A small collection of mechanisms I’ve animated using Rhino 8 with Bongo 3
Main portfolio site: Josephbilski.github.io
A roller clutch is a component that connects two shafts, while only allowing relative motion in one direction. Commonly used in applications such as bicycles and pottery wheels, where power needs to be transferred in only one direction.
It accomplishes this through the use of ‘rollers’, that when driven in the free spinning direction, simply spin. When backdriven, however, they interfere with the wedge shaped profile from the outer race wall.
Note that the springs in some designs allow for pretension of the rollers against the wedge, helping to minimize backlash.
A 6-DOF platform that manipulates position and rotation, typically through 6 prismatic actuators connected by universal joints(though other configurations exist).
Applications include flight simulators, NASA’s Low Impact Docking System (LIDS), and motion compensation(such as for crew transfer during off-shore operations)
Link to a kinematics breakdown
Models for linear actuators and universal joints taken from McMaster-Carr #6530K938 and #6452K1
A simple bistable mechanism concept comprised of three links, where one link is flexible in length — often acting as a spring and pulling(or pushing) the rotating link into one of two states.
Two examples of mechanisms that use this concept are given below — a jar clasp and a simplified version of a gas-spring assisted trunk hatch.
The jar clasp is an example of a compliant bistable linkage. The green connection acts as a lever that pulls the blue connection into one of two states, either tightening it around the top link, or releasing it.
This simplified model of a trunk opening mechanism demonstrates the same principle as the other bistable over center mechanisms, with the gas-spring acting as the length changing link and changing behaviors based on the current state — initially resisting the opening motion and keeping the trunk shut, and then helping to hold the trunk open.
The differential drive allows for power to be transmitted to two axles, while allowing them to also rotate at different speeds. This is commonly used in vehicles to allow them to smoothly turn without slipping (as the inside wheel rotates at a lower speed than the outer wheel during a turn).
Note that power is being transmitted to the wheels through the yellow connection and green gears.
In order for a vehicle to turn without its tires slipping, the axes on which they rotate must intersect around a common center of rotation (see the rightmost image).
In order for this to happen, the front inner and outer tires must be at different angles during a turn. A common way to achieve this is the Ackermann steering geometry, which utilizes a four bar linkage that turns the wheels at different rates and in a “pro-Ackermann” configuration turns the outer wheel more than the inner wheel, leading to the tires bowing outward.
Note that while a simple geometrical model may suggest that vehicles should have 100% pro-Ackermann steering configurations, more complex models that take into account factors such as tire slip angle give rise to “anti-Ackermann” configurations (where the tires bow inward) as well as varying degrees of bowing.
Additional reading: https://en.wikipedia.org/wiki/Ackermann_steering_geometry#External_links