Assumption Of Point Contact Research Articles

Investigation of Power Consumption in Face Milling Operations

In oblique cutting, the assumption of point contact between the tool and theworkpiece often results in the consideration of only the forces in the three principaldirections. This paper disregards these assumptions and confirms the existence ofmoments around the three principal directions through measurements of themechanical factors during a face milling operation. The cutting forces and moments atthe three directions achieved by using Kistler 9275B dynamometer in this paper, andthe development of a calculation algorithm that allows the transport of the cuttingmoments from the center of the dynamometer at the tip of the tooth is developed.Based on the mechanical actions’ theory, the power consumed during the cuttingprocess is determined. A comparative study on the power consumed during thecutting process is undertaken.

3-D Biped Walking Using Double Support Phase and Swing Leg Retraction Based on the Assumption of Point-Contact

This paper describes 3-D biped walking control based on the assumption of point-contact. We previously realized 3-D biped walking on unknown terrain using the Passive Dynamic Autonomous Control (PDAC) approach, which is based on the assumption of pointcontact of a robot foot and virtual holonomic constraint as to robot joints. However, the stable range of walking is narrow and the robustness of walking is not enough for practical use. In order to increase the robustness of walking, we propose swing leg retraction and double support phase in this paper. Swing leg retraction facilitates the stabilization ability of PDACbased walking; also, by use of the double support phase, robot dynamics converges to stable orbit even if disturbance happens at foot-contact. Finally, the proposed biped walking algorithm is verified by numerical simulation and experiments.

Quadruped Walking by Joint-interlocking Control Based on the Assumption of Point-contact (Comparison between Pace Gait and Crawl Gait Based on the Energy Consumption)

This paper proposes a control algorithm for pace gait of a quadruped walking robot, using a passive dynamics autonomous control algorithm (PDAC). The PDAC realizes an efficient motion based on the intrinsic dynamics of a robot. This paper first calculates an energy consumption of the pace and a crawl gait at various walking parameters such as a stride length and a walking period. The optimal walking parameters are obtained for each gait at various walking speed in the simulation and their parameters are confirmed by applied to an experimental walking robot. The trend of the energy consumption transition measured in the experiments are similar to those in the simulation. For example the consumption energy of the pace gait becomes less than that of crawl gait when a walking speed becomes relatively high. As a result, quadruped walking parameters corresponding to the desired walking speed such as the type of gait, the stride length and the walking period are designed on the energy-consumption-basis.

点接触仮定に基づく2足動歩行制御

点接触仮定に基づく2足動歩行制御

Control of the Lateral Motion in Biped Walking Based on the Assumption of Point-contact

This paper proposes the novel control method named Passive Dynamic Autonomous Control (PDAC) PDAC is based on the following concept which Grizzle et al. employed previously : 1) point-contact 2) Virtual constraint. Point-contact means that the contact state between a robot and the ground is point. This makes it possible to generate the robot motion based on the robot inherent dynamics although it becomes difficult to control. Virtual constraint means that all robot joints are connected and interlocked. We present the new approach by means of these concepts to express the whole robot dynamics an an 1-dimensional autonomous system. Due to autonomy, this approach has two following notable points : 1) period from foot-contact to next foot-contact can be obtained 2) there is a conservative quantity to make it possible to stabilize the motion. As the first step of realization of 3 D dynamic walking, this paper applies PDAC to the lateral motion and builds the controller. In addition, the stabilization and motion period control are reported. The validity of these control is confirmed by experiment and desired lateral motion is realized.

1P1-S-043 点接触の仮定に基づく3次元動歩行制御(2足歩行ロボット2,生活を支援するロボメカ技術のメガインテグレーション)

1P1-S-043 点接触の仮定に基づく3次元動歩行制御(2足歩行ロボット2,生活を支援するロボメカ技術のメガインテグレーション)

Modelling nondestructive impacts macroscopically

Rigid body motion resulting in impact can be modelled on either a microscopic or a macroscopic level. Three methods of modelling impact macroscopically, where the post-impact motion of the impacting bodies is of primary concern, are discussed: the rigid body impulse-momentum model, the spring-damper model, and the elastic model. The impulse-momentum model is limited by an assumption of point contact and by the difficulty of accurately predicting the coefficient of restitution. Since it stems from rigid body dynamics, the model does not consider elastic deformation and is unable to predict tangential rebound during a collision. The spring-damper model is a conceptual model rather than a physical model and does not provide for an accurate method of determining its parameters. The elastic model is based on a finite area of contact and allows simultaneously some slipping areas and some sticking areas. It is limited to treating only spherical-like objects in fully elastic impacts. When compared with two-dimensional experimental impact data, the three models were shown to be unable to predict accurately the motion of bodies after impact. A modified elastic impact model, with the coefficient of friction varying with tangential velocity and normal force, was shown to match the experimental data more closely.

Kinematic design optimization of the variable lead screw mechanism with cone meshing element

The variable lead screw mechanism is proven to be an overconstrained mechanism. Transmission quality of the mechanism is evaluated by two methods. One is based on the pressure angle under the assumption of point contact. The other is measured by the virtual coefficient of screw theory. Comparisons of the two results are studied. An optimization is conducted to minimize sliding velocity and maximize the transmission performance simultaneously. Results show that the kinematic characteristic of the mechanism has been improved.