Mechanisms and Design Newsletter: July 2023 

Welcome Message from Co-Chairs

The IEEE RAS Technical Committee on Mechanisms and Design seeks to bring together this population of researchers within the Robotics and Automation Society community in order to share knowledge, standardize practices, and raise the profile of the exciting new work being done in robot mechanisms and design. We seek to establish strong ties to the robotics and robotic components industries to facilitate technology transfer, educate researchers on new available technologies and approaches, and help anchor research approaches to commercial needs and market viability. Ultimately, we want to support the making of robots that better address a wide variety of applications from the perspective of the body to address applications needs.

This is the first newsletter initiated after a change in leadership. We are thrilled to start supporting and connecting with you. We also wish to thank the previous founding Co-Chairs for their vision and effort in bringing this community together, with the TC starting in 2014 -- Dr. Matei Ciocarlie, Dr. Kyujin Cho, Dr. Aaron Dollar, and Dr. Claudio Semini. 

We plan to release quarterly newsletters. Please reach out to the us if you would like to contribute content to a future edition: tcmechdesign [at] gmail [dot] com

-- Co-Chairs Dr. Darwin Lau, Dr. Pauline Pounds, Dr. Hannah Stuart, and Dr. Cynthia Sung

Important Notices

Join the IEEE Technical Committee Catalog for the Technical Committee on Mechanisms and Design

The IEEE Robotics and Automation Society is taking steps to re-energize our Technical Committees (TCs) and improve our data privacy options by incorporating them into existing IEEE infrastructure. This will allow for easier management, communication, and organization as it will provide access to tools like Collabratec communities and Marketo email campaigns (for things like eNewsletters).

In order to do so, we will need all members such as yourself to re-register to the TCs by going to the IEEE Membership catalog and checking out your TCs. All you will need is a free IEEE Account, an IEEE membership is NOT required, and joining a TC is free.

Continued participation in TCs is dependent on this as current TC lists will be purged on 15 August 2023.

Call for Associate Co-Chairs

To support our TC's mission and continuing development, we are on the lookout for Associate Co-Chairs who are enthusiastic to contribute to the Mechanisms and Design community! Associate Co-Chairs would be involved in the on-going activities of the TC, and are of course welcomed to also propose new initiatives that can bring mechanisms and design researchers together. 

For those interested, please contact us at tcmechdesign [at] gmail [dot] com.

Boston Dynamics AI Institute is hiring!

The Boston Dynamics AI Institute is hiring hardware developers!

The AI Institute’s mission is to solve the most important and fundamental challenges in AI and Robotics to enable future generations of intelligent machines that will help us all live better lives.

We are building an environment that fosters the kind of blue-sky thinking found in academic labs and quickly drives it to practice through the development discipline and resources more common to top-tier industry teams.

We are searching for outstanding talent at all experience levels to help us build exciting new mobile robots. In a company pushing the state of the art in artificial intelligence, you will bring novel hardware products and processes to life that are, themselves, celebrated research advances.

Mechanical engineers, electrical engineers, embedded systems engineers, electrical and mechanical technicians, operations and logistics experts, we’re looking for all the pieces needed to advance complex hardware development. Follow this link to see if there is a post that looks like you, get at us here if you don’t.

Contributed Articles

Simple, stable, scalable: seeking small strider schemes

Justin Yim et al. (Department of Mechanical Engineering at Carnegie Mellon University)

Can small robots walk by leveraging passive dynamics? To investigate, we designed a simple biped robot inspired by passive dynamic walking with an eye towards easy scaling. To work at smaller scales, the design minimizes construction and control complexity by using an open-loop stable walking gait excited by only two actuators that extend and retract its rounded feet. Despite this simplicity, it can start walking from standstill and steer left and right. We are working on designs to scale down from the robot's current height of 15 cm and designs using only one actuator.

