A method for the optimal design of complex systems is developed by effectively combining multi-objective optimization and analytical target cascading techniques. The complex systems with high dimensionality are partitioned into manageable subsystems that can be optimized using dedicated algorithms. The multiple objective functions in each subsystem are treated simultaneously, and the interactions between subsystems are managed using linking variables and shared variables. The analytical target cascading algorithm ensures the convergence of the optimal solution that meets the system level targets while complying with the subsystem level constraints. A design optimization of electric vehicles with in-wheel motors is formulated as a two-level hierarchical scheme where the top level has a model representing the electric vehicle and the bottom level contains models of battery and suspension. The vehicle model includes an electric motor model and a power electronics model. Pareto-optimal solutions are derived holistically. The effectiveness of the proposed method for optimizing the complex systems is compared against the conventional all-in-one optimization approach.

This paper presents a novel design approach to systematically synthesize available configurations for dedicated hybrid transmission (DHT) systems subject to design constraints and required operation modes by using simple planetary gear sets (PGSs). The configuration synthesis process includes two main steps. The first step is the synthesis of the PGSs by synthesizing all the components to a simple PGS subject to the design constraints. The second step is to combine the structural and shift elements into all configurations and detect those meeting the requirements with the mechanical and operation mode constraints. By applying the proposed design approach, the configurations of the Toyota’s hybrid systems (THSs) and Voltec-II prove the feasibility of the method. Furthermore, several new DHT configurations are synthesized under the new design conditions. The proposed design approach is capable of systematically synthesizing new DHT systems with multiple PGSs, variable design constraints, and expected modes.

This work presents a finite element analysis-based, topology optimization (TO) methodology for the combined magnetostatic and structural design of electrical machine cores. Our methodology uses the Bi-directional Evolutionary Structural Optimization (BESO) heuristics to remove inefficient elements from a meshed model based on elemental energies. The algorithm improves the average torque density while maintaining structural integrity. To the best of our knowledge, this work represents the first effort to address the structural-magnetostatic problem of electrical machine design using a free-form approach. Using a surface-mounted permanent magnet motor (PMM) as a case study, the methodology is first tested on linear and nonlinear two-dimensional problems whereby it is shown that the rapid convergence achieved makes the algorithm suitable for real-world applications. The proposed optimization scheme can be easily extended to three dimensions, and we propose that the resulting designs are suitable for manufacturing using selective laser melting, a 3D printing technology capable of producing fully dense high-silicon steel components with good soft magnetic properties. Three-dimensional TO results show that the weight of a PMM rotor can be slashed by 50% without affecting its rated torque profile when the actual magnetic permeability of the 3D-printed material is considered.

Commonality or the use of same components (parts, assemblies, or subsystems) among multiple products can reduce component inventory and simplify processes and logistics while accommodating variations in product demand. Excessive commonality, however, causes some products to use high-performance components and increase product cost. This paper presents an approach for evaluating profitability of component commonality by integrating commonality and supply chain decisions. The proposed approach is demonstrated using commonality of electric-bicycle motors as an illustrative example. This paper presents a sensitivity analysis of the optimum commonality with respect to motor cost, demand variability, inventory-tracking cost, and inventory-ordering cost.

An attractive but little explored field of application of the shape-memory technology is the area of rotary actuators, in particular for generating endless motion. This paper presents a miniature rotary motor based on shape-memory alloy (SMA) wires and overrunning clutches, which produces high output torque and unlimited rotation. The concept features an SMA wire tightly wound around a low-friction cylindrical drum to convert wire strains into large rotations within a compact package. The seesaw motion of the drum ensuing from repeated contraction–elongation cycles of the wire is converted into unidirectional motion of the output shaft by an overrunning clutch fitted between drum and shaft. Following a design process developed in a former paper, a six-stage prototype with size envelope of 48 × 22 × 30 mm is built and tested. Diverse supply strategies are implemented to optimize either the output torque or the speed regularity of the motor with the following results: maximum torque = 20 Nmm; specific torque = 6.31 × 10 −4 Nmm/mm 3 ; rotation per module = 15 deg/cycle; and free continuous speed = 4.4 rpm.

