Gripper Telemanipulation System for the PR2 Robot

Advisor: Dr. Camillo J Taylor

Abstract: The most common method of teleoperation has an operator using a joystick to drive a robot, but also having to manipulate each joint of a robotic arm plus its end effector. But while this a working solution at the moment, it is inefficient and makes controlling the robot difficult without extensive training. Our goal was to create a telemanipulation device that would mimic a robot’s end effector, in this case the PR2. This device will also provide haptic feedback, track the hand pose of the operator, and simultaneously control the arm joints regardless of the operators skill level. All of this was accomplished by using a combination of electrical hardware, mechanical engineering and software. And even though this device was developed for the PR2 robot, this device can serve as a template to develop controllers for any robot design. Read report.

Wall Following for Autonomous Navigation

Advisor: Dr. Daniel Koditschek

Abstract: Self-sufficiency in robotics motivates the need for continual improvement in autonomous navigation for mobile robots. Wall-following provides a simplification of 2-D navigation problems by providing a reference by which these problems are reduced to 1-D. A laser scanner for wall detection (abstracted as an active tangent/curvature sensor) is used on a kinematic unicycle robot, together with a controller inspired by [1] with an explicit representation of the wall as a planar curve. With bounded curvature and some other conditions, we are able to prove global Lyapunov stability of the controller. Reported experiments (performed using the X-RHex [2] robot) include straight wall trials to demonstrate the efficacy of the controller for a variety of initial conditions, as well as longer trials in more complicated environments including concave and convex corners up to and exceeding 90º. Lastly, the wall-following behavior is used to augment existing stair climbing routines [3] for faster landing exploration. Read report.

[1] V. Kallem and N. J. Cowan, “Task-Induced Symmetry and Reduction With Application to Needle Steering” IEEE Trans. Autom. Control., 2010.

[2] K. C. Galloway, G. C. Haynes, B. D. Ilhan, A. M. Johnson, R. Knopf, G. Lynch, B. Plotnick, M. White and D. E. Koditschek, “X-RHex: A Highly Mobile Hexapedal Robot for Sensorimotor Tasks,” University of Pennsylvania, 2010 [Online]. Available: http://kodlab.seas.upenn.edu/Kod/Xrhextech

[3] Aaron M. Johnson, Matthew T. Hale, G. C. Haynes, and D. E. Koditschek. “Autonomous Legged Hill and Stairwell Ascent,” IEEE International Symposium on Safety, Security, and Rescue Robotics, November 2011, Kyoto, Japan, pp 134-142

Effects of Rotor Afrodynamics in Micro UAV Flight

Advisor: Dr. Vijay Kumar

Abstract: Rotor aerodynamics is known to be significant in quadrotor flight. We design a simulation for flight in small spaces by extending a previously proposed aerodynamic model. This simulation accurately models the role of relative air velocity, rotor angle of attack, and proximity of both the ground and the ceiling in quadrotor flight. We design and build a platform for conducting flight tests, consisting of a four foot long tunnel with an expandable, square cross section. We present preliminary data from flight tests and offer suggestions for future work on refining our controller. Read report.

Programmable Time Division Multiple Polarization Graphic

Advisor: Dr. Jan Van der Spiegel

Abstract: Polarization is an intrinsic and fundamental property of light, just as color is. Its direction is determined by the direction of the electric field found in light. The orientation of the electric field changes as it interacts with objects, including particles in the air. Using this principle, powerful image enhancement tools such as the polarization-difference imaging (PDI) were developed. PDI consists in capturing frames at different polarization angles by rotating a polarizer placed in front a camera and performing the net difference between those frames to reveal elements previously invisible. Previous studies had made use of non-portable systems that required the rotation of the polarizer to be done manually. In order to minimize sources of errors and increase its flexibility, we improved this system by automating the process and by centralizing the frame capturing and processing system to render it portable. We also tested the system to showcase its versatility and possible application in material detection, object recognition and fingerprint identification. Read report.

Separator Membranes Produced from Polymers by Electrospinning for Applications in Electrical Double Layer Capacitors

Advisor: Dr. Jorge Santiago

Abstract: Electrochemical capacitors are able to achieve high levels of capacitance and store large amounts of charge due to the ample availability of surface area. The porous separator membrane that separates the electrodes of an electrochemical capacitor allows ions to diffuse across to the opposite electrode, without recombination, when voltage is applied. This paper presents general information concerning electrochemical capacitors and electrospinning and presents the results from the research project intended to produce polymer which is environmentally-friendly and can be used as the separator membrane between super-capacitor electrodes. Various polymer solutions were made and electrospun onto a current collector forming a mat. Samples of the mats produced could then be analyzed based upon such characteristics as viscosity, chemical attributes, and mechanical attributes. Samples of the mats produced through electrospinning were also tested to see if they could achieve a greater level of capacitance than the separator membranes currently used. 15% weight/volume poly-lactic acid produced the highest capacitance, along with 15% weight/volume poly-lactic acid mixed with 3.5% weight/volume poly (ethylene oxide) and 12 mg of silver powder. The set-up that proved most useful for electrospinning these mats, was to electrospin the poly-lactic acid and poly (ethylene oxide) combination in layers using a dual-syringe pump. Read report.