Ring Screw Transmission Mechanism

Roy Featherstone (Italian Institute of Technology IIT)

The ring screw is a power transmission mechanism that performs the same function as a ball screw but can operate at much higher speeds.  The extra speed allows the ring screw's rod to be connected directly to the output shaft of even the fastest brushless DC motors, allowing the motor to deliver its maximum power output without the need for an intervening step-down gear.  The result is a simpler, lighter, more efficient actuator with fewer moving parts. We are currently building a highly athletic monopedal robot, called Skippy, which will demonstrate the high performance made possible by the ring screw.

More information can be found here.

A Spiral-Cable Forearm Exoskeleton that Assists Supination for Hemiparetic Stroke Subjects

A. Chen, L. Winterbottom, K. O'Reilly, S. Park, D. Nilsen, J. Stein and M. Ciocarlie (Columbia University Department of Mechanical Engineering and Department of Rehabilitation Medicine)

We recently introduced a cable-based passive forearm exoskeleton that is designed to assist supination for hemiparetic stroke survivors. Our device uniquely provides torque sufficient for counteracting spasticity within a below-elbow apparatus. The mechanism consists of a spiral single-tendon routing embedded in a rigid forearm brace and terminated at the hand and upper-forearm. A spool with an internal releasable-ratchet mechanism allows the user to manually retract the tendon and rotate the hand to counteract involuntary pronation synergies due to stroke. We characterize the mechanism with benchtop testing and five healthy subjects, and perform a preliminary assessment of the exoskeleton with a single chronic stroke subject having minimal supination ability. The mechanism can be integrated into an existing active hand-opening orthosis to enable supination support during grasping tasks, and also allows for a future actuated supination strategy.

More information can be found at here.

ICRA 2022 Outstanding Mechanisms and Design Paper Award

The following papers 

Winner: Design of a Biomimetic Tactile Sensor for Material Classification

Kevin Dai; Xinyu Wang; Allison M. Rojas; Evan Harber, Yu Tian, Nicholas Paiva, Joseph Gnehm, Evan Schindewolf, Howie Choset, Victoria Webster-Wood, and Lu Li

Researchers from Carnegie Mellon University have developed a low-cost tactile sensor for robots, using biomimetic features from the cutaneous structure of human fingertips. Robotic systems with tactile perception could actively explore their environments using touch without visual feedback, but existing tactile sensors lack high dynamic sensing ranges and low hardware cost. The sensor, designed by a collaborative research team from Carnegie Mellon University’s College of Engineering, Robotics Institute, and Manufacturing Futures Institute, uses the Hall effect and a magnet to sense physical perturbations, along with a rubber structure that can be fabricated using injection molding. The inclusions of superficial fingerprint ridges and dual stiffness rubbers, similar to the human finger, provide the magnet-based design with sensitivity to vibrations during contact with external objects. The sensor has demonstrated capabilities for classifying materials using vibratory data and could be implemented in the future for robotic applications such as material rendering and object recognition. Details of the work can be found in the 2022 IEEE ICRA proceedings, and the paper was recently awarded as an ICRA 2022 Outstanding Mechanisms and Design Paper.

Image: Human hand (Cherus, CC-BY-SA-3.0) and skin structure (Nefronus, CC-BY-SA-4.0) adapted from Wikimedia Commons.

Finalist Paper: A Wearable Fingertip Cutaneous Haptic Device with Continuous Omnidirectional Motion Feedback

Peizhi Zhang, Mitsuhiro Kamezaki, Yutaro Hattori, Shigeki Sugano

In both teleoperation in real space and exploration in virtual space, ‘passive’ and ‘active’ haptic feedback can help to improve the performance of the task, especially in object handover and exploring. Therefore, we developed a cutaneous haptic device, which enables continuous omnidirectional motion feedback. By applying small smart actuators and closed-loop PTFE belts with a plain-woven structure, our device can generate contact force and omnidirectional shear force. With these mechanical structures, our developed device is promising to generate ‘active’ and ‘passive’ haptic feedback by exhibiting continuous omnidirectional motion feedback, making it possible to be used for precise teleoperation.

