Integration
Estimated time: 2 hours
This page will guide you through the process of installing all components into the frame.
Rope ratcheting
We will use rope ratchets to secure the following components to the frame:
- Portable power station
- SLA battery
- Mini PC
Here is a demonstration of using a rope ratchet to secure a small box to the bottom acrylic plate. See video (2x speed):
Note
We use rope ratchets because they enable components to be installed or removed in just a few seconds. For a more permanent setup, custom component mounts can be designed.
Portable power station
Estimated time: 15 minutes
Follow the steps below to secure the portable power station (camping battery) to the frame.
Note
It is important to secure the camping battery to the frame because:
- We don't want the camping battery to move around or fall out of the base during operation
- For controller setup, we need to elevate the wheels off the ground by turning the base on its side
Tip
Make sure the portable power station is operational before installing it into the frame. Check that the AC outlets can power your arm and mini PC.
Attach the bottom acrylic plate using 10mm screws:
Secure the camping battery to the bottom plate using 3 double-looped rope ratchets:
Note
The AC outlets should be on the right side of the mobile base.
Here is a view of the bottom of the mobile base:
Note
On the underside of the base, perpendicular ropes should be arranged such that they do not touch each other.
Note
We place the front edge of the camping battery on the bottom plate rather than the crossbar, as we found this arrangement to be less prone to sliding:
Move one of the bottom crossbars to create an opening for inserting the camping battery:
Insert the camping battery, then move the crossbar back to its original position:
Secure the camping battery to the bottom crossbars using 3 rope ratchets in the front-to-back direction:
Note
The AC outlets should be on the front side of the mobile base.
Use 4 more rope ratchets in the side-to-side direction to secure the battery to the top crossbars:
Note
These ropes should be looped around the top crossbars to keep the battery from sliding side to side:
To maintain compatibility with the top acrylic plate, loop around the crossbars only at these specified locations.
Here is a view of the bottom of the mobile base:
Note
On the underside of the base, perpendicular ropes should be arranged such that they do not touch each other.
Attach the bottom acrylic plates using 4 support brackets, 10mm screws, and slide-in T-nuts:
Note
Turn the mobile base on its side to test the stability of the mounting. If the rope ratchets are sufficiently tight, the camping battery should remain securely in place.
Attach the bottom acrylic plate using 10mm screws:
Secure the camping battery to the bottom plate using 2 double-looped rope ratchets:
Note
The AC outlets should be on the front side of the mobile base.
Once the portable power station is securely attached to the frame, plug in the charging cable:
SLA battery
Estimated time: 5 minutes
Follow these steps to set up the SLA battery mount on the back side of the mobile base:
- Attach the 3D-printed battery mount to the bottom plate using four 10mm screws and T-nuts
- Install a rope ratchet on the bottom plate for securing the SLA battery to the mount
Place an SLA battery into the mount and secure it with the rope ratchet:
Verify that the mount functions properly by turning the robot on its side. The SLA battery should stay securely fixed in place:
Caster modules
Estimated time: 20 minutes
Install the caster modules into the frame according to the following schematic:
Note
This is the caster configuration used by our low-level controller.
For each caster module, start by using the alignment jig to position the eight T-nuts:
Next, use eight 10mm screws to secure the caster module to the frame. See video (2x speed):
Note
Make sure to use the longer 10mm screws, not the 8mm screws.
Note
We are using the 1/4" tapped holes in the caster module main plate as M5 clearance holes.
Tip
The screws are not supposed to feel tight until they are fully inserted. However, these screw holes are highly sensitive to misalignment. If a screw feels stuck, loosen it slightly and wiggle the module to correct the alignment before continuing.
Note
After installing the caster modules, check that each one is completely flush against the frame like in the left photo. There should not be a gap like in the right photo.
After installation, the configuration of the caster modules should match the schematic:
Power system
Estimated time: 30 minutes
Use zip ties to secure the PDP to the left side of the mobile base:
Connect all motor power cables to the PDP and organize them using zip ties:
Due to the large size of the camping battery, 8 of the 16 motor cables are too short to reach the PDP. Follow these steps to set up extensions for those cables:
- Cut eight pieces of 10 AWG wire (4 red and 4 black) to a length of 10–20 cm
- Connect the wires to the PDP
- Attach a 10 AWG wire connector to the free ends of the wires
Use zip ties to secure the PDP to the left side of the mobile base. Then, connect all motor power cables to the PDP and organize them with zip ties:
Tip
Wires can easily detach if not fully inserted into the connectors. Check that all connections are secure by giving each one a tug:
The 120A circuit breaker can stick out of the frame (left photo), which can lead to motors shutting off unexpectedly if the red manual trip button is accidentally bumped. To avoid this, secure the breaker to the camping battery using a zip tie (right photo).
Tip
Double-check all PDP connections and make sure there is no exposed metal like with the black wire in this photo:
Connect all encoder power cables to the PDP using the previously assembled wiring harness:
CAN system
Estimated time: 10 minutes
Secure the CANivore to the portable power station using a zip tie. Connect the CANivore to motor 1 and the termination resistor to motor 8:
Next, connect the remaining CAN bus cables and organize them using Velcro cable ties:
Mini PC
Estimated time: 5 minutes
Attach the mini PC to the frame using rope ratchets, zip ties, and/or frame gussets. Next, plug the power adapter into an AC outlet on the portable power station:
Install the USB hub and HDMI extender, which are useful for connecting a monitor, keyboard, and mouse to the mini PC.
Note
Make sure all cables are securely fastened to prevent them from accidentally getting caught in the caster module gears.
Integration testing
The mobile base should now be ready for integration testing with the software. Before proceeding, please perform the following checks:
- Double-check the polarity of all power and CAN connections
- Verify that all connections are securely attached by gently tugging on each one
If everything checks out, please proceed to the Software page for further setup.
Once the mini PC and codebase are ready, we typically perform an integration test using gamepad teleoperation. This involves turning the base on its side and verifying that the casters move as expected:
After confirming that the mobile base is operational, return to this page to complete the remaining integration steps.
Cable organization
Estimated time: 5 minutes
After confirming that the mobile base is operational, use cable sleeves to further organize the CAN wiring:
Base camera
Estimated time: 5 minutes
Install the Logitech camera to the front of the mobile base using these steps:
- Insert the 3D-printed shim into the hinge to lock the camera angle
- Place the camera between the top and bottom parts of the 3D-printed camera mount
- Secure the mount to the frame using two 10mm screws and roll-in T-nuts
- Route the USB cable to the mini PC and plug it in