Customer reviews posted online provide a massive dataset that can identify product defects. Locating informative reviews of a specific product is straightforward. However, it can be challenging to extract information that informs product designers of potential defects and drives useful testing to investigate the potential defect. Such data extraction can be manually performed in a reliable and effective manner by skilled engineers. However, such an approach can be time-consuming and expensive. On the other hand, completely automated data extraction would likely yield generic results that are not particularly useful. This paper describes a semi-automated process wherein researchers develop an informed search algorithm that is based on an initial engineering assessment of a product that identifies potential design problems and words sets that are associated with the potential defects. An automated search process then operates on the review database to greatly streamline the data analysis process. The product reviews that indicate product defects are grouped together and associated with design features. The design features that are linked to the largest classes of complaints are then rigorously tested to evaluate the credibility and accuracy of the online complaints. The process is illustrated via a case study and testing of a cantilever-style bassinet.

Robotic landing gear (RLG) for rotorcraft improves performance in landing on sloped uneven terrain, unprepared areas, and ship decks. The interaction between the feet of the RLG and the landing surface are pivotal to a successful landing event. Slipping or bouncing of the feet can lead to a failed landing and a catastrophic accident. Proposed herein is the use of locking mechanisms on the RLG feet in order to eliminate landing gear slip and bounce during the landing event. Through the use of a comprehensive multibody dynamic simulation, locking mechanisms on the RLG feet are shown to eliminate landing event failures that can occur with nonlocking landing gear configurations, at the expense of a moderate increase in landing gear loads during a landing event. Results indicate that landing event failures are eliminated even in the situation where some feet-locking mechanisms are inoperable or break away. Furthermore, RLG with feet locking mechanisms permit the reduction or elimination of the need for active control of the RLG legs. The results herein give guidance to the development of integrated RLG with locking mechanisms.

This paper describes a method to use data-mined customer reviews to identify potential product defects. The process involves locating negative reviews of a specific product and then extracting comments that have potential connections with the product design. The extracted comments are then categorized and correlated with features of the product. Given that the customer comments are generally not specifically tied to engineering requirements, or even posed in engineering terms, this correlation requires some degree of engineering analysis to establish a correlation. After these complaint-feature correlations are established, then engineering tests directed at understanding the possible defects are performed. This data-mining process effectively harnesses the massive amount of in-situ testing and evaluation that is performed by customers of the product. The process is illustrated via a case study of an infant bassinet. Customer reviews of the product were studied to identify and categorize key complaints about the bassinet. These complaints were correlated with features and potential defects in the product, including assembly difficulties, as well as a sleeping surface that tilts and causes infants to roll and press into the mesh side wall while sleeping. Then, assembly and sleeping surface deflection tests were conducted. The sleeping surface deflection tests include measurements of how bassinet leg separation affects the deflection, as well as long-duration progressive deflection that occurs from repeated use of the product. The results of the engineering testing confirm the presence of defects in the bassinet and its assembly instructions, as suggested by the reviews. This case study illustrates how data-mined customer reviews provide a valuable source of engineering data and indications of product defects.

Crawler crane designers continually extend the height of the machines. Models that reach over 500 feet high are commercially available. Of course, as the crane height increases, so do the hazards associated with tip-over accidents. Destabilizing tip-over moments are generated by the boom and the suspended payload when they extend beyond the base of support. Stabilizing moments are generated by the crane base and counterweights. Counterweights are normally secured by mechanical fasteners such as pins, bolts, or chains. However, some cranes use unrestrained counterweights that are held in place only with friction. This paper investigates the dynamic behavior of such unrestrained counterweights during tip-over accidents. The analysis shows that counterweight blocks can break free and slide off the crane when the tip angle is as small as 20 degrees. Scale-model testing of cranes with unsecured counterweights demonstrates that the fall path of the spilling counterweights on certain crane models intersects the operator cab and thus presents a deadly hazard.

