Boe-Bot Battery Issues
Hi All,
I'm having an interesting time with my Boe-Bot, firstly it appears to eat AA batteries & seem to be having difficulty calibrating my servos & perfecting my 90 deg turns. My main issue appears to be a lack of consistency. I'm working my way through the manual quite nicely, but I can seem to nail the tuning of my right & left turns etc etc. My forward for ten seconds & backwards for ten seconds work fine, but by the time I get around to tuning my 90 turns things go fubar.
This leads to to reload the forward for ten seconds routine to check my calibration and all of a sudden all my previous work calibrating my Boe-Bot seems wrong, in as much as I can't seem to get any consistency in getting my Boe-Bot keep going in a straight line (no code changes, nothing, yesterday straight line repeatedly - today it's curving).
I'm assuming my batteries have flattened, thus causing my issues? How long are they mean't to last?
Cheers
Murdoch
I'm having an interesting time with my Boe-Bot, firstly it appears to eat AA batteries & seem to be having difficulty calibrating my servos & perfecting my 90 deg turns. My main issue appears to be a lack of consistency. I'm working my way through the manual quite nicely, but I can seem to nail the tuning of my right & left turns etc etc. My forward for ten seconds & backwards for ten seconds work fine, but by the time I get around to tuning my 90 turns things go fubar.
This leads to to reload the forward for ten seconds routine to check my calibration and all of a sudden all my previous work calibrating my Boe-Bot seems wrong, in as much as I can't seem to get any consistency in getting my Boe-Bot keep going in a straight line (no code changes, nothing, yesterday straight line repeatedly - today it's curving).
I'm assuming my batteries have flattened, thus causing my issues? How long are they mean't to last?
Cheers
Murdoch
Comments
The battery issue is probably due to a short. Have you tried with a separate battery pack?
Are your encoders installed correctly? That would cause complete inconsistency, anywhere from a small issue to a huge issue.
Many thanks for replying, I'm using a standard original Boe-Bot Robot Kit (USB), not an Activity Bot, hence no encoders. My power is supplied via the Boe-Bot battery pack (4 x AA's).
My servo's appear to be mis-matched as to get it to run in a straight line I'm using the following commands:
PULSOUT 13, 810
PULSOUT 12, 650
Last night the Boe-Bot repeated went in a straight line, this morning and afternoon was spent working through chapter 4, activity #2. Mainly tuning my 90 deg turns on ForwardLeftRightBackward.bs2. The first thing that struck me when trying to work on my turns was that my BB wasn't moving consistently in a straight line, my curves were good one minute, then bad the next, despite NO code changes.
Okay I thought - lets take another look at ForwardTenSeconds.bs2. Yesterday this was pretty good, followed a straight line repeatedly, today it's all over the place. Each time a press reset, it reacts differently - The only thing I can think thats different is perhaps my batteries have run down, as I assume this is the only logical answer to my issues.
Baffled & confused,
Murdock
Servos need quite a bit of power and will turn slower as the batteries weaken. Servos vary a lot from each other so it's normal to have different values for each one. Your batteries should not be wearing that fast unless they are old or a very cheap brand.
Double-check all your wiring. Check all your cables for cuts or any other kind of damage. Also look at the cable connectors for bare wire (there should not be any).
I repeatedly tried to get a robot to perform a figure 8 but changing charge level would throw off the calibration.
I ended up using a higher voltage pack and regulating the voltage to the servos. This solved my calibration issues. I go into a bit more detail in this post.
Without a regulated power source the only other way I know of to get consistent performance from a CR servo is to use encoders.
Servos suck a lot of power from batteries. It's not at all unusual for batteries to drain quickly in this sort of application. IMO, rechargeable batteries are practically a necessity with a robot as power hungry as a BOE-Bot.
BTW, Welcome to the forum. Robotics and electronics in general is the most frustrating when one is first starting out. It gets to be a lot more fun once you gain a bit more experience.
Don't stay frustrated long. As you can see, there are plenty of people willing to help when you ask a question.
Well.....It appears I was having a bad morning
If you look on one of the sides of the servos, there is a place where you can place a screw driver and turn to calibrate the servos. Program the robot with the following:
PULSOUT 13, 750
PULSOUT 12, 750
then turn the screw for each servo until they stop moving. Does this fix your issue?
Good luck,
Vale
Even after setting the zero speed position, it's not unusual for the servos to require different speed settings to in order to travel straight.
810 (speed 60) and 650 (speed 100) is not unexpected. Many motors require more power to turn one direction than the other and gearboxes are all a little different. It's next to impossible to get a robot to travel straight consistently without some sort of feedback (encoders). Without encoders or a line to follow, a regulated voltage source is probable the easiest way to improving performance.