Automated Actuator Gear Shifting....

Hello,

I am looking to create a device for my car for shifting the gears automatically by a push of a button. The transmission is set up in a H pattern formation as any standard manual car. .. I want to Program a Pic Micro-controller to control two pneumatic or electronic actuators independently. One push button switch will run through all the gears 1-5th, and two other buttons will control the Neutralizing and Reversing of the car. Every time the button is pushed the actuators will move in a different direction selecting the gear. The Pic controller will also control an LCD screen, which would show you what gear your in 1...2...3...4...5...N....R.

My questions are:

- Pic Controller code for operation.(havent choosen a device, Worked with the PIC16F877A-IPT.
- I need someone to help me develop a circuit which would implement these functions using the 12volts supplied by the car.
- LCD screen to depict what gear your in.
- Push Button Controls.

Please this is a project i've been trying to pull off for years....now i have the funds to make it happen. Any help, tips, ideas, and websites that can assist me would be appreciated...

Thank You EdaBoard Users

help please any info is greatly appreciated!

Hi,

You said you want to use two actuators. I guess one is for left/right and one is for up/down when moving the shifting level? What do you do about the clutch then? And without some kind of throttle control, the engine will rev up a lot during the shifting process. Or did you intend to only control the shifter automatically and still do the pedals manually?

The electronics would be pretty simple. Controlling the actuators too, although I think shifting into reverse would be tricky. You might need some kind of position or force feedback to keep the thing from getting confused.

But I think the most important question is: isn't this kind of dangerous? What if the software or hardware malfunctions and you suddenly can't shift the car? Doubly so if you intent to control the clutch as well. It kind of raises a red flag in my mind.

Regards,
Chris

Yes i want to use 2 accuators. Left and right, and back and forth.

As for the clutch it would be manually pressed triggering a push button switch to select a new gear.

The throttle pedal will be manually controlled too. The only thing that is automated is the shifting of the gears(exactly as you wrote).

Is there any way you can help me put this idea into a small model device used for testing!.

Thank You very much for your insight. I greatly appreciate it!

Marc

Hi Marc,

XtremeTuningSolutions said:

Is there any way you can help me put this idea into a small model device used for testing!.

Click to expand...

Well I can't do the design for you (day job and all) but I can give you a few pointers.

I guess the first thing to do would be to pick out the actuators. Figure out how your shifting mechanism will be built and find some actuators with the appropriate force and travel distance. I think electric would be easier than pneumatic, although they will require more current (not much problem in a car though). Plus then you won't have to worry about a pump, air tank, relief valves, etc. Also I think pneumatic components remain pressurized after the movement is complete, which would be dangerous if you ever have to shift by hand in an emergency since you will be fighting against the actuator. On the downside, you will probably need four electric actuators versus two pneumatic actuators since electric only works in one direction (as far as I know). With pneumatic, you will just need two valves per actuator. I assume you know where to get all these components. If you're in the US, maybe McMaster Carr or something like that.

I would hook some switches up to the actuators and practice shifting while parked and without any kind of controller just to see if the mechanism works. Such a design is completely out of my field but I guess you have some experience with mechanical work. Then you can also see if some kind of positional feedback is necessary. For example, if the mechanism ever gets stuck someplace, your controller will have to know that so it can back off and try again or wiggle the stick a bit. As I mentioned in my previous post, I think reverse would be tricky in this regard based on my own driving experience. ;-)

Regards,
Chris

u can use pulley system....
take a fixed radius pulley for driving shaft and for driven shaft take a conical pulley whoz radius decreases linearly....
make the conveyor belt to move along the width of the driven shaft pulley so that different radious can provide u different torque n speed....u can do this displacement using stepper motor or a servo motor too....
if u need a clutch that u may go through pulley mechanisms...when u want to disengage the driven shaft/driving shaft u can simply reduce the tension with the help of third pulley n when u want to engage then again increase the tension in the convayor belt by pulling the pulley in such direction that the whole conveyor belt get tight....

I am thinking of doing the same thing.
The gearbox gear selection is usually controlled by TWO cables...one is used for up/down selection of the gears and the other is for controlling the neutral position ie neutral left, neutral middle and neutral right. In the position NL, one can select 1st and 2nd, in NM, one can select 3rd and 4th and in NR one can select 5th and Reverse. One could control this motion using TWO 12v linear actuators..these actuators are like hydraulic rams except the in/out motion of the piston is controoled by DC motors. By reversing the polarity of the DC power to the motors one can get the piston to extend and retract and when the piston rod is coupled to the gearbox cable, one can implement the push/pull movement that was caused by the gearstick. These actuators need to have positional control built into them and this usually means having actuators that have potentiometers and limit switches built into their design ( these can be purchased with this functionality). You then need to control these actuators and this can be done by getting PLC devices ( 12v power again) and implementing a suitable program that will respond to a paddle switch up near the steering wheel.
One may need to replace the existing control cables by longer ones that need to extend into the boot and at the entry point into the boot place the actuator assembly in a suitable housing.

i havent implement this arrangement but i can suggest u a simple design...
use 5 diffrential gears linked one by one...
end one(1st or 5th gear) conncted to the driven shaft(tyres)...
after that use a worm wheel which can slide back and forth tangentially to the diffrential gear, touching its threads to the teeth of gears...such as worm wheel links with the larger radius teeths...motion of this worm wheel can be easily controlled by a servo motor and a rack and penion arrangement...

e.g..
if u take diffrential gears of velocity ratio 2:1...
let the fifth gear is linked to the tyres...
if the worm wheel is rotating the first wheel i.e linked with first wheel u can have 2^6:1 i.e 32:1 velocity ratio!!!...and mininmum u can get 2:1 velocity ratio...

for clutch mechanism u can use pullies...

if possible i'll give u the diagram....

We are also doing a similar project. We would like to know which controller you used. Was it PIC or some other controller because we heard that PIC is not reliable.

QUOTE=XtremeTuningSolutions;713618]Yes i want to use 2 accuators. Left and right, and back and forth.

As for the clutch it would be manually pressed triggering a push button switch to select a new gear.

[/QUOTE]

Hello

This way it will lead to mis-match problem between the clutch and gear shifting. Instead if the manual clutch is replaced with another actuator or motor will be little better. Also we have to think of fail-safe mode in case of problems in MCU or motors or actuators it should be switched back to manual mode for clutch and gear shifting.

Mechanical Part:
The idea can be borrowed from power stearing. As in power stearing there is a torque sensor installed along with a motor to help in turning. The same way we have to use a sensor for clutch either motored or manual. The moment the clutched is pressed a little the gear shifter get ready to shift the gear upon pressing the button. We should have two buttons here one for up and other for down. The gear changer handle is connected to 2 motors one is for left-right and other is for forward and back so that we also have manual gear shifting. I think this should be fare enough explaination.

Electronics Part:
The electronics part is some what straight forward with a MCU and a clutch sensor. There will be 3 DC Motors and it's drivers. The gear count is done by tracking the up and down shift and memorised in the MCU. This arrangement is the most crude and simplest form.

Additional idea:
The gear shifting can be limited on the speed as it is done in automatic transmission vehicles. This requires an additional sensor for speed. The gears will be shifted only at certain speed. The gear shifting will not work below or above this limit.

Maybe my idea is very crude but it can take some shape if I sit and put something on paper. This is just what it has come to mind after reading the first post.

Thankyou

I am working on a project of conversion of a conventional transmission system into semi automated transmission i.e. auto clutch and and a choice between either manual or automatic gear shifting since I am from mechanical background so I would like to know about the electronics involved as well the basic design pattern for the actuation of gears and what will be the main components required.