Im not sure… Center of Gravity? 30 pound belly pan made from steel ensures very low center of mass. yes we do need to worry about “wheelies” if top heavy… and acceleration limits would be part of PID
Edit: refer to Upgrade Swerve MK4i Increase acceleration and speed w 2X drive motors - #17 by electroken
If you are acceleration limiting a 1 traction motor swerve, there’s no need for a 2 traction motor Swerve
During our first regional (Central Illinois Regional) we ran with 2 falcons with custom top plates on each module. We struggled to have enough battery to finish the match and brownouts were always happening. For Seven Rivers and Worlds we were running a single falcon per module with much better results. I don’t recall the gearing we were using but I can find out if someone wants to know.
See all important motor characteristics on this post… and a working 4414 robot using dual drive motors… SICK !!!
yep - thanks… mee too
From the MK Battery ES17-12 data sheet:
What if only 2 of the modules have 2 drive motors, would the other 2 modules with only one drive motor drag the other down?
yes; it won’t be too noticeable but it will happen
But you will still have more speed (with the proper config) than using only one drive motor per module, right?
maybe? it feels really sketch to me, not to mention programming’s suffering
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With a ~0.02 ohm overall system resistance (most of which is internal to the battery), the voltage at the Rio will drop 4 volts at 200A. That puts it in brown-out territory. I think some teams have been able to push past 200A (2.4kW), but I usually consider that the robot limit.
Each motor will contribute a force (rotationally called torque) toward its modules, the acceleration is governed by a=f/mass… so 6 drive motors will accelerate 6/4 times faster than 4 motor system, assuming all wheels maintain good traction with ground.
That’s only true if you can deliver 6/4 the amount of electrical power to the 6 motors (instead of just adding more current to four motors)
You’d gain a slight efficiency gain by reducing losses by going to 2 motors as you’d pull about half the current per motor for the same torque, probably pretty small ROIs though. I think Falcons on “L3” will be pretty close to about the same performance and you still have to have highly capable trained drivers that can keep up with a fast robot.
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“Limits are made to be broken”
You also get to transfer more torque to carpet during initial acceleration when the robot weight tends to shift onto the back wheels only (so having four motors there instead of two is beneficial). But I also hand-wavey think this effect is small.
I feel like this is an incorrect interpretation of an asymmetric swerve system. To me it feels more like having two motors on one side of a wcd and four on the other side, the robot will tend to go in arcs.
top speed is a function of gear ratio and can be faster slower or same as one motor… acceleration is roughly doubled with a second drive motor… so getting to whatever that top speed takes half the time. mechanics equations: change in velocity = acceleration x time. angular velocity (rpm) of wheels = product of all gear ratios x top speed (rpm) of motor and linear speed = angular velocity (rpm) of wheels x circumference (pi 3.14 x diameter) and be sure to convert units of length properly.
Right, but you can get similar effect by just applying more torque with 1 motor per module, although with increased electrical loss. Falcons and NEOs are extremely low internal resistance motors and can make a crap ton of torque if you give them higher current limits. The Falcon more so than the NEO but similar point. Doubling motors only doubles torque if you keep the current limits the same, id be willing to bet 2 Falcons per module means not using 80A current limits per Falcon.
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