Mechanical Designer - Safe Robot Dock Charging Contact Adapters Anyone

We're Addition Robotics, building Plus, a bimanual mobile robot that works alongside care teams in senior living communities.

SCOPE
Replace the existing Anderson connectors with a safe automatic docking contact interface. We already have the battery, selected charger, and autonomous docking system. The robot can dock and reach its charging position. Your work is selecting suitable charging contacts and designing simple dock-side and robot-side adapters around them, not redesigning the charger or autonomous docking system.

We have a 24V 50Ah battery and a selected 20A charger, described as 25.6V; we will provide the actual battery/BMS and charger specifications so contact ratings and operating voltage can be verified. The additional charging interface should stack vertically with our existing docking interface without interfering with it. We will provide robot/dock CAD, mounting constraints, and docking-position tolerance information.

REQUIREMENTS
- Prefer suitable off-the-shelf contacts and simple printed holders. Basic CAD sufficient for manufacture and assembly is all that is needed; cosmetic detailing is not required.
- Carry the charger's 20A output at the verified operating voltage, with suitable contact resistance and thermal performance.
- Mate reliably despite docking-position variation, with appropriate alignment, compliance, contact force, and travel.
- Protect against accidental short circuits, reversed polarity, conductive objects bridging contacts, and unintended contact during misalignment.
- Provide insulation, secure retention, and cable strain relief on both sides.
- Address safe engagement/disengagement and whether contacts can mate under load. Flag any required interlock or charge-enable changes during the concept phase; do not assume mechanical shielding alone resolves every electrical risk.

FIXED DESIGN BUDGET: US$300 TOTAL
Milestone 1 - Contact solution and concept ($50): Review supplied information; recommend contacts with specifications, concept sketches, protective geometry, and the safety approach. Identify key risks and any scope dependencies. No detailed CAD required. This is a standalone paid concept phase. We may choose whether to proceed after review.
Milestone 2 - Basic CAD and testing support ($250, subject to written approval and funding): Deliver native editable Fusion 360 models for both adapters, print-ready files, BOM, connection/assembly instructions, and a practical test procedure. Review our test results and support 1-2 planned revision rounds. Do not start this phase before approval.

We will 3D-print the parts, purchase components, assemble, and test in-house. We will share photos, videos, measurements, and issues for you to address. Purchased components and printing are separate from the design fee.

Testing should cover repeated docking, alignment tolerance, charging behavior, contact voltage drop and temperature rise, and protection against foreseeable unintended contact. Agree measurable acceptance criteria before detailed design. Any fault testing must use an appropriate controlled procedure, not an uncontrolled battery short circuit.

TIMELINE
Start ASAP; target completion in 3-4 weeks including our printing, testing, and your revisions.

YOU
Experience designing physically built electromechanical interfaces, charging contacts, or repeated-mating connectors; sound understanding of DC power-contact selection and protection; native Fusion 360 capability; clear English and reliable async updates.

TO APPLY
Start your proposal with "dock" and include:
1. Photos/video of a relevant interface you personally designed and built, explaining your contribution.
2. One failure found during testing and how you corrected it.
3. How you would approach alignment and accidental-short protection for this interface.
4. Your availability and whether you can deliver the stated scope within $300 ($50/$250) and 3-4 weeks.

Charger/battery design, autonomous docking development, and custom charging electronics are outside scope. Flag any required changes to those systems before proceeding. read less