Prototyping and Simulating the Powertrain of An Electric Vehicle

Advisor: Dr. Rahul Mangharam

Abstract: Electric vehicles are a promising alternative to vehicles powered by fossil fuels due to their cleaner energy emission, but current limitations in battery technology are preventing electric vehicles from burgeoning in the mass consumer market. Therefore, simulating and prototyping various power trains become paramount for finding different energy efficient models. A portable power train platform, known as Protodrive, is introduced to provide a stage in between pure software simulation and full-scale hardware simulation. This platform allows energy to transfer between the vehicle power train and the load power train through the use of regenerative braking. Protodrive is also able to accept a plethora of drive cycles and trajectories to help determine the forces acting on the vehicle. Through the use of mathematical models of these forces, the platform is capable of applying the proper load on the vehicle power train to determine the power consumption. Additionally, introduction of a super capacitor to the vehicle power train model allows for the analysis of various control schemes to better manage the power consumption. The resulting simulated drive data can be viewed in real time through an intuitive web application that will allow users to enter drive cycles and define trajectories using Google Maps. The platform data can then be validated by comparing it with actual vehicle drive data. Read report.

Design and Implementation of Programs for an Autonomous Robotic Arm to be Attached to a Terrestial Robot

Advisor: Dr. Daniel lee

Abstract: Terrestrial robots used in reconnaissance or disaster-relief encounter obstacles throughout their missions, which necessitates the use of robotic arms to manipulate the objects that obstruct them. Over the course of ten weeks, the author participated in a research project which had the development of a control program for such an arm as its goal. This paper describes a set of programs that were designed to aid the user in removing obstacles from the path of an Unmanned Ground Vehicle (UGV) remotely. The programs use LIDAR data to plot a robot’s surroundings in three dimensions, and then identify the nearest object that the arm can move. The coordinates of that object are then sent to an inverse kinematics program, which determines the best path for the robotic arm, with no additional assistance from the user. This paper details the techniques used by the author and his colleagues to characterize and implement these programs, along with the mathematics used in the inverse kinematics needed for controlling said arms. Read report.

Portable Radio Signal Source Localization Device

Advisor: Dr. Vijay Kumar

Abstract: Wireless sensor networks have inspired tremendous research interest in recent decades with a wide variety of potential prospects. There is a wide spectrum of sensor systems and localization technologies available in today’s industry to approach the localization problem. Point-to-point wireless networking is one such approach. It involves the use of radio frequency transceivers and a ranging module to communicate, control, coordinate and sense in a cost effective manner at a higher detection range. This requires two or more radio nodes; which brings in the need for radio propagation through the radio antenna. When it comes to adapting this principle to human applications such as search-and-rescue missions –firefighters in disaster areas for instance, – a more practical solution requires the design and manufacturing of a portable device for humans to wear. In this paper we analyze the use of Radio Frequency (RF) technology applied to mobile robots and persons in their environment. In particular, we study the problem of localizing a person equipped with a mobile sensing device integrating a nanoPAN 5327 RF and a radio antenna. We researched, identified, designed, built, and implemented a light-weight, resilient, heat-refracting and wearable device powered with DC source to carry a computer, a hard drive, a nanoPAN 5327 RF module and a radio antenna. Finally, once the device was successfully built, we collected and analyzed data using the new box to validate our approach. Read report.

A Novel Method for Fast Collision for the PR2

Advisor: Dr. Camillo J Taylor

Abstract: In the current robot motion planning pipeline for Willow Garage’s PR2 robot, inefficient collision detection algorithms present a bottleneck. This paper provides background information, proposes a new, more efficient method for quickly determining whether a robot is in collision with a depth map, and gives a basic outline of the implementation process. The new method treats the PR2 robot as a collection of spheres that, given an array of joint angles, are positioned in the coordinate system of a depth camera. Whereas the old technique treats a depth map as a 3 dimensional set of voxels that can be tested for collision using an octree, the new technique uses the idea that a depth map is a 2 dimensional representation of free space from the perspective of the depth camera. If the robot is also rendered from the camera’s perspective, and every point on each sphere that comprises the robot has a depth value lower than its corresponding point on the depth map, then the robot is not in collision with its environment. In addition, this technique can be applied to multiple camera perspectives of the same robot model. Finally, preliminary results and further possible optimizations are explored. Read report.

