Файл: Advanced Robotics with the Toddler (Paralax, student guide, v1.3, 2004).pdf

Page 8 · Advanced Robotics with the Toddler

Download your code using the Run/Run menu or by pressing the ►button on the toolbar. This program runs in an endless loop. When the servos stop moving (this will happen almost instantaneously) move the power switch to off (position 0). Disconnect the servos from the Toddler board. Remove the batteries from the battery box and disconnect the leads from the Toddler’s screw terminal.

Step #4: Install Servo Horns

The following parts are required for this step:

•Two straight servo horns

•(2) Small black screws to hold horn to servo

The servo horns should be installed as straight as the spline notches allow without turning the motor from its centered position (Figure 1-4). Secure each servo horn with the small black Phillips head screw using a screwdriver. The screws were removed from the servo spline in Steps 1 and 2.

Figure 1-4

Both servo horns are installed on centered servos.

Chapter #1: Assembling the Toddler Robot · Page 9

Step #5: Install Brass Wire Keepers on Stride Servo

The following parts are required for this step:

•(2) Brass wire keepers (brass holder, set screw and holding grommet – also called E- Z connectors)

Attach the two brass wire keepers on the outermost holes of the stride servo’s control horn (the white two-arm plastic piece attached to the servo in Figure 1-5). Using pliers, press the rubber “keeper” onto the post of the brass wire keeper. Put the two small screws into the threads of the brass wire keeper so they don’t get lost (Figure 1-6

Figure 1-5

Install brass wire keepers on the stride servo only.

Figure 1-6

Put the two set screws back into the brass wire keeper so they don’t get lost.

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Step #6: Install Top Plate

The following parts are required for this step:

•Toddler Top Plate

•(4) 4/40 3/8” flathead machine screws

•(4) 4/40 nuts

The top plate is most easily installed by turning the Toddler body upside down as shown in Figure 1-7. Position a 4/40 nut over the hole and insert a 4/40 3/8” flathead screw through the top plate from the bottom. Hold the nut with one hand and tighten the screw with the other hand. Repeat process for three more holes. Note: This step uses the “flathead” countersunk 4/40 screws, not the flat “panhead” screws with the round top.

Figure 1-7

Install the Top Plate with the flathead screws.

Chapter #1: Assembling the Toddler Robot · Page 11

Step #7: Install Body Rods for Legs

The following parts are required for this step:

•(2) 3/16” 3” long stainless steel rods

•(4) plastic washers

Slide the two 3” 3/16” stainless steel rods through the two holes in the Toddler’s body (Figure 1-8). Slide a plastic washer over each rod. This washer will keep the Toddler’s legs from rubbing against the body.

Figure 1-8

Slide two rods into body and install four plastic washers.

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Step #8: Slide Legs onto Toddler Body

The following parts are required for this step:

•(4) Toddler legs

Slide the four Toddler legs onto the ends of the stainless steel rods going through the body (Figure 1-9).

Figure 1-9

Slide four legs onto body

Chapter #1: Assembling the Toddler Robot · Page 13

Step #9: Secure Legs with Collars

The following parts are required for this step:

•(4) 3/16” collars with setscrew

•L hex-key wrench in collar package

Find the package of 3/16” metal collars and L-key. Slide the collars onto the stainless steel rod. Tighten each collar using the L-key wrench as shown in Figure 1-10. If the setscrew doesn’t seem to tighten, slightly angle the wrench to prevent stripping of the set screw or wrench. The legs should move freely against the body without binding. If the legs are too tight against the body the servos will strain and the Toddler won’t walk well.

Figure 1-10

Use the 3/16” metal collars. Be sure legs move fairly freely against the body.

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Step #10: Assemble Stride Linkages

The following parts are required for this step:

•(2) 4/40 plastic wire keepers (also called E-Z adjust horn brackets)

•(2) 3/8” 4/40 panhead machine screws

•(2) brass right-angle wires

This is a two step process.

First, insert a 3/8” 4/40 panhead screw through the holes on the rear left leg Figure 1-11. Tighten the screw into the plastic right-angle bracket. Repeat for the process for the rear right leg. Leave the screws loose enough so the bracket and screw can rotate on the leg. Rotate the body 180 degrees.

Figure 1-11

Attach the 4/40 plastic wire keepers with a 3/8” 4/40 screw.

Chapter #1: Assembling the Toddler Robot · Page 15

Using the two right-angle brass wires, slide the straight end through the brass wire keeper hole Figure 1-12. Insert the short end through the top of the plastic right-angle bracket. Tighten the screw to hold the wire.

