Let's Make Robots!

Restless PID controller


I am building @ mecanum bot and am in the process of tuning the PID-controller for the wheels. The PID-algorithm I implemented works pretty well (I think), but still I am not satisfied. I could do with some advice.

I define motor speed in terms of the number of state changes per second (SC/sec). Max number of SC/s is 5000. If I set the desired speed at 3000 the results are as depicted in the graph. 

How to fix suspension problems @ mecanum bot

I finally have my mecanum bot up & running and did some testing today (http://youtu.be/81F_xTLLb2w). I found the bot drifting due to a lack of traction (not too bad on the video, but erratic behavior elsewhere in the living room ;-). The alloy frame is pretty rigid causing not all four wheels always to be firmly on the ground. Looking for solutions I encountered the idea of dividing the chassis in two parts that can rotate (twist vertical) relative to each other (see pictures). My question regards the "rotation component". What is this for component and were can I buy it.

UDP not working with static IP-address @ WiFi-shield

I use a WiFi-shield (firmware 1.1.0) in conjunction with an Uno R3 and IDE 1.0.5 r2.

If I use DHCP for assign an IP-address to the shield the Arduino UDP NTP-example works fine.

If I set a static IP-address (Wifi.config) I stop receiving UDP packets from the NTP-server.

Any ideas?

Websocket implemenation @ Arduino or @ NodeJS + Firmata

There seems to be something wrong with my latest comments => repost them to be certain.

Architecture @ wifi controlled mecanum robot

Last year I made a mecanum robot controlled by a Spectrum DX8 radio transmitter. Goal of my next project is to control the bot with a tablet. Plan also is to add a video camera on the bot and plaback the video stream on the tablet.

Effect of timers on PWM

All the pwm-pins on my Uno are occupied and I would like to use timer 1 or 2 to set up a timer interrupt to resolve some timing issues. I have learned that using timers cause losing pwm-pins, since the timers are also used for generating pwm-signals by the analogWrite function.

More powerful motors @ Rover 5 ?!

My Rover 5 has become quite heavy (2.5 kg), and the engines are not powerful enough to run it smoothly. I would like replace the motors for somewhat stronger motors. Does anyone have experience with it? Will this goes well with the encoders and the gearbox? Or is it better to switch to a different chasis? And if yes, what would you recommend me?

Dual MC33926 motor driver - control pins

I am looking into the “Dual MC33926 motor driver carrier” and have a question about the control pins  (D1, D2, IN1 and IN2).

Avrdude error @ Dagu Mini Driver

I am not able to upload a sketch to Dagu Mini Driver and get the error message avrdude:
verification error, first mismatch at byte 0x0000 0x3f = 0x41.