Guo Zhan Lum

Alumni

Physical Intelligence

Design Automation
Magnetic Microrobots
Compliant Mechanism Synthesis

Ph.D: Mechanical Engineering, Carnegie Mellon University and Nanyang Technological University 2017
MS: Mechanical Engineering, Carnegie Mellon University, 2015
BS: Eng with first class honours: Mechanical Engineering, Nanyang Technological University, 2010

11 results (BibTeX)

2018

Small-scale soft-bodied robot with multimodal locomotion

Hu, W., Lum, G. Z., Mastrangeli, M., Sitti, M.

Abstract

Untethered small-scale (from several millimetres down to a few micrometres in all dimensions) robots that can non-invasively access confined, enclosed spaces may enable applications in microfactories such as the construction of tissue scaffolds by robotic assembly1, in bioengineering such as single-cell manipulation and biosensing2, and in healthcare3,4,5,6 such as targeted drug delivery4 and minimally invasive surgery3,5. Existing small-scale robots, however, have very limited mobility because they are unable to negotiate obstacles and changes in texture or material in unstructured environments7,8,9,10,11,12,13. Of these small-scale robots, soft robots have greater potential to realize high mobility via multimodal locomotion, because such machines have higher degrees of freedom than their rigid counterparts14,15,16. Here we demonstrate magneto-elastic soft millimetre-scale robots that can swim inside and on the surface of liquids, climb liquid menisci, roll and walk on solid surfaces, jump over obstacles, and crawl within narrow tunnels. These robots can transit reversibly between different liquid and solid terrains, as well as switch between locomotive modes. They can additionally execute pick-and-place and cargo-release tasks. We also present theoretical models to explain how the robots move. Like the large-scale robots that can be used to study locomotion17, these soft small-scale robots could be used to study soft-bodied locomotion produced by small organisms.

link (url) [BibTex]

2018

pi Hu, W., Lum, G. Z., Mastrangeli, M., Sitti, M. Small-scale soft-bodied robot with multimodal locomotion Nature, 554, pages: 81-85, Macmillan Publishers Limited, part of Springer Nature. All rights reserved., January 2018 (article)

link (url) [BibTex]

2017

An XY ϴz flexure mechanism with optimal stiffness properties

Lum, G. Z., Pham, M. T., Teo, T. J., Yang, G., Yeo, S. H., Sitti, M.

In 2017 IEEE International Conference on Advanced Intelligent Mechatronics (AIM), pages: 1103-1110, July 2017 (inproceedings)

Abstract

The development of optimal XY θz flexure mechanisms, which can deliver high precision motion about the z-axis, and along the x- and y-axes is highly desirable for a wide range of micro/nano-positioning tasks pertaining to biomedical research, microscopy technologies and various industrial applications. Although maximizing the stiffness ratios is a very critical design requirement, the achievable translational and rotational stiffness ratios of existing XY θz flexure mechanisms are still restricted between 0.5 and 130. As a result, these XY θz flexure mechanisms are unable to fully optimize their workspace and capabilities to reject disturbances. Here, we present an optimal XY θz flexure mechanism, which is designed to have maximum stiffness ratios. Based on finite element analysis (FEA), it has translational stiffness ratio of 248, rotational stiffness ratio of 238 and a large workspace of 2.50 mm × 2.50 mm × 10°. Despite having such a large workspace, FEA also predicts that the proposed mechanism can still achieve a high bandwidth of 70 Hz. In comparison, the bandwidth of similar existing flexure mechanisms that can deflect more than 0.5 mm or 0.5° is typically less than 45 Hz. Hence, the high stiffness ratios of the proposed mechanism are achieved without compromising its dynamic performance. Preliminary experimental results pertaining to the mechanism's translational actuating stiffness and bandwidth were in agreement with the FEA predictions as the deviation was within 10%. In conclusion, the proposed flexure mechanism exhibits superior performance and can be used across a wide range of applications.

