1.2 - Kinematic Analysis

1.2 - Kinematic Analysis

Kinematic Analysis

Plots/description of ideal motion/force profiles for the problem statement

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The desired position profile is a relatively flat one parallel to the ‘wall’ in which the robot will be climbing. Our chosen linkage has the position profile as depicted above.

Mobility calculation for all systems/subsystems

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Gruebler’s equation can be used to find the degrees of freedom of our mechanism. Despite having 3 mechanisms, they are all identical and actuated by the same shaft, so the DOF of the entire system is 1.
We can verity that our proposed linkage allows for at least one link to make a full rotation by ensuring that it complies with the Grashof condition which states that the following condition must be met:
Grashof condition is satisfied

Kinematic analysis resulting in determination of positions, velocities, and accelerations of all the points and links of interests in full range of operation of the mechanism

Velocity Analysis

The above plot shows the velocity profile of the end effector joint of our chosen linkage both with x and y components as well as the magnitude of the velocity vector. There are two noticeable points at which the velocity is equal to zero, which occurs when the linkage switches directions.

Acceleration Analysis

The above plot depicts the acceleration profile of the end effector joint of our chosen linkage with x and y components as well as the magnitude of the acceleration vector.

 

Force analysis resulting in determination of forces/torques/mechanical advantage of all points and links of interest in full range of operation of the mechanism

Transmission Ratio Analysis

The above plot depicts the transmission ratio between the input linkage and output (end effector) linkage. It’s worth noting that the mechanical advantage has vertical asymptotes at points corresponding to the zero velocity points from the velocity analysis. This is not expected to be a problem as the mechanical advantage is not equal to zero at any point in the travel.

Force Analysis

The above plot depicts the signed magnitude of the output force at our end effector given the torque specs of the motor we have selected and the transmission ratio throughout the travel. The minimum absolute value of this force is approximately 90N, which is more than enough to support the weight of our robot, showing that the motor we have selected will be sufficient for this project.