Cam and Follower Motion Profile simulation
What's on screen
Two panels. Top panel shows a rotating cam (2D profile view) with a translating follower riding on it, complete with guide rails, return spring, and displacement dimension. Bottom panel shows three motion diagrams stacked vertically: displacement, velocity, and acceleration vs cam angle (0° to 360°). A vertical gold cursor line sweeps through all three diagrams at the current angle.
The follower assembly:
Rectangular follower body slides vertically in guide rails
Contact face at bottom touches the cam surface
Return spring drawn with coils between follower top and fixed bracket
Displacement dimension arrow shows current y value
Three stacked motion diagrams (bottom panel):
Each diagram has:
The full curve across 360° for the selected profile
Light blue/red phase backgrounds (rise/return)
Dashed vertical phase boundary lines
Gold vertical cursor at current θ with a dot on the curve
Phase labels at top: RISE, DWELL, RETURN, DWELL
Switch between SHM and cycloidal and watch the acceleration curve change shape completely. SHM has cosine acceleration (finite at start/end = shock). Cycloidal has sine acceleration (zero at start/end = smooth). That one difference is why cycloidal cams are used in every high-speed machine.
4 sliders:
θ (0° to 360°): Manual cam rotation. Drag slowly to see the follower rise, dwell, return, dwell.
Stroke h (10 to 60 mm): Maximum follower travel. Bigger stroke = taller cam lobe. All motion values scale proportionally.
Rise angle β₁ (60° to 180°): How many degrees the cam takes to complete the rise. Smaller β₁ = faster rise = higher acceleration.
Return angle β₂ (60° to 180°): Same for return stroke. Can be different from rise angle (asymmetric cam).
Play button + speed control:
Hit Play and the cam rotates continuously at 60°/s (adjustable 0.5× to 2×). The follower bobs up and down, the cursor sweeps through all three diagrams, and metrics update every frame. You see the direct connection between cam shape, follower motion, and the derivative curves.
Key slider experiments::
Set uniform velocity and hit Play. The follower moves at constant speed but the acceleration diagram shows nothing until the exact moment of dwell transition, where in theory acceleration is infinite (instantaneous velocity change).
Now switch to cycloidal. Same stroke, same angles, but acceleration starts and ends at zero. No shock. No infinite forces. That's why motion profile selection matters.