22 research outputs found
Vehicle Suspension Design Based on a Six-Bar Linkage
A synthesis technique for designing novel vehicle suspension linkages based on the Watt I six-bar is presented. The goal is to maintain near vertical alignment of the wheels to the road during cornering. The complete suspension is analyzed as a symmetric planar 12-bar linkage with ground pivots located at the contact patches. The design procedure specifies the vehicle chassis orientation and the tire camber angles of the vehicle when cornering. As well, two task positions of the wheels with respect to the chassis are specified for suspension movement in straightaways. The result is 18 design equations with 18 unknowns that have a total degree of 2,097,152, though only 336 roots. An example design is presented
Controlling the Movement of a TRR Spatial Chain With Coupled Six-Bar Function Generators for Biomimetic Motion
This paper describes a synthesis technique that constrains a spatial serial chain into a single degree-of-freedom mechanism using planar six-bar function generators. The synthesis process begins by specifying the target motion of a serial chain that is parameterized by time. The goal is to create a mechanism with a constant velocity rotary input that will achieve that motion. To do this we solve the inverse kinematics equations to find functions of each serial joint angle with respect to time. Since a constant velocity input is desired, time is proportional to the angle of the input link, and each serial joint angle can be expressed as functions of the input angle. This poses a separate function generator problem to control each joint of the serial chain. Function generators are linkages that coordinate their input and output angles. Each function is synthesized using a technique that finds 11 position Stephenson II linkages, which are then packaged onto the serial chain. Using pulleys and the scaling capabilities of function generating linkages, the final device can be packaged compactly. We describe this synthesis procedure through the design of a biomimetic device for reproducing a flapping wing motion
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Controlling the Movement of a TRR Spatial Chain with Coupled Six-bar Function Generators for Biomimetic Motion
This paper describes a synthesis technique that constrains
a spatial serial chain into a single degree-of-freedom mechanism
using planar six-bar function generators. The synthesis
process begins by specifying the target motion of a serial
chain that is parameterized by time. The goal is to create
a mechanism with a constant velocity rotary input that will
achieve that motion. To do this we solve the inverse kinematics
equations to find functions of each serial joint angle with
respect to time. Since a constant velocity input is desired,
time is proportional to the angle of the input link, and each
serial joint angle can be expressed as functions of the input
angle. This poses a separate function generator problem to
control each joint of the serial chain. Function generators
are linkages that coordinate their input and output angles.
Each function is synthesized using a technique that finds 11
position Stephenson II linkages, which are then packaged
onto the serial chain. Using pulleys and the scaling capabilities
of function generating linkages, the final device can
be packaged compactly. We describe this synthesis procedure
through the design of a biomimetic device for reproducing a
flapping wing motion
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Kinematic synthesis of Stephenson III six-bar function generators
This paper presents a direct solution of the kinematic synthesis equations for Stephenson III six-bar function generators to achieve as many as 11 accuracy points. The approach is similar to that used to design Stephenson II function generators, except additional algebraic manipulations reduce the system to a multihomogeneous degree of 55,050,240. A numerically general multihomogeneous homotopy was used to obtain 834,441 nonsingular solutions, which were then used to construct an efficient parameter homotopy for specific tasks consisting of 11 accuracy points. The thousands of linkage solutions found by this parameter homotopy are sorted and analyzed to verify nonbranching movement through the specified task positions. An example is presented of a function generator that creates a specified torque-angle profile for a dynamic wrist splint that cancels the effects of spasticity in the wrists of stroke survivors