be a valuable task for assistive robots to perform, yet detailed information about the needs of patients with respect to this task has been lacking. In this paper, we present our efforts to better understand the needs of motor impaired patients with amyotrophic lateral sclerosis (ALS) with the goal of informing the design and evaluation of assistive mobile robots.

Dusty: an assistive mobile manipulator that retrieves dropped objects for people with motor impairments

People with physical disabilities have ranked object retrieval as a high-priority task for assistive robots. We have developed Dusty, a teleoperated mobile manipulator that fetches objects from the floor and delivers them to users at a comfortable height. In this paper, we first demonstrate the robot’s high success rate (98.4%) when autonomously grasping 25 objects considered being important by people with amyotrophic lateral sclerosis (ALS). We tested the robot with each object in five different configurations on five types of flooring. We then present the results of an experiment in which 20 people with ALS operated Dusty. Participants teleoperated Dusty to move around an obstacle, pick up an object and deliver the object to themselves. They successfully completed this task in 59 out of 60 trials (3 trials each) with a mean completion time of 61.4 SD = 20.5 seconds), and reported high overall satisfaction using Dusty (7-point Likert scale; 6.8 SD = 0.6). Participants rated Dusty to be significantly easier to use than their own hands, asking family members, and using mechanical reachers (p < 0.03, paired t-tests). Fourteen of the 20 participants reported that they would prefer using Dusty over their current methods. Implication for Assistive Technologies A simple robot hand can effectively pick up a wide variety of objects relevant to people with motor impairments from common flooring. A relatively low cost, compact mobile robot can use a simple hand and a vertical lift to pick up and deliver dropped objects to people with motor impairments. In a laboratory setting, people with motor impairments were able to use a semi-autonomous mobile robot named Dusty to successfully pick up an object from the floor and deliver it. Participants reported high satisfaction with the robot Dusty, and on average they reported that it was easier to use than their current methods.

Older Adults' Needs for Assistance as a Function of Living Environment

As the older adult population grows and becomes more diverse, so will their needs and preferences for living environments. Many adults over 65 years of age require assistance in their living environment (Administration on Aging, 2009), however it is important for their feelings of well-being that the assistance does not restrict their autonomy (e.g., Barkay & Tabak, 2002). Moreover, autonomy enhancement may improve older adults’ functionality (e.g., Greiner et al., 1996). This paper provides an overview of older adults’ diverse living situations and an assessment of their needs for assistance with activities of daily living (ADLs) and instrumental activities of daily living (IADLs) when living in the community or in a long-term care residence, such as assisted living or skilled nursing. We also examine older adults’ residential mobility patterns to understand potential unmet needs for assistance. This needs assessment highlights the specific areas that could benefit from human factors interventions to support older adults in making choice-driven decisions about where they live.

Assistive mobile manipulation for self-care tasks around the head

Human-scale mobile robots with arms have the potential to assist people with a variety of tasks. We present a proof-of-concept system that has enabled a person with severe quadriplegia named Henry Evans to shave himself in his own home using a general purpose mobile manipulator (PR2 from Willow Garage). The robot primarily provides assistance by holding a tool (e.g., an electric shaver) at user-specified locations around the users head, while he/she moves his/her head against it. If the robot detects forces inappropriate for the task (e.g., shaving), it withdraws the tool. The robot also holds a mirror with its other arm, so that the user can see what he/she is doing. For all aspects of the task, the robot and the human work together. The robot uses a series of distinct semi-autonomous subsystems during the task to navigate to poses next to the wheelchair, attain initial arm configurations, register a 3D model of the persons head, move the tool to coarse semantically-labeled tool poses (e.g, “Cheek”), and finely position the tool via incremental movements. Notably, while moving the tool near the users head, the robot uses an ellipsoidal coordinate system attached to the 3D head model. In addition to describing the complete robotic system, we report results from Henry Evans using it to shave both sides of his face while sitting in his wheelchair at home. He found the process to be long (54 minutes) and the interface unintuitive. Yet, he also found the system to be comfortable to use, felt safe while using it, was satisfied with it, and preferred it to a human caregiver.