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New MIMA Thread

244K views 1K replies 151 participants last post by  retepsnikrep 
#1 ·
As of 12/2/2007, we are re-opening MIMA discussion in this dedicated thread. Please refer to the last post in this thread for further details.

We ask that all participants follow the Forum Rules when posting at InsightCentral.net. In particular, any discussion on how to bypass the manufacturer's warranty is strictly prohibited. (Please read the rules!)

Thanks in advance for your cooperation!
 
#577 · (Edited)
I have spent a good part of last week building up plug in adapter boards, joysticks, displays, and testing only to end up with the last 6 MIMA systems that are ready to ship.

If I add up the hours invested, and the cost of the parts, as I stated before, I could make more money working at Burgerking, not to mention what other things I could have been working on, so the big problem is the time.

I don't think I will try to use up the remaining boards by building more MIMA plug in systems, as it will simply take too much of my time.
So the PLUG in MIMA system as it presently exist will end when the last 5 are sold.
The DIY kit will no longer be available , as some of the required parts are no longer available.
Sorry.
MIMA availability
http://99mpg.com/mima/people/
 
#578 ·
Just finished helping Andrew in UK with Mima 158 install I believe. Seems to work fine. Awesome attention to detail in the kit Mike!

I also got a chance to try Mima V2.00 in my phev car with the modified joylock routine. Basically i asked Mike for a special version where I could dial up an amount of assist using manual mima. lock it with joylock and it would then remain active until I touched buttons/joystick or released throttle completely. I didnt like the way the map sensor used to cause it to drop out of assist when lean burn dropped out or you as much as sneezed. The result is a lot better and assist continues as I hoped. Using manual control it's easy to burn up amps by being over generous with the joystick ;) but this allows low/moderate assist to be implemented for long periods without constant interuption or attention to the controls. Thanks Mike
 
#579 · (Edited)
Happy to hear that the new Joylock worked out well for you, and that Paul Andrews has the second MIMA installed. All that attention to detail is what made the MIMA plug and Play systems so difficult and costly to build.

I may have all the remaining MIMA systems sold,or waiting for confirmation so If any of you guys wanted one, you may be out of luck.
Watch the countdown list: MIMA Honda Insight Modified Integrated Motor Assist - MIMA Users Page and system availability countdown
to see if all of the people come through with their documents and payment.
I am saving the last system to use in my Insight on a stand battery testing.
Two systems are not yet confirmed, so if someone wants to get one and they bail out, give me an e-mail.
I already have one guy on the back up list.
 
#580 ·
The last two plug and play MIMA systems will go out this morning. The last one that I was hoping to keep for the insight on a stand was also sold, as the guy was willing to pay the full price, and I still have the one in the silver Insight which will have to timeshare.

Now we have to decide where to go from here.

A lot has happened to increase our knowledge about how the IMA functions, mostly due to the brilliant work done by Peter Perkins and the many guys working with him on the BCM gauge.
The next logical step would seem to be to develop a new IMA control system that ties all of the ideas together into a single computer.

A small LCD display, either 2X16 or 4X20 would display information.

A steering wheel mounted controller would send user control information to a receiver on the main computer.

The computer would read the OBDII data like the scan guage,
It would read the Battery serial like the BCM guage,
and would control the IMA like MIMA does,
and possibily control the SOC, assist/regen display on the dash.

The system would now have much more information about what is happening in the car,without the need to hard wire to the signal of interest, so a smarter PIMA mode could be developed.

Data logging, GPS input, are all possibilities that could be included.
Since we have at least 150 operating MIMA systems in place, with experienced owners, the place to start is to give them some of the things many have been asking for.
A wheel mounted controller, possibility something like Peters cool pushbutton design, or the same analog type joystick.
I would like to try and make it something that does not involve steering wheel disassembly, but hope to look at all the possibilities including that option.

The need for better feedback of MIMA settings to the operator has been asked for by many people, it is dificult to determine where the ABC or PIMA settings are while trying to jog them. An LCD display for the present MIMA systems .

3 wheeler is looking at a cool shifter mounted controller, and is getting set up to also work on MIMA code development on a new MIMA C-L system.

MIMA Computer Lite V2
is a basic manual IMA controller, without all of the current sensor, optoisolated signal taps, temperature sensors and fan controls.
MIMA C-L Present functions:
MIMA on demand with joylock (unlock by moving the joystick)
MIMA mode 1 (IMA disabled) manual override with joylock
Dual joysticks with calibration support
Display shows requested assist/regen not battery current.
Max assist option selection and other calibration adjustments are functioning.

