Eating is a daily challenge for over 60 million adults with essential tremors and other mobility limitations. For these users, traditional utensils like forks or spoons are difficult to manipulate -- resulting in accidental spills and restricting the types of food that can be consumed. Prior work has developed rigid, hand-held utensils that often fail to secure food, as well as soft, shape-changing utensils made strictly for robot-assisted feeding. To assist a broader range of users, we introduce a re-designed kiri-spoon that can be leveraged as either a hand-held utensil or a robot-mounted attachment. Our key idea -- developed in collaboration with stakeholders -- is a pivot-based design. With this design the kiri-spoon behaves like a pair of pliers: users squeeze the handles to change the shape of the utensil and enclose food morsels. In practice, users can apply this kiri-spoon as either a spoon (that scoops food) or as a fork (that pinches food); when the handles are closed, the utensil wraps around the morsel and prevents it from accidentally falling. We characterize the amount of force required to open or close the kiri-spoon, and show how designers can modify this force through kinematic or material changes. A highlight of our design is its accessibility: the hand-held version consists of just four 3D printed parts that snap together. By adding a servo motor, we can extend this same kinematic structure to robot-assisted feeding. Across our user studies, adults with disabilities and elderly adults with Parkinson's reported that the kiri-spoon better met their needs and provided a more effective means of spill prevention than existing alternatives. See a video of our kiri-spoon here: https://youtu.be/FFIomm5RL98
Figures & tables
Figure 1: By using a pivot design similar to pliers, we enable hand-held and robot-mounted kiri-spoons. Rotating the pivot causes the kirigami mesh to extend, changing its shape from a flat sheet to an ellipsoid enclosure. The kirigami enclosure prevents accidental spills. a) Hand-held kiri-spoon. b-c) User squeezing the kiri-spoon to acquire cereal from a bowl. d) Robot-mounted kiri-spoon. e) Robot arm leveraging the kiri-spoon to grasp foods.
Figure 2: Assembling a hand-held kiri-spoon. (a) The handles can be snapped together by aligning the two bumps. (b) The kirigami mesh is then attached by pushing its side holes onto their respective pegs. (c) A band is wrapped around the posts. This optional band acts as a spring to open the mesh when the squeezing force is removed. (d) The completed assembly.
Figure 3: Schematic of the applied forces, moments, and generated displacements. (a) The forces of the kirigami and band are applied horizontally to their respective pegs, while the squeezing force is applied perpendicular to the handle. (b) The blue lines represent the moment arms and similar triangles utilized in Equation ( 2 ). The central vertical line represents the line of symmetry for the full kiri-spoon assembly.
Variable
Description
Value
LA
Applied Force Moment Arm
69.6 mm
KK
Kirigami Stiffness Factor
4.55 mm
E
Kirigami Young’s Modulus
14.9 MPa
HK
Kirigami Hypotenuse
59.2 mm
b
Kirigami Offset
20.7 mm
KB
Band Stiffness
2.18 N/mm
Table I: Constants for the Force-Displacement Equation.
Figure 4: Results from Section IV used to model the kirigami mesh. (Left) Force vs. Displacement from real-world experiments and ANSYS simulations. Each separate graph represents a change in the kirigami sheet’s parameters. From top to bottom, the sheet is increasing in size from 1× to 1.5× . From left to right, the sheet is increasing in material stiffness, ranging from a Shore hardness of 85 A to 95 A. (Right) Force vs. Young’s modulus times displacement. Here we group all nine experimental plots on a single graph, and show that (a) we can approximate the kirigami mesh as a spring, and (b) the spring constant is of the form KKE . A line of best fit is overlaid to highlight the kirigami stiffness factor KK from our model.
Figure 5: Setup for our preliminary study with university students without mobility limitations. (Left) In the Manual phase participants completed two tasks using hand-held utensils: transferring food from a bowl to a pitcher, and eating food from the bowl. (Right) In the Robotic phase we mounted the utensil to the end-effector of a UR5 robot arm. Using a combination of teleoperation and programmed motions, participants controlled the robot to eat cereal from a bowl. We compared our pivot-based kiri-spoon to a Liftware utensil in both phases.
