I’m building a robot hand that mimics a human hand. I’m using a simple glove with sewed in flex sensors on each finger and for the actual robot hand (to move the fingers) I’m using 5 servo motors TowerPro SG 90.
I also wrote a simple code for processing to keep track the gloves finger movement. Arduino UNO reads analog pins (where the flex sensors are connected) and moves the servos accordingly. Also sends the data to processing which then graphs the bending of each finger.
The servos are connected to an external power supply. The signal pins for the servos are all PWM pins on arduino UNO.
Now, everything works fine, except for a small detail. Looking at the graph, finger bending is smooth when the servos aren’t connected, but when I do connect them - small pulses appear (more of them as I attach more servos). This results in a twitching motion of the servo. Even if I attach a small diode instead of a servo the pulses still appear.
I don’t understand what is causing this and how to remove it. :S
I’ve attached two photos of the graphs for one finger:
- servos are attached to Arduino (not powered on, though)
- servos are not attached to Arduino
The grounds are all connected.