He is trying to create a traction control device AKA ABS controller by verifying that each wheel is spinning for application of regen (and, I presume also acceleration as that typically puts more torque on each wheel from the controller than the regen braking part)
If the application is just regen braking then you are over-thinking it and the better way would be to simply use an OEM ABS controller. It is true that the force that can be applied to different wheels is different in a turn and while braking, but the difference is not very big unless you are cornering hard and (almost) lifting one wheel on the inside. Also your description is reverse - the inside wheel turns *slower* than the outside wheel for obvious reasons. But the diff takes care of that. As long as the weight on all wheels is not too different, all wheels can contribute equally to the regen braking. Only in extreme cornering will it make sense to take into account that the inside wheels are off-loaded. Some cars have proportion valves coupled to suspension travel so that the deeper the suspension is compressed, the larger the portion of braking force on that wheel. ABS is not doing any proportioning but simply cutting out. That is why it is annoying for trigger-happy ABS systems to cut out when simply driving over a slick line or metal cover or some warning dots as suddenly all braking force will be gone for a second and you have to compensate to avoid a crash. In other words: the intention to avoid loss of grip can backfire and cause a much bigger problem. I understand you want to convert a performance car, which will be able to corner hard and lift a wheel in a turn, so that any regen braking at that point would cause that wheel to start spinning backwards, which is very undesired - understood totally. More than likely the OEM ABS (tone ring) wheel sensors and/or suspension compression measurement will do the job. Good luck and let us know how it works for you! Cor van de Water Chief Scientist Proxim Wireless office +1 408 383 7626 Skype: cor_van_de_water XoIP +31 87 784 1130 private: cvandewater.info http://www.proxim.com This email message (including any attachments) contains confidential and proprietary information of Proxim Wireless Corporation. If you received this message in error, please delete it and notify the sender. Any unauthorized use, disclosure, distribution, or copying of any part of this message is prohibited. -----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of corbin dunn via EV Sent: Thursday, February 23, 2017 2:49 PM To: ROBERT Cc: ev@lists.evdl.org; evtuc...@googlegroups.com Subject: Re: [EVDL] Wheel Speed Sensor For some reason, this doesn't make sense to me. You are saying that you need a speed sensor on each wheel, or else regen would create instability. You could say the same thing for forward power applied by the motor. I think this would only matter if you had a controller on each wheel -- which, maybe you do...I'm not exactly sure what you are trying to do without way more information. -corbin On Thu, Feb 23, 2017 at 1:37 PM, ROBERT <bhensle...@msn.com> wrote: > > No sensor mounted in the transmission will work for regenerative braking. > The motor/engine is directly connected to the transmission. The > transmission is connected to the differential. The differential allows one > wheel to rotate faster than the other wheel. Think about going around a > curve. The inside wheel must rotate faster than the outside wheel or the > vehicle will slide. This is the purpose of the differential. Any speed > sensor mounted in the transmission measures the speed of the motor as ratio > of the gearing. It is a fixed ratio. However, because the differential > can allow one wheel to rotate faster than other wheel i.e no direct ratio. > regenerative braking can cause an instability via loss of traction on one > wheel. To prevent this instability, the inverter must know the speed of > each wheel and reduce regenerative braking. Now you know why I want to > install wheel speed sensors on my Porsche 914. > > > ------------------------------ > *From:* Corbin Dunn <cor...@corbinstreehouse.com> > *Sent:* Thursday, February 23, 2017 8:10 AM > *To:* ROBERT > *Subject:* Re: [EVDL] Wheel Speed Sensor > > Ah! Okay..I haven't heard of those. It sounds just like my Bug's > speedometer though. I think using speed would work just fine...but there are > so many variables, like the type of car, motor, and controller. > > corbin > > Il giorno 22 feb 2017, alle ore 8:46 PM, ROBERT <bhensle...@msn.com> ha > scritto: > > Wheel speed sensors are installed at the wheel. The wheel has a tone ring > with gear teeth and the sensor reads the teeth as the wheel rotates. It is > sometimes called an ABS wheel speed sensor because the ABS brakes use the > signal to determine if one wheel is "locking up" during braking. The > sensor is also used by the regen braking system to prevent causing an > instability. I would like to install sensors on the rear wheel of an EV > conversation. > > > ------------------------------ > *From:* Corbin Dunn <cor...@corbinstreehouse.com> > *Sent:* Wednesday, February 22, 2017 3:34 PM > *To:* ROBERT; Electric Vehicle Discussion List > *Subject:* Re: [EVDL] Wheel Speed Sensor > > A wheel speed sensor? You found a car without a speedometer? I mean, it is > proportional. I removed my tach gauge once I knew what speed produced what > RPM. > > corbin > > > Il giorno 17 feb 2017, alle ore 9:09 AM, ROBERT via EV < > ev@lists.evdl.org> ha scritto: > > > > Has anyone installed a wheels speed sensor on an EV conversion? I am > referring to a vehicle that was not originally supplied with a wheel speed > sensor. Has anyone connected a wheel speed sensor to an inverter (AC > motor controller)? > > > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/ > attachments/20170217/89cc349b/attachment.htm> > > _______________________________________________ > > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > <http://www.evdl.org/help/index.html#usub> > EVDL Subscription Information and Help > <http://www.evdl.org/help/index.html#usub> > www.evdl.org > About the EVDL: The Electric Vehicle Discussion List, founded in 1991 by > EV enthusiast Clyde Visser, is an active and vital source of information > and help for people ... > > > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > EV -- Electric Vehicle Discussion List - lists.evdl.org ... > <http://lists.evdl.org/listinfo.cgi/ev-evdl.org> > lists.evdl.org > The Electric Vehicle Discussion List is a forum for discussing the current > state of the art and future direction of electric vehicles (EVs). 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