I hope to make the basic assembly language MIMA functions a C function so more programmers can dig in and help to fully develop the possibilities in an easier to use language.

The MIMA C-L systems will be offered as:
I fully assembled and tested version
A build it your self system with all the parts.
Connection to the car is presently by tapping and cutting the required wires.

At this point further MIMA C-L kits will not be available.
I want to see what the two C-L users experience is, and will be ordering some parts.
Hope to be ready to sell more beginning of March.
Target price <$200.


I am involved with some contract design work and the grid charger project , which has been difficult to proceed with due to being buried with snow.
Blew a motor and auger drive in my snowblower, have 30+" of heavy snow on my roofs, and we had an icestorm last night.
I am ready for spring.
V-buck is moving nicely.
Hoping for a lot of projects to start moving once the weather gets better.
 
#581 · (Edited)
The next logical step would seem to be to develop a new IMA control system that ties all of the ideas together into a single computer.
Good idea but must be careful not to bite off too much.

A small LCD display, either 2X16 or 4X20 would display information.
Great idea it is a pain setting up some of the modes on current mima. A simple retro fit serial lcd device would only need code changes as there is probably one spare pin.

A steering wheel mounted controller would send user control information to a receiver on the main computer.
Excellent I would not go back to any other form of joystick now after using wheel mounted controls. I prefer the feel of the simple cheap click momentary push buttons but the analog pressure pads are also cool and can be configured as more expensive buttons. I'm going to try the little 5 way joystick button I use with the bcm gauge fitted into my last spare steering wheel shortly to give one switch right handed control with more functions.

The computer would read the OBDII data like the scan guage,
It would read the Battery serial like the BCM guage,
and would control the IMA like MIMA does,
and possibily control the SOC, assist/regen display on the dash.
This gets tricky now, the ODBII data and bcm data would be cool but I believe that is too much. The key for this new version is simplicity and low price IMHO.
We haven't done any work on getting the odbii signals yet asfaik. Yes it would be possible but it wil be a lot of work

The system would now have much more information about what is happening in the car,without the need to hard wire to the signal of interest, so a smarter PIMA mode could be developed. Data logging, GPS input, are all possibilities that could be included.
Cool but too much to achieve in a realistic time frame.

Since we have at least 150 operating MIMA systems in place, with experienced owners, the place to start is to give them some of the things many have been asking for.
A wheel mounted controller, possibility something like Peters cool pushbutton design, or the same analog type joystick.
I would like to try and make it something that does not involve steering wheel disassembly, but hope to look at all the possibilities including that option.

The need for better feedback of MIMA settings to the operator has been asked for by many people, it is dificult to determine where the ABC or PIMA settings are while trying to jog them. An LCD display for the present MIMA systems .
I think you have it here. Three core things to do for the moment.

1) Display for current mima. Easy needs one spare output pin and code changes

2) Steering wheel controls for current mima. Fairly easy with manual cars using cvt clock spring to divert one joystick axis function to buttons/sensors. Possible to have five way joystick button thing as well.

3) Develop New Simple cheap mima system which can use 1 & 2 above. Pretty easy I envisage a possible two chip solution PIC16F88 & MAX4619.

3 wheeler is looking at a cool shifter mounted controller, and is getting set up to also work on MIMA code development on a new MIMA C-L system.

MIMA Computer Lite V2
is a basic manual IMA controller, without all of the current sensor, optoisolated signal taps, temperature sensors and fan controls.
MIMA C-L Present functions:
MIMA on demand with joylock (unlock by moving the joystick)
MIMA mode 1 (IMA disabled) manual override with joylock
Dual joysticks with calibration support
Display shows requested assist/regen not battery current.
Max assist option selection and other calibration adjustments are functioning.

I hope to make the basic assembly language MIMA functions a C function so more programmers can dig in and help to fully develop the possibilities in an easier to use language.

The MIMA C-L systems will be offered as:
I fully assembled and tested version
A build it your self system with all the parts.
Connection to the car is presently by tapping and cutting the required wires.

