Past Projects

Compliant Mechanisms Synthesis for Adaptive Shape Change Applications

Kerr-Jia Lu

One of the many superior features of compliant mechanisms is the distributed deformation field, which is particularly attractive when dealing with adaptive systems, such as shape change in aircraft wings and antenna reflectors. In order to achieve a desired shape change, the objective of this research is to develop a systematic compliant mechanism synthesis approach for a desired shape change.

Related Papers:
  • Design of Compliant Mechanisms for Morphing Structural Shapes
  • Parameterization Strategy for Optimization of Shape Morphing Compliant Mechanisms Using Load Path Representation
  • Synthesis of Shape Morphing Compliant Mechanisms Using Load Path Representation Method
  • Compliant Mechanism Syntheses for Shape-Change Applications: Preliminary Results

Compliant Building Block Synthesis

Charles Kim

The synthesis of fully compliant mechanisms is typically performed either by optimization or intuition. Research in synthesis by optimization has yielded satisfactory results that are usually eclipsed by designs produced by intuition. In this work, a conceptual approach is taken for the design of compliant mechanisms. To this end, a building block methodology is implemented at the conceptual stage of compliant mechanism design, while a size and geometry optimization is implemented to refine the design to satisfy performance criteria. To implement a building block synthesis, it is necessary to both identify and characterize specific building blocks. A library of building blocks is to be identified along with tools to quantify a building block's kinematic and energy characteristics. Additionally, a method for task decomposition is being investigated for the building block methodology.

Five basic building block functions

A combination of two or more building blocks can create a dynamic compliant model.
Related Papers:
  • G. Krishnan, C. Kim, S. Kota. ‘Synthesis of single port compliant mechanisms using serial concatenation of building blocks’, presented at the ASME-IDETC/CIE, San Diego, CA, Sept. 1-3 2009.
  • G. Krishnan, C. Kim, and S. Kota. "Building block method: a bottom-up modular synthesis methodology for distributed compliant mechanisms," Mechanical Sciences 3 (2012).

Disk Drive Microactuation

Charles Kim

One of the bottlenecks limiting data density in conventional disk drives is the resonant frequency of the suspension arm connecting the actuator and the read-write elements. In this work a compliant transmission is integrated with a secondary electrostatic microactuator to address this limitation. The compliant transmission was designed to reduce overall footprint.

Related Papers
  • Design of a Novel Compliant Transmission for Secondary Microactuators in Disk Drives

Embedded Actuation and Biomimetic Compliant Systems

Brian Trease

While all compliant mechanisms are "biologically-inspired" in their dependence on elastic deformation, I am working to take biomimetic design several steps further, beyond singly-actuated, planar isolated mechanisms. The goal is to include actuators, sensors, structures, and other material needs all in one optimization problem. Thus, the research effort is to move from compliant mechanisms to compliant systems.

Related Papers
  • Synthesis of Adaptive and Controllable Compliant Systems with Embedded Actuators and Sensors

Compliant Joints

Brian Trease

Biologically Inspired Compliant Mechanisms

Christine Vehar

I propose that medical applications, such as the cleverly intrinsic, multi-part prosthetic devices and artificial organs, can be astronomically improved if redesigned as biologically inspired compliant mechanisms. I wish to unlock nature's design "rules of thumb" and put it in a language that can be understood by both design engineers and optimization software. I feel that my approach to compliant mechanism creation is innovative and more comprehensive than other approaches since it is based on flexible mechanisms that work, and have been working for millenniums.

Tape Springs as Elements of Fully Compliant Mechanisms

Christine Vehar

This research introduces tape springs as elements of fully compliant mechanisms. The localized folds of tape springs serve as compact revolute joints, with a very small radius and large range of motion, and the unfolded straight segments serve as links. By exploiting a tape spring's ability to function as both links and joints, we present a new method of realizing fully compliant mechanisms with further simplification in their construction. Tape springs, typically found in carpenter tape rules, are thin-walled strips having constant thickness, zero longitudinal curvature, and a constant transverse curvature. This research presents a closed-loop tape spring mechanism. By representing its folds as idealized revolute joints and its variable length links as sliding joints connecting rigid links, we present a modified Gruebler's equation to determine its kinematic and idle degrees of freedom. To realize practical utility of tape spring mechanisms, we demonstrate a simple actuation scheme incorporating shape memory alloy (SMA) wire actuators in a physical tape spring model.

