effect gradually increase and recalculate if collide with objects?

Unity Engine
1

hi all,
i face some problem in my works.
which i intended to slow the player if collide with objects for 5 secs which in the 5 secs, the movement speed will decrease and increase back to the original speed in 5 secs.
just like if the movespeed is 1 and once it collide with the object it turn to 10.6,and in the next seconde, it turns to 10.7, and until 5 sec the speed will increased back to 1.
following is the code i working on:

void OnTriggerEnter(Collider other)//function for obstacles to cause slow on gameobject
	{	
		if ((other.tag == "Obstacle")(trigState==0))
		{
			slow = (float)(speed * 0.6);
			trigState = 1;
			StartCoroutine(shake());
			Invoke("Delay",1f);
		}
void Delay() 
	{
		slow = (float)(speed*0.7);
		Invoke("Delay2",1f); //seconds for gameobject to collide another obstacles
	}
	void Delay2()

	{
		slow = (float)(speed*0.8);
		Invoke("Delay3",1f);
	}
	void Delay3()
	{
		slow = (float)(speed*0.9);
		Invoke("RepeatDelay",1f);
	}
	void RepeatDelay() 
	{
		slow = 1;
		trigState = 0;//reset					
	}
	public void Update() 
	{
		transform.Translate(Vector3.forward * speed * slow);
        }
	}

this is the way i am doing, but maybe there is more effecient way to do it.
the main problem i facing is that
if i want to recalculate the slow time if player collide another object in the periods of 5 secs,
how could i make it?
thanks if guides and helps could get from u…thanks =)

2

anyone can help?@@

3

One way to do something like this is:

if collide then
  curSpeed = baseSpeed * speedModifier

In Update
  every 1 second
    if curSpeed < baseSpeed
      curSpeed *= 1.1 //math is probably off a bit
      if curSpeed > baseSpeed
         curSPeed = baseSpeed