PR2 –Telemanipulation Device

Advisor: Dr. Camillo J Taylor

Abstract: Robotics is a field that has many facets that make it special. One pivotal aspects of robotics involves the manipulation of the robot itself. For decades the scientific community has been hindered by the traditional joystick style controller. The research that I have done over the course of the summer is a bold attempt at changing that. By using the Vicon cameras along with the robot operating system (ros) I, and my fellow researchers were able to build a prototype that has the potential to dexterously control the PR2’s gripper. This is done using a system that integrates Ros, the Vicon system, and a mechanical hand motor that allows the user to interact with the PR2 in a innovative way. When an individual is allowed to control a robot using the natural motion of their own hand, something special happens; telemanipulation spontaneously becomes unambiguous. Nearly anyone with a properly functioning hand instantly gains the ability to manipulate a previously complex system teleoperational system with ease. Read report.

Gripper Telemanipulation System for the PR2 Robot

Advisor: Dr. Jay Zemel

Abstract: Neonates lack the ability to communicate information regarding their physiological state; therefore neonatologists need proper equipment to be able to monitor their health. [1] The lack of electronic infrastructure has limited the usefulness of previous devices. To be able to simultaneously monitor relative physiological parameters of these infants, a compact and reliable sensing device is required. This project proposes the development of an attachable breathing sensor on a baby bottle ring, specifically using a pyroelectric approach. The breathing sensor, composed of polyvivylidene fluoride (PVDF) film with lead-attachments is integrated onto a rigid ring. This sensor design improves practically in comparison to previous apparatuses by reducing the size of the sensor while being able to detect timing relative to the neonate’s sucking signal. The change in temperature on opposite sides of the film is linearly proportional to the sensor output voltage. Conversely, current generated by the film is proportional to the change in temperature. This device provides a very viable solution to understand the correlation between breathing and sucking data. These results indicate that using this device, neonatologists can improve their monitoring and analysis of neonatal development. Read report.

Characterization of Distance Sensors for use on a MAV

Advisor: Dr. Vijay Kumar

Abstract: This paper details the characterization of the Hokuyo UTM-30LX and the Xbox Kinect for use on a Micro Aerial Vehicle (MAV). The MAV is to be used for the exploration of unknown territories, and thus must be able to localize itself in various different conditions. To accomplish this, both the indoors and outdoors performance of the sensors are examined with different objects in their immediate surroundings.

The characterization begins with tests using objects with different surface properties and in different indoor lighting conditions. Furthermore, tests are conducted indoors to see how the data received by the sensor is distributed. Hence it shows how it can be implemented using a probability distribution in software to aid exploration algorithms. The same experiment is carried out outdoors to compare the data. The effects of sunlight on the sensors are noted. Then, further experiments allow us to determine the conditions in which the data from each sensor cannot be trusted. We can make the quadrotor ignore these values when exploring.

Finally, an experiment is performed using the laser range finder to test whether the information gained from the characterization of the sensors can produce greater accuracy when exploring a new area with the quadrotor. Read report.

Effect of Impact Injury on Engineered Cartilage using a High Throughout Mechanical Screening Device

Advisor: Dr. Robert Mauck

Abstract: Post-traumatic osteoarthritis (PTOA) occurs when a joint suffers a traumatic injury causing progressive degeneration of the cartilage. Our goal was to develop, in a micro-scale format, methods to mechanically impact native cartilage or cartilage tissue analogs (CTAs) using a high throughput device to initiate the degradative pathways that are associated with PTOA. Our device is designed to measure 48 samples simultaneously, using a customized matrix array of force sensitive resistors (FSRs). These FSRs, when compressed above a baseline threshold, show a repeatable change in resistance with increasing load application. By measuring the voltage drop across each sensor, we determined the relationship between applied load and voltage, and then used a calibration curve to determine the load response of a series of hydrogel samples. We also calculated the peak stress of these materials from the area of the sample measured prior to application of an impact load. For validation of impact protocols using our high throughput device, we evaluated cell viability, biochemical content, and release of cell stress signaling molecules in cell-based engineered constructs that had been grown for 16 weeks in the laboratory to take on cartilage-like properties. Results showed that the response of the CTAs followed the trends of degeneration observed previously in single impact tests. Following this validation process, the device will stand ready to identify molecules important in chondrocyte response to injury, and ultimately provide a tool to characterize small molecules that may aid therapeutically in the cartilage repair response. Read report.