MotionVisualizer software

After both being impressed by, and raising an eyebrow over SimCalc I wrote something kind of similar. It's pretty rough in some regards but I've done some testing comparing it to CAD models and it seems to be giving accurate results but I fully encourage others with access to CAD software to do the same (roughly speaking, if you adjust your CTC angles by 1 degree and compare that to how much the main platform moves, that's the same ratio as the torque of the motor to the pitch or roll torque, and similar stores for speeds)

I intentionally left out a lot of stuff like linear velocities and max values because they all seemed redundant or potentially misleading. Also, more outputs means more development time and room for mistakes If people have ideas, recommendations, or questions, please don't hesitate.

Download: https://github.com/chadat23/MotionVisualizer/releases/download/v0.0.3/MotionVisualizer_0.0.3.exe

Change Log v0.0.3:

• Fixed rounding bug.
• Added Pushrod Max Force.
• Added Min / Max Angles.
• Added Pitch / Roll Ratio.
• Clarified some labels.

Change Log v0.0.2:

• Fixed math bug.
• Added Save and Open functionality.
• Updated Info tab.
• Added linear speed and acc. tabs.
• Added inspection radii to inputs.
• Fixed plot labels.
• Added pushrod length to outputs.
• Added Alphas tab.
• Added max angular speeds to outputs.
• Added inertia to inputs.

This looks like a great tool. I'm not a Mechanical engineer, so maybe missing the obvious but I've never understood the need to connect rods to the top of the seat, why not shorter ones in the same location at the bottom?

Anyway, I'm hoping to build something as compact as possible, with motors at the front as it will not change the footprint of my existing rig. My general plan is shown in the diagram below. I just want to check the feasibility of it before going too much further.

Sorry to ask directly, but can your tool be used for this calculation? Any clues on what values go where? The motors are 0.7Nm with 50:1 wormgears. Are there other measurements or specs needed?

Thank you for any guidance

John

According to the basic equations, there's no need to have everything so spread out. The equations only care about the angles, relative lengths, and mass moment of inertias, but not absolute lengths of the CTCs, pushrods, or ujoint-rod mount lengths. That said, manufacturing tolerances and rodend slop don't scale the same so the smaller everything gets, the more prominent those factors will become and the further the actual performance will be from the predicted.

I played around with similar geometry and the tool seems to work fine with it, but in order to get similar performance as compared to higher rod-mount points, you either need much more powerful (expensive) motors, or you need extremely short (hard to make accurately and slop magnifying) CTCs.

For your design, to keep units consistent between length and torque (have meters everywhere (no millimetres)), motor torque is 0.7, Rod Mount Position X=0.25, Y=0, Z=0.2, Motor Mount Position X=0.25, Y isn't given, Z=0.2, or there abouts. Angles both look to be 0, and CTC length isn't given. It'd take a much more complete model to get mass moments of inertia.

Thanks very much for your effort with this @chadat23. I've entered the values you suggested (I think) but to be honest I'm not sure what it's telling me. Certainly the Pushrod Max Force value looks a little odd.


No need for you to reply to this, as you've helped me come to the decision to mock this up in a temporary wooden frame to see what works or doesn't work before I start cutting and welding a final frame in steel.

Thanks once again
John