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This paper proposes an efficient direct yaw moment control (DYC) capable of minimising tyre slip power loss on contact patches for a four-independent wheel drive vehicle. Simulations identified a s...

Driving force distribution control is one of the characteristic performance aspects of in-wheel motor vehicles and various methods have been developed to control direct yaw moment while turning. However, while these controls significantly enhance vehicle dynamic performance, the additional power required to control vehicle motion still remains to be clarified. This paper constructed new formulae of the mechanism by which direct yaw moment alters the cornering resistance and mechanical power of all wheels based on a simple bicycle model, including the electric loss of the motors and the inverters. These formulation results were validated by an actual test vehicle equipped with in-wheel motors in steady-state turning. The validated theory was also applied to a comparison of several different driving force distribution mechanisms from the standpoint of innate mechanical power.

In the structural design of mechanical products, natural frequencies must be controlled to reduce noise and vibration. In particular, the stiffness of the joints which assemble the structural components affects the natural frequencies. Therefore, it is important to predict the influence of joint stiffness on natural frequencies. Generally, these effects are determined by iterative finite element analyses of assembled structural models. Because this results in high computational costs, the sensitivity of natural frequencies to joint stiffness should be determined by a different approach to make the structural design process more efficient. Therefore, this paper proposes the use of reflection and transmission coefficients of elastic joints to predict the dependency of natural frequencies on joint stiffness. First, we formulate the reflection and transmission coefficients of joint stiffness, and then organize the coefficients using a ray tracing method. These formulations enable us to discuss the mechanisms which determine the natural frequency of a structure based on a wave approach using the phase-closure principle. Therefore, by applying the phase-closure principle to the frame structure, we investigate the formation of bending modes, which suggests that the effects of joint stiffness on natural frequencies correspond to the dependence of the reflection and transmission coefficients on joint stiffness. Therefore, these coefficients are useful indicators for estimating the influence of joint stiffness.

Tripod constant velocity joints are used in the driveshafts of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. This paper surveys some methods for reducing the thrust force based on the mechanisms inducing the thrust force, focusing on a method that creates dual contact between a roller and groove. This method has the advantage of requiring only a few design modifications, but its thrust force reduction mechanism has yet to be clarified. Therefore, a theory was constructed to describe the induction of thrust force by this method through the application of sliding velocities generated between the roller and dual contact groove. Subsequently, the effect of the thrust force reduction was investigated. This paper also describes the appropriateness of this theory. It was validated by comparing theoretical results with computational results based on a multibody dynamics approach and with experimental results of a prototype joint equipped with the dual contact grooves.

Tripod constant velocity joints are used in the driveshaft of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. To determine the mechanisms inducing the thrust force, a detailed model is constructed based on a multibody dynamics approach. Although the joint is equipped with three rollers and grooves, this model consists of the principal parts for one roller and groove in order to precisely analyze frictional phenomena occurring between the roller and the groove. These principal parts are defined as rigid bodies and are connected by force elements of contact and friction. The appropriateness of this model is verified by comparing computational and experimental results and it is clarified that the principal factors inducing the thrust force are three kinds of sliding friction force at the point of contact between the roller and the groove. This paper also describes the reason why the third rotating order component of the thrust force is induced by one roller and groove.

A tripod constant velocity joint is used in the driveshaft of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. To analyze the thrust force, a detailed model is constructed based on a multibody dynamics approach. This model includes all principal parts of the joint defined as rigid bodies and all force elements of contact and friction acting among these parts. This model utilizes a new contact modeling method of needle roller bearings for more precise and faster computation. By comparing computational and experimental results, the appropriateness of this model is verified and the principal factors inducing the second and third rotating order components of the thrust force are clarified. This paper also describes the influence of skewed needle rollers on the thrust force and evaluates the contribution of friction forces at each contact region to the thrust force.

Japanese macaques (Macaca fuscata) exchange coo calls with group members to maintain contact. I examined the relationship between the distance between group members and (1) the latency of vocal responses to spontaneous calls, and (2) the latency of spontaneous call repetition in the absence of vocal responses. After a subject monkey's spontaneous call, the latency of vocal response by another group member was longer when the subject was farther from the group members than when the subject was near the group members. Furthermore, subject repeated calls with longer intervals in the absence of vocal response, which suggests that they wait longer for the vocal responses of other group members when the expected response latency is longer. These results reveal that Japanese macaques flexibly alter the timing of their calls based on others' vocal responses.