Figure 6: Results from our preliminary study in Section V . This experiment was performed by users without disability. There were two phases as shown in Figure 5 : Manual and Robotic . We quantify performance using the total Time to finish 5 repetitions of each task — transferring cereal from a bowl to a pitcher, eating cereal with a hand-held utensil, and eating cereal with a robot-mounted utensil. We also report the average number of Cheerios Spilled during each of the tasks. For both metrics we find that the Manual results are better for Liftware, and the Robotic results are better for kiri-spoon. Since the Liftware spoon functions similarly to a standard spoon — and our participants here had no mobility limitations — it is not surprising that they were more effective with the hand-held Liftware as compared to the hand-held kiri-spoon. The asterisk (*) indicates statistical significance.
Figure 7: A prototype of the non-porous kiri-spoon. We 3 D-print the kirigami mesh on top of a plastic sheet to allow deformation while keeping the gaps sealed. This continuous mesh is necessary for liquid food such as soup.
Robot-assisted feeding enables people with disabilities who require assistance eating to enjoy a meal independently and with dignity. However, existing systems have only been tested in-lab or in-home, leaving in-the-wild social dining contexts (e.g., restaurants) largely unexplored. Designing a robot for such contexts presents unique challenges, such as dynamic and unsupervised dining environments that a robot needs to account for and respond to. Through speculative participatory design with people with disabilities, supported by semi-structured interviews and a custom AI-based visual storyboarding tool, we uncovered ideal scenarios for in-the-wild social dining. Our key insight suggests that such systems should: embody the principles of a white glove service where the robot (1) supports multimodal inputs and unobtrusive outputs; (2) has contextually sensitive social behavior and prioritizes the user; (3) has expanded roles beyond feeding; (4) adapts to other relationships at the dining table. Our work has implications for in-the-wild and group contexts of robot-assisted feeding.
Atharva S Kashyap, Ugne Aleksandra Morkute, Patricia Alves-Oliveira
Robotics University of Michigan Ann Arbor, Michigan, USA · Leiden University Leiden, Netherlands
This paper presents a demonstration-based robotic feeding framework that integrates human demonstration, Dynamic Movement Primitive-based motion planning, vision-based scene perception, and robot control. A human operator first demonstrates the scooping and feeding motions while the position and Euler-angle orientation of the spoon are recorded using a motion-capture system. The recorded trajectory is segmented into scooping and feeding motions, which are encoded using separate Dynamic Movement Primitives. Before task execution, an RGB-D camera estimates the participant's mouth position, while two AprilTags are used for robot-frame registration and tray localization. The detected tray pose is used to position the scooping motion, whereas the detected mouth position defines the positional goal of the feeding motion. The approach, scooping, and feeding trajectories are then executed sequentially by a Kinova Gen3 manipulator through a ROS~2-based framework. A real-world experiment demonstrates the feasibility of the integrated pipeline and shows that the learned spoon motions can be reproduced within the detected experimental scene.
Kenzhi Iskandar Wong, Kitti Thamrongaphichartkul, Sri Harsha Turlapati +10
Robotics Research Centre, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore. · School of Science and Technology, Singapore University of Social Sciences, Singapore. · Department of Mechano-Informatics, University of Tokyo, Japan. +1
We consider the nonprehensile object transportation task known as the waiter's problem, in which a robot must move an object balanced on a tray from one location to another. In contrast to prior works on the robotic waiter's problem, which make the robot tilt a tray rigidly held by its end effector (EE), we use a tray suspended from the EE by ropes, such that it behaves like a three-dimensional pendulum. Some prior works have actuated the robot so that the EE simulates the behavior of a pendulum, because pendular motion reduces the shear forces acting on the transported objects, minimizing the sliding of rigid objects and sloshing in containers of liquid. In contrast, our use of a real hanging tray allows us to obtain the benefits of pendular motion while only actuating a 3 degree-of-freedom (DOF) mobile base, rather than requiring a full 6-DOF manipulator arm. Our experiments in simulation and on real hardware show that the hanging tray substantially reduces both sliding and sloshing compared to a static, rigidly-grasped tray. Furthermore, we integrate the hanging tray into an interactive robot waiter demonstration, which uses computer vision to identify people with a raised hand and visual servoing to steer toward them and allow them to access the tray.
Adam Heins, Angela P. Schoellig
University of Toronto · Toronto, Canada · Technical University of Munich +1