Servo-actuated presses may provide maximum pressing force at any ram position in the same manner that hydraulic presses do, while offering several benefits in terms of precision, energy-conversion efficiency, and simplicity, due to their lack of hydraulic circuitry and oil. Several press builders have developed servo-actuated presses; however, issues relating to overconstrained multi-axis architecture have been disregarded. This study proposes an innovative method to avoid overconstrained architectures in multi-axis presses, by implementing a family of modular parallel mechanisms that connect multiple servo-axes to the press ram. Parallel mechanisms, which can be applied in several fields of robotics and industrial automation, exhibit important benefits for the application at hand, including high-load capacity, stiffness, and compactness. A biaxial industrial servo press prototype with a nonoverconstrained and modular architecture was built and presented as a proof of concept. Each axis comprises a servomotor, a gearbox reducer, and a ball-screw transmission. It is shown that such a press may be constructed from commercially available components, achieving high energy efficiency and high press force with relatively simple construction. A direct comparison with an equivalent hydraulic-press model is carried out, thus highlighting the servo press energy efficiency.

In this paper, different measures for reducing the maximum contact force during blunt collisions between a robot and a human are evaluated using simulations. An existing collision model is adapted to include a nonlinear compliant covering, articular safety mechanisms (compliant joint and two types of torque limiters), and a collision detection system. Several scenarios are simulated in which the collision occurs at a low or high velocity, the head of the person (on which the collision occurs) is constrained by a wall or free to move and the reflected motor inertia is large or small compared to the link inertia. The results show that a torque limiter in series with each actuator has the potential to significantly improve safety without reducing the robot's performances.

In this paper, the mechanical behavior and performance of the onager, an ancient war machine, are analyzed. This study is based on torsional motors, as previously described. Because the onager has been investigated very little in modern times and the details given by ancient engineers are very scarce, this study starts from the available literature of both ancient and modern times. The mathematical models are developed through analytical mechanics along with integrations carried out numerically. Simulations performed provide interesting results which are in good agreement with the information recorded by ancient historians, and thus validating conjectures regarding the design of these machines. Finally, this investigation clarifies the role and effectiveness of these machines in ancient warfare, helping to understand many aspects of both ancient engineering design and historical events.

This paper describes the AmBot, a centipede-inspired amphibious robot for monitoring the Swan-Canning River, the most important estuary system in Western Australia. The major challenge in developing such a robot lies in that the limited physical size of the robot allows only one type of propulsion system to be used both on land and on water. This is in contrast to large amphibious robots that use wheels or track systems when on land and switch to propellers when on water. The focus of this paper is on the design of a single propulsion method suited to a small-sized amphibious robot. To achieve this, centipede-inspired tracks were engineered with each track-piece consisting of an aluminum base and a polystyrene-block float. It was hypothesized that tracks fixed with floats might be able to provide effective actuation both on land and on water for small-sized robots. When on water, the tracks provide propulsion force and buoyancy so that the waterline is well controlled. When on land, the tracks effectively spread the contact force across multiblocks, leading to effective actuation and low pressure on the sandy terrain, hence protecting the beach ecosystem. Finite element analysis (FEA) was applied to optimize the main components of the AmBot for weight reduction without sacrificing functionality and safety. The AmBot uses an Android-based remote-control system via the Internet, where the accelerometer, gyroscope, global positioning system (GPS), and camera on the Android device provide integrated navigation and monitoring sensing. A prototype was developed to validate the proposed design by conducting empirical studies.

This paper presents the mechanical design of a novel surgical robotic platform, specifically developed for single-port laparoscopy (SPL). The greatest constraint is the small size of the skin incision through which the robot must operate. Several technical and technological challenges have been tackled to meet the stringent requirements imposed by the surgical procedure at hand. In this paper, a detailed mechanical description of the system is provided, fulfilling the necessary design requirements. The main outcome of this work is a compact, light-weight (total weight approximately 6 kg) and highly dexterous bimanual robot capable of overcoming the current drawbacks experienced in SPL when using traditional medical devices. The system has been assessed in terms of tracking accuracy, resulting in satisfactory and promising performance.