DOI [BibTex]

2017

pi Lum, G. Z., Pham, M. T., Teo, T. J., Yang, G., Yeo, S. H., Sitti, M. An XY ϴz flexure mechanism with optimal stiffness properties In 2017 IEEE International Conference on Advanced Intelligent Mechatronics (AIM), pages: 1103-1110, July 2017 (inproceedings)

DOI [BibTex]

2016

Soft Actuators for Small-Scale Robotics

Hines, L., Petersen, K., Lum, G. Z., Sitti, M.

Advanced Materials, December 2016 (article)

Abstract

This review comprises a detailed survey of ongoing methodologies for soft actuators, highlighting approaches suitable for nanometer- to centimeter-scale robotic applications. Soft robots present a special design challenge in that their actuation and sensing mechanisms are often highly integrated with the robot body and overall functionality. When less than a centimeter, they belong to an even more special subcategory of robots or devices, in that they often lack on-board power, sensing, computation, and control. Soft, active materials are particularly well suited for this task, with a wide range of stimulants and a number of impressive examples, demonstrating large deformations, high motion complexities, and varied multifunctionality. Recent research includes both the development of new materials and composites, as well as novel implementations leveraging the unique properties of soft materials.

DOI [BibTex]

2016

pi Hines, L., Petersen, K., Lum, G. Z., Sitti, M. Soft Actuators for Small-Scale Robotics Advanced Materials, December 2016 (article)

DOI [BibTex]

Six-degree-of-freedom magnetic actuation for wireless microrobotics

Diller, E., Giltinan, J., Lum, G. Z., Ye, Z., Sitti, M.

The International Journal of Robotics Research, 35(1-3):114-128, SAGE Publications Sage UK: London, England, June 2016 (article)

Abstract

Existing remotely actuated magnetic microrobots exhibit a maximum of only five-degree-of-freedom (DOF) actuation, as creation of a driving torque about the microrobot magnetization axis is not achievable. This lack of full orientation control limits the effectiveness of existing microrobots for precision tasks of object manipulation and orientation for advanced medical, biological and micromanufacturing applications. This paper presents a magnetic actuation method that allows remotely powered microrobots to achieve full six-DOF actuation by considering the case of a non-uniform magnetization profile within the microrobot body. This non-uniform magnetization allows for additional rigid-body torques to be induced from magnetic forces via a moment arm. A general analytical model presents the working principle for continuous and discrete magnetization profiles, which is applied to permanent or non-permanent (soft) magnet bodies. Several discrete-magnetization designs are also presented which possess reduced coupling between magnetic forces and induced rigid-body torques. Design guidelines are introduced which can be followed to ensure that a magnetic microrobot design is capable of six-DOF actuation. A simple permanent-magnet prototype is fabricated and used to quantitatively demonstrate the accuracy of the analytical model in a constrained-DOF environment and qualitatively for free motion in a viscous liquid three-dimensional environment. Results show that desired forces and torques can be created with high precision and limited parasitic actuation, allowing for full six-DOF actuation using limited feedback control

DOI Project Page [BibTex]

pi Diller, E., Giltinan, J., Lum, G. Z., Ye, Z., Sitti, M. Six-degree-of-freedom magnetic actuation for wireless microrobotics The International Journal of Robotics Research, 35(1-3):114-128, SAGE Publications Sage UK: London, England, June 2016 (article)

DOI Project Page [BibTex]

Gallium Adhesion: Phase Change of Gallium Enables Highly Reversible and Switchable Adhesion (Adv. Mater. 25/2016)

Ye, Z., Lum, G. Z., Song, S., Rich, S., Sitti, M.

Advanced Materials, 28(25):5087-5087, May 2016 (article)

Abstract

Gallium exhibits highly reversible and switchable adhesion when it undergoes a solid–liquid phase transition. The robustness of gallium is notable as it exhibits strong performance on a wide range of smooth and rough surfaces, under both dry and wet conditions. Gallium may therefore find numerous applications in transfer printing, robotics, electronic packaging, and biomedicine.

