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main site > home > Mechanisms for simple walking robots   David Buckley - 06 April 2009

Simple Walker Mechanisms

If you can't see a video of the robot working, or the design isn't by a well known toy-manufacturer, then the design may not work! Hexapods
Heavy Duty Hexapod - G McComb book
BoeBot Crawler
Mechanical Insect
Soccer Jnr
Green Hexapod
Karl Williams Hexatron
Quadrupeds
Tamiya Race Horse - forwards/backwards only
Tamiya Tiger - forwards/backwards only
Meccanoe Elephant - forwards/backwards only
HE - Walking Robot
Bipeds
BigFoot, Toddler and Ambler
Karl Williams Biped
HE - Walking Robot

Hexapods


Hexapod based on Robot Builder's Bonanza by Gordon McComb
Chapter 22 Build a Heavy-Duty Six-Legged Walking Robot
Seen - Denver Area Robotics Club - Gallery - video

www.ranchbots.com/club/photos/photos.htm

Operation
Each leg is operated by a crank-axle and constrained at the top by a pin sliding in a slot in the chassis.



Bigger image


Animated GIF of crawler
BoeBot Crawler
The Crawler is a ready to assemble kit that converts a Parallax BOE-BOT into a high quality precision walker. It works with all standard BOE-BOT code -- "No special programming". The Crawler has a full range of movement. It can walk forward and backwards, and turn left and right. It responds instantly to terrain changes and adjusts its walking pattern to compensate without special programming. It has a high level of ground clearance and can walk over most obstacles under one inch.

Operation
Centre legs operated by a crank-axle and constrained at the top by a pin on the chassis sliding in a slot in the leg. Other legs swing by push/pull rods from their tops to the crank-pin.


Mechanical Insect
  • Total length: 116mm
  • Total weight: 135g (w/ out batteries)
  • Body material: ABS resin
  • Gearbox, motor, remote-control also included.
  • A screwdriver for the assembly is provided.
  • Requires two R6/AA/UM3 batteries (sold separately).
  • Continuous running time with Alkaline battery, 2 hrs.
Operation
Same as BoeBotCrawler except top of centre leg constrained by a radius-arm from rear axle.

Soccer Jnr
Mfr. # OWI-9820

Operation
Same as BoeBotCrawler.


Green Hexapod
Google Images
Spider 3 Walking Avoider Robot Kit
http://www.robotstore.com/store/product.asp?pid=254&catid=1633

a two motor, six legged walking robot

Operation
Same as BoeBotCrawler except front and rear legs are connected by a rigid beam driven back and forwards by the crank axle riding in a vertical slot. And the middle leg is driven by a crank axle at the top and (must) have a vertical slot which slides on a pin behind the middle white hemisphere.


Hexatron
thinkbotics.com - Karl Williams

a two motor, six legged walking robot with a pic 16F819 microcontroller brain and infrared obstacle avoidance capabilities.

Operation
Same as Mechanical Insect.
Link from top of rear leg to crank-arm on Potentiometer.
The Potentiometers seem to be an unneccessary complication except when the computer uses them to count the number of steps each leg has taken.


Quadrupeds


Mechanical Racehorse
Tamiya Robocraft Series

Power from the rotating motor is transferred to the legs via link rods to make the horse gallop. Two link rod holes on the back legs allow you to choose between two running styles. Run on flat, smooth surfaces. Avoid running over slopes, on bumpy roads or on thick carpet.

Specifications:

  • Total length: 193mm
  • Total height: 95mm
  • Body material: ABS resin
  • Gearbox, motor, reverse switch also included.
  • Stickers for horse's mask and number, and jockey's clothes are included.
  • Requires one R6/AA/UM3 battery. (sold separately)
  • Continuous running time with alkaline battery: 1.5hrs.
Comments
Can't turn as only one motor

Operation
Same as HE-Walking Robot 4 legs, except crank-axle at rear and rear leg radius-arm goes to front axle.rods from crank-pin.


Mechanical Tiger
Tamiya Robocraft Series

Power from the rotating motor is transferred to the legs via crank plates to make the tiger walk. 2 possible gear ratios coupled with 4 different strides let you choose 8 different speeds. A reverse switch also allows backward movement. A see-through switch with yellow transparent parts adds a cool, futuristic look. Moreover, this feature also allows you to see internal mechanisms.

