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11
Software / Re: Need help for Voice recognition car
« Last post by APJ1234 on April 13, 2015, 01:18:12 PM »
Any new updates?????
12
Misc / Re: Analyzing the Axon series: Coding, Contruction, and Contraptions
« Last post by mklrobo on April 13, 2015, 10:02:48 AM »
Axon Series: What is this thing?
OK,  :D I went back through my KDE C++ programming environment,
and also saw messages. NOW, some messages are critical, some
messages are not.(for user/author info) When I compiled the
source code file, no compilation errors occurred; just a message
like I posted earlier. SO, I will try to download the program into
the Axon anyway  :P, and hope I do not damage the MCU. If I destroy
the MCU, and do not find help or a resolution, that may end my
journey with the Axon series. :'(
13
Misc / Re: Analyzing the Axon series: Coding, Contruction, and Contraptions
« Last post by mklrobo on April 13, 2015, 09:05:01 AM »
Axon Series: What is this thing?
Definitely ran into a problem! :'( The compilation process is
more involved than in the tutorials. :-X  Tried Webbot Studio,
and that was even more frustrating. :( Do not know what to
do to make the program compile properly. Will have to delve
into the software; see if I can find notes in any files to help me
out. No info in the tutorials. Will cross reference with other similar programs, to find out what is going on. :o Makes using the Axon, hard for me.
Hope I can work through this, make take awhile.  :'(
14
Mechanics and Construction / Re: piston crankshaft help
« Last post by bdeuell on April 12, 2015, 03:00:39 PM »
why not use the motor to drive the vehicle and the piston to actuate the steering? Remember the KISS principle it is your friend despite how much you hate it.

anyways if you insist on using the piston to generate rotary motion you can tie the control valve to the rotational position to control what position the piston moves for that angular position, i.e. the piston moves up 0-180 and down 180-360. if your piston only a power stroke in one direction you would need to start in the region of that power stroke, i.e. for a up only power stroke it would need to start in the 0-180 range. if your piston is powered in both directions it could start in either the 0-180 or 180-360 regions but if it started at the top dead center TDC or bottom dead center BDC there would be no torque to rotate the. the possible starting regions will actually be a little smaller because near the TDC and BDC positions the torque would be too low to overcome friction. I suggest you take a look at some steam engines.
15
Mechanics and Construction / Re: piston crankshaft help
« Last post by dvdngu on April 11, 2015, 05:43:27 PM »
start it in only one direction (i.e. starter motor)... inertia will do the rest assuming you fire the piston at the correct time

with multiple pistons you may be able to use firing sequence to start the direction of rotation as well.

If I am understanding you correctly, you are saying to add a motor specifically for the purpose of giving the crank shaft an initial push in the direction that I want? If that is the case, I would rather not add a motor, as the project I am working on is only allowed to have one motor (which I am using for steering) and one pneumatic piston (which I am using for the propulsion of the robot). I was wondering if there was a specific/clever way in which I build a stereotypical piston/crankshaft system in which it would rotate in one direction only. For example, I was thinking about putting the axle of the crankshaft slightly offset from the plane of the axle of the piston, but I fear that the crankshaft will not rotate at all in this case or high stresses will be created on the system.
16
Mechanics and Construction / Re: piston crankshaft help
« Last post by bdeuell on April 11, 2015, 04:38:17 PM »
start it in only one direction (i.e. starter motor)... inertia will do the rest assuming you fire the piston at the correct time

with multiple pistons you may be able to use firing sequence to start the direction of rotation as well.
17
Electronics / Re: Electric bicycle
« Last post by bdeuell on April 11, 2015, 04:29:50 PM »
the maximum discharge rate of a battery is its maximum discharge rate without risk of damaging or destroying (depending on the battery chemistry explosion or fire can also be a very serious concern) the battery is capable of supplying much greater currents. Unless there is a battery protection circuit/device the current it can supply will be limited by the internal resistance of the battery. The maximum discharge spec may be listed with several values depending on length of time i.e. it may be capable of handling a higher current for 30 seconds than one hour. Higher discharge rates will also negatively impact battery life and capacity. the discharge rate is often listed in terms of C (for example maximum continuous discharge rate of 2C) where C is equal to the batteries capacity (for example a 12Ah battery C=12A).

Remember that brushed DC motors draw the full stall current when the speed is zero (regardless of load) which will occur every time your motor starts. However under a light load it is likely that your motor will accelerate quickly and the current draw will correspondingly decrease.

Also assuming you will be driving your motor with PWM (which relies on the inductance and resistance of your motor to produce an analog voltage) you must consider how the frequency will impact your motor controller. low pwm frequencies will not be filtered by the motor (acting as a LR filter) and high frequencies may result in excessive losses within the transistors.

I am by no means an expert in designing motor controllers /H-bridges but I suggest if you plan to build your own for this project you do some extensive research on proper design. you are dealing with some pretty extreme currents that can easily blow up components or melt wires. I haven't built a high powered h-bridge  like this myself but I worked on a project where the electrical engineers built their own for some motors with 110A stall currents... we had lots of problems smoking components and literally blowing up the transistors (pieces of the component flying)...not sure what the problem was but everything can have an impact including the firmware driving the motor controller.

in addition to all the design that goes into the electrical circuits you will also have to consider the thermal design.

I provide this information not in an attempt to discourage you from building your own controller but to share my knowledge of the complexity that is involved in developing a robust motor controller (especially for higher current requirements).


18
Electronics / Re: What control engineer should to know
« Last post by mklrobo on April 11, 2015, 07:41:25 AM »
 ;D Hello!
I do not know of any books readily, but Amazon has a whole world of
books. in the practical sense, go to the Parallax.com chat forum, and you will
find practical applications, as they build the next upgrade of Propeller.(MCU)
The president of the company chats with users online, as they work out
the manufacturing, planning, software, electronics, and applications for the
chip. This is a great opportunity to get real world experience in going through
the design process; and who knows? They may even hire your there!   ;D
19
Electronics / What control engineer should to know
« Last post by Ana_Dig on April 10, 2015, 09:19:39 PM »
I search after information that can explain to me more about what a control engineer in robotics company should to know how to do in these areas:
1. Choose the right controler
2. Control methods and analysis
3. Write the code for all the robot include sensors, motors, drivers, hydraulic and pneumatics, data structure, operating system, signals,  electronics circuit, communication or other
What more maybe need to know a good control engineer that work in robotics applications?
If you know about company that produce a controller and this company wrote a book \ booklet about how to wrote the code for the controller that they did so I will glad  if you can wrote a link to this website also any other website that can be good for this information that I search
20
Mechanics and Construction / piston crankshaft help
« Last post by dvdngu on April 10, 2015, 06:45:14 PM »
Hi all,
I am making a pneumatic piston with a rod and a crank shaft system. How would you make it so the crank shaft only rotates in a specific direction? Thanks in advance!
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