i am working on a robotic hand with 5 servos and 5 flex sensors.the problem is i have only one ground for 5 pins to be grounded on arduino board how do i connect them
Servos have 3 lines.GroundV+SignalFlex Sensors Probably have 2 lines.GroundV+ Connect all the V+ to the positive terminal of your battery or the 5V from the arduino (depends on setup/component). Connect all the grounds to the negative terminal of your battery or the Ground on the arduino (The -ve terminal of the battery and ground of the arduino are connected internally on the arduino board if you plug into the jack) Connect the Signal lines on the servos to digital pins on arduinoConnect the flex sensors to analogue pins on the arduino with a pullup resistor/voltage divider circuit. To answer your question you need to expand the ground on the arduino to accommodate a ground from each of the components you plan to add.
Ground is usually the -ve connection to the battery and a wire(s) connecting all of the ground points of the circuit.