Related Papers
  • Closed-Loop Tape Springs as Fully Compliant Mechanisms - Preliminary Investigations

Design of Compliant Mechanisms for Dynamic Performance

Tanakorn Tantanawat

When analyzing or designing compliant mechanisms, early researchers usually assumed a quasi-static condition. Consequently, the analysis and design tools developed based on this assumption are limited to quasi-static applications. In addition, some benefits of compliant mechanisms in dynamic applications may be hidden by a quasi-static assumption. In this research, energy storage capability of compliant mechanisms, which has not been fully exploited at least in a systematic manner in any previous research, will be exploited to reduce energy consumption of a system under dynamic loads. A design method directly addressing energy consumption is proposed as a proof of concept. Design of a flapping mechanism for a mechanical flying insect will be used as a case study to illustrate the proposed design method.

Related Papers
  • Design of Compliant Mechanisms for Minimizing Input Power in Dynamic Applications

Application of Compliant Mechanisms to Active Vibration Isolation Systems

Tanakorn Tantanawat

In this research, we explore an application of compliant mechanisms for active vibration isolation systems. An actuator and a compliant mechanism are used to cancel undesired disturbance, resulting in attenuated output amplitude. An actuator provides external energy to the system while a compliant mechanism functions as a transmission controlling the amount of displacement transmitted from the actuator to the payload to be isolated.

Related Papers
  • Application of Compliant Mechanisms to Active Vibration Isolation Systems

Motorcycle Suspension System with Large-Displacement Compliant-Joints

Cavin Daniel

The relatively high number of parts present in traditional suspension systems can often adversely affect the total cost and weight of the system. Minimizing suspension weight and complexity through use of compliant revolute joints has many benefits in manufacturing and system performance. Minimizing complexity reduces the assembly costs of creating the suspension and minimizing sprung weight will enable a suspension to perform better (i.e. more responsive). The compliant-joint suspension omits many of the bearings, bushings, and coil spring(s) of a conventional system and replaces the joints with stiffness supplying compliant joints.

Five-Bar Haptic Control Device

Audrey Plinta and Brian Trease

Compliant revolute joints were integrated into a five-bar haptic device with two degrees of freedom. This haptic device was used for testing by undergraduate students. The mechanism provides a force-feedback interface with the student at a single point in the working plane. Any two-dimensional virtual environment can be created, complete with interactive virtual springs, sprung masses, walls, gratings, viscous fluids, negative stiffness, and more.

Navy Fins

Brian Trease

Minimally Invasive Vascular Clamp

Michael Cherry and Tanakorn Tantanawat

A blood vessel clamp is a device commonly used during an organ transplant to stop flow in a blood vessel. However, with the current blood vessel clamp design, many doctors found that the clamp often damages the vessels (more than 50% of cases). After investigating the current clamp design, we were able to identify two issues. In this project, a compliant vascular clamp was designed to solve the problems through the use of material compliance.

Compliant Hemostat

Christine Vehar and Zachary Kreiner

Compliant Mechanical Pencil

Charles Kim, Kerr-Jia Lu, Audrey Plinta, Tony Tantanawat, Christine Vehar, Sridhar Kota

A new, compliant mechanical pencil offers novel features through the consolidation of multiple parts into one. The current design of a mechanical pencil consists of various small parts. The function of the pencil\'s mechanism is to feed an object by using a reciprocal input motion to produce a unidirectional output motion on the object. The compliant mechanical pencil utilizes flexural elements to provide various functions usually performed by the members of conventional mechanical pencils. The mechanism is scalable and a building block for compliant feeding mechanisms. Further benefits include ease of assembly and reduced manufacturing capital costs.

The conventional mechanical pencil typically includes up to nine parts.
A compliant mechanism can replace six of the parts into a single piece. The compliant pencil design includes an actuator in the form of a return spring that pushes a pencil lead forward, a retention spring that provides forward and reverse paths for the chuck that is stiffer than the retention spring and holds the lead in place.

Statically Balanced Compliant Mechanisms

Brian Trease

Robo-Fish

Dragan Maric

Medical Devices: Compliant Hemostat — Vessel Occlusion Device

Zachary Kreiner, Christine Vehar and Dr. Sridhar Kota, with contributions from Dr. Juan Arenas, MD

Hemostats are surgical tools that clamp blood vessels to cclude blood flow. Kidney and liver transplants require occlusion of the inferior vena cava whose diameters range from 1 to 4cm. The hemostat in common use today often damages the vessel due to excessive stresses cased by its scissor-like pinching of portions of the blood vessel. Additionally, its large handles create a surgical obstacle. We designed a compliant hemostat that can provide a parallel-jaw-like clamping action while providing direct haptic feedback to the surgeon. Additional design features include: on-handed operation, quick lock/release and ergonomic advantages, and it is reusable or disposable as needed.

A single-piece compliant hemostat mechanism can replace currently used surgical devices.
Different manual interfaces may be allowed.
The device may be made of disposable or reusable materials.

