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Cams and Followers
Published in Eric Constans, Karl B. Dyer, Introduction to Mechanism Design, 2018
The jerk is the time derivative of acceleration. Since acceleration is proportional to force, the jerk gives a measure of how quickly the force on the follower changes. If the acceleration is a continuous function, then the jerk will necessarily be finite – spikes to infinity occur when we take the derivative of a discontinuous function. The problem is now to find a displacement function that is continuous through its first and second derivatives. As we will see, there are several functions that meet this criterion, and we will examine a few of the more common ones.
Hearing, Sound, Noise, and Vibration
Published in R. S. Bridger, Introduction to Human Factors and Ergonomics, 2017
“Shock” is the term used in some quarters when referring to “jerk,” which is the third derivative of position (ms−3) or the rate of change of acceleration. Jerk is dangerous for humans because the normal adaptive and balance responses do not react quickly enough to it, unless it is expected. Jerk can be experienced when a car gradually brakes under steady resistance and finally stops with the brake still applied. At that point, the driver may experience a slight jerk as the deceleration suddenly ceases. Compare this to a gradually reducing the breaking just before the car comes to a stop. In some situations, people are exposed to high levels of potentially injurious vibration and shock. High-speed craft (Figure 11.12) are an example of this. Shock mitigation is normally achieved through the installation of better seats, such as the suspension seat shown in Figure 11.12, to protect the occupants from injury such as the vertebral wedge fracture described in Chapter 2.
Linear Filter Applications
Published in David C. Swanson, ®, 2011
Perhaps the most important and popular use of digital state variable systems is in tracking systems. Common examples of tracking filter use include air-traffic control systems, stock and futures market-programmed trading, autopilot controllers, and even some sophisticated heating, ventilation, and air conditioning (HVAC) temperature and humidity controllers. What makes a tracking filter unique from other digital filters is the underlying kinematic model [3]. Rather than a state transition matrix based on the specific parameters of the physical system, such as the mass, stiffness, and damping in Equation 5.16, a tracking filter’s state transition matrix is based on the Newtonian relationship between position, velocity, acceleration, jerk, and so on. “Jerk” is the term used for the rate of change of acceleration with time. However, our discussion here will be mainly limited to “position-velocity” states with no input signal uk to simplify presentation of the tracking filter concept.
Mode switching analysis and control for a parallel hydraulic hybrid vehicle
Published in Vehicle System Dynamics, 2021
Shilei Zhou, Paul Walker, Yang Tian, Nong Zhang
During the engine start process, the clutch slip introduces jerk and frictional work [31]. Jerk is the derivative of vehicle acceleration. For the convenience of control strategy design, the driveshaft can be treated as a rigid body [1,20]. So, the jerk is further determined by the clutch torque and the HPM output torque changing rate. Jerk and frictional work are indicated as follows: where is the vehicle jerk, the vehicle acceleration, the driveline mechanical efficiency, the vehicle gyrating mass conversion coefficient, clutch frictional work. and are the start time and end time of the engine clutch slipping process.
Novel dynamic modeling of feed drive system using subspace method
Published in Journal of the Chinese Institute of Engineers, 2019
Teng-Yi Huang, Meng-Shiun Tsai, Ming-Tzong Lin, Chih-Chun Cheng
In estimating the tracking and contour accuracies of CNC machine tools, the interpolator and servo drive should be considered simultaneously. The interpolator generally plans the trajectory based on the given interpolation parameters such as acceleration, jerk, corner velocity, etc. (Wan et al. 2009; Chen and Lee, 1998). It is well known that setting higher acceleration and jerk may result in vibration during motion. However, it is difficult to evaluate the vibration characteristics under different interpolation parameters without an accurate dynamic model of the feed drive system. Another important factor to affect the contour accuracies is the servo control system, which includes the current, velocity, and position loops. Furthermore, friction behaviors such as stick-slip, static friction, and Stribeck effects (Armstrong-Hélouvry, Dupont, and De Wit 1994; Johanastrom and De Wit 2008) were investigated in the past. The integration of servo control with feed drive system was studied in Lee et al. (2003) where the machine-to-ground dynamics and servo control were included. Ebrahimi and Whalley (2000) and Younkin (1991) simulated a single-axis servo feed system which included the motor, viscous frictions, and backlash. But how to obtain an accurate structural subsystem was a challenging problem.
Inferring safety critical events from vehicle kinematics in naturalistic driving environment: Application of deep learning Algorithms
Published in Journal of Intelligent Transportation Systems, 2023
Zulqarnain H. Khattak, Jackeline Rios-Torres, Michael D. Fontaine, Asad J. Khattak
Snap quantifies the rate of change of jerk with respect to time or indicates the fourth derivative of displacement with respect to time.Where is snap, indicates jerk and indicates incremental time change.