What is Servo Easing?

Servo easing is a technique used to improve the smoothness of the movement of servo motors. It is achieved by using a mathematical algorithm to adjust the acceleration and deceleration of the servo motor as it moves between two positions. This helps create a smoother, more natural motion and can help reduce motor noise and wear.

Get the Servo Easing cheatsheet PDF and support my work

You can download a Servo Easing cheatsheet PDF and support my work at the same time, its available on my Buy Me A Coffee page. It only costs £5 and will help support my YouTube channel and keep me making more robots!

Click Here to get the PDF

Types of Servo easing algorithms

There are quite a few common servo easing algorithms, we’ll look at the most common here.

There are 3 types of algorithm:

1. Ease In - starts with a slow changing value and builds up towards the end position
2. Ease Out - starts with a fast changing value and slows towards the end position
3. Ease In-Out - Starts and ends with a slow changing value, with a burst of speed half way through

For each of the Ease-in, Ease-out and Ease-in-out, there are also many different algorithms which change the speed of increase and decrease of the easing:

• linear - (no easing applied)
• Sine
• Circular
• Quad
• Cubic
• Quart
• Quint
• Exponential

How easing works

Easing algorithms take 3 initial values:

• Start value
• End Value
• Duration

The ease function will calculate the position of the servo, given a time value.

A time value of 0 will give the the start value, a time value of the duration with give the end value, and any time value inbetween 0 and duration will give the servo value, based on which easing algorithm is used.

Here is an example snippet of code, for the ease in quad algorithm.

def ease_in_quad(t: float) -> float:
    """ t is the time value, returns the servo position"""
        return t * t

Code

Here is the link to the Github repository that contains the easing.py code: https://github.com/kevinmcaleer/bubo-2t

Pancake-Bot

As of the writing of this article, its nearly Pancake day (also known as Shrove Tuesday), so I thought it would be fun to create a robot that can flip pancakes. This would also be useful for experimenting with servo easing techniques, to find the best one for flipping a tiny 3d printed pancake.

Features

This small robot has two servo controlled arms, with cooking implements attached:

• a cooking spatula
• a frying pan

The robot also has a small pancacke, and an optional chef’s hat.

Bill of Materials

Download the STLS and print today

There are quite a few parts, some of which are very delicate so becareful when removing them from the build surface and when removing suport structures.

• chef.stl
• hat.stl
• head.stl
• left_arm.stl
• pan.stl
• pancake.stl
• right_arm.stl
• spatula.stl

Pancake-Bot code

The code for Pancake-Bot is bundled with the Bubo-2t Repository; you’ll need to upload the bubo folder to the Pico or Servo 2040, along with the chef.py Python file.

There is also a Jupyter Notebook named notebook.ipynb which contains code for you to explore and experiment with.

Wiring

The left_arm (the one with the frying pan) is connected to servo socket 1 on the Servo 2040, the right_arm (the one with the spatula) is connected to servo socket 3 on the Servo 2040.