Actively controlled gun-launched projectiles require a means of modifying the projectile flight trajectory. While numerous potential mechanisms exist, microspoiler devices have been shown to be a promising control actuator for fin-stabilized projectiles in supersonic flight. These devices induce a trim force and moment generated by the boundary layer–shock interaction between the projectile body, rear stabilizing fins, and microspoilers. Previous investigations of microspoiler mechanisms have established estimates of baseline control authority, but experimental results have been restricted to cases in which the mechanism was statically deployed. This paper details the design and flight testing of a projectile equipped with a set of active microspoilers. A mechanical actuator is proposed that exhibits unique advantages in terms of robustness, simplicity, gun-launch survivability, and bandwidth compared to other projectile actuator mechanisms considered to date. A set of integrated test projectiles is constructed using this actuator design, and flight experiments are performed in which the microspoilers are oscillated near the projectile roll frequency. Data obtained from these flight tests are used in parameter estimation studies to experimentally characterize the aerodynamic effects of actively oscillating microspoilers. These predictions compare favorably with estimates obtained from computational fluid dynamics (CFD). Overall, the results presented here demonstrate that actively controlled microspoilers can generate reasonably high levels of lateral acceleration suitable for trajectory modification in many smart-weapons applications.

When a product is a complex dynamic system that interacts directly with a human, engineers must consider a wide range of possible motions and forces that the device could exert on the human. Such an analysis goes beyond a simple thought exercise and requires detailed knowledge about the system dynamics and the operating environment. This paper presents such an analysis of inverted-pendulum human transporters. The list of hazards is constructed by using knowledge of the dynamics and mechanical design obtained through simulation and experimentation. However, the dynamics are so complex that the list is augmented with hazards that are revealed by studying accident videos posted on the Internet. The severity of the hazards is estimated using an energy-based measurement of the hazard onset conditions as well as compounding factors from the mechanical design. In addition, experimental and simulation results of sample hazard conditions illustrate their danger and severity. The analysis reveals that inverted-pendulum human transporters have several hazards with unacceptable risk.

Rotorcraft are essential to operations at sea, primarily due to their ability to perform vertical takeos and landings. However, due to the motion of the ship deck, ship landings can be dangerous for the pilot and result in damage to the helicopter. The addition of an articulated landing gear to a rotorcraft increases the number of degrees of freedom that can be used to land on a moving surface, such as a ship deck. Instead of relying solely on the rotor thrust magnitude and direction to land safely, the articulated landing gear can also be used to conform to the ship deck while maintaining a level fuselage, potentially allowing for quicker and safer landings. This paper presents a multi-body simulation tool to simulate the dynamics of a rotorcraft with robotic gear landing on a moving surface. A virtual model controller is developed to produce appropriate actuator torques. Dynamic simulation results show that an articulated, legged landing gear system can aid helicopters to landing on a moving ship deck.

Best practices in product design require engineers to perform preliminary hazard analyses on the most promising conceptual designs, as well as a more rigorous hazard analysis when the details of the product are being finalized. When the product is a complex dynamic system that interacts directly with a human, the engineers must consider the wide range of possible motions and forces that the device could create. Such an analysis goes beyond a simple thought exercise and requires detailed knowledge about the system dynamics and operating environment. This paper presents such an analysis of an inverted-pendulum human transporter The list of hazards is constructed by using fundamental knowledge of the dynamics and the mechanical design obtained through simulation and experimentation. However, the dynamics are so complex that the list is augmented with hazards that are revealed by searching through accident videos posted on the Internet. The severity of each hazard is estimated using an energy-based measurement of the hazard onset conditions. While this case study is interesting, it also provides a systematic approach to hazard analysis that can be applied to other complex and dangerous dynamic systems.

