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MTR - A planetary surface exploration rover - My PhD

My PhD work from concept to implementation :)



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Hi mintvelt,

 Thanks for the positive feedback :)

Now on your questions:

- I used 24v motors with 3000:1 serial gearboxes for drive (x4) and body rotation motors (x2) (yes the body rotates around the axis that links the two shoulders via an active differential:), with 800:1 serial gearboxes for Steering (x4), with 100:1 epicyclic gearboxes (x4) for suspension

 -I used a distributed control architecture with 20 PIC controllers, 4 inside each leg electronics compartment and four inside the body. Each compartment also included its associated motor drivers. 14 DOF full PID control. Gumstix verdex was going to be the main controller - never integraded as time did not allow.

- In terms of sensors i used limits for stering and suspension, quadrature encoders HEDS as well as US robotics for all motors, potentiometers to get absolute posistion for steering, suspension and body rotation, Sharp IR rangefinders (8 on body, 1 on each leg, one one each steering bracket), Freescale 3-axis accelerometer, a number of photodiodes for alligning with other systems and wanted to integrade digital compass and GPS but time did not allow. 


The wheels (hubs-pims-spokes) I machined myself on a standard lathe. The tires came from 1/24 scale monster truck. It  took 4 full-time weeks for those four! Apart from the wheels and small spacers etc. all the remaining parts where made on 3-axis CNC

The video was made sometime during the summer of 2005. The cables coming of are motor/logic power and comms. It now supports wifi and has 220 Wh of lithium polymer on-board. I will soon be making the second generation model:))

What is not shown on the video is:

-Full 360 body rotation (around the axis that links the two pairs of legs to the body with custom made electrical union)

-Tip-over recovery 

-Wheel-Walking capability

-Picking-up/disposing tools using hooks on the body. In the pic you can see a Battery Pack being picked-up and integraded on the MTR's body, hence its name MTR - Multi Tasking Rover!

You've just upped the Wow factor tenfold! 4 weeks for those wheels. Definitely worth it! They look absolutely amazing. You've also raised many more questions. 

- 3000:1 drive gears. How fast are those motors? What type of motors?

- 20 pics. Thats quite a lot. What type? what are their functions? how do they talk to each other? 

- 12 Sharp sensors. I cant make out the ones on the legs. In fact  I cant make out any. Do you have detailed pictures?

- "Photodiodes for aligning with other systems" : what other systems? With what kind of interface?

- Which moves can it do autonomously and which moves are remote controlled? 

 Terribly sorry about all those questions, but you have to realize that you've posted your robot on a website with some of the most curious of robot builders. We need to steal every idea you've had ;)


Hi mintvely,

I am happy to answer all your questions after all my aim is to give this system to the community :)

I will soon be designing a half scale model of which the CAD files i am planning to give online :))

Now on your questions:

 -planetary rovers move with exceptionaly low speeds. this a funtion of comm delays, reduced on-board computing muscles and totally unknown hostile environments. I used inexpensive motors from MFA como drills, which i wouldn't recommend to anybody. the rover's final speed came to approx. 5cm/sec consistent with all mars rovers (to date).

-20 PICS: 14 pre-programmed motor contollers came from http://www.jrkerr.com/ these support full PID speed/position servo control. the rest were PIC18F452 and were used for local behavioral loops as well as for data acquisition from sensors. I used an RS458 electrical protocol for the comms bus

-16 sharp sensors :)))

-the rover is called MTR - Multi Tasking Rover because rover functionality is decoupled from rover mobility. i.e. the rover doen not carry any instruments or tools. these come in separate modules called Packs which encapsulate all the necessary functionality to carry out a mission objective. for example a manipulator pack, a weather station pack a drill pack etc. these systems use an 850nm laser diode which the rover picks up and uses to allign with them and acquire. once on-board the pack comms with the rover through the rs485 bus, which it becomes a member of. in effect you can get multiples of the functionality a single rover can nowadays deliver with only a fraction of the payload. very important for a space system as you may understan. A closer look at the PIC will show the first and only Pack that has been designed to date (for concept evaluation purposes) 

-the rover is controlled via a behaviour based architecture. a number of safety and traversal enhancement behaviours are enabled by the tele-operator as they may wish. by utilising sensor data you can do automatically fancy things like (((:

accelerometers: adjust body pitch and roll

Sharp IR: avoid obstacles, stop within a certain range from obstacle, level body 

I want to be part of this community and give my knowledge as much as I can. After all knowledge is there to be spread! So keep asking:))))