At this point further MIMA C-L kits will not be available.
I want to see what the two C-L users experience is, and will be ordering some parts.
Hope to be ready to sell more beginning of March.
Target price <$200.
Lots there and I hope other members do chip in with requests and assistance. I do feel we plough a lonely furrow sometimes with little feedback apart from a few core supporters ;)

A simpler version of mima is def possible, I use one in my project car with the button controls and which I am developing to include a cruise control function for my phev cars. Dial in the speed you want, dial in the assist regen limits you want, press go and ima maintains choosen speed as far as possible within your current/power limits.

A few more thoughts on the lcd display. I use a 16x2 9600 baud 8,N,1 serial device which quite a few people are using with the bcm gauge. If you can utilise a similiar device or a parallel display with serial interface then users can use the display they already have, and with addition of a simple switch they can switch the feed from one gizmo to the next. Say mima/bcm gauge/odbii thingy when we get it built. That avoids need for multiple lcd displays :)

Finally a vote of thanks to Mike for all the time an effort he puts in. I probably never would have got into a lot of this insight or phev stuff without having bought a Mima kit first and seeing what was possible.
 
#582 ·
To add to the steering wheel button click idea, if this could be done in some wireless way where the buttons are setup like the wireless Rostra cruise control button system(looks exactly like the S/D buttons on the CVT), we could use a steering wheel mounting control without the wiring or steering wheel hack, could be attached with epoxy or double sided tape. I'm not sure what is possible but it's an idea.

I like the cruise control idea that Peter has too.
 
#586 ·
The project will be incremental, with the basic MIMA as discussed above being the starting point.

The second MIMA-CL should be up and running today or tomorrow.

The MIMA based cruise control was proposed some time ago, and will require the vehicle speed, and the brake input.
I question how useful it would be without a larger capacity pack to supply it with the required assist?
Lots of possibility's to explore down the road a bit.
 
#587 ·
The MIMA based cruise control was proposed some time ago, and will require the vehicle speed, and the brake input.
I question how useful it would be without a larger capacity pack to supply it with the required assist?
I agree it's no use having a cruise mode without at least 20ah of capacity.
 
#589 ·
Not sure what you are asking?
The thing that has gone away is the plug and play harness, which was very expensive and time consuming to build. As I have said several times, building MIMA with the plug and play harness at the reduced price was a big time sink with a small return on the many hours it took to build each one.

The MIMA CL is presently the same board as the full MIMA, and if fully populated would be the same, but without the plug in adapters, one would have to connect 21 wires like the original install.
Stripping the install down to the minimum MIMA functionality still gives the primary MIMA control over the IMA, but makes the board much less expensive and time consuming to build and install.
At this point nothing is locked in, and I am open to suggestions as to the best way to proceed.
I want to offer a steering wheel mounted controller and LCD display for the present MIMA systems and then migrate those featured into the MIMA -CL.
Right now, I have to get 24-30 inches of heavy snow off the roof of my home and garage so the roofs don't cave in, and my snowblower broke, and all the stores are out of stock, so it is roof shoveling tied to the chimney with a rope for safety.
Anyone want to come over and help?
Ice storm predicted for tonight and tomorrow, with more snow on Thursday.
Winter is beginning to suck big time.
 
#590 · (Edited)
Mima

Dear Mike,

I may have the wrong idea about the redesign, I assumed that the recent developments such as decoding Battsci would lead to economies in Mima LC, ie no need for thermistors for pack temp (battsci has this in digital form) and no need to measure IMa currents (Battsci again) etc etc.

I am not advocating that you continue to produce or supply the plug in adaptors for ECM and MCM for the new Mima system. I can see they are very costly and time consuming to construct

I am hoping that new Mima is made in such a way that existing owners may easily substitute new Mima CPU pcb for old, gaining the benefit of LCD display/steering wheel controls etc.

I realise that we may need to run Battsci down the 25 way cable,for new Mima, there are ample unused lines for this, a couple of wires soldered onto the MCM adaptor, connectors C9 and C10 to the plated holes M6 and M7 on MCM adaptor pcb for example
 
#591 · (Edited)
I intend to get the LCD display to first operate on the existing MIMA systems, with information about where the Setpoints are for ABC,PIMA, an actual display of battery and MPI temperature, and current and whatever else is worth displaying, then move to displaying the Battery parameters, but that may be better implemented by sharing Peters Battery monitor display for those that have the unit.
Lots of details to work out about where to take this, but support of the 160+ systems that are out there is my first priority.
The CL MIMAs will start with only the basic IMA control functions, and as things evolve, and we look at connecting into the OBDII data, many new possibilities will emerge, which will also be backwards compatible with all of the systems in place.
This is why the MIMA controller is on a socket. New code becomes available, I send you a new micro controller, you make any changes in connections, and off you go with the latest and greatest MIMA operating system.
We did a lot of that during the early days of MIMA.
Should be fun, and I hope to get more people involved in the development.

