r4.11 is electrically, mechanically, and software compatible with r4.3, r4.5, and r4.8.
This revision supports two alternate footprints for the CAN-FD transceiver to better support component availability and refines the power stage for the DRV8353 gate driver. moteus r4.8 was the first version to use the DRV8353 because of, once again, component availability issues. However, it was developed on a very abbreviated schedule. With r4.11 the EMI is much improved over r4.8 and r4.5, and the efficiency is much better than r4.8 at all input voltages and PWM frequencies.
95% / 0.28W
94% / 0.20W
95% / 0.30W
92% / 0.25W
93% / 0.35W
88% / 0.25W
90% / 0.38W
85% / 0.30W
91% / 0.36W
84% / 0.30W
89% / 0.40W
84% / 0.35W
moteus r4.11 and r4.8 thermal efficiency and idle power driving nearly stationary motor
The matching development kit will be available shortly, once the r4.8 developer kits sell out.
Due to the ongoing semiconductor apocalypse, this minor release uses some alternate components which were easier to source. It remains compatible with the r4.5 and r4.3 both electrically, mechanically, and with firmware.
There are no top-level feature changes versus the previous r4.4. What is different is that the connector for the Raspberry Pi has reverted to the fixed height version that the r4.3 and earlier used, and the IMU is slightly better.
There are a lot of steps necessary to get a product to market, not just a fancy render. I admit to being far from covering all the bases yet, but we’re getting there. In that spirit, I recently upped the packaging game of the qdd100 with some custom boxes and foam inserts. Pick one up at mjbots.com!
It seems like all the posts I’m writing these days are for new products! Here’s the pi3hat r4.4:
There are two changes from the previous r4.2. First, it now supports voltage inputs up to 44V. Second, in support of future upgrades, the 5th CAN-FD port has been upgraded to support 8Mbps, but downgraded to no longer have a wide common mode voltage range.
THUS, IT IS NOT SAFE TO CONNECT THE CAN-FD PORT ON THE pi3hat r4.4 TO A power_dist r3.X BOARD.
That said, the worldwide electronic supply chain is still in shambles. That combined with the Chinese New Year means that stock may be intermittent, and slight alternate versions to adjust to different parts may be forthcoming.
This is a high quality 5208 sized 330Kv wound brushless motor with short pigtails intended to connect to moteus controllers. All the moteus devkits as of last week are shipping using this motor instead of the previous “semi-random” motor.
Peak torque: 1.7 Nm
Mass (with wires): 193g
Peak power: 600W
There are two bolt patterns on the output, a 3x M3 17mm diameter one, and a 2x M3 pattern spaced at 12mm. The stator side has a 4x M3 pattern spaced at 25mm radially and a 3x M2.5 spaced at 32mm. The axle protrudes a few mm from the stator, making it easy to adhere the diametric magnets needed for moteus.
The moteus controller is capable of a lot of instantaneous power. However, to fully make use of that power, you’ll need to keep the mosfets cool on the board. moteus has two mechanisms for that:
A heatsink can be mounted to the bottom side of the PCB between the board and the motor. This is most useful when integrated into a servo motor, and the servo housing can be used as a heatsink.
Mounted to the top of the board, attaching to the MOSFETS directly.
In addition to the MOSFETs, the gate driver chip, the DRV8323 can produce large amounts of heat, especially when the controller is run at a higher voltage, like the 44V that the moteus r4.5 supports.
Getting the heat out of all those irregularly spaced components on the top can be tricky, thus mjbots.com now has the moteus heat spreader:
This precision machined and stylish black anodized aluminum piece fits over the top of the PCB and mounts flush against both the MOSFETs and the DRV8323 to ensure optimal heat dissipation from all components. It can be used as-is, or with an additional heat sink fixed to the flat upper surface.