Quote:
Originally Posted by sanddrag
Team 968 did a 4-speed gearbox a couple different years. I want to say it was 2004 and 2005. I don't remember if it was autoshifting though.
On 696, we tried an autoshifting algorithm on our 2-speed this year and did not find any appreciable distance in field-crossing time when compared to leaving it in high gear, even with varying the shift point through a range of set points.
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One of our mentors made an excel graph of acceleration without friction with selectable speeds and calculus and stuff. It basically showed that speeds from 10-30fps will accelerate at almost the same rate until they top out at max speed. The only real change in accleration rate was noticed when we changed the inputs from 4 cim to 6 cim.
It's not extremely difficult to autoshift. Normally you would be in high gear, but the driver would have a low gear override pushbutton to go into low gear for normal driving. Then you could just put a current sensor in the motor circuit and shift into low gear whenever current gets too high.
4 speeds seems excessive to me, because all you really ever need is a normal drive gear and a low pushing/ positioning gear.
You can also just use PWM control to lessen the duty cycle of the motors if current spikes.