Of course the easiest existing MIMA systems to modify the hardware connections on will be the plug and play with the extra conductors, but the older systems will also be able to be modified.

The CL being the same hardware as all previous systems will always have the possibility of being brought to the same place as the other MIMA C systems, by simply making more connections to the car and populating that associated parts of the board.
You can look at the hardwired or pin replacement instructions for connection points, and the MIMA kit instructions for building up the rest of the board.
Many people have told me that they would be satisfied with a bare boned MIMA.
That's MIMA CL, and you can upgrade to the full system if you like, but are not forced to do so to experience the MIMA grin.

The downside of MIMA CL:

You don't have the automatic battery fan activation when it gets too hot.
A single wire run to the the battery fan connector in back, and you can turn on the fan manually.
You can use a cheap indoor outdoor thermometer with the outdoor probe in the pack to tell you how hot the pack is.
Not elegant, but it does the job.

The real time battery current meter becomes joystick requested assist/regen, but since I know the car so well, I can more or less tell how much actual regen or assist is happening, and the conditions where it does not happen, so I miss the information, but don't miss the current sensor wiring required to get the signal to the MIMA card.

No MAP or VSS signal acquisition on MIMA CL as presently configured eliminates PIMA and ABC.
I for one would miss this mode as I tend to use it on long highway runs over the rolling hills of New England, but may people have told me that they either can't get it adjusted to maintain a charge, or they can do better manually?
Only a few more connections at the ECM, some board components and we can retain PIMA and ABC?
Where do we draw the line. Ian suggested that we make the system incremental, so you can start with manual and build the system a bit at a time.
While this is great for the technically minded people, by requiring people to cut and tap wires, we are making it more difficult for non technical people to get The MIMA grin, but even that can be potentially solved with a plug and play solution that is limited to the ECM connector that carries the MIMA signals.
instead of the 220 connections passing through the plug and play adapters.
Once we get MIMA reading OBDII data (a lot of work as peter warns) , then MIMA will become very well informed about what else is going on in the car, and the differences between the older MIMA systems and the CL will become much less, and the I/O that is presently being used for acquiring the real time MAP and TPS signals could be used for other I/O task that we have not even thought of, like the Auto hot air mod adjustment that 3 wheeler spoke to me about, Auto AC turnoff when climbing hills, Ians overall efficiency meter, lots of un explored possibilities.
On the wheel mounted joystick, some form of wireless connection without the need to open the wheel for installation would be my design goal, but we will see where all of this goes.
 
#595 ·
Where do we draw the line. Ian suggested that we make the system incremental, so you can start with manual and build the system a bit at a time.
While this is great for the technically minded people, by requiring people to cut and tap wires, we are making it more difficult for non technical people to get The MIMA grin, but even that can be potentially solved with a plug and play solution that is limited to the ECM connector that carries the MIMA signals.
Where to draw the line will be a hard one.

I'd expect some to be interested in the plug and play easier solutions ... perhaps , to avoid some of the overhead issues seen last time in $ and labor with plug and and play , the plug and play harness could be another one of the options ... some people might be willing to pay extra for it ... other more technical DIYers might prefer to do it themselves.
 
#592 ·
Great news Mike,
LCD will be great for people like me which get easily confused with less graphic solutions,

one other thing, is there any way you can program a cycling program for the IMA battery pack, so the MIMA can do a full discharge and full charge at optimal amperage, while driving on the morning commute.

If this was possible then that would be a clean alternative of the wall charger (only downside would be the extra gas, but in the name of a battery in good shape I could live with that)

I tried to do that manually and I think I overheated my pack at that time...
 
#593 ·
Hi Jivko,
The lcd will allow us to have better ability to set up things like that,with menus and the ability to watch different parameters of the systems operation.
Because we really don't know what a pack whack is actually doing to the pack, or if it balances the pack as well as the constant current grid charger, I think a smart grid charger like I will be selling will do a better job of battery maintenance, and you could leave it in the car, with a nice weather proof AC plug on the rear bumper. Plug it in each night and start the next day with a warm fully charged and balanced pack.
 