  • Total length: 155mm
  • Total weight: 105g (w/ out batteries)
  • Body material: ABS resin
  • Gearbox, motor and reverse switch included.
  • 2 possible gear ratios coupled with 4 different strides let you choose 8 different speeds.
  • A screwdriver for the assembly is provided.
  • Requires one R04/AAA/UM4 battery (sold separately).
  • Continuous running time with Alkaline battery, 2 hours.
Comments
Can't turn as only one motor

Operation
Same as Race-Horse, except mechanism reversed front to back.rods from crank-pin.


Meccano Walking Elephant
by Arup Dasgupta
http://www.users.zetnet.co.uk/dms/meccano/nutty/index.html

Based on the walking mechanism from the French set 9550 Mammoth.

Comments
Can't turn as only one motor

Operation
Front (to left) leg on a crank-pin on yellow crank-wheel and push/pull link to rear leg all in one.


Walking Robot, 4 legs
http://www.hobbyengineering.com
  • Build either 2, 4, or 6-legged walking robot powered by single motor.
  • Use the sound activated sensor (pre-assembled) to start and stop the robot by clapping or making other loud noise.
  • Simple, easy-to-build design uses small number of parts and pre-built gearbox.
  • Assembly uses no screws, only simple-to-use yet secure push rivets.
  • Uses two R6/AA/UM3 batteries (Not included).
  • Sound sensor unit (assembled)
  • Motor
  • Universal plate (clear) x 2
  • Long universal arm x 4
  • Universal bolts x 4
  • Push rivets (full set)
  • Gearbox (pre-built)
  • Battery case
Comments
Can't turn as only one motor.
Six legs is same as Mechanical Insect but can't turn as only one motor.

Operation
Front legs on crank-axle, top constrained by radius-arm. rear legs operated by push/pull rods from crank-pin.


Bipeds


BigFoot Walking Robot
www.davidbuckley.net/DB/BigFoot.htm

Toddler Walking Robot
inspired by BigFoot
www.parallax.com

Ambler Walking Robot
www.davidbuckley.net/DB/Ambler.htm

Someone has made a Beam version of BigFoot

Operation
Uses two servos, one to roll so the weight is over one foot then the other servo to move one foot back and the other forward

  • BigFoot video
  • Toddler videos on Parallax's site
  • Ambler videos on YouTube

  • Bipedal Walking Robot
    thinkbotics.com - Karl Williams

    I have been unable to find anyone who has built this and got it to walk successfully. There seems to be a problem with the design. The feet need to overlap when walking otherwise it would fall over when it lifted a foot from the floor, however then the toes would hit when doing a skid steer turn (one foot goes back, the other forward). It may work due to sloppy enginering so that when walking the body sags and the in-air foot swings in so the toes overlap, then when turning, because the of the friction between the feet and the floor, the feet are forced out and the toes miss as the feet pass each other. The robot has a look which says 'build me' but I think you will be very disapointed if you do.

    Uses overlapping Feet
    Walks on two legs with the help of a microcontroller and the same electronics as the Hexatron robot. Also uses a twin-motor gearbox [Tamiya 70097 Twin-Motor-Gearbox] - one motor/gbox for each leg, an inexpensive H-bridge motor controller, leg position sensors, and the Sharp GP2D12 infrared sensor. See - Build Your Own Humanoid Robots

    "...Each leg bends at the knee and has a position sensor (potentiometer) so that the walking routines can be accurately programmed. This robot gains stability statically by using a large foot in the form of three sides of a square.
    ...It lifts one foot up so that the lateral rods of this foot pass over those of the other, by bending at the knee. The center of gravity of the body is always over the foot that is on on the ground..."
    Build Your Own Humanoid Robots

  • Build Your Own Humanoid Robots - Karl Williams - bookcover
  • this walker as built by Ken York
  • below from Humanoid Robotics Design Considerations by Karl Williams, Servo Magazine March 2004

  • Walking Robot, 2 legs
    http://www.hobbyengineering.com
    • Build either 2, 4, or 6-legged walking robot powered by single motor.
    • Use the sound activated sensor (pre-assembled) to start and stop the robot by clapping or making other loud noise.
    • Simple, easy-to-build design uses small number of parts and pre-built gearbox.
    • Assembly uses no screws, only simple-to-use yet secure push rivets.
    • Uses two R6/AA/UM3 batteries (Not included).
    • Sound sensor unit (assembled)
    • Motor
    • Universal plate (clear) x 2
    • Long universal arm x 4
    • Universal bolts x 4
    • Push rivets (full set)
    • Gearbox (pre-built)
    • Battery case
    Comments
    Can't turn as only one motor

    Operation
    Overlapping feet, each leg on a crank-axle, constrained at top by red radius-rod.