A central issue in studies of vocalizations of non-human primates is the extent of their plasticity. Japanese macaques, Macaca fuscata, frequently utter coo calls and exchange these calls with other group members to maintain contact vocally. I conducted a playback experiment to examine whether monkeys that respond vocally match the acoustic features of their reply to those of the calls they have heard. Six to eight stimulus calls with different acoustic properties in terms of fundamental frequency components were played back to each of seven females, in an attempt to elicit replies from the subjects. There were significant positive regressions of the frequency range of stimuli with that of the replies. Japanese macaques thus matched some of the acoustic features of their replies to those of the preceding calls, suggesting that they might be able to modify the acoustic features of their calls according to the features of the prior calls of another group member.Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.

A series of censuses of wild Yakushima macaques (Macaca fuscata yakui) was carried out in a 127.26km2 area around the coast of Yakushima Island, Japan. The census area was estimated to have 131 troops in total. Monkeys seem to depend on natural broad-leaf forests. Troop density was highest in the western coastal area, where the greatest population of natural vegetation remained undisturbed. In total, 1, 852 monkeys were counted, giving an estimate of 2, 000-3, 850 monkeys inhabiting the census area.

The First Order Analysis for Torsion Beam Suspension (FOA/TB)/design tool has been developed as a CAE tool for suspension designers. Reflecting the needs of suspension designers, this tool tends to become more detailed and complex. In addition, FOA/TB is also used by torsion beam component designers since it is capable of creating detailed models of the torsion beam itself. However, in the design phase, torsion beam designers cannot obtain all the parameters included in the current FOA/TB model and have to provisionally set unknown parameters. To overcome this problem, this paper introduces a method for abstraction and masking of design parameters based on the concept of modular designing. It also shows how usability was improved using the new concept FOA/TB.

Vocal exchanges of coo calls in female Japanese macaques were observed in two populations. Temporal patterns of occurrence of these vocalizations during vocal interaction were studied by analyzing inter-call intervals between two consecutive coos. When the second call was uttered by a different caller from the first (DC sequence), most of the second calls occurred at intervals shorter than approximately 0.8 sec, and the remaining ones at intervals longer than approximately 0.8 sec. These results indicate that the second coos of DC sequence are of two different types, and that second calls separated by short intervals may occur in response to the first call, whereas second calls separated by a relatively longer interval may occur independently of the preceding call. When an animal responds to a coo given by another, she appears to do so within a certain period of time. When two consecutiove calls were uttered by the same caller (SC sequence), the second coos rarely occurred within 0.8 sec, but mostly at longer intervals. These results suggest that when an animal utters a coo spontaneously, it remains silent for a short interval and when no response occurs, she is likely to give further coos addressing groups members. Acoustic analysis of two consecutive coos in DC sequence showed that the second coos given by a different caller and occurring within 0.8 sec significantly correlated with those of first coos with respect to several acoustic parameters. This correlation was not observed when coos occurred at intervals of more than 0.8 sec. This phenomenon was confirmed by a playback experiment. The results suggest the possibility that an animal is able to alter acoustic features of responding coos and matches those of preceding coos.

Computer Aided Engineering (CAE) has been successfully utilized in automotive industries. CAE numerically estimates the performance of automobiles and proposes alternative ideas that lead to the higher performance without building prototypes. Most automotive designers, however, cannot directly use CAE due to the sophisticated operations. In order to overcome this problem, we proposed a new concept of CAE, First Order Analysis (FOA). The basic ideas include (1) graphic interfaces using Microsoft/Excel to achieve a product oriented analysis (2) use the knowledge of the mechanics of materials to provide the useful information for designers, and (3) the topology optimization method using beam and panel elements. In this paper, outline of FOA and application are introduced.

In current automotive development, innovations to reduce development time and to use a virtual prototype have been numerous and progressive. Computer Aided Engineering (CAE) has played an important role in these innovations. CAE numerically estimates the performance of automobiles and proposes alternative ideas that lead to higher performance without building physical prototypes. However, current CAE can not usually be used at the initial design phase due to their difficult, and complex functions and characteristics. In this paper, we propose a new type of CAE, First Order Analysis (FOA). The basic ideas include: (1) graphic interfaces using Microsoft /Excel to achieve a product-oriented analysis, (2) use of mechanics of materials to provide useful information regarding structural mechanisms, and (3) a topology optimization method using function oriented elements. Also, some prototype software is presented to confirm the applicability of method presented here to the automotive designs.

A central issue in the study of primate vocalizations concerns the extent of control over vocal production. Information on the ontogeny of vocal communication of non-human primates is limited and conflicting. Until recently, our primary data were from squirrel monkeys (Saimiri sciureus), focusing on infant isolation peeps. The major finding was that call structures were inherited, not learned (Newman and Symmes, 1982). Failure to find evidence of learning is somewhat surprising, given the influence of learning on other behaviors, and the fact that there are some clear parallels in the development of bird song and the development of human speech (Marler, 1970).