DOI Project Page [BibTex]

pi Ye, Z., Lum, G. Z., Song, S., Rich, S., Sitti, M. Gallium Adhesion: Phase Change of Gallium Enables Highly Reversible and Switchable Adhesion (Adv. Mater. 25/2016) Advanced Materials, 28(25):5087-5087, May 2016 (article)

DOI Project Page [BibTex]

Shape-programmable magnetic soft matter

Lum, G. Z., Ye, Z., Dong, X., Marvi, H., Erin, O., Hu, W., Sitti, M.

Proceedings of the National Academy of Sciences, pages: 201608193, National Acad Sciences, May 2016 (article)

Abstract

Shape-programmable matter is a class of active materials whose geometry can be controlled to potentially achieve mechanical functionalities beyond those of traditional machines. Among these materials, magnetically actuated matter is particularly promising for achieving complex time-varying shapes at small scale (overall dimensions smaller than 1 cm). However, previous work can only program these materials for limited applications, as they rely solely on human intuition to approximate the required magnetization profile and actuating magnetic fields for their materials. Here, we propose a universal programming methodology that can automatically generate the required magnetization profile and actuating fields for soft matter to achieve new time-varying shapes. The universality of the proposed method can therefore inspire a vast number of miniature soft devices that are critical in robotics, smart engineering surfaces and materials, and biomedical devices. Our proposed method includes theoretical formulations, computational strategies, and fabrication procedures for programming magnetic soft matter. The presented theory and computational method are universal for programming 2D or 3D time-varying shapes, whereas the fabrication technique is generic only for creating planar beams. Based on the proposed programming method, we created a jellyfish-like robot, a spermatozoid-like undulating swimmer, and an artificial cilium that could mimic the complex beating patterns of its biological counterpart.

DOI Project Page Project Page [BibTex]

pi Lum, G. Z., Ye, Z., Dong, X., Marvi, H., Erin, O., Hu, W., Sitti, M. Shape-programmable magnetic soft matter Proceedings of the National Academy of Sciences, pages: 201608193, National Acad Sciences, May 2016 (article)

DOI Project Page Project Page [BibTex]

2015

Structural optimization for flexure-based parallel mechanisms–Towards achieving optimal dynamic and stiffness properties

Lum, G. Z., Teo, T. J., Yeo, S. H., Yang, G., Sitti, M.

Precision Engineering, 42, pages: 195-207, Elsevier, May 2015 (article)

Abstract

Flexure-based parallel mechanisms (FPMs) are a type of compliant mechanisms that consist of a rigid end-effector that is articulated by several parallel, flexible limbs (a.k.a. sub-chains). Existing design methods can enhance the FPMs’ dynamic and stiffness properties by conducting a size optimization on their sub-chains. A similar optimization process, however, was not performed for their sub-chains’ topology, and this may severely limit the benefits of a size optimization. Thus, this paper proposes to use a structural optimization approach to synthesize and optimize the topology, shape and size of the FPMs’ sub-chains. The benefits of this approach are demonstrated via the design and development of a planar X − Y − θz FPM. A prototype of this FPM was evaluated experimentally to have a large workspace of 1.2 mm × 1.2 mm × 6°, a fundamental natural frequency of 102 Hz, and stiffness ratios that are greater than 120. The achieved properties show significant improvement over existing 3-degrees-of-freedom compliant mechanisms that can deflect more than 0.5 mm and 0.5°. These compliant mechanisms typically have stiffness ratios that are less than 60 and a fundamental natural frequency that is less than 45 Hz.

DOI [BibTex]

2015

pi Lum, G. Z., Teo, T. J., Yeo, S. H., Yang, G., Sitti, M. Structural optimization for flexure-based parallel mechanisms–Towards achieving optimal dynamic and stiffness properties Precision Engineering, 42, pages: 195-207, Elsevier, May 2015 (article)

DOI [BibTex]

Integrating mechanism synthesis and topological optimization technique for stiffness-oriented design of a three degrees-of-freedom flexure-based parallel mechanism

Lum, G. Z., Teo, T. J., Yang, G., Yeo, S. H., Sitti, M.