The present research focuses on the development of a multifunctional wheel-embedded assembly for electrically powered vehicles. It must perform the core functions of a road-going vehicle—propulsion, braking, steering, and suspension—with all functional mechanical elements within the wheel envelope. The originality of the research lies in the integration of all aforementioned functions at once. The proposed concept exhibits two off-center electric motors, sliding pillar-type suspension with direct-drive steering at the top, and braking is achieved by means of a conventional disk and caliper assembly, but servohydraulically actuated with magnetically actuated parking brake. It makes extensive use of geometric nesting and function sharing—the large transmission gear doubles as hub and wheel carrier, the suspension pillar is also used for steering torque transmission. Finally, the advantages and disadvantages of the proposed concept are addressed, as well as practical applications.

This study investigated why the design of ancient throwing machines evolved from eutitonon (arms outside the mainframe) to palintonon (arms inside the mainframe) from the end of the first century B.C. to the first century A.D. and evaluated the mechanical advantages of the new design. Palintonon was first used for big machines; in the following centuries, it was also used for much smaller machines. Essentially, the palintonon design has several advantages: more elastic energy can be stored in the hair bundles representing the motors of these machines, heavier projectiles can be thrown with the same charging effort, projectiles are stressed by lower acceleration in the machine with the same muzzle velocity, and the throwing machines have higher efficiency. Results are also presented regarding the “internal ballistics” of these ancient throwing machines by using simulation software.

The process of designing integrated biological systems across scales is difficult, with challenges arising from the modeling, understanding, and search of complex system design spaces. This paper explores these challenges through consideration of how stochastic nanoscale phenomenon relate to higher level systems functioning across many scales. A domain-independent methodology is introduced which uses multi-agent simulations to predict emergent system behavior and structure–behavior–function (SBF) representations to facilitate design space navigation. The methodology is validated through a nanoscale design application of synthetic myosin motor systems. In the multi-agent simulation, myosins are independent computational agents with varied structural inputs that enable differently tuned mechanochemical behaviors. Four synthetic myosins were designed and replicated as agent populations, and their simulated behavior was consistent with empirical studies of individual myosins and the macroscopic performance of myosin-powered muscle contractions. However, in order to configure high performance technologies, designers must effectively reason about simulation inputs and outputs; we find that counter-intuitive relations arise when linking system performance to individual myosin structures. For instance, one myosin population had a lower system force even though more myosins contributed to system-level force. This relationship is elucidated with SBF by considering the distribution of structural states and behaviors in agent populations. For the lower system force population, it is found that although more myosins are producing force, a greater percentage of the population produces negative force. The success of employing SBF for understanding system interactions demonstrates how the methodology may aid designers in complex systems embodiment. The methodology's domain-independence promotes its extendibility to similar complex systems, and in the myosin test case the approach enabled the reduction of a complex physical phenomenon to a design space consisting of only a few critical parameters. The methodology is particularly suited for complex systems with many parts operating stochastically across scales, and should prove invaluable for engineers facing the challenges of biological nanoscale design, where designs with unique properties require novel approaches or useful configurations in nature await discovery.

This article discusses the design and testing of a powered ankle prosthesis. This new prosthesis mimics nonamputee (normal) ankle moments during the stance phase of gait through the use of an optimized spring loaded four-bar mechanism. A prototype prosthesis based on the optimization was designed, fabricated, and tested. The experimental results achieved 93.3% of the simulated theoretical ankle moment giving substantial evidence that this approach is a viable in designing powered ankle prostheses.

This paper presents the analysis and design of a novel air vane motor. Air motors have a very high specific power. They require compressed air rather than electricity to produce motion; thus, they avoid sparks and can be used in demanding environments. Similar to other types of rotary machines, air vane motors exhibit torque fluctuations. The varying torque curve is a result of unmatched torques generated by the vanes in one revolution. Accompanying the torque fluctuations are dynamic speed ripples that produce undesirable vibration on the load side. Rather than using auxiliary flywheels or dampers to smoothen the fluctuation, we propose a new motor with noncircular stator profile so as to increase the flexibility of balancing vane torques. Through numerical optimization of the parametric noncircular profile, a nearly constant torque curve can be achieved. Experiments validate that the speed ripples are greatly suppressed without compromising performance, when compared with traditional air vane motors that employ circular stator profiles. We expect that the noncircular stator profile design can be applied to air vane motors of various sizes to minimize torque and speed ripples.

