Hey all, this is my first post in this forum.

I'm writing because I am concerned on a project that I was given in my uni. We are given a bug and some instructions, so we need to make the circuit to the bug in order to follow this instructions.

Time delay circuit of 8 seconds - this has been sorted out by an RC circuit.
Follow the black line in a white table - Has been sorted out with gates

However my main problem is on the last part, when the bug finishes the white line it has to turn by a decreasing radius until it stops. So that means that I have to decrease its power in order to make it zero but linearly, (we dont care how many seconds it will take). So I am thinking of an attenuator or a differential amplifier. Will they help me to succeed the circuit?

Any other possible analogue implementations?

 

welcome to the forum. you can solve this using discrete parts and gates or... using microcontroller. with microcontroller you could easily generate delays, ramps etc. if you prefer to stick with non-programmable logic, you need to produce signal forms using one way or another. ramp can be generated using RC or better replace R with constant current source (to get linear response). we don't know how your line follower works. one way is to have two larger wheels which are used for propulsion and caster(s) to allow rolling. if one of the wheels keeps on spinning at same speed while another spins faster and faster, you would get what you seek. all it is left is to control motor speed. this can be done with PWM. here is one PWM circuit that is easy to modify for your needs:
http://www.pcsilencioso.com/cpemma/pwm.html