Abolfazl Pourghodrat

Power harvesting systems design for railroad safety

Railroad crossings represent a significant danger in railroad transportation systems. Each year thousands of accidents occur that involve trains and other vehicles at unprotected railroad crossings, resulting in hundreds of fatalities and injuries. Additionally, derailments occur on average once every 6 h across the United States due to mechanical failures and improperly maintained track, endangering property and lives. The lack of electrical infrastructure in remote areas is a primary barrier impeding the installation of safety enhancements such as warning light systems and track health monitoring sensors that could reduce the frequency of such accidents. Providing on-demand power by harvesting energy from deflecting railroad track during the passage of trains is a promising approach compared with the cost of installing electrical power lines or the lack of robust solar and/or wind power solutions. This paper discusses the design and development of several power harvesting devices capable of scavenging power from the vertical deflection of railroad track. The design of a cam-based generator device driven by the train wheels is also discussed. Simulation and testing results on these devices are also presented in this paper.

On-track testing of a power harvesting device for railroad track health monitoring

A considerable proportion of railroad infrastructure exists in regions which are comparatively remote. With regard to the cost of extending electrical infrastructure into these areas, road crossings in these areas do not have warning light systems or crossing gates and are commonly marked with reflective signage. For railroad track health monitoring purposes, distributed sensor networks can be applicable in remote areas, but the same limitation regarding electrical infrastructure is the hindrance. This motivated the development of an energy harvesting solution for remote railroad deployment. This paper describes on-track experimental testing of a mechanical device for harvesting mechanical power from passing railcar traffic, in view of supplying electrical power to warning light systems at crossings and to remote networks of sensors. The device is mounted to and spans two rail ties and transforms the vertical rail displacement into electrical energy through mechanical amplification and rectification into a PMDC generator. A prototype was tested under loaded and unloaded railcar traffic at low speeds. Stress analysis and speed scaling analysis are presented, results of the on-track tests are compared and contrasted to previous laboratory testing, discrepancies between the two are explained, and conclusions are drawn regarding suitability of the device for illuminating high-efficiency LED lights at railroad crossings and powering track-health sensor networks.

Design and preliminary evaluation of a self-steering, pneumatically driven colonoscopy robot

Abstract Colonoscopy is a diagnostic procedure to detect pre-cancerous polyps and tumours in the colon, and is performed by inserting a long tube equipped with a camera and biopsy tools. Despite the medical benefits, patients undergoing this procedure often complain about the associated pain and discomfort. This discomfort is mostly due to the rough handling of the tube and the creation of loops during the insertion. The overall goal of this work is to minimise the invasiveness of traditional colonoscopy. In pursuit of this goal, this work presents the development of a semi-autonomous colonoscopic robot with minimally invasive locomotion. The proposed robotic approach allows physicians to concentrate mainly on the diagnosis rather than the mechanics of the procedure. In this paper, an innovative locomotion approach for robotic colonoscopy is addressed. Our locomotion approach takes advantage of longitudinal expansion of a latex tube to propel the robot’s tip along the colon. This soft and compliant propulsion mechanism, in contrast to minimally invasive mechanisms used in, for example, inchworm-like robots, has shown promising potential. In the preliminary ex vivo experiments, the robot successfully advanced 1.5 metres inside an excised curvilinear porcine colon with average speed of 28 mm/s, and was capable of traversing bends up to 150 degrees. The robot creates less than 6 N of normal force at its tip when it is pressurised with 90 kPa. This maximum force generates pressure of 44.17 mmHg at the tip, which is significantly lower than safe intraluminal human colonic pressure of 80 mmHg. The robot design inherently prevents loop formation in the colon, which is recognised as the main cause of post procedural pain in patients. Overall, the robot has shown great promise in an ex vivo experimental setup. The design of an autonomous control system and in vivo experiments are left as future work.

Pneumatic Miniature Robot for Laparoendoscopic Single Incision Surgery

The transition from open surgery to Laparoendoscopic Single-Site (LESS) surgery to minimize cost and recovery time and improve cosmetic scarring has introduced complexities such as reduced dexterity, restricted workspace, and unintuitive controls. Surgical robotic systems can come into play to address these complexities. The most recent miniature in vivo robots have demonstrated the capability of performing LESS surgery. Since size has been a key driving force for designing these motor-driven robotic platforms, delivering adequate force and torque to perform the surgical tasks has been a primary challenge for improving these robots.This paper presents a robotic platform actuated primarily by pneumatics, offering the following advantages over motor-driven systems: higher joint torque and tool actuation force, faster actuation, better biocompatibility, better overall robustness, and lower cost. Initially one representative robot joint has been fabricated, to demonstrate the proof of concept and investigate the feasibility of angular position control of the pneumatic joint by deploying a minimal number of electronic components and two low-cost solenoid valves in place of costly fast solenoid valves or expensive servo valves.The robot design, pneumatic system, implementation of PID and PWM controls, and experimental results are presented.Copyright

Improving an energy harvesting device for railroad safety applications

Due to hundreds of fatalities annually at unprotected railroad crossings (mostly because of collisions with passenger vehicles and derailments resulting from improperly maintained tracks and mechanical failures), supplying a reliable source of electrical energy to power crossing lights and distributed sensor networks is essential to improve safety. With regard to the high cost of electrical infrastructure for railroad crossings in remote areas and the lack of reliability and robustness of solar and wind energy solutions, development of alternative energy harvesting devices is of interest. In this paper, improvements to a mechanical energy harvesting device are presented. The device scavenges electrical energy from deflection of railroad track due to passing railcar traffic. It is mounted to and spans two rail ties and converts and magnifies the tracks entire upward and downward displacement into rotational motion of a PMDC generator. The major improvements to the new prototype include: harvesting power from upward displacement in addition to downward, changing the gearing and generator in order to maximize power production capacity for the same shaft speed, and improving the way the system is stabilized for minimizing lost motion. The improved prototype was built, and simulations and tests were conducted to quantify the effects of the improvements.

