Biorobotics Laboratory BioRob

Elmar Dittrich

"Modular Robot Unit - Characterisation, Design and Realisation"

summer internship 2004

Introduction

The aim of this project was to develop a modular robot unit in real hardware. After several simulations have been done already by D. Marbach and B. Mesot it was on time to have some physical implementations. Contrary to the simulations one has to deal with multiple defiances:

• mechanical degrees of freedom (DOF)
• size/force/energy-consumption - ratios
• connections-mechanism

Everything had to be done under the constraint of "cheap design" - because the price really matters when you want to have a hundred of them.

Therefore it is absolutely necessary to use as much off-the shelf products and parts as possible. We decided to use standard servos with a good price/torque - ratio. The other materials are pretty light-weighted (PCB-circuit-base and aluminum). The power comes from Lion-rechargeable-batteries which are used for several other projects in the lab. Even the aluminum-lever is a standard u-profile modified with some holes and cuts.

The setup consists of six-handmade modules and one control unit. The control unit represents FPGA-development-board and Bluetooth-device to communicate wireless with some host pc. The two wires leading from the modules to the board are providing the PWM signal for the servos and ground signal to have the same zero potential like the FPGA.

On the host PC are two possibilities to control the modules. You can run a Java-GUI developed by J.-P. Egger and modified to send the trajectories via the serial interface (RS232) to the Bluetooth device connected to the computer or to create any trajectory by an external program, like Matlab and write it to a file. This file can be transmitted in the same way like before.

Rico Möckel has just finished integrating all electronics, controller and Bluetooth on-board. Now we have fully autonomous modules in sense of power supply and communication.

Pictures

JAVA-Motion-Interface

JAVA-Motion Interface_instrutions.avi (11.5 MB) Here you can see how to use the JAVA-GUI to create trajectories.

Documentation

modrob.pdf (7 MB) documentation of the project
presentation_modrob.ppt (5 MB) compact version without videos
presentation_modrob_all.zip (42 MB) zip-file of the presentation including videos

Videos

Modules individual:

3-modules-pulling-truck.avi (1 MB) three modules moving autonomously and pulling truck
3-modules-pulling-truck.mpg (4 MB) three modules moving autonomously and pulling truck

With two modules:

2-head2head_plastic.avi (388kB) two modules connected head-to-head
2-head2head_plastic.mpg (1.2 MB) two modules connected head-to-head
2-head2head_carpet.avi (1.3 MB) two modules connected head-to-head moving over carpet
2-head2head_carpet.mpg (3.7 MB) two modules connected head-to-head moving over carpet
2-head2tail_plastic_slope.avi (1.6 MB) two modules connected head-to-tail (snake like) climbing slope
2-head2tail_plastic_slope.mpg (4.7 MB) two modules connected head-to-tail (snake like) climbing slope
2-head2tail_wood.avi (1.3 MB) two modules connected head-to-tail moving over slippery wood floor (**)
2-head2tail_wood.mpg (4.1 MB) two modules connected head-to-tail moving over slippery wood floor (**)
2-head2tail_plastic.avi (1 MB) two modules moving over plastic (*)
2-head2tail_plastic.mpg (3.1 MB) two modules moving over plastic (*)

With three modules:

3-head2tail_dragon.avi (600 kB) three modules connected in-line moving dragon like (*)
3-head2tail_dragon.mpg (1.7MB) three modules connected in-line moving dragon like (*)
3-head2tail_dragon_carpet.avi (800 kB) three modules connected head-to-tail changing movement autonomously (**)
3-head2tail_dragon_carpet.mpg (2.2 MB) three modules connected head-to-tail changing movement autonomously (**)
3-modules_hopping.avi (900 kB) three modules moving by indirect push of on helper-module (*)
3-modules_hopping.mpg (2.5 MB) three modules moving by indirect push of on helper-module (*)

With four modules:

4-modules_sidewinder.avi (980 kB) four modules moving like sidewinder (*)
4-modules_sidewinder.mpg (4.7 MB) four modules moving like sidewinder (*)
4-modules_traveling_wave.avi (1.1 MB) four modules moving like snake (traveling wave)
4-modules_traveling_wave.mpg (3.1 MB) four modules moving like snake (traveling wave)
4-modules_inchworm.avi (1.1 MB) four modules moving like inchworm
4-modules_inchworm.mpg (3.2 MB) four modules moving like inchworm
4-modules_dragon.avi (900 kB) four modules moving dragon like
4-modules_dragon.mpg (2.5 MB) four modules moving dragon like
4-modules_runner.avi (700 kB) four modules braking sonic barrier (**)
4-modules_runner.mpg (2 MB) four modules braking sonic barrier (**)
4-modules_dog_walking.avi (1.4 MB) four modules forming 2D-dog
4-modules_dog_walking.mpg (1.9 MB) four modules forming 2D-dog
4-modules_hopping.avi (1.1 MB) four modules hopping with the help of inertia
4-modules_hopping.mpg (1.6 MB) four modules hopping with the help of inertia
4-modules_turtle_in_the_sand.avi (2.5 MB) four modules crawling like a turtle on the beach (*)
4-modules_turtle_in_the_sand.mpg (3.1 MB) four modules crawling like a turtle on the beach (*)

With five modules:

5-modules_hopping_dog.avi (1 MB) five modules hopping like a dog with fixed forelegs (**)
5-modules_hopping_dog.mpg (1.4 MB) five modules hopping like a dog with fixed forelegs (**)
5-modules_walking_dog.avi (1.1 MB) five modules walking like dog
5-modules_walking_dog.mpg (1.5 MB) five modules walking like dog
5-modules_snake_large_ampli.avi (2 MB) five modules snake like (traveling wave with large amplitude) (*)
5-modules_snake_large_ampli.mpg (2.6 MB) five modules snake like (traveling wave with large amplitude) (*)
5-modules_snake_small_ampli.avi (2.8 MB) five modules snake like (traveling wave with small amplitude) (*)
5-modules_snake_small_ampli.mpg (3.5 MB) five modules snake like (traveling wave with small amplitude) (*)
5-modules_crawler.avi (2.9 MB) five modules connected in serial crawling on the floor
5-modules_crawler.mpg (3.6 MB) five modules connected in serial crawling on the floor

With six modules:

6-modules_rolling_track_far.avi (900 kB) six modules doing the famous "rolling track" (*)
6-modules_rolling_track_far.mpg (1.5 MB) six modules doing the famous "rolling track" (*)
6-modules_rolling_track_crazy.avi (900 kB) six modules as rolling track with higher frequency (**)
6-modules_rolling_track_crazy.mpg (1.5 MB) six modules as rolling track with higher frequency (**)

* interesting
** most interesting