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Provide stabilization
Published in Michael Wiklund, Kimmy Ansems, Rachel Aronchick, Cory Costantino, Alix Dorfman, Brenda van Geel, Jonathan Kendler, Valerie Ng, Ruben Post, Jon Tilliss, Designing for Safe Use, 2019
Michael Wiklund, Kimmy Ansems, Rachel Aronchick, Cory Costantino, Alix Dorfman, Brenda van Geel, Jonathan Kendler, Valerie Ng, Ruben Post, Jon Tilliss
Toppling objects can cause injury as well as property damage. Consider the consequences of a parked motorcycle falling onto a bystander, a ladder falling sideways with a house painter aboard, and a chest of drawers pitching forward onto a toddler who is climbing it to fetch a toy (see Principle 63 - Childproof hazardous items). An object is naturally stable when its center of gravity is within its footprint rather than outside of it. Move the center of gravity beyond the footprint (i.e., beyond the area of support) and the result is instability plus the potential to tip over. It also helps to keep the center of gravity low so that applied forces, such as the centrifugal force acting on a riding lawnmower turning sharply, do not overcome the stabilizing forces.
Centre of gravity and centre of mass
Published in Paul Grimshaw, Michael Cole, Adrian Burden, Neil Fowler, Instant Notes in Sport and Exercise Biomechanics, 2019
The centre of gravity (COG) of an object is defined as the point at which the entire weight of an object is assumed to be concentrated. This can be further clarified to mean that the centre of gravity of an object is the point at which the force of gravity for the entire object can be placed so that the object will behave the same as when the force of gravity is distributed across the entire object. The term centre of mass (COM) is defined as the point that corresponds to the mean (average) position for the concentration of the entire matter in the body. Within biomechanics the two terms are often used synonymously (i.e. having the same meaning). The terms centre of gravity and centre of mass are used for imaginary points (i.e. they do not physically exist as a point that can be seen) that describe concentrations of weight or matter.
The Free-Body Diagram
Published in G. Boothroyd, C. Poli, Applied Engineering Mechanics, 2018
In all the preceding examples we have neglected the weight of the body under consideration. In many situations this is acceptable because the external forces acting on a body are much larger than its weight. In all other cases the weight of a body must be shown on the free-body diagram and included in the analysis. For this purpose it is necessary to know the position of the center of gravity of the body. The center of gravity is defined as the point through which the line of action of the weight of the body may be assumed to act. For bodies of uniform density the center of gravity is at the geometric center (centroid) of the body. Determination of the position of the center of gravity for other than simple shapes requires special techniques and will be dealt with in Chapter 5.
Design and analysis of smart assistive humanoid robot for isolated patients
Published in Australian Journal of Mechanical Engineering, 2023
Dhruba Jyoti Sut, Prabhu Sethuramalingam
The stability of a robot or any object is significantly impacted by the placement of its centre of gravity (CG). For a more reliable system, the CG should be placed as low as possible. When a robot is pushed, the further its CG is from the touch surface, the more likely it is to topple over. The robot’s stability is improved when the contact surface of the wheels is more extensive, and when the base is larger, the object’s stability is also enhanced. The assistance robot’s wheel formula is 64 (Number of Actuated Wheels (4) × Total Number of Wheels (4) × Number of Steerable Wheels (4)). The wheel formula is used to determine the robot’s mobility arrangement. The CG of the entire body is located around the second sacral vertebra in the case of a human being. In a mobile robot, it is usually located directly ahead of the robot’s centre point for performing applied forces analysis. Consider a 3D frame for the calculation (x, y, and z axes). Divide the entire robot structure into many pieces to calculate the mass centres quickly. The following formulas (1) are used to calculate the coordinate point of the centre of gravity.
Impact of biometric and anthropometric characteristics of passengers on aircraft safety and performance
Published in Transport Reviews, 2018
Damien J. Melis, Jose M. Silva, Richard C.K. Yeun
The payload location relative to the aircraft’s centre of gravity is a crucial factor in determining its stability characteristics and other flight parameters. General aviation aircraft pilots usually use the true weights of their passengers for weight and balance purposes. For large transport category aircraft though, weighing individual passengers is considered impractical. As of 2009, the International Civil Aviation Organisation (ICAO) standard for calculating the average weight for passengers is 100 kg per passenger, including 20 kg for baggage (2009). This standard was derived from 28 global airlines responding to a brief survey conducted by the International Air Transport Association at the request of ICAO.