IROS 2022 Outstanding Mechanisms and Design Paper Award

The following papers 

Winner: Aerial Grasping and the Velocity Sufficiency Region

Tony G. Chen, Kenneth Hoffmann, Jun En Low, Keiko Nagami, David Lentink, and Mark Cutkosky

A largely untapped potential for aerial robots is to capture airborne targets in flight. A team at Stanford has developed a gripper and control algorithm that allows a ``predator’’ quadrotor to pursue and grasp a ``prey’’ quadrotor. The work is motivated by the occasional need to remove nuisance drones from airports and other sensitive sites. The team’s approach begins with a force-sufficiency region for which the predator’s gripper should be able to acquire and hold the prey. A model of the interaction dynamics maps the gripper force sufficiency region to an envelope of relative velocities for which capture should be possible, without exceeding the capabilities of the quadrotor controller. The sufficiency region could then be used to inform planning and control. The modeling approach motivates a gripper design that emphasizes compliance and is passively triggered for fast response. The resulting gripper is lightweight (23 g) and closes within 12 ms. In flight experiments, a 550 g drone can capture an 85 g hovering target at various relative velocities between 1 m/s and 2.7 m/s. 

PCBot: a Minimalist Robot Designed for Swarm Applications

Jingxian Wang and Michael Rubenstein

Complexity, cost, and power requirements for the actuation of individual robots can play a large factor in limiting the size of robotic swarms. Here we present PCBot, a minimalist robot that can precisely move on an orbital shake table using a bi-stable solenoid actuator built directly into its PCB. This allows the actuator to be built as part of the automated PCB manufacturing process, greatly reducing the impact it has on manual assembly. Thanks to this novel actuator design, PCBot has merely five major components and can be assembled in under 20 seconds, potentially enabling them to be easily mass-manufactured. Here we present the electro-magnetic and mechanical design of PCBot. Additionally, a prototype robot is used to demonstrate its ability to move in a straight line as well as follow given paths.

Finalist: 1-degree-of-freedom robotic gripper with infinite self-twist function

Toshihiro Nishimura, Yosuke Suzuki, Tokuo Tsuji, and Tetsuyou Watanabe

This study proposed a novel robotic gripper that can achieve grasping and infinite wrist twisting motions using a single actuator. The gripper is equipped with a self-motion switching mechanism that allows switching between the grasping and twisting motions according to the magnitude of the tip force. This study also proposed a special grasping mode, "Twist grasping", which allows the wrapping of a flexible thin object around the fingers of the gripper. It can be achieved by the twisting motion. Twist grasping is effective for handling objects with flexible thin parts, such as laminated packaging pouches, and has enabled large payload (over 10kg).

Finalist: Automated design of task specific additively manufacturable coupled serial chain mechanisms for tracing predefined planar trajectories

Simon Schiele, Sebastian Baumgartner, Simon Laudahn, and Tim C. Lueth

This work presents the automatic design of additively manufacturable serially linked one degree of freedom manipulators whose end effectors move along individually prescribed 2D trajectories. The kinematic coupling of the links is done by using gear stages consisting of spur gears and toothed belt gears. The basic design parameters of these mechanisms are determined using a Fourier series. The calculated Fourier elements with their respective frequency, amplitude and phase are interpreted as rotating 2D vectors which represent the manipulator links. Based on this, the kinematic coupling of the links is calculated and the corresponding gears are designed. All parts of these mechanisms, including the toothed belts, can be manufactured using a low cost 3D printing process. The software for the automated design of these manipulators from Fourier decomposition to CAD file generation has been implemented in MATLAB. To validate the automated design process, various test mechanisms were manufactured and examined for accuracy and precision. This paper serves as an example, that with automated design in combination with additive manufacturing, the design and manufacturing process of a mechanism can be almost as fast as reprogramming a manipulator with more degrees of freedom.