Micro-Electro-Mechanical Systems (MEMS) High Performance Micro Scale Motion Amplifier

Sridhar Kota, Joel Hetrick, Steve Rodgers

By connecting a MEMS electrostatic or thermal actuator to a compliant motion amplifier we are able to build highly robust and reliable micro machines. We have fabricated mechanisms ranging from 12x to 60x using Sandia National Lab’s SUMMiT-V advanced 5-level machining process and built specimens that have executed a 20 micron stroke, at 27KHz, for up to 10 billion cycles without failure. The overall size of the device is only 400 x 300 microns.

Related Papers
  • S. Kota, J. Hetrick, Z. Li, S. Rodgers, T. Krygowski, \"Synthesizing High-Performance Compliant Stroke Amplification Systems for MEMS\", Proc. of the IEEE Thirteenth Annual International Conference on Micro Electro Mechanical Systems, Miyazaki, Japan, J
  • Rodgers S.M., Kota S., Hetrick J., Li Z., Jensen B.D., Krygowski T.W., Miller S.L., Barnes S.M., Burg M.S., A New Class of High Force, Low-Voltage Compliant Actuation Systems, Solid-State Sensor and Actuators (Biennial) Conference, Hilton Head Island, Sou

Micro-Electro-Mechanical Systems (MEMS) High Performance Micro Scale Motion Amplifier

Sridhar Kota, Joel Hetrick, Steve Rodgers

By connecting a MEMS electrostatic or thermal actuator to a compliant motion amplifier we are able to build highly robust and reliable micro machines. We have fabricated mechanisms ranging from 12x to 60x using Sandia National Lab’s SUMMiT-V advanced 5-level machining process and built specimens that have executed a 20 micron stroke, at 27KHz, for up to 10 billion cycles without failure. The overall size of the device is only 400 x 300 microns.

Related Papers
  • S. Kota, J. Hetrick, Z. Li, S. Rodgers, T. Krygowski, \"Synthesizing High-Performance Compliant Stroke Amplification Systems for MEMS\", Proc. of the IEEE Thirteenth Annual International Conference on Micro Electro Mechanical Systems, Miyazaki, Japan, J
  • Rodgers S.M., Kota S., Hetrick J., Li Z., Jensen B.D., Krygowski T.W., Miller S.L., Barnes S.M., Burg M.S., A New Class of High Force, Low-Voltage Compliant Actuation Systems, Solid-State Sensor and Actuators (Biennial) Conference, Hilton Head Island, Sou

Micro-Electro-Mechanical Systems (MEMS) High Performance Micro Scale Motion Amplifier

Sridhar Kota, Joel Hetrick, Steve Rodgers

By connecting a MEMS electrostatic or thermal actuator to a compliant motion amplifier we are able to build highly robust and reliable micro machines. We have fabricated mechanisms ranging from 12x to 60x using Sandia National Lab’s SUMMiT-V advanced 5-level machining process and built specimens that have executed a 20 micron stroke, at 27KHz, for up to 10 billion cycles without failure. The overall size of the device is only 400 x 300 microns.

Related Papers
  • S. Kota, J. Hetrick, Z. Li, S. Rodgers, T. Krygowski, \"Synthesizing High-Performance Compliant Stroke Amplification Systems for MEMS\", Proc. of the IEEE Thirteenth Annual International Conference on Micro Electro Mechanical Systems, Miyazaki, Japan, J
  • Rodgers S.M., Kota S., Hetrick J., Li Z., Jensen B.D., Krygowski T.W., Miller S.L., Barnes S.M., Burg M.S., A New Class of High Force, Low-Voltage Compliant Actuation Systems, Solid-State Sensor and Actuators (Biennial) Conference, Hilton Head Island, Sou

Micro-Electro-Mechanical Systems (MEMS) Dual-Ratchet Micro Engine

Sridhar Kota and Steve Rodgers

In less than one square millimeter, this micro-engine integrates two compliant motion amplifiers set at 90° of one another and coupled to two electrostatic linear actuators to drive a three gear train. The device was fabricated using the Sandia National Lab’s SUMMiT-V advanced 5-level machining process to construct all gears, axles, and actuators.

The entire drive train is less than 1mm square.

Micro-Electro-Mechanical Systems (MEMS) A 3-D Repositionable Mirror

Sridhar Kota and Steve Rodgers

In less than one square millimeter, this micro-engine integrates two compliant motion amplifiers set at 90° of one another and coupled to two electrostatic linear actuators to drive a three gear train. The device was fabricated using the Sandia National Lab’s SUMMiT-V advanced 5-level machining process to construct all gears, axles, and actuators.