#594 ·
Thanks , yes I agree, I did something similar for a couple of weeks with a cheap grid charger, but stopped as I was affraid I might be constantly overcharging the battery pack and eventually ruining it....
 
#596 ·
Minimizing mini-PHEV cycle life depletion

Folks -

Which is tougher on the (stock NiMH) battery pack:

1) Lots of small discharge / charge cycles maintaining the stock SOC range or

2) fewer cycles consisting mostly of discharge while driving (with occasional regen bumping the SOC up a bit) and gradual grid-based 350mA or 700mA trickle-charging, with a large TPS range / span inside which the battery pack is just along for the ride?


The idea is to get the benefits of a mini PHEV without quickly using up the pack's cycle life. A simple knob would determine what TPS threshold starts 50% assist (where the IMA is most efficient), with gear ratio -independent regen of 50% at closed throttle, 100% upon brake pedal switch triggering. A pack overvolt condition could be prevented by reducing the regen upon the pack's exceeding, say, 185V (I've seen 195+ from stock IMA). (I also figure the 2nd gear synchro would last longer as regen would no longer sometimes suddenly disappear from 3rd, negating a need to snag 2nd.)

The total energy discharged each day from the pack (i.e. Assist occurrences only) wouldn't change much (possibly even be less than when stock), but most of its recharging would be via very gentle, long trickle-charging instead of 15A or so of background / ghost charging over a much shorter interval. Would the gentler home-charging compensate some for the much larger daily SOC swings vs. stock?

I put this question here as I see it mostly as a significant issue in design of a MIMA_L -based system.

Thanks,
Roger
 
#597 ·
One of the issues with using MIMA for battery cycling is that MIMA does not know the battery voltage.With the pack whack, We presently let the car stop the charging, but when we see over 180V, it makes me think we may be pushing it too high, and since the charge at that point is still well over 10A, I do not recommend that people keep doing it to try and balance the pack. The gentle 350ma is a better safer way to rebalance in my opinion.
uhtrinity has been grid charging his dual pack for quite some time, and has confirmed that the cell capacity seems to be the same as when he first did the test, so it is not likely that a controlled grid charge each night will shorten the pack life, and it may actually extend it as the pack will always be well balanced?
Time will tell.
TPS control of assist /regen via MIMA does not work very well, as the TPS position in different gears and different load conditions is not consistan. The MAP works much more smoothly, and if I had tapped the rpm and speed, I could have compensated the PIMA setting so the resopnse would have been repeatable in different gears.
Since these signals are reported on the OBDII port, once that info is available, it will give us a lot more possibilities.
 
#598 ·
Minimizing mini-PHEV cycle life depletion

uhtrinity has been grid charging his dual pack for quite some time, and has confirmed that the cell capacity seems to be the same as when he first did the test, so it is not likely that a controlled grid charge each night will shorten the pack life, and it may actually extend it as the pack will always be well balanced?
That's a very helpful bit of data, suggesting 350mA trickle charging does indeed possibly balance out deeper cycling, at least so far for uhtrinity.

TPS control of assist /regen via MIMA does not work very well, as the TPS position in different gears and different load conditions is not consistent. The MAP works much more smoothly, and if I had tapped the rpm and speed, I could have compensated the PIMA setting so the response would have been repeatable in different gears.
Since these signals are reported on the OBDII port, once that info is available, it will give us a lot more possibilities.
I was figuring a MAP sensor -based assist threshold would cut back assist at higher rpm regardless of throttle position at less than WOT conditions, not ideal... But then the IMA is more efficient at lower rpm anyway, so somewhat restricting assist more to lower rpm does make some sense (especially if the TPS sensor output lacks smoothness).

Using the MAP sensor instead of the TPS could also lead to some significant 500 - 1500 rpm "quiet" torque, where the engine isn't running fast enough to pull any real vacuum (or generate any real torque), probably making for interesting idle-speed throttle response pulling away from a stop at intersections, possibly a little jerky but nearly impossible to stall (again, depending on MIMA response speed).

Thanks,
Roger
 
#600 ·
Roger,
One of the reasons I used VSS (speed) to turn off PIMA at <19mph, the second reason was that if autostop kicked in while PIMA was active, the car would restart as the MAP signal would look to the system like WOT.
MIMA was a tradeoff of how many signals and which signals to acquire, to make the wiring manageable.
If I can get the data from the OBDII port many new possibilities will available,without all the wiring.
The bottom line is to make the basic MIMA functions available for a price that is in the budget of many more people, and then we work to add new functionality.
 
