Mission to Mars 4 Wheel Rover Build Instructions April 2008

FRODO the NXT Rover Modular design 4 wheels differential drive –Turns left, right, goes forward and reverse Front collision avoidance detection bumper –Left, right, both Light sensor for path detection in front –Protected from ambient light Rear wheel to maintain balance Rover frame decoupled from NXT controller –Controller easily removes from rover (2 pins) ½” clearance from ground Can climb obstacles ¾” high Location for rock capture device Rock deflector in front

Light Sensor Assembly We first insert 2 3X pins into the frame of the light sensor. We then attach 3x5 lift arms to each side of the sensor.

Using regular pins fasten 2 1x9 lift arms to the sides of the 3x5 lift arms. Attach 4 more regular pins into the 1x9 lift arms. These will be used to secure the assembly to the rover’s frame.

Front Collision Avoidance Bumper Position as illustrated 2 1x9 lift arms and 3 3x connectors. Push 2 2x notched axles into the center 3x connector. Push 2 pin axles into the other two 3x connector.

Push 2 4x axles into the top 3x connector, and 2 3x axles at the other end of the same connectors. Finally push 2 regular pins into the center holes of the top connectors. Slip a 4x5 bent lift arm onto the axles and pins. This forms the rock deflector.

Push the axle pin onto the ends of the 2 touch sensors. Attach the other side of the rock deflector and cap the axle ends with full bushings. Finally, attach 2 1x9 lift arms to the casing of the touch sensors with 4 regular pins.

Rear Wheel for Balance We start the assembly by pushing 4 regular pins at the extremity of a 1x9 lift arm. Then we push 3x pins in holes 3 and 7. We attach 90 degrees connectors to the 3x pins. To which we insert 2 2x notched axles. We now install a 4-way connector between the 2 90 degrees connectors and secure it with the notched axles.

We now create a pivot point with a 5x axle that is held in place with a ½ bushing. We push a 4 way pin piece onto the free end of the axle. We make a fork with two 3x5 lift arms, by attaching them to the 4 way pin piece. We then insert two small wheels between the fork and secure them with a 3x axle.

Differential Drive Unit – you will need to make 2 units, this is the right unit. We start the assembly with two 1x16 beams and one 1x4 beam. We position the motor as to line up the holes in the back of the casing with the last 3 holes of the top 1x16 and the motor’s axle hole should line up with the middle hole of the 1x4. We fasten the motor to the frame with 3 regular size pins at the back of the frame. Then we slip a 4x axle through the 1x4 into the axle hole of the motor. We attach a 24 tooth spur gear to the axle.

We then push 2 pin axles, to the left and right of the spur gear, in the 1x16 beam. Then we insert 2 4x axles into the bottom beam in holes 6 and 14. Cap the inside end of these axles with full bushings. Push 2 24 tooth spur gears onto the axles you just installed. Push 2 ½ bushings on top of the gears. Now install 2 small double bevel gears onto the two axle pins. Finally push the two wheels onto the axles.

Module Assembly We start the rover assembly with the drive units. Note that only one unit is shown here. Attach the back wheel to the casing of the motors. Make sure that all 6 pins are properly inserted. Now attach the bumper assembly to the motors with 2 pins on each motor. Temporarily remove the bumper from the touch sensors. Slide the light sensor assembly between the motors and attach it to the motors and bumper.