Precision Engineering, 39, pages: 125-133, Elsevier, January 2015 (article)

Abstract

This paper introduces a new design approach to synthesize multiple degrees-of-freedom (DOF) flexure-based parallel mechanism (FPM). Termed as an integrated design approach, it is a systematic design methodology, which integrates both classical mechanism synthesis and modern topology optimization technique, to deliver an optimized multi-DOF FPM. This design approach is separated into two levels. At sub-chain level, a novel topology optimization technique, which uses the classical linkage mechanisms as DNA seeds, is used to synthesize the compliant joints or limbs. At configuration level, the optimal compliant joints are used to form the parallel limbs of the multi-DOF FPM and another stage of optimization was conducted to determine the optimal space distribution between these compliant joints so as to generate a multi-DOF FPM with optimized stiffness characteristic. In this paper, the design of a 3-DOF planar motion FPM was used to demonstrate the effectiveness and accuracy of this proposed design approach.

DOI [BibTex]

pi Lum, G. Z., Teo, T. J., Yang, G., Yeo, S. H., Sitti, M. Integrating mechanism synthesis and topological optimization technique for stiffness-oriented design of a three degrees-of-freedom flexure-based parallel mechanism Precision Engineering, 39, pages: 125-133, Elsevier, January 2015 (article)

DOI [BibTex]

2014

Structural optimization method towards synthesis of small scale flexure-based mobile grippers

Lum, G. Z., Diller, E., Sitti, M.

In Robotics and Automation (ICRA), 2014 IEEE International Conference on, pages: 2339-2344, 2014 (inproceedings)

Project Page [BibTex]

2014

pi Lum, G. Z., Diller, E., Sitti, M. Structural optimization method towards synthesis of small scale flexure-based mobile grippers In Robotics and Automation (ICRA), 2014 IEEE International Conference on, pages: 2339-2344, 2014 (inproceedings)

Project Page [BibTex]

Six-Degrees-of-Freedom Remote Actuation of Magnetic Microrobots.

Diller, E. D., Giltinan, J., Lum, G. Z., Ye, Z., Sitti, M.

In Robotics: Science and Systems, 2014 (inproceedings)

Project Page [BibTex]

pi Diller, E. D., Giltinan, J., Lum, G. Z., Ye, Z., Sitti, M. Six-Degrees-of-Freedom Remote Actuation of Magnetic Microrobots. In Robotics: Science and Systems, 2014 (inproceedings)

Project Page [BibTex]

2013

A hybrid topological and structural optimization method to design a 3-DOF planar motion compliant mechanism

Lum, G. Z., Teo, T. J., Yang, G., Yeo, S. H., Sitti, M.

In Advanced Intelligent Mechatronics (AIM), 2013 IEEE/ASME International Conference on, pages: 247-254, 2013 (inproceedings)

[BibTex]

2013

pi Lum, G. Z., Teo, T. J., Yang, G., Yeo, S. H., Sitti, M. A hybrid topological and structural optimization method to design a 3-DOF planar motion compliant mechanism In Advanced Intelligent Mechatronics (AIM), 2013 IEEE/ASME International Conference on, pages: 247-254, 2013 (inproceedings)

[BibTex]

Guo Zhan Lum

2018

Small-scale soft-bodied robot with multimodal locomotion

2018

2017

An XY ϴz flexure mechanism with optimal stiffness properties

2017

2016

Soft Actuators for Small-Scale Robotics

2016

Six-degree-of-freedom magnetic actuation for wireless microrobotics

Gallium Adhesion: Phase Change of Gallium Enables Highly Reversible and Switchable Adhesion (Adv. Mater. 25/2016)

Shape-programmable magnetic soft matter

2015

Structural optimization for flexure-based parallel mechanisms–Towards achieving optimal dynamic and stiffness properties

2015

Integrating mechanism synthesis and topological optimization technique for stiffness-oriented design of a three degrees-of-freedom flexure-based parallel mechanism

2014

Structural optimization method towards synthesis of small scale flexure-based mobile grippers

2014

Six-Degrees-of-Freedom Remote Actuation of Magnetic Microrobots.

2013

A hybrid topological and structural optimization method to design a 3-DOF planar motion compliant mechanism

2013

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