Members: Jiao Qian; Yineng Han; Kyle Pan; Jiawei Liang

 

Introduction

Significance

Microrobots capable of performing robotic tasks in constrained environments are critical for applications including micro medical remote treatment and remote drug delivery that is inaccessible to traditional micro wheeled robot

Challenge

Strong global nonlinearity and bistability are introduced into the internal oscillation during vibration-based locomotion

Goal

Leverage broad frequency bandwidth for high average locomotion speed and multiple locomotion modes

Literature

Project goal

Electro- Mechanical Objectives

By tightly integrating the driving circuit (electronic part) and microbot body and leg (mechanical part), We plan to design a quadruped  microbot driven by vibration motors.
Different from traditional mechanical actuation mechanisms, the microbot can also have degrees of freedom in its planar motions by just using vibration motors.

Software Objectives

By writing different Arduino codes, the microbot can carry out some tasks such as  locomotion, steering, and remote control.

Microbot-α

System decomposition map

Section 1: Design of driving circuit

By integrating the lithium battery, boost circuit module, Arduino and motors, we design the driving circuit (left figure). Through programming, we can active four motors together or in turn, which demonstrate that the driving circuit can work well. The details of actual driving circuit and vibration vedios can be see in “driving circuit page“.

Section 2: Assembled body and legs

We designed several types of assembled body and legs. 

Let’s first have a general idea of them, and then we will tell you about them more detailedly.

Here is the entire history!

Kyle Pan
Our first prototype

The body part (orange) is made by 3D printing with PLA material with legs (green ones) do with flexible.

It is  an relatively successful first prototype. But there are still some improvement that can be made:

  1. Reduce its overall size and weight since it is a microbot
  2. Try with soft material for compliant legs

 

One of the objectives of robot design is to imitate human and animal behavior in order to create machines capable of coexisting in our environment and working alongside us. There is also a strong motivation to emulate the softness of human and animal tissue to ensure safe interaction between humans and robots by developing actuators and sensors that allow moving conformable and deformable structures. 

Our second version prototype, idea comes from the above compliant legs

The body part (black) is made by 3D printing with PLA material with legs (transparent) do with resin material, thus more flexible. 

When we tried with motor, here are some problems:

1. The contact areas are big, increasing the friction
2. Legs are so soft (hollow structure) that they absorb all the force,thus hardly to move foraward

 

Kyle Pan
Third version

Based on the problems from the second version, we made some improvements. We reduced the contact areas and made legs the  solid structure as well. 

It came out that when using the motors, our microbot can go forward via vibration.

Let’s check it out in the following video!

Fourth version

We found that some part of  vibration through soft material will be absorbed by contact surface. Therefore, we want to check if this situation can be fixed when we change soft material (resin) to hard one (PLA).

It turned out to be successful. Microbot vibrates faster than before. The goal for next step is to keep the overall shape and reduce the weight. So we decided to reduce the thickness of legs to one half.

Fifth version-1

Compared to the version four, we reduced the weight by changing the thickness of four legs by 1/2, thus making it more compliant which can be seen in the following GIF.

 

Let’s check it out in the following GIF animation.

Fifth version-2

We also made another version by  changing the “clip  into” assembly method to ” screws and nuts”. In that case,  both reducing the torque and fixing legs to adjust the angle can be achieved.

Section 3: Microbot tasks

By assembling the driving circuit and microbot body and legs, we successfully designed two versions of microbot that can carry out some tasks.

Left is the first version
The driving circuit is placed on the microbot body and the lithium battery is attached on the bottom of the body. Four motors are attached on the bottom of four leg (3,5,9,10), respectively.

Left is the second version
The whole driving circuit is placed on the microbot body. Four motors are attached on the surface of four leg (3,5,9,10), respectively. Note the microbody and leg are fixed together by using screw.

 

Microbot-β

On the Microbot-α, we put motors on the robot’s leg.

But, could we put the motor on the robot’s body?

 

 

Body Structure

Body parts (orange and bule) are made by 3D printing with PLA material. And the leg is made by iron wire.

Why do we use wire for legs? The answer is as follows:

  1. Hard enough. ​                                                 Good vibration transmission effect.​

      2. Small contact area between the iron wire and the ground.  

            Friction is small. 

Movement Mechanism

Video nn the left is the video for going straight.The red line in the video is a reference straight line. When the two motors are started at the same time, the robot will walk along the red straight line.

Video on the bottom is that only turn on one motor.

Problem & Solution

So far, the robot can only walk in a straight line and cannot rotate on its own. To solve this problem, we improved the robot body shape and added new motors.

Application:Sensor

We plan to put the sensors on the micro-robots, so that the micro-robots can take our sensors to some dangerous places and help us collect data.

The sensor we use is a DHT11 sensor, which can help us collect temperature and humidity.

Result

We put sensors on the robot to control the movement of the robot and measure the humidity and temperature of the air. The result is shown on the right, and the robot and sensor work well.

Remote Control System Pipeline

Remote Control System Pipeline

 

Wifi based control of MicroBot​

Cloud UI available anywhere in the world​

A demo of LED control (same principle as vibration motor)

UI wireless control of MicroBot

Timeline and proposed deliverables