420 The mechanism testing and subsequent system- level testing had sequences and current profiles that could  not be predicted. The solution was to use a simplified thermal model on both the rover and control electrical  ground support equipment  (EGSE) , which was the same implementation used on the MER rovers. The  model is supplied with a case temperat ure from a platinum resistance thermometer ( PRT) and the current  telemetry feeds the Joule heating. The thermal protection watches for nodes and can shut down motion if  temperatures r ise above certain limits.  

Acceptance and Qualification Testing  

An acceptance test program was implemented to determine JPL acceptability of the M32 and M20 motors.  The acceptance testing centered on workmanship and functional performance of each unit , whereas a  qualification program subjects designated units to the gambit of JPL- margined dynamic and thermal  environments and life tests to verify that the design of units from the same production and manufacturing  lots would meet the mission requirements. Qualification was completed at the gearmotor level, with some  actuators further qualified at the mechanism  level. Portions of the M20 gearmotor qualification testing were  completed at maxon using their testing facilities, where feasible. The residual tests were completed at JPL  due to infrastructure availability as well as long -duration (life test) activities outside of the scope of maxon’s   contractual effort.  

All M32 FM units were subjected to the acceptance tests listed in Table 3 , with defined criteria when  appropriate.  No-load characterization was used as a functional check to confirm the specific motor was  performing as expected and within family for the M32 flight motors.  

Table 3. M32 motor acceptance tests  Notes: CW = clockwise; CCW = counter -clockwise  

The M20 motor was subjected to similar acceptance testing (Table 4)  prior to integrati on into the M20   gearmotor .  M32 Motor Acceptance Test  Test Conditions  Acceptance Criteria   Dielectric strength  500V AC, 60  Hz for 60 ±5 seconds  I < 1 mA  Insulation resistance (R) 500V DC, for 60 ±5 seconds  R > 100  MΩ  Electrical bonding  N/A R (flange to housing) < 25 mΩ  R (flange to shaft) < 100 Ω  Run-in 60 seconds CW and 60 seconds CCW  at 28V  N/A  Hall effect Integrated NonLinearity (INL)  sensor  Maxon defined test  <10°  INL (target <7.5° )   Natural cogging torque (T)  harmonic magnitude  CW and CCW over two revolutions, speed 2  rpm T = Detent Value (10 or 20 mN•m) ± 10%  Powered torque ripple plot  Powered in direction of motion, powered opposite  direction of motion  N/A (characterization only) , validates torque  is produced at all rotor positions   Load  12V/20V/28V, CW and CCW, ambient temperature  Motor torque constant = 50 mN •m/A ± 10%   Start -up sensitivity  CW only, 22°C /+70°C  /-70°C   N/A (characterization only)   No load  28V, CW only, 22°C /+70°C  /-70°C  /22°C  N/A (characterization only)   “Launch” random vibration   Frequency (Hz)  Protoflight/Design  Verification (Qual/PF)  Test Level   20 0.15 g2/Hz  30–90 0.5 g2/Hz  166–450 0.08 g2/Hz  2,000  0.0040 g2/Hz  Grms 10  (in all 3 axes, 1 min each)  N/A (exposure only)