[uavcan] Fix unitless actuator range conversion

[niklaut]

Solved Problem

When attaching a UAVCAN servo, the output does not work.
The UAVCAN message that gets sent is uavcan.equipment.actuator.ArrayCommand, but all command_values are in the range [1, 3], while the COMMAND_TYPE_UNITLESS expects a range of [-1, +1].

Solution

The formula for conversion was wrong, the input is [1000, 2000] and should map to [-1, +1]. The subtraction was -1, instead of -3.

Changelog Entry

For release notes:

Bugfix: Fix UAVCAN actuator output conversion

Test coverage

• Tested in hardware

[MaEtUgR]

the input is [1000, 2000]

Where is that from? As I understand it, UAVCAN servos currently need to be configured in the Actuator tab with an output range of [0, 1000] because the input is of type uint16_t. We want to switch to float to support arbitrary units and negative values for reversible motors, simulations, UAVCAN, and non-PWM rover ESCs, .... Related PR: #21656

If you now change the input range for UAVCAN servos from [0, 1000] to [1000, 2000] then it would break all existing configurations for UAVCAN servos and users would need to adjust to it (FYI @TedObrien). I'd suggest to keep the current [0, 1000] input range and then when we finally support floats make it [-1, 1] directly instead of some temporary positive integer range.

Please correct me if I misunderstood.

[niklaut]

The issue was miscommunicated to me and this is not the solution and didn't help.