#603 · (Edited)
With the Prius we have more control from the stock system than a stock Insight.

As an example we have an EV button that will allow us to pull up to 120A in electric only mode up to 34MPH.

For higher speeds there are some tricks used in the Plug in market that trick the car into providing more assist. Useful only if you have the extra battery. Kind of like the Insight.

On the regen side we can control how much regen we get with just the brake pedal. Unlike the Insight where it pretty much all or nothing.

So in short a MIMA like control for the Prius would not be that useful but it might be nice.

If you want more information priuschat.com would have just about everything your looking for.


Also if this MIMA 2.0 comes out with some kind of visulation of what the PIMA and other settings are I'll be first in line to purchase one.
 
#604 ·
It isn't all or nothing, it is the small amount of regen when coasting or everything. What I like about the Insight is that I don't have to use friction braking to get maximum assist. According to the Prius rep at the St Louis auto show I just went to, there is a decent amount of friction braking since the car is trying to blend in friction braking to make it 'feel like a normal car'. I prefer to full as much as I can without friction. The EV button isn't stock on the Prius and I've looked at Priuschat with a number of people concerned over warranty issues if they add the button to allow it, granted its the same for MIMA, but I wouldn't call something that people are concerned with warranty issue something that is stock, when it isn't on the 2nd Gen.
 
#605 ·
I have been luck to have had the opportunity to play with some prius at the hybrid training classes.
The problem with the EV mode on the prius is that the tranny oil pump only runs when the engine runs, and Toyota designed the car so the EV mode would be more or less intermittent,with enough of an oil film on the bearings between runs to keep things properly lubed, so the people with PHEV booster packs that can run for many miles in that mode risk excessive bearing wear.
The wear may make the difference between 300K and 200K of life?

I know a guy that had 350K on a first gen prius when he totaled it, and the thing was running on the original battery pack.
Wish we could get that kind of miles on our batterys, the difference is in battery management, not the cells.
 
#606 ·
...the second reason was that if autostop kicked in while PIMA was active, the car would restart as the MAP signal would look to the system like WOT.
That's a very good point I never considered.

A couple more ideas of what I'd consider part of ideal system:

To help minimize the time it takes the car to do a positive recal I see benefit in having a 25% continuous regen mode with an Assist threshold knob at minimum; this would also help minimize warm-up time.

Low knob settings could also allow 25% regen under light to moderate load for background recharging, with very high engine loading triggering 100% Assist at higher knob settings.

On U.S. cars there are blanks in the dashboard where DRL adjustments are in Canadian cars; in the U.S. at least a potentiometer can fit in one of the non-middle ones, hence the knob idea. Takes minimum space, requires minimum customization (simple), requires minimum driver involvement (safe).

One intended benefit of 50% regen at closed throttle would be regen during coasting and idling while parked (with a possibly cold engine), to get the engine up from what would otherwise be 0% efficiency, figuring probably only roughly 10 - 15A is available at idle anyway.
 
#609 ·
CRX

I think the way forward is build your mima-l. Add a simple control pot for testing to adjust regen up/down, and try that with engine ticking over to get an idea of speed of change reqd and ecm reaction time to ensure a smooth increase in regen load on engine without it stalling. Please post your results.

The TPS is smooth and stable in my experience I use it for my rally mode IMA control. Proportional MIMA assist control using the TPS is perfectly possible.

A cmdpwr duty cycle of 40% gives around 8A of regen at tickover, but it can nearly stall when first engaged. A ramp up would be better I must include that in my system.

My steering wheel 4 position regen button gives 40 - 30 - 20 - 10% stepped cmdpwr duty when clicked. Ditto assist 60 - 70 - 80 - 90% when clicked in other direction. I may well increase this to 8 steps in each direction increasing by 5% each click.

Fiddling with the cmdpwr, mamode1 & mamode2 MIMA signals will not generate IMA errors unless you get them out of sequence or out of spec.

Setting an aggresive level of regen can still lead to the BCM/MCM limiting regen scenario we encounter on long descents when braking. Regen fades away after a few 10 of seconds at 50A or so.
 
