Mechanisms and Design Newsletter: July 2023 

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.

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.

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.

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

• (Finalist) TaTa: A Universal Jamming Gripper with High-Quality Tactile Perception and Its Application to Underwater Manipulation
  Shoujie Li, Xianghui Yin, Chongkun Xia, Linqi Ye, Xueqian Wang, and Bin Liang

• (Finalist) A Wearable Fingertip Cutaneous Haptic Device with Continuous Omnidirectional Motion Feedback
  Peizhi Zhang, Mitsuhiro Kamezaki, Yutaro Hattori, Shigeki Sugano

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.

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.

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

• (Finalist) PCBot: a Minimalist Robot Designed for Swarm Applications
  Jingxian Wang and Michael Rubenstein

• (Finalist)  1-degree-of-freedom robotic gripper with infinite self-twist function
  Toshihiro Nishimura, Yosuke Suzuki, Tokuo Tsuji, and Tetsuyou Watanabe

• (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

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. 

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.

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).

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.