Disposable Fluidic Actuators for Miniature In-Vivo Surgical Robotics

Fusion of robotics and minimally invasive surgery (MIS) has created new opportunities to develop diagnostic and therapeutic tools. Surgical robotics is advancing from externally actuated systems to miniature in-vivo robotics. However, with miniaturization of electric-motor-driven surgical robots, there comes a trade-off between the size of the robot and its capability. Slow actuation, low load capacity, sterilization difficulties, leaking electricity and transferring produced heat to tissues, and high cost are among the key limitations of the use of electric motors in in-vivo applications. Fluid power in the form of hydraulics or pneumatics has a long history in driving many industrial devices and could be exploited to circumvent these limitations. High power density and good compatibility with the in-vivo environment are the key advantages of fluid power over electric motors when it comes to in-vivo applications. However, fabrication of hydraulic/pneumatic actuators within the desired size and pressure range required for in-vivo surgical robotic applications poses new challenges. Sealing these types of miniature actuators at operating pressures requires obtaining very fine surface finishes which is difficult and costly. The research described here presents design, fabrication, and testing of a hydraulic/pneumatic double-acting cylinder, a limited-motion vane motor, and a balloon-actuated laparoscopic grasper. These actuators are small, seal-less, easy to fabricate, disposable, and inexpensive, thus ideal for single-use in-vivo applications. To demonstrate the ability of these actuators to drive robotic joints, they were modified and integrated in a robotic arm. The design and testing of this surgical robotic arm are presented to validate the concept of fluid-power actuators for in-vivo applications.

A novel articulated drive mechanism for multifunctional NOTES robot

This paper presents a novel articulated drive mechanism (ADM) for a multifunctional natural orifice transluminal endoscopic surgery (NOTES) robotic manipulator. It consists mainly of three major components including a snakelike linkage, motor housing, and an arm connector. The ADM can articulate into complex shapes for improved access to surgical targets. A connector provides an efficient and convenient modularity for insertion and removal of the robot. Four DC motors guide eight cables to steer the robot. The workspace, cable displacement and force transmission relationships are derived. Experimental results give preliminary validation of the feasibility and capability of the ADM system.

Dimensional Optimization of a Two-Arm Robot for Single-Site Surgery Operations

Unlike open surgery, minimally invasive surgery (MIS) involves small incisions through which instruments are passed to perform surgery. This technique is preferred since it reduces postoperative pain and recovery time. Laparoendoscopic single-site (LESS) surgery is the next step in MIS; a single incision is created instead of multiple access points for allowing the instruments to enter the peritoneal cavity. However, such minimally invasive techniques force the surgeon to perform more complex movements, hence the interest to use robotic systems. Design of robots for LESS is challenging to avoid collisions, reduce weight, and improve compactness while respecting the technical requirements (minimum forces, velocities). In this paper, we present the dimensional synthesis of a two-arm robot used for LESS. Each arm has a 2R-R-R architecture with link lengths optimized to respect the workspace constraints and maximize compactness while improving the performance in terms of forces and velocities (kinetostatic properties).Copyright

A System for Generating Electricity Using the Passage of Train Wheels for Improving Railroad Track Safety

The dangerous nature and history of railroad grade crossings (especially unprotected crossings in remote areas lacking costly electrical infrastructure) motivates engineering efforts to reduce the number of fatalities and injuries. Several approaches and devices have been investigated and developed to harvest energy, mostly from vertical deflection of railroad track to power automated warning systems and track health monitoring sensors. While most of this previous work relied on harvesting energy from the vertical deflection of the railroad track, this paper proposes a mechanism for generating electricity from the passage of each train wheel. A cam-follower mechanism was designed initially to meet the requirements of low noise, shock and wear, and was subsequently used and improved to design a system capable of generating electricity efficiently from the motion of trains traveling in either direction. The development of the device as well as analysis of its predicted power production capability is presented in this paper.Copyright

Energy Harvesting From Vertical Deflection of Railroad Track Using a Hydraulic System for Improving Railroad Track Safety

Grade crossings are locations of significant interest for prevention of collisions, injuries and fatalities in the railroad transportation system. Another area of concern is track maintenance, since derailments resulting from mechanically deficient track structures can cause significant endangerment to property and lives. A commonality between these two classes of incidents is that many occur in remote areas due to the lack of electrical infrastructure to power automated warning systems and/or track health monitoring sensor networks. Providing electrical infrastructure to railroad crossings in remote areas is often not economical, and other alternative sources of electricity such as solar and wind energy are not reliable and robust. This motivated development of a hydraulic system capable of harnessing power from vertical deflection of railroad track due to passing railcar traffic. A hydraulic cylinder mounted under the bottom of the rail is compressed and relaxed by passage of each railcar, forcing the hydraulic fluid towards a hydraulic motor and converting the hydraulic pressure and flow into rotational motion and torque. The rotational motion is amplified to drive a PMDC generator. The hydraulic system was developed and testing was performed to verify the functionality of the hydraulic system and quantify the power output.© 2011 ASME