An analysis of a physically-motivated friction model called the Elastic/Perfectly-Plastic (EPP) friction model was performed on a steadily rotating flat belt drive. The EPP friction law is modeled as an elastic spring in series with an ideal Coulomb damper. The belt kinematics were developed and the nonlinear equations of motion and equilibrium solutions were derived using Hamilton’s Principle. Unlike the belt mechanics analyzed with Coulomb friction, the current study predicts the absence of adhesion zones. A stability analysis demonstrates that the non-linear equilibrium solution found is stable under local perturbation. A two-pulley belt drive with equal radii is analyzed and the dynamic response is studied. The results are compared to those computed using a dynamic finite element model. Excellent agreement between the two methods is documented.

Oscillation of crane payloads makes it challenging to manipulate payloads quickly, accurately, and safely. The problem is compounded when the payload creates a double-pendulum effect. This paper evaluates an input-shaping control method for reducing double-pendulum oscillations. Human operator performance testing on a 10-ton industrial bridge crane is used to verify the effectiveness and robustness of the method. Fifty operators drove the crane with a standard control pendent, as well as a wireless touchscreen interface. Data from these experiments show that human operators drive the crane much faster and safer with the input-shaping control scheme. Furthermore, considerably less operator effort is required when input shaping is used to limit the oscillation. Additional tests required the operators to drive the crane numerous times over a period of eight days. These experiments show that significant learning occurred when operators did not have the aid of input shaping. However, the performance never approached that achieved by untrained operators using input shaping.

The usefulness of cranes is limited because the payload is supported by an overhead suspension cable that allows oscillation to occur during crane motion. Under certain conditions, the payload dynamics may introduce an additional oscillatory mode that creates a double pendulum. This paper presents an analysis of this effect on tower cranes. This paper also reviews a command generation technique to suppress the oscillatory dynamics with robustness to frequency changes. Experimental results are presented to verify that the proposed method can improve the ability of crane operators to drive a double-pendulum tower crane. The performance improvements occurred during both local and teleoperated control.

The large-amplitude and lightly-damped oscillation of crane payloads is detrimental to safe and efficient operation. The problem is further complicated when the payload creates a double-pendulum effect. Previous researches have shown that single-mode oscillations can be greatly reduced by properly shaping the inputs to the crane motors. This paper builds on previous developments by thoroughly describing the double-pendulum dynamic effects as a function of payload parameters and the crane configuration. Furthermore, an input-shaping control method is developed to suppress double-pendulum oscillations created by a payload with distributed-mass properties. Experiments performed on a 10-ton industrial bridge crane verify the effectiveness of the method. A critical aspect of the testing was human operator studies, wherein numerous operators utilized the input-shaping controller to perform manipulation tasks. The performance improvements provided by the input-shaping controller, as well as operator learning effects, are reported.

There are numerous methods for controlling unwanted vibration in machines. One possible approach is to design reference command profiles that move the system without inducing significant residual vibration. Many approaches have been proposed for designing such low-vibration commands. Some of these methods design the command profiles by minimizing the residual energy, while others minimize the residual vibration amplitude. Given that energy functions are naturally quadratic in nature, problem definitions using residual energy are generally easier to solve than those based on residual vibration. However, minimizing residual vibration, rather than residual energy, is the more direct approach to achieving the desired goal. So, the question naturally arises as to whether minimizing residual energy is a good approach to minimizing residual vibration. This paper explores this issue and demonstrates that minimizing residual energy is not necessarily a good approach to minimize residual vibration of multi-mode systems.

Oscillation of crane payloads makes it challenging to manipulate payloads quickly, accurately, and safely. The problem is compounded when the payload creates a double-pendulum effect. This paper evaluates an input-shaping control method for reducing double-pendulum oscillations. Human operator performance testing on a 10-ton industrial bridge crane is used to verify the effectiveness and robustness of the method. The tests required the operators to drive the crane numerous times over a period of eight days. Data from these experiments show that human operators perform manipulation tasks much faster and safer with the proposed control scheme. Furthermore, considerably less operator effort is required when input shaping is used to limit the oscillation. These experiments also show that significant learning occurred when operators did not have the aid of input shaping. However, the performance never approached that achieved with input shaping without any training. With input shaping enabled, only moderate learning occurred because operators were able to drive the crane near its theoretical limit during their first tests.

