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Subject: 
Re: JCB JS220 Excavator
Newsgroups: 
lugnet.technic
Date: 
Tue, 25 Nov 2003 10:40:04 GMT
Viewed: 
4074 times
  
In lugnet.technic, Ross Crawford wrote:
  
One question I have though - did you investigate using an adder-subtracter in the base? using the centre axle for drive and the clutch gears for turning might make driving easier, eliminating the lag problem with the clutch gears, which would only affect turning. Not sure what effect it would have on the slewing problem though....

I have done some tests in the past with adder-subtracter based tracked vehicles and have two major problems with them. The first is that in straight line travel you are only getting the benefit of one motor driving the tracks, whereas with the normal method of one motor per track you get two motors doing this. The other is that I found control of the vehicle less intuitive with the adder/subtractor.

In any case, with the large gear reduction after the clutch gears, the lag is really insignificant. You have to really look for it to notice, and if you didn’t know about it I don’t think you would know it was there.

I think if one was to slew with an adder/subtracter it would drive the vehicle and turn it simultaneously, probably a worse outcome than the current situation which only drives the vehicle in a straight line.

My suspicion is that adder/subtracter diff arrangements are more appropriate for robotic than human control.

Jennifer



Message has 1 Reply:
  Re: JCB JS220 Excavator
 
(...) Hmmmm you may be right - I'm still disappointed you didn't implement automatic bucket release though ;) And have you seen those new mini excavators that have the ability to move the dipper assembly sideways? they have a sort of parallelogram (...) (21 years ago, 27-Nov-03, to lugnet.technic, FTX)

Message is in Reply To:
  Re: JCB JS220 Excavator
 
(...) Thanks for another great write-up Jen - and another great model! Been looking forward to the details :) One question I have though - did you investigate using an adder-subtracter in the base? using the centre axle for drive and the clutch (...) (21 years ago, 25-Nov-03, to lugnet.technic, FTX)

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