#610 · (Edited)
Roger,

The new MIMA C-L in the simplest form, does not acquire MAP,VSS, TPS, so regen and assist is available without a speed based limit.
Feeding it a fixed voltage rather than one from the joystick, will allow any level of regen or assist. The input impedance is pretty high, so simply send MIMA a voltage and you are good to go. 5V-0V with 2.5 being neutral assist/regen.

Using MIMA-L, any change in resistance will skew the 25% duty cycle, so you will be constantly be fooling with resistor values if you try to get creative.
I Don't recommend MIMA-L for those reasons.
MIMA L is resistance based input, MIMA C is voltage based input.
MIMA C-L is crystal clock controlled, so no calibration is required.
MIMA L requires precise resistance/capacitance ratios to even work.

The TPS is not noisy (after optoisolation), or is there too low a resolution. The problem is that it has to be in a specific position for each speed in each gear. The IMA boost or regen level being controlled by that voltage does not work. Shift gears, and you could see full assist when you are looking for none, due to the TPS voltage required to maintain engine rpm.

The MAP is sensitive to engine load, which is related to the TPS input plus the engine load, so it pretty much gives smooth infinitely variable IMA control with your foot.
Lift the foot, engine load is reduced, MAP responds proportionately, and there is your PIMA regen control. Step down on the TPS, engine load increases the MAP, there is your assist control.
I tried it both ways, and the TPS is not the right signal. Could a combination of the VSS, TPS, and MAP signals be processed into a better controller, probably yes with some clever programming.
 
#611 ·
... Using MIMA-L, any change in resistance will skew the 25% duty cycle, so you will be constantly be fooling with resistor values if you try to get creative.
I Don't recommend MIMA-L for those reasons.
I had written "It would use... op-amp ... output resistance to ramp up and down..." I meant to write optocoupler, whose output resistance would serve as the MIMA_L joystick. I've looked into PICAXE use for circuit stability purposes, and once I get a little more familiar with what PICAXE code can do that might be the better, far more flexible bet. It'll take a little while more though.

... I tried it both ways, and the TPS is not the right signal. Could a combination of the VSS, TPS, and MAP signals be processed into a better controller, probably yes with some clever programming.
I've been thinking fairly simply in terms of a carburetor's secondary: does it open up purely mechanically upon full opening of the primary (i.e TPS-based MIMA_L), or by manifold vacuum (i.e. MAP sensor...), knowing the latter works only if mechanically limited by the throttle cable position to prevent stupid throttle tricks at idle-like speeds (hence MAP sensor + TPS...). Most carb secondaries were in the last category, pure TP-based ones being more for racers (maybe from their knowing not to go right to WOT from idle?). Stock IMA assist by comparison gets conservative as speed rises, probably to prevent lethargic urban throttle response combining with quick draining of the pack on the highway, probably closely related to MIMA / PIMA use of the VSS signal. The Regen/Assist bias knob would need turning down as speed rises to prevent quick pack depletion, depending partly on terrain... That could be sufficient reason to include the VSS signal, despite the extra processing required... Unless of course I simply use a microswitch to call on manual assist (which apparently Formula One Ferrari drivers can also do, using an IMA-like system with Saft cells), which would radically simply the system, but not the driving.
 
#612 · (Edited)
I am still working on an arduino based controller, tweaking it here and there to appear correct on the scope before i do anything with the car. These schematics may give some ideas for your project(s):

board:

schematic:

actual board and setup:


You can see in the setup photo where the scope is hooked up. The I/O connector for the MIMA to car is on the left edge of the board. LCD wires pop out the top, arduino header on the left side.

You'll notice the lack of DP relays because with the use of diodes and pullup resistors, SP relays are all you need, even if the system goes haywire and fries. Also the joystick emulator is a SPI controlled 10k digital pot.

I'm using a Wii nunchuck controller because it's clean, durable, easy to add a connector in the car, and feature packed.

I plan to use the blank switch plates on the left of the wheel to install the Wii port, and maybe a 2x8 LCD along with RGB status LED.

There's a failsafe incase the controller hits something where it'll shut off the MIMA. Reading these posts is interesting cause I actually had put a few lines of code that snag the stock signals and "add" them to the MIMA joystick in one of the modes.. So you can allow it to smooth idle / idle stop without worry.

Unfortunately I copied the schematic on 99mpg.com and read later in theory of operation that the CMDPWR is 2khz, not 20khz, and in the mean time my soldering iron's heater stopped working ($65 for the heater alone). I should be getting this thing nearly finished and ready for the car in a week or two.
 
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