📋 Engineering Design Reviewauto-generated for this build
Degrees of freedom6
Power draw (est.)est. typical load ~21 W avg · ~68 W peak
Battery (est.)est. 2-3S LiPo ~2200 mAh (~16 Wh) → ~45 min
Energy systemLi-ion 21700 · 2S1P · ~0.08 kg · 900 cycles
Green optionSolar trickle/float: a ~4 W panel (pwr-solar-10w ×1) through an MPPT controller (pwr-mppt) makes it ~energy-neutral in daylight (assumes ~80% usable depth-of-discharge and ~5 peak-sun-hours — adjust for your location/battery).
RechargeOnboard charge port (CC/CV charger, charge in place) or contactless Qi pad for low power (pwr-charger-3s / pwr-wireless-qi).
Brain / controllerArduino Uno R3
Est. parts cost$67
Note: power, battery and cost figures are engineering estimates (estimated typical load), not measured values — verify on the bench.
Open design questions
▸ How long must it run between charges?
sets the battery capacity (Wh).
At ~21 W, 2-3S LiPo ~2200 mAh (~16 Wh) → ~45 min. Want more? scale Wh linearly.
▸ How will it recharge?
manual plug, dock, or wireless changes the chassis design.
Onboard charge port (CC/CV charger, charge in place) or contactless Qi pad for low power (pwr-charger-3s / pwr-wireless-qi).
▸ Can the supply handle the current peaks?
peak draw ~68 W ≫ average — stalls/startup spike.
Use a pack with enough C-rate (LiPo handles it) + a buffer capacitor on the servo rail; fuse the battery.
▸ Is position-control enough, or do you need force/torque feedback?
plain servos can't sense load.
Add current-sense or FSRs if it must grip gently / detect contact; else position control is fine.
▸ How are the boards mounted + wired (orderly + reproducible)?
serviceability + repeatability.
3D-printed trays on M2.5/M3 standoffs to each board's real footprint, one internal hole-grid standard, labeled JST connectors, battery low. The auto BOM + netlist make it 1:1 reproducible.
▸ Safety: e-stop, fusing, current limit?
protect the pack + people.
Inline fuse + a master switch / e-stop on the battery; BMS for over-current/over-discharge; soft-start the servo rail.
▸ Can the energy system be greener / smaller / longer-lived?
always optimise the energy part.
Solar trickle/float: a ~4 W panel (pwr-solar-10w ×1) through an MPPT controller (pwr-mppt) makes it ~energy-neutral in daylight (assumes ~80% usable depth-of-discharge and ~5 peak-sun-hours — adjust for your location/battery). Lighter pack: Li-ion 21700 (~0.08 kg). Add a supercap to buffer peaks and shrink the pack.