Micro-Electro-Mechanical Systems (MEMS) Robust Electrostatic Motor Design

Charles Kim, Sridhar Kota, fabricated by Steve Rodgers, MEMX Inc. 2002

In less than one square millimeter, this micro-engine integrates two compliant motion amplifiers set at 90° of one another and coupled to two electrostatic linear actuators to drive a three gear train. The device was fabricated using the Sandia National Lab’s SUMMiT-V advanced 5-level machining process to construct all gears, axles, and actuators.

Related Papers
  • Kim, C., Kota S., An Instant Center Approach to Conceptual Design of Compliant Mechanisms, ASME Design Technical Conferences, September 2004, Salt-Lake City

Macro Scale High Frequency Large Displacement Actuator

This macro-scale linear motion amplifier can use conventional actuators to create high frequency motions at high speed and reliability. Using a voice coil, this Vortex Generator is able to reproduce a displacement of 5mms of vibration amplitude at 80 to 220 Hz making it useful for active flow control of an aircraft wing or other surface.

A High Frequency Vortex Generator
Active Flow Control can affect the adhesion of linear flows over an airfoil.
Related Papers
  • Kota, R. Osborn, J. Joo, D. Giester, and J. Hetrick, “Active Flow Control Using High Frequency Compliant Structures”, Proceedings of the 2001 ASME Fluids Engineering Divison Summer Meeting (FEDSM 2001), New Orleans, May 2001.Symposium on Active Flow Contr

Medical Devices: Compliant Endoscopic Device

This multi-degree of Freedom compliant mechanism enables a meso-scale 1mm dia. Mirror to be manipulated 45° pitch with 45° roll and packaged within a 1.5mm envelop using 4 SMA actuators.

Schematic showing postion of actuators
SEM of actuator unit
Actuator unit side view

Medical Devices: Kidney Gripper for Minimally Invasive Transplant Surgery

An insertable compliant gripper for manipulating organs for use in Laparascopic Surgery. This device permits minimally invasive insertion through a 1.4cm incision to grasp the organ and manipulate it providing haptic feedback to the surgeon. The device is made of titanium wire in an EDM process and provides a quick-release mechanism for the instrument.

Gripper head is inserted into the body cavity and then the sleeve is retracted allowing the gripper elements to deploy and manipulate the organ. The gripper elements are single-piece compliant mechanisms designed to contact the organ body without injuring the tissue. The quick-release mechanism allows the actuator motor to be detached after deployment.
Each gripper element is a single compliant mechanism.
Quick-release mechanism
Related Papers
  • S. Kota, K-J Lu, Z-Kriener, B. Trease, J. Arenas, J. Gieger, Design and Application of Compliant Mechanisms for Surgical Tools, ASME Journal of Biomechanical Engineering, Vol. 127, Nov 2005, pp 981-989.

Medical Devices: A Compliant Prosthetic Wrist Design

Charles Kim, Sridhar Kota, fabricated by Steve Rodgers, MEMX Inc. 2002

A compliant “open-cross” universal joint may be used to replace a damaged wrist section, providing rigidity and flexion. Using kevlar composite beams, the prosthetic device allows flexion and extension well within target ranges of motion before yielding with a total mass of 51.5g, nearly 1/3rd of other designs. The design provides an off-axis load capacity of 240N at 0.83mm and up to 3000N when combinde with elastomeric shock stops.

Medical Devices: A Laproscopic Port Seal and Anchor Mechanism

David Krumanaker, Brandon Lloyd, David Ohrin, Sridhar Kota and Dr. James Geiger (Medical School)

Medical Devices: A Compliant Cutter for Arthroscopic Joint Fusion

Froukje E. Euwe and Sridhar Kota

The device offers a new and minimally invasive technique for performing fusion of the subtalar, or talocalcaneal joint by removing cartilage and layers of bone from between the Talus and Calcaneus, and then fusing the two exposed surfaces together. The compliant cutter device can passively follow the curved shape of the joint surface in one plane without requiring complete disarticulation of the joint then developing a compliant guide shaft to control and direct the cutting head.

Approximate path of cutting head contacting surfaces of both Talus and Calcaneous in situ.
3-D Model of arthroscopic shaver and uni-flexible cutter head.
Model of uni-flexural cutter head.
Cutter assembly and retractable shaver element.
Related Papers
  • Patent: S.Kota, F.W. Euwe, Surgical Tools and Components Thereof, U.S. 8.394,116 B2, March 2013

Medical Devices: Artificial Heart Pump

Joshua Bishop-Moser, Sridhar Kota

Single-piece compliant mechanisms may provide a valuable alternative to other designs for reduced wear, weight and performance. The device employs a number of rigid and compliant sections in a single-piece configuration that pumps blood inside the body. As the pump expands, blood is pulled into the one-directional valve and when compressed, the pump forces blood out through the second one-directional valve.

An alternative compliant heart pump prototype.