Robot Tank With Arm

I am now working on a project of a small robot - a tank with a hand manipulator.

Chassis - Chinese toy tank hand - 5 servo MG996R Driver chassis - Shield L298N Dual H Bridge DC. for servo motors.

From China im waiting parts: Shield 32 Channel Servo Control Board and Raspberry Pi Model B for robot control the first tests on the Arduino Uno, but very few contacts. Only 6 servo or tank chassis and 4 servos. since 6 PWM outputs