The large amplitude oscillation of crane payloads is detrimental to safe and efficient operation. With certain payloads, the problem is complicated when a double-pendulum effect is created. However, most crane control research to date has focused on single-mode dynamics. For example, several researchers have shown that signal-mode oscillations can be greatly reduced by properly shaping the inputs to the crane motors. This paper builds on those previous developments to create a method for suppressing double-pendulum oscillations of a distributed payload. Theoretical models are initially used to develop and evaluate an input-shaping control algorithm. Then, experiments performed on a portable bridge and a 10-ton industrial bridge crane are used to verify the practical effectiveness of the method.

Large amplitude oscillation of crane payloads is detrimental to safe and efficient operation. Under certain conditions, the problem is compounded when the payload creates a double-pendulum effect. Most crane control research to date has focused on single-pendulum dynamics. Several researchers have shown that single-mode oscillations can be greatly reduced by properly shaping the inputs to the crane motors. This paper builds on those previous developments to create a method for suppressing double-pendulum payload oscillations. The input shaping controller is designed to have robustness to changes in the two operating frequencies. Experiments performed on a portable bridge crane are used to verify the effectiveness of this method and the robustness of the input shaper.

Human manipulation of suspended payloads using cranes can be difficult. Cable sway is easily induced into the lightly damped system, which inhibits efficient, safe, and accurate payload manipulation. This problem is compounded when the payload forms a double-pendulum configuration. To aid operators, a wireless touchscreen controller was integrated into the control system of a 10-ton industrial bridge crane. This touchscreen allows an operator to move freely around the workspace and drive the crane with a simple graphical user interface. The operational effects of the touchscreen was compared to that of a standard pendent interface through a series of human operator performance studies. An oscillation suppression algorithm was used in conjunction with each interface. The touchscreen provides greater operator mobility while producing comparable manipulation performance.

Ahstract- Crane oscillations make it challenging to manip­ ulate payloads quickly, accurately, and safely. The problem is compounded when the payload creates a double-pendulum effect. This paper presents an input-shaping control method for reducing double-pendulum oscillations. Experiments with human operators driving a 10-ton industrial bridge crane are used to verify the effectiveness of the method. These experiments show that operators perform manipulation tasks faster and safer with the proposed control scheme. I. INTRODUCTION Heavy lifting at industrial sites such as nuclear plants, warehouses, construction sites, and shipyards is often ac­ complished with cranes, like the one shown in Figure 1. Cranes are large, complex and powerful machines whose performance is critical to the success of many industries. Furthermore, cranes routinely operate in dangerous environ­ ments that require highly-skilled human operators to move the payloads with low levels of oscillation. However, even a skilled crane operator can have difficulty maneuvering a complex payload without inducing large amounts of sway. A secondary control scheme may be added to ensure low­ sway motions. Any such controller necessarily modifies the operator's intended cOlmnands. This modification has the potential of confusing or annoying an operator. Previous work on crane control has concentrated on single­ pendulum dynamics. A computer controller can be used to generate time-optimal commands that result in zero residual vibration [1], [2]. Hoisting of the payload during transverse motion increases the difficulty of generating the optimal con­ trol because the oscillation frequency is time varying. Even when optimal commands can be generated, implementation may be impractical because the desired move distance must be known at the outset of the motion. This is a very unlikely condition for most cranes. When feedback measurements are available, adaptive controllers and combinations of open- and

The payload oscillation inherent to all cranes makes it challenging for human operators to manipulate pay-loads quickly, accurately, and safely. Under certain conditions, the problem is compounded when the payload creates a double-pendulum effect. This paper presents an input-shaping control method for suppressing double-pendulum payload oscillations. Local and teleoperation experiments performed on a portable tower crane are used to verify the effectiveness of the method. Data from these experiments show that operators performed manipulation tasks faster and safer when input shaping was utilized to reduce payload sway. Furthermore, the teleoperation delays did not degrade the input shaping effectiveness.