In this study, the mechanical design of a fully flexible valve actuation system (FFVA) for intake valves of naturally aspirated internal combustion engines is optimized. The original FFVA design used a connecting rod in order to transform the rotating motion of the actuator to translating motion of the valve. In the improved design introduced here, the connecting rod is replaced by a flexible linkage. This step is taken in order to eliminate wear and play in the mechanical connections. A detailed design procedure is presented to optimize the heavy fatigue load on this element. Simulations and experimental tests are carried out in order to validate the system performance. It is shown that valve trajectory and energy consumption of the actuation system obtained by simulations are consistent with those observed experimentally. The present redesigned FFVA system then provides more reliable valve motion than previously shown designs.

In decomposition-based design optimization strategies such as analytical target cascading (ATC), it is sometimes necessary to use reduced representations of highly discretized functional data exchanged among subproblems to enable efficient design optimization. However, the variables used by such reduced representation methods are often abstract, making it difficult to constrain them directly beyond simple bounds. This problem is usually addressed by implementing a penalty value-based heuristic that indirectly constrains the reduced representation variables. Although this approach is effective, it leads to many ATC iterations, which in turn yields an ill-conditioned optimization problem and an extensive runtime. To address these issues, this paper introduces a direct constraint management technique that augments the penalty value-based heuristic with constraints generated by support vector domain description (SVDD). A comparative ATC study between the existing and proposed constraint management methods involving electric vehicle design indicates that the SVDD augmentation is the most appropriate within decomposition-based design optimization.

Development of a family of products that satisfies different market niches introduces significant challenges to today’s manufacturing industries—from development time to aftermarket services. A product family with a common platform paradigm offers a powerful solution to these daunting challenges. This paper presents a new approach, the Comprehensive Product Platform Planning ( CP 3 ) framework, to design optimal product platforms. The CP 3 framework formulates a generalized mathematical model for the complex platform planning process. This model (i) is independent of the solution strategy, (ii) allows the formation of sub-families of products, (iii) allows the simultaneous identification of platform design variables and the determination of the corresponding variable values, and (iv) seeks to avoid traditional distinctions between modular and scalable product families from the optimization standpoint. The CP 3 model yields a mixed integer nonlinear programming problem, which is carefully reformulated to allow for the application of continuous optimization using a novel Platform Segregating Mapping Function (PSMF). The PSMF can be employed using any standard global optimization methodology (hence not restrictive); particle swarm optimization has been used in this paper. A preliminary cost function is developed to represent the cost of a product family as a function of the number of products manufactured and the commonality among these products. The proposed CP 3 framework is successfully implemented on a family of universal electric motors. Key observations are made regarding the sensitivity of the optimized product platform to the intended production volume.

This paper studies the motion of the ancient siege tower. Many considerations and different pieces from the classics strongly suggest that those war machines were powered by internal motors; for this reason, the authors examine some mechanical systems, all certainly used in the Classic Age, that could be easily adopted to power the siege towers. This war machine was first used in Europe by Greek engineers and called Helepolis ( ε ` λ ε ´ πoλις, “taker of cities”); however, there are earlier examples of siege towers built in Mesopotamia. First of all, some pieces from Classic authors have been reported in which it is possible to find several traces on what we propose. Then some possible ancient motors suitable to be installed into the helepolis are proposed: capstans, tread wheel motors like the ones used by the Greek-Roman cranes, and counterweight motors. The proposed motors are also analyzed from a mechanical point of view in order to examine, at least theoretically, their effectiveness in such applications. Results obtained by a simulation with a Working Model 2D™ model showed that the proposed device is certainly possible and also suitable and effective.

This technical brief presents a dynamic model based on the traditional transfer matrix method (TMM) and Jones–Harris nonlinear rolling bearing model to study the effects of the extended structure parameters on the vibration behavior of a high-speed motorized spindle-bearing system. The first critical speed and the dynamic stiffness of the high-speed motorized spindle-bearing system are systematically studied. A design sensitivity analysis of the structure parameters is then conducted to identify the main factor to affect the first critical speed of the spindle-bearing system. The results show that the processing condition, the shaft shoulder, the dimension of motor, and the bearing arrangement are sensitive to the spindle dynamic behavior. The TMM model of the spindle-bearing system is verified by measuring the high-speed motorized spindle overall dynamic stiffness.