Research

My research at Georgia Tech has focused on the use of pneumatic power at the human scale and for human-machine interaction. I initially worked on the Compact Rescue Robot (CRR), a testbed for the Center for Compact and Efficient Fluid Power, focusing on robot and interface development. As part of the project, I developed an associated simulation, which culminated in my Master's thesis. For my PhD dissertation, I have focused more on the actuator-level control challenges of working with pneumatics, and am studying the use of model predictive control to ensure low-impedance, accurate position control of pneumatic systems.

Scroll down to read more. I've also worked on several other research (and design) projects, which can be found on the Projects page.

Dissertation Research

Pneumatic systems possess a number of assets, including high force and power density, low cost, and clean actuation. Further, inherent compliance makes them appealing for situations prone to human contact and collision. However, the compliance, as well as the prevalence of stiction, make them difficult to control, and typically necessitate stiff controllers such as sliding mode or high gain PD control. This research employs predictive control to balance tracking and low-impedance performance, and further investigates the use of predictive friction compensation to improve friction compensation for slow systems.

Related Publications

  1. Daepp, HG and WJ Book, "Model Predictive Control for compliant pneumatic systems". In ASME 2014 Dynamic Systems and Control Conference, October 22-24, San Antonio (TX), USA (2014).
  2. Daepp, HG and WJ Book, "Predictive friction compensation for control of pneumatic actuators". Proceedings of the 8th Fluid Power Net International (FPNI) PhD Symposium, June 11-13 2014, Lappeenranta, Finland (2014).

A user interacts with the CRR.

Compact Rescue Robot Testbed

Two- and four-legged CRRs

The Compact Rescue Robot, a former testbed for the Center for Compact and Efficient Fluid Power, focuses on the application of pneumatic power to emergency response. Human scale fluid-powered equipment exists only to a limited degree and with limited functionality. The large forces possible from fluid power could provide dramatic advancements in applications ranging from agriculture to construction to emergency response, particularly if it were compact, efficient and easy to use. The testbed and its associated projects were established in part to demonstrate the improvements in capability that properly designed pneumatic systems, interfaces, and compact power sources could provide to human-scale applications, and particularly search and rescue operations. Two robots were developed: a four-legged robot with custom-valves for use with high-pressure, compact power sources was designed and built at Vanderbilt University, while a two-legged sister robot with a wheeled backend was built at Georgia Tech. Additionally, a simulation was developed that enabled users to explore interface and robot design modifications. The robots were designed to be controlled semi-autonomously. A user interface was designed by researchers at Georgia Tech and North Carolina A & T that enabled the user to control the two front legs of the robot using two 3-DoF Phantom ™ haptic joysticks, while also receiving visual and audio feedback through a headset.

Interface and simulation. The highlighted phantoms control the corresponding legs, colored in green in the simulation.

As a researcher on the project, I worked with several collaborators on interface design and control, improved the mechanical and electrical systems to improve the capabilities and robustness of the two robots, and contributed a dynamic simulation, which also culminated in my master's thesis. For more information on the testbed goals, associated projects, and affiliated researchers, visit its project page on the main IMDL site.

Related Publications

  1. Mizumoto, H, H Daepp, WJ Book and F Matsuno, "Teleoperation system using past image records for legged robot". IEEE/RSJ International Symposium on Safety, Security, and Rescue Robotics (SSRR), Kyoto, Japan, November 1 - 5, 2011.
  2. Chipalkatty, R, H Daepp, M Egerstedt and W Book, "Human-in-the-Loop: MPC for shared control of a quadruped rescue robot". IEEE/RSJ International Conference on Intelligent Robots and Systems, San Francisco (CA), USA, September 25 - 30, 2011.
  3. Daepp, HG and WJ Book, "A user interface with multisensory feedback for a fluid powered rescue robot". Proceedings of 6th FPNI PhD Symposium, June 15-19 2010, West Lafayette (IN), USA (2010).

Master's Thesis

A video of a user controlling the simulated robot with the Phantom joysticks.

As with most complex systems, goal-oriented design of the CRR's mechanical and software components is better achieved if the system is well understood. A simulation, consisting of an actuator model and a kinematic and dynamic model of the robot, was developed to aid this understanding. Since the simulation of the robot and environmental interactions is solved in real-time, researchers are able to fully examine altered dynamics and effectiveness of control schemes following system modification. Additionally, the simulation provides flexibility in design of the operator interface: The outputs are related to the operator via graphic output and haptic feedback, providing user insight to the effects of fluid power on legged rescue robot versatility. While many simulations are available that allow the user to model a complete device from the ground up, this particular configuration combines multiple platforms to achieve a balance of accuracy and ease of practical implementation. The kinematic and dynamic model of the robot was constructed in SrLib, a dynamics library that accepts input torques and provides the resulting motion, as well as simulating environmental interaction. The actuator model, written in Simulink, was based on the configuration on the hardware. Comparison tests between simulated and actual actuator behaviors validated a close correlation in both the open and closed loop for a range of relevant inputs. The actuator model was then integrated with the simulation and adjusted to perform truthfully to the actual device despite approximations in the modeling and platform configuration approach.

Related Publications

  1. Daepp, HG and WJ Book, "Value of a high fidelity actuator model for dynamic simulation of a pneumatic rescue robot". Proceedings of the 19th International Federation of Automatic Control (IFAC) World Congress, August 24-29, Cape Town, South Africa (2014).
  2. HG Daepp, 2011. "Development of a multi-platform simulation for a pneumatically-actuated quadruped robot". Thesis, Georgia Institute of Technology.
  3. Daepp, HG and WJ Book, "Modeling and simulation of a pneumatically-actuated rescue robot". Proceedings of the 52nd National Conference on Fluid Power, Las Vegas (NV), USA, March 23 - 25, 2011.
  4. Daepp, HG, WJ Book, TY Kim and PP Radecki, "An interactive simulation for a fluid-powered legged search and rescue robot". Proceedings of 2010 International Symposium on Flexible Automation, Tokyo, Japan, July 12-14, (2010).

Acknowledgement

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