Adjust the linkages so the legs are vertical, not slanted to either side. Electrically center the servos again if necessary if the servo was accidentally moved. Repeat for the other rear side.

Figure 1-12

Slide four legs onto body.

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Step #11: Attach Ankles

The following parts are required for this step:

•(2) ankle parts

•(4) 4/40 ¼” panhead machine screws

Attach the ankles to the legs using four 4/40 ¼” screws (Figure 1-13). The longer part of the ankle should be oriented towards the back of the Toddler’s body. This placement moves the weight of the robot forward and provides better overall control.

Figure 1-13

Attach ankles.

Chapter #1: Assembling the Toddler Robot · Page 17

Step #12: Attach Feet

The following parts are required for this step:

•Toddler left foot

•Toddler right foot

•(4) 4/40 stainless steel alan-cap screws

•3/32” hex L-key wrench

Line up the ankle into the foot’s 3rd hole from the instep (Figure 1-14). If it is too tight slightly bend the tabs of the feet outward.

Attach the left ankle to the left foot using two plastic 4/40 screws and the 3/32” L-key wrench. These screws have a round head that acts as a bearing surface on the robot’s foot. Repeat for the right side. Ensure free tilting of each foot before proceeding to the next step.

Figure 1-14

Attach feet with Allen-cap screws.

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Step #13: Install Ball Joints

The following parts are required for this step:

•(4) ball joints (ball joint with post, nut)

Install a ball joint on the outermost hole of each foot (Figure 1-15). Securing the nut may require a small wrench to tighten the ball joint unless you have a pair of needle nose pliers. One way to do this is to hold the nut with a finger and turn the ball joint until tight. Don't grip the ball with pliers as this can damage it and prevent it turning freely in its plastic socket when assembled.

Figure 1-15

Install ball joints on feet.

Chapter #1: Assembling the Toddler Robot · Page 19

Install two ball joints on the tilting servo control horn (Figure 1-16). Use the outermost two holes for these ball joints.

Figure 1-16

Install ball joints on servo horn.

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Step #14: Install Tilting Rods

The following parts are required for this step:

•(2) .090” diameter 5.4” stainless steel rod, 2/56 thread on each end

•(4) ball joint plastic cups with 2/56 thread

Thread two plastic ball joint cups onto the ends of the 5.4” stainless steel rod. Place the rod next to the control horn and foot for sizing. To properly position the ball joints make the finished piece about 1/16” longer than it needs to be as the robot stands straight up; this ensures that the out step of the feet will be firm on the ground and aids with turning.

When you’ve got the length about right, snap the rod onto the foot and servo control horn (Figure 1-17

.

Figure 1-17

Install tilt rods.

Chapter #1: Assembling the Toddler Robot · Page 21

Repeat for the other side.

There is an easy way to remove the ball cups from the ball joint. If you need to make adjustments simply place a screwdriver between the ball cup and the Toddler’s foot and carefully pry (snap) it off. It should pop off and can be pressed back on after you make a few turns to adjust.

Toddler Tuning Tips: Toddler functions best when its body is shifted slightly toward the rear feet. Also, with both servos centered verify that the Toddler’s feed are flat on the ground or that the outsteps are angled slightly downward.

When you’re done with this step your robot should look like the one shown in Figure 1- 18. The Toddler functions best when its body is shifted slightly toward the rear feet.

When you pick up the robot, verify that the robot’s feet are flat on the ground, or that the outsteps are angled slightly downward. Electronically center the servos with the BASIC Stamp again if needed to tune the hardware again.

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Figure 1-18

Final installation of tilt rods

Step #15: Install Battery Pack

The following parts are required for this step:

•Battery pack

•(2) 4/40 3/8” long flathead countersunk machine screws

•(2) 4/40 nuts

Stand the Toddler up on its feet.

Install the plastic battery pack using two 4/40 3/8” flathead screws and nuts (Figure 1- 19). The flathead screws will be countersunk into the battery pack when tightened. The screws should be out of the way of the batteries.

Page 24 · Advanced Robotics with the Toddler

Step #16: Install Standoffs

The following parts are required for this step:

•(4) 1” female/female 4/40 standoffs

•(4) 4/40 ¼” panhead machine screws

Using four 4/40 ¼” screws install the four 1” standoffs on the top plate (Figure 1-20